Novel Cancer Therapies Aim to Destroy the Disease at Its Root: The Cancer Stem Cell
Novel Cancer Therapies Aim to Destroy the Disease at Its Root: The Cancer Stem Cell
The Pink Sheet Daily. 2009 Apr 28, S Haley
Among the therapies showcased at the recent American Association for Cancer Research meeting in Denver were a growing number aimed at attacking cancer from a new or at least a different angle, through the specialized tumor cells known as cancer stem cells.
Cancer stem cells, the very aggressive cancer cells believed responsible for tumor metastases, are not stem cells in the way embryonic stem cells have captured the scientific imagination, but they are a very small, defined population of cancer cells than can go forth and generate a new tumor. And there's a good chance that if their migration in the body can be stopped, cancers can be made more susceptible to chemotherapy and tumors eliminated entirely, with no nasty surprises years down the road. When a tumor cell divides it creates one new cancer stem cell, which goes into a resting state, and progeny cells, which become the mass of the tumor. It is these resting cells that are thought to be responsible for not only metastasis but also chemoresistance. They have a very low proliferation rate - so antiproliferatives don't reach them entirely - they overexpress paths that carry drugs out of the cell, and they have more detoxifying enzymes than other tumor cells, Patrick A. Baeuerle, chief scientific officer at Micromet, a company working in the space, explained at the firm's R&D day April 24.
In fact, Baeuerle said, "there is good evidence" that chemotherapy actually enriches the environment for cancer stem cells. When the other cancer cells are eliminated, there are more stem cells to "very rapidly repopulate the tumor." Micromet harnessing immune system with BiTE antibodies
Micromet's BiTE antibody MT110 can successfully direct the immune system's T-cells to eliminate human colorectal cancer stem cells in cell culture and in animal models, the company reported at AACR.
At the R&D day, Baeuerle explained the significance of MT110's efficacy "in a dish and in a mouse." Eradicating 100 percent of the cells is important because as few as 100 stem cells left in the body after treatment can give rise to a new tumor later on, he said. In both the Petri dish and mouse model, MT100 yielded complete inhibition - meaning there was no further colonization in culture and no tumor growth in the animals.
Using its bispecific T-cell engager (BiTE) technology, the biotech engineered an antibody able to tether resting T-cells to tumor cells, then deliver a cytotoxic payload. MT110 is specific for epithelial cell adhesion molecule (Ep-CAM), a target antigen highly expressed on the surface of cancer stem cells from a variety of tumor types. The biologic is in a Phase I dose-escalating clinical trial in patients with lung or gastrointestinal cancer. Geron going after telomerase inhibition with imetelstat
Another company working in the cancer stem cell space, Geron, gave five presentations at AACR involving its telomerase inhibitor imetelstat (GRN 163L). It is being studied against cancer stem cells from non-small cell lung, breast, pancreatic, prostate and pediatric neural tumors. Imetelstat is a short chain oligonucleotide with a high affinity and specificity to the telomerase site, thus inhibiting enzyme activity.
Imetelstat currently is in six clinical dose-ranging/safety trials. The drug is being tried in combination with standard of care carboplatin and paclitaxel in a Phase I/II trial testing it against non-small cell lung cancer. Preclinical data shared at AACR showed that continued treatment of NSCLC cell lines with imetelstat induced progressive decreases in telomere length, resulting in cell death. Treatment over several months resulted in "a dramatic decrease" in colonies in culture, investigators said. In addition, they noted "marked" changes in the number of genes associated with stem cell proliferation. Together, the results mean imetelstat will have to be administered over a sustained period and that the cancer stem cells responsible for NSCLC proliferation were indeed targeted by the drug, investigators said.
Geron also presented preclinical data against four human prostate cancer cell lines, in which tumors express high levels of telomerase activity, suggesting clinical trials could produce a positive result in that cancer. Telomerase is absent or expressed occasionally and only at low levels in normal adult tissue. In another presentation of research, in pediatric neural tumors, including neuroblastoma, preclinical data show telomerase is only active in the tumor's stem cells and that treatment resulted in inhibition of telomerase, loss of replicative potential, and cell aging. In addition, cells pre-treated with imetelstat appeared more susceptible to radiation.
Geron, in Menlo Park, Calif., is best known as the stalwart company that continued its research with human embryonic stem cells during the Bush administration ban on federally funded investigations in that area, a complication that hindered the ability of university researchers to participate in studies of Geron candidates.
In January, FDA lifted a clinical hold on Geron's regenerative stem cell therapy OPC1, allowing Geron to proceed with human trials in spinal cord injury. Biotechs not alone: big pharma pursuing cancer stem cells, too
Big pharmas also have been edging into the cancer stem cell space, as the increasing emphasis on oncology portfolios increases demand for novel approaches.
In 2007 Sanofi-Aventis formed a collaboration with Chinese researchers at the Tianjin Institute of Hematology and Blood Diseases Hospital. That same year, GlaxoSmithKline and Redwood City, Calif.-based OncoMed formed a back-end loaded relationship worth up to $1.4 billion for the biotech if the cancer stem cell bet pays off. Then in 2008, Roche paid $190 million in cash to take over Canadian antibody company Arius Research and gain control of its cancer stem cell program.
That leaves plenty of big pharma firms focused on oncology that could be interested in the programs from Micromet and Geron.
5. May 2009 19:09Hoping to develop more effective long-term attacks on cancer, researchers at the Indiana University School of Medicine are conducting the first human tests of a breast cancer drug regimen that includes a compound meant to force cancer cells to grow old and die.
The early stage clinical tests are an attempt to block a mechanism cancer cells use to avoid the aging process that affects most normal cells. If successful, the new therapy could enhance the effects of other cancer treatments.
"This is really a completely different way of trying to tackle the problem that hasn't been tested in the clinic before," said Kathy Miller, M.D., associate professor of medicine and Sheila D. Ward Scholar at the IU School of Medicine and medical oncologist at the Indiana University Melvin and Bren Simon Cancer Center.
The clinical test is a good example of how positive results in basic science experiments can push a promising compound from the laboratory to the bedside - a process known as "translational research."
The new approach is based on research into telomeres, the caps that protect the ends of the 46 chromosomes in each cell that contain our genetic information. The telomeres, which some compare to the tips of shoelaces, help prevent genomic instability. Each time a cell divides, the telomeres shorten. When they become too short, losing their protective ability, it's a signal to the cell to die, or to go into a state of permanently arrested growth called senescence.
Telomeres in cancer cells generally are shorter than those in normal cells. That offers a tempting target, except that cancer cells know a trick. Cancer cells produce an enzyme called telomerase, which provides maintenance services on the telomeres, preventing them from reaching the critically short stage that would set off the cell death signal.
So, researchers have figured, if you could block cancer cells from producing telomerase, you could make them easier to kill. But how to do that? Several approaches seemed possible, including one that Brittney-Shea Herbert, Ph.D., then a post-doctoral researcher, was working on 10 years ago at the University of Texas Southwest in Dallas. Her approach: Find a special type of chemical compound, called an oligonucleotide, that would block access to telomerase and prevent it from doing its job. She began working with a new compound, with the chemical name GRN163L, that had been developed by Geron Corp. of Menlo Park, Calif.
Dr. Herbert has continued to work with GRN163L - now called imetelstat sodium - in the laboratory since coming in 2003 to the IU School of Medicine, where she is an assistant professor of medical and molecular genetics. She has published work showing that imetelstat disrupts telomere maintenance, in the process suppressing both tumor growth and metastasis - the appearance of tumors in other tissues. Another study found that telomere damage in breast cancer cells treated with the compound caused the cells to be more susceptible to radiation treatment. Furthermore, she has shown that imetelstat can restore the sensitivity of Herceptin-resistant breast cancer cell lines in the laboratory.
"What's interesting about GRN163L is that it can get into almost any cancer cell type, including drug resistant cancer cells. That's been a problem: A lot of agents cannot be taken up into drug resistant cells. This telomerase inhibitor can be taken up in any cell type - you can target those cells. So that's why we hope this will be great for reducing recurrence and metastasis," said Dr. Herbert.
Such results have made imetelstat an attractive compound to test in conjunction with other anti-cancer drugs, which is what brought Drs. Miller and Herbert together. They are testing imetelstat with the drugs Taxol and Avastin, initially to determine the appropriate dose of imetelstat, test whether the three drugs are safe to give in combination, and to determine whether there are side effects that must be dealt with.
Assuming the first phase goes well a second phase of testing will begin more formal evaluation of how well the combination therapy works.
Dr. Miller's research has shown that Taxol and Avastin are more effective in combination than Taxol alone, shrinking tumors in about twice as many women and providing such benefits more than twice as long. The therapy doesn't cure metastatic disease, though. Eventually the tumors become resistant to the drugs and other treatments are necessary. If, as expected, imetelstat doesn't raise side effects issues, and "if it makes the cells more sensitive to the effects of the Taxol and Avastin, and allows the benefits of that therapy to continue for a much longer period of time, that would be a big benefit for those ladies with metastatic disease. It would also then give us the support for looking at this agent even earlier in the course of disease," said Dr. Miller.
Dr. Herbert's research indicated that imetelstat can reduce metastatic spread of cancer, though it's not yet clear what the mechanism is. But, as Dr. Miller points out, for patients that will be a distinction with little difference.
"Whether it actually prevents the cells from spreading or they spread but can't grow to make clinically apparent tumors we don't know, but I can tell you my patients don't care," she said. http://www.iupui.edu
Hum Pathol.. [Epub ahead of print] Reduction of CD44(+)/CD24(-) breast cancer cells by conventional cytotoxic chemotherapy.
Aulmann S, Waldburger N, Penzel R, Andrulis M, Schirmacher P, Sinn HP.
Institute of Pathology, Heidelberg University, 69120 Heidelberg, Germany.
Breast cancer cells with the CD44(+)/CD24(-) phenotype have been associated with stem cell properties. To analyze effects of cytotoxic chemotherapy on these cells, we examined a series of 50 breast carcinomas before and after neoadjuvant chemotherapy with epirubicin/cyclophosphamide using double immunofluorescence. Before treatment, an average of 4.4% of the tumor cells displayed a CD44(+)/CD24(-) phenotype. However, after chemotherapy, the frequency of CD44(+)/CD24(-) cells dropped to 2% (P = .008). To test this unexpected finding, we analyzed a second collective of 16 patients that preoperatively had received either 4 cycles of doxorubicin/pemetrexed, followed by 4 cycles of docetaxel or 4 cycles of doxorubicin/cyclophosphamide, followed by 4 cycles of docetaxel with similar results (8.7% CD44(+)/CD24(-) cells on average before and 1.1% after chemotherapy). In addition, no association was observed between the frequency of CD44(+)/CD24(-) cells and the response to chemotherapy or patient survival. However, patients with tumors containing high numbers of CD44(+)/CD24(-) cells more frequently developed bone metastases in the course of disease. In conclusion, our findings challenge the proposed role of CD44(+)/CD24(-) cells as cancer stem cells in tumor resistance to chemotherapy as they apparently are not selected by conventional cytotoxic agents.
PMID: 20004947 [PubMed - as supplied by publisher]
Int J Cancer. 2009 Nov 11. [Epub ahead of print] The effects of telomerase inhibition on Prostate tumor-initiating cells.
Marian CO, Wright WE, Shay JW.
University of Texas Southwestern Medical Center, Department of Cell Biology, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9039.
Prostate cancer is the most lethal malignancy in men and the patients with metastatic disease have poor outcome even with the most advanced therapeutic approaches. Most cancer therapies target the bulk tumor cells, but may leave intact a small population of tumor-initiating cells (TICs), which are believed to be responsible for the subsequent relapse and metastasis. Using specific surface markers (CD44, integrin alpha(2)beta(1) and CD133), Hoechst 33342 dye exclusion, and holoclone formation, we isolated TICs from a panel of prostate cancer cell lines (DU145, C4-2 and LNCaP). We have found that prostate TICs have significant telomerase activity which is inhibited by imetelstat sodium (GRN163L), a new telomerase antagonist that is currently in Phase I/II clinical trials for several hematological and solid tumor malignancies. Prostate TICs telomeres were of similar average length to the telomeres of the main population of cells and significant telomere shortening was detected in prostate TICs as a result of imetelstat treatment. These findings suggest that telomerase inhibition therapy may be able to efficiently target the prostate TICs in addition to the bulk tumor cells, providing new opportunities for combination therapies. (c) 2009 UICC.
PMID: 19908230 [PubMed - as supplied by publisher]
The drug's actions, observed in isolated human cells in one trial and in rodents in the other, are especially encouraging because they attacked not only the bulk of the tumor cells but also the rare cancer stem cells that are believed to be responsible for most of a cancer's growth, said Jerry Shay, professor of cell biology and a senior co-author of both papers.
Quote:
In the glioblastoma study, performed in mice, the drug also crossed from the bloodstream into the brain, which is especially important because many drugs are not able to cross the blood-brain barrier. "Because it attacks a mechanism that's active in most cancers, it might prove to be widely useful, especially when combined with other therapies," said Shay.
Shay and his colleagues study telomeres, bits of DNA that help control how many times a cell divides. Telomeres are protective "caps" of DNA on the ends of chromosomes, the structures that contain the body's genes. As long as telomeres are longer than a certain minimum length, a cell can keep dividing. But telomeres shorten with each cell division, so a cell stops dividing once thetelomeres are whittled down to that minimum.
In cancer cells, however, an enzyme called telomerase keeps rebuilding the telomeres, so the cell never receives the cue to stop dividing. In essence, they become immortal, dividing endlessly.
The drug used in these studies (imetelstat or GRN163L) blocks telomerase. It is already in clinical trials as a potential treatment for breast and lung cancer, as well as for chronic lymphocytic leukemia.
Herbal complex suppresses telomerase activity in chemo-endocrine resistant cancer cell lines.
Lian Z, Fujimoto J, Yokoyama Y, Niwa K, Tamaya T.
Department of Obstetrics and Gynecology, Gifu University School of Medicine, Gifu City, Japan.
A herbal complex consisting of Hoelen, Angelicae radix, Scutellariae radix and Glycyrrhizae radix suppressed cell viability and telomerase activity in hormone-refractory and chemo-resistant cancer cell lines, namely poorly differentiated uterine endometrial cancer cell line AN3 CA, adriamycin-resistant breast cancer cell line MCF7/ADR and cisplatin-resistant ovarian cancer cell line A2780. Furthermore, the herbal complex suppressed the expression of the full length of human telomerase reverse transcriptase (hTERT), which is related to telomerase activity. This indicates that the herbal complex can suppress the tumor growth of chemoendocrine resistant cancers, at least in part via suppression of telomerase activity associated with down-regulated hTERT.
PMID: 11766737
Scientists at the University of Michigan Comprehensive Cancer Center have uncovered an important link between inflammation and breast cancer stem cells that suggests a new way to target cells that are resistant to current treatments.
Quote:
"Developing treatments to effectively target the cancer stem cell population is essential for improving outcomes. This work suggests a new strategy to target cancer stem cells that can be readily translated into the clinic," says senior study author Max S. Wicha, M.D., Distinguished Professor of Oncology and director of the U-M Comprehensive Cancer Center. Wicha was part of the team that first identified stem cells in breast cancer.
Results of the current study appear online Jan. 4 in the Journal of Clinical Investigation and will appear in the journal's February print issue.
CXCR1 is a receptor for Interleukin-8, or IL-8, a protein produced during chronic inflammation and tissue injury. When tumors are exposed to chemotherapy, the dying cells produce IL-8, which stimulates cancer stem cells to replicate. Addition of the drug repertaxin to chemotherapy specifically targets and kills breast cancer stem cells by blocking CXCR1.
Mice treated with repertaxin or the combination of repertaxin and chemotherapy had dramatically fewer cancer stem cells than those treated with chemotherapy alone. In addition, repertaxin-treated mice developed significantly fewer metastases than mice treated with chemotherapy alone. "These studies suggest that important links between inflammation, tissue damage and breast cancer may be mediated by cancer stem cells. Furthermore, anti-inflammatory drugs such as repertaxin may provide a means of blocking these interactions, thereby targeting breast cancerstem cells," Wicha says.
Repertaxin has been tested in early phase clinical trials to prevent rejection after organ transplantation. In these studies, side effects seem to be minimal. There are no reports of using repertaxin to treat cancer.
More information: Journal of Clinical Investigation, Vol. 120, No. 2, February 2010; doi:10.1172/JCI39397
Other available Interleukin-8 inhibitors:
Thymiquone from Nigella Sativa or black cumin
(used in Indian spice Charnushka)
Herbal extract inhibits pancreatic cancer development LINKABSTRACT
April 20th, 2009
Dr. Arafat said that Nigella sativa seeds and oil, used in traditional medicine by many Middle Eastern and Asian countries, helps treat a broad array of diseases, including some immune and inflammatory disorders.
Previous studies have also shown it to have anti-cancer effects on prostate and colon cancers.
Based upon their previously published findings that thymoquinone inhibits histone deacetylases (HDACs), Dr. Arafat and her colleagues compared the anti-inflammatory properties of thymoquinone and trichostatin A, an HDAC inhibitor that has previously shown to ameliorate inflammation-associated cancers.
The researchers used pancreatic ductal adenocarcinoma (PDA) cells, some of which were pretreated with the cytokine TNF-alpha to induce inflammation. Thymoquinone almost completely abolished the expression of several inflammatory cytokines, including TNF-alpha, interleukin-1beta, interleukin-8, Cox-2 and MCP-1, an effect that was more superior to the effect of trichostatin A. The herb also inhibited the activation and synthesis of NF-kappaB, a transcription factor that has been implicated in inflammation-associated cancer.
Activation of NF-kappaB has been observed in pancreatic cancer and may be a factor in pancreatic cancer’s resistance to chemotherapeutic agents. When animal models of pancreatic cancer were treated with thymoquinone, 67 percent of the tumours were significantly shrunken, and the levels of proinflammatory cytokines in the tumours were significantly reduced.
Cancer Res. 2009 Jul 1;69(13):5575-83. Epub 2009 Jun 23. Antitumor activity of gemcitabine and oxaliplatin is augmented by thymoquinone in pancreatic cancer.
Banerjee S, Kaseb AO, Wang Z, Kong D, Mohammad M, Padhye S, Sarkar FH, Mohammad RM.
Department of Pathology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, USA.
Previous studies have shown biological activity of thymoquinone, an active compound extracted from Nigella sativa, in pancreatic cancer cells; however, preclinical animal studies are lacking. Here, we report, for the first time, the chemosensitizing effect of thymoquinone to conventional chemotherapeutic agents both in vitro and in vivo using an orthotopic model of pancreatic cancer. In vitro studies revealed that preexposure of cells with thymoquinone (25 mumol/L) for 48 h followed by gemcitabine or oxaliplatin resulted in 60% to 80% growth inhibition compared with 15% to 25% when gemcitabine or oxaliplatin was used alone. Moreover, we found that thymoquinone could potentiate the killing of pancreatic cancer cells induced by chemotherapeutic agents by down-regulation of nuclear factor-kappaB (NF-kappaB), Bcl-2 family, and NF-kappaB-dependent antiapoptotic genes (X-linked inhibitors of apoptosis, survivin, and cyclooxygenase-2). As shown previously by our laboratory, NF-kappaB gets activated on exposure of pancreatic cancer cells to conventional chemotherapeutic agents; interestingly, thymoquinone was able to down-regulate NF-kappaB in vitro, resulting in chemosensitization. In addition to in vitro results, here we show for the first time, that thymoquinone in combination with gemcitabine and/or oxaliplatin is much more effective as an antitumor agent compared with either agent alone. Most importantly, our data also showed that a specific target, such as NF-kappaB, was inactivated in animal tumors pretreated with thymoquinone followed by gemcitabine and/or oxaliplatin. These results provide strong in vivo molecular evidence in support of our hypothesis that thymoquinone could abrogate gemcitabine- or oxaliplatin-induced activation of NF-kappaB, resulting in the chemosensitization of pancreatic tumors to conventional therapeutics.
Subcutaneous injection or oral administration of parthenolide showed significant tumor growth inhibition in the xenograft model via decreased production of interleukin-8 (IL-8) or vascular endothelial growth factor (VEGF). Immunohistochemistry and Western blot analysis showed decreased nuclear localization of NF-KB and phosphorylated NF-KB protein and subsequently expression of MMP-9, Bcl-xL and Cox-2 in response to parthenolide treatment.
J Clin Endocrinol Metab. 2007 Aug;92(8):3213-8. Epub 2007 May 15. Metformin suppresses interleukin (IL)-1beta-induced IL-8 production, aromatase activation, and proliferation of endometriotic stromal cells.
Takemura Y, Osuga Y, Yoshino O, Hasegawa A, Hirata T, Hirota Y, Nose E, Morimoto C, Harada M, Koga K, Tajima T, Yano T, Taketani Y.
Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
CONTEXT: Metformin, a widely used treatment for diabetes that improves insulin sensitivity, also has both antiinflammatory properties and a modulatory effect on ovarian steroid production, two actions that have been suggested to be efficacious in therapy for endometriosis. OBJECTIVE: To determine whether metformin may be effective for the treatment of endometriosis, we evaluated the effects of this agent on inflammatory response, estradiol production, and proliferation of endometriotic stromal cells (ESCs). DESIGN: ESCs derived from ovarian endometriomas were cultured with various concentrations of metformin. MAIN OUTCOME MEASURES: IL-8 production, mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs were measured. RESULTS: Metformin dose-dependently suppressed IL-1beta-induced IL-8 production, cAMP-induced mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs. CONCLUSION: These results suggest that further investigation into the unique therapeutic potential of metformin as an antiendometriotic drug is warranted.
PMID: 17504902 [PubMed - indexed for MEDLINE]
Arterioscler Thromb Vasc Biol. 2006 Mar;26(3):611-7. Epub 2005 Dec 29. Metformin inhibits proinflammatory responses and nuclear factor-kappaB in human vascular wall cells.
Isoda K, Young JL, Zirlik A, MacFarlane LA, Tsuboi N, Gerdes N, Schönbeck U, Libby P.
Donald W. Reynolds Cardiovascular Clinical Research Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
OBJECTIVE: Metformin may benefit the macrovascular complications of diabetes independently of its conventional hypoglycemic effects. Accumulating evidence suggests that inflammatory processes participate in type 2 diabetes and its atherothrombotic manifestations. Therefore, this study examined the potential action of metformin as an inhibitor of pro-inflammatory responses in human vascular smooth muscle cells (SMCs), macrophages (Mphis), and endothelial cells (ECs). METHODS AND RESULTS: Metformin dose-dependently inhibited IL-1beta-induced release of the pro-inflammatory cytokines IL-6 and IL-8 in ECs, SMCs, and Mphis. Investigation of potential signaling pathways demonstrated that metformin diminished IL-1beta-induced activation and nuclear translocation of nuclear factor-kappa B (NF-kappaB) in SMCs. Furthermore, metformin suppressed IL-1beta-induced activation of the pro-inflammatory phosphokinases Akt, p38, and Erk, but did not affect PI3 kinase (PI3K) activity. To address the significance of the anti-inflammatory effects of a therapeutically relevant plasma concentration of metformin (20 micromol/L), we conducted experiments in ECs treated with high glucose. Pretreatment with metformin also decreased phosphorylation of Akt and protein kinase C (PKC) in ECs under these conditions. CONCLUSIONS: These data suggest that metformin can exert a direct vascular anti-inflammatory effect by inhibiting NF-kappaB through blockade of the PI3K-Akt pathway. The novel anti-inflammatory actions of metformin may explain in part the apparent clinical reduction by metformin of cardiovascular events not fully attributable to its hypoglycemic action.
Xie K.
Department of Gastrointestinal Medical Oncology and Cancer Biology, M.D. Anderson Cancer Center, The University of Texas, Box 78, 1515 Holcombe Boulevard, Houston, TX 77030, USA. kepxie@mail.mdanderson.org
The aggressive nature of metastatic human cancer has been shown to be related to numerous abnormalities in growth factors and their receptors. These perturbations confer a tremendous growth advantage to the malignant cells. Interleukin-8 (IL-8), originally discovered as a chemotactic factor for leukocytes, has recently been shown to contribute to human cancer progression through its potential functions as a mitogenic, angiogenic, and motogenic factor. While it is constitutively detected in human cancer tissues and established cell lines, IL-8 expression is regulated by various tumor microenvironment factors, such as hypoxia, acidosis, nitric oxide, and cell density. Understanding the mechanisms of both inducible and constitutive IL-8 expression will be helpful in designing potential therapeutic strategies of targeting IL-8 to control tumor growth and metastasis. In this review, the role and regulation of IL-8 expression in the growth and metastasis of human cancer with a focus on human pancreatic adenocarcinoma will be discussed.
Telomerase, inflammation/IL-8....let's keep adding to the list of cancer stem cell strategies.
Hmmm..
However it does it, Milk thistle seems to reduce a proposed cancer stem cell marker:
Am J Transl Res. 2009 Jan 1;1(1):80-6. Silibinin suppresses CD44 expression in prostate cancer cells.
Handorean AM, Yang K, Robbins EW, Flaig TW, Iczkowski KA. Prostate cancer (PCa), like most human cancers, features dysregulated CD44 expression. Expression of CD44 standard (CD44s), present in benign epithelium, is lost in PCa while pro-invasive splice variant isoform CD44v7-10 is overexpressed. The role of CD44 in silibinin's anti-growth effects was uncertain. To assess silibinin's effects on CD44 promoter activity, PC-3M PCa cells were transfected with luciferase-CD44 promoter construct 24 h prior to 25-200 muM silibinin treatment for 48 h. Also, cells' expression of CD44 RNA (by qRT-PCR) and protein (Western blot analysis) was studied. Silibinin was further tested preoperatively on a pilot cohort of 6 men with PCa compared with 7 matched placebo-treated men, with immunostaining for CD44v7-10 in their prostates. In PC-3M cells, silibinin dose-dependently inhibited CD44 promoter activity up to 87%, caused a 90% inhibition of total CD44 and 70% decrease in CD44v7-10 RNA, and at the protein level, decreased total CD44 at 100-200 muM dose and decreased CD44v7-10 after 3 days. Silibinin decreased adhesion to hyaluronan and fibronectin. Silibinin at 100-200 muM inhibited Egr-1, a regulator of CD44 promoter activity. Men treated with silibinin did not differ in tissue CD44v7-10 expression. In conclusion, CD44 inhibition is one mechanism by which silibinin reduces PCa tumorigenicity.
PMID: 19966941 [PubMed - in process]
Proc Natl Acad Sci U S A. 2010 Feb 3. [Epub ahead of print] Selective targeting of radiation-resistant tumor-initiating cells.
Zhang M, Atkinson RL, Rosen JM.
Department of Molecular and Cellular Biology and Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030-3498. Tumor-initiating cells (TICs) have been shown both experimentally and clinically to be resistant to radiation and chemotherapy, potentially resulting in residual disease that can lead to recurrence. In this study, we demonstrate that TICs isolated from p53 null mouse mammary tumors repair DNA damage following in vivo ionizing radiation more efficiently than the bulk of the tumor cells. Down-regulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was observed both in fluorescence activated cell sorting (FACS)-isolated TICs as compared to non-TICs and in TIC-enriched mammospheres as compared to primary tumor cells depleted of TICs. This effect was accompanied by increased Akt signaling, as well as by the direct activation of the canonical Wnt/beta-catenin signaling pathway specifically within the TIC subpopulation by phosphorylation of beta-catenin on serine 552. Using limiting dilution transplantation performed on p53 null tumor cells transduced with Wnt reporter lentivirus, we demonstrated that FACS sorting of cells expressing TOP-eGFP resulted in a marked enrichment for TICs. Furthermore, FACS analysis demonstrated that cells with active Wnt signaling overlapped with the TIC subpopulation characterized previously using cell surface markers. Finally, pharmacological inhibition of the Akt pathway in both mammospheres and syngeneic mice bearing tumors was shown to inhibit canonical Wnt signaling as well as the repair of DNA damage selectively in TICs, sensitizing them to ionizing radiation treatment. Thus, these results suggest that pretreatment with Akt inhibitors before ionizing radiation treatment may be of potential therapeutic benefit to patients.
PMID: 20133717 [PubMed - as supplied by publisher]
Oncolytics Biotech is directing a broad clinical trial program with the objective of developing REOLYSIN® as a human cancer therapeutic. The current clinical program includes human trials using REOLYSIN® alone and in combination with chemotherapy or immune modulation, and delivered via local administration and/or intravenous administration. The Company's first pivotal trial will be a Phase III randomized clinical trial examining the intravenous administration of REOLYSIN® in combination with paclitaxel and carboplatin in patients with platinum-failed head and neck cancers.
Clinical Trial Chart
Click on clinical trial for more detailed information
Trial Name
Delivery Method
Trial Program
and Cancer Indication
Location
Status
REO 016
Intravenous administration in combination with paclitaxel and carboplatin
"We're working on a product that is widely applicable to quite a few indications of cancer and is based on a naturally occurring virus that's commonly found in the environment and that happens to have a preference of growing in cancer cells as opposed to growing in normal tissue."
It's called a reovirus (short for Respiratory Enteric Orphan virus), and it's a type which most people pick up by age 12 through inhalation or contact that causes few or no health problems. But when the virus enters cancer cells, it kills them.
On-Off Switch
Viruses, naturally, prefer cells that can't fight them off. And these cancer cells all have a common characteristic: They have a certain growth pathway, called the Ras pathway, turned on. "If a cell doesn't have that pathway turned on, nothing happens, so it's like an on-off switch for the virus's growth," Thompson explained. In the human body, very few normal cells have that Ras pathway turned on, and those die in the same amount of time the virus takes to kill them, so the body is not affected. "And that's where the story would end if only these few cells had the Ras pathway turned on all the time," Thompson added. "But it happens to be the state in most cancers."
"When the Ras pathway is turned on, it turns off the virus defense mechanism in the cell so the virus can go in and replicate itself," Thompson continued. It keeps replicating until its host -- the cancer cell -- is overwhelmed and dies, which happens within three days. "Anywhere between two-thirds to 75% of the primary carcinomas -- ovarian, prostate, non-small cell lung cancer and so on -- actually have that pathway turned on," Thompson said. "In metastatic disease, which spreads beyond the primary tumor, it's between 95% to 100% that have the Ras pathway. So you have a disease that has this pathway, and a virus that for other reasons requires that pathway to grow."
Infecting the Cancer
That's where Oncolytics and its drug, Reolysin, come in play. Reolysin is "a variant of the virus we found in nature," explained Thompson. The treatment "is rather straightforward," he said. It involves five days of intravenous injections, and the side effects are few: Most commonly, patients run a small fever and feel a little tired.
Once the virus has killed the cancer cells, "the body actually clears the virus pretty effectively," Thompson explained, because the body mounts a normal immune response to the infection. "Normally, the latest we ever find the virus in the body is a couple of weeks after the first injection, and then it's completely gone," he says.
Thompson lost his mother and an uncle to cancer, and himself got melanoma. "Right after that, while the surgery was still healing in my leg, I got a call from a colleague of mine in the Alberta government asking me whether I would talk to this group of researchers at the University of Calgary who were working on a virus. I had very heightened sensitivity to cancer at that time and had expertise in the area. So I got a close look at it, and that's how I got involved in it."
"That's how Oncolytics started," he added. "In less than a year, we went public, cross-listed and did six financings."
Phase 3 Clinical Trial
The company has completed about a dozen early-phase clinical trials so far, and has seven to eight ongoing for a broad range of cancers, including melanoma, lung and ovarian. But the real test will be the upcoming Phase 3 clinical trial for head and neck cancer.
The study is designed to combine Reolysin with the standard chemotherapy care for head and neck. In earlier studies, the response rate to the treatment was 42% when Reolysin was added to common therapy, much higher than the average 10% response rate for the disease.
If that response rate holds up, no doubt patients would be eager for the drug to reach the market. "We could be selling product by 2012, if everything lines up properly," said Thompson. "The sad part about head and neck patients is that you know very quickly whether your product works on them or not. The patients we're looking at have a median life expectancy of 4.5 months, so you don't have to wait much to know whether your product had benefit for the patients."
1: Mol Ther. 2009 Jun;17(6):972-9. Epub 2009 Mar 17. Links
Oncolytic reovirus effectively targets breast cancer stem cells.
Marcato P, Dean CA, Giacomantonio CA, Lee PW.
Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Recent evidence suggests that cancer stem cells (CSCs) play an important role in cancer, as these cells possess enhanced tumor-forming capabilities and are resistant to current anticancer therapies. Hence, novel cancer therapies will need to be tested for both tumor regression and CSC targeting. Herein we show that oncolytic reovirus that induces regression of human breast cancer primary tumor samples xenografted in immunocompromised mice also effectively targets and kills CSCs in these tumors. CSCs were identified based on CD24(-)CD44(+) cell surface expression and overexpression of aldehyde dehydrogenase. Upon reovirus treatment, the CSC population was reduced at the same rate as non-CSCs within the tumor. Immunofluorescence of breast tumor tissue samples from the reovirus- and mock-treated mice confirmed that both CSCs and non-CSCs were infectible by reovirus, and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay showed that both populations died by apoptosis. Ras, which has been shown to mediate reovirus oncolysis, was found to be present at similar levels in all cell types, and this is consistent with their comparable sensitivity to reovirus. These experiments indicate that oncolytic reovirus has the potential to induce tumor regression in breast cancer patients. More important, the CSC population was equally reduced and was as susceptible to reovirus treatment as the non-CSC population.
PMID: 19293772 [PubMed - indexed for MEDLINE]
Synergistic antitumor activity of oncolytic reovirus and chemotherapeutic agents in non-small cell lung cancer cells
Reovirus type 3 Dearing strain (ReoT3D) has an inherent propensity to preferentially infect and destroy cancer cells. The oncolytic activity of ReoT3D as a single agent has been demonstrated in vitro and in vivo against various cancers, including colon, pancreatic, ovarian and breast cancers.
Its human safety and potential efficacy are currently investigated in early clinical trials. In this study, we investigated the in vitro combination effects of ReoT3D and chemotherapeutic agents against human non-small cell lung cancer (NSCLC).
Results: ReoT3D alone exerted significant cytolytic activity in 7 of 9 NSCLC cell lines examined, with 50% effective dose, defined as the initial virus dose to achieve 50% cell killing after 48 hours of infection, ranging from 1.46 +/- 0.12 ~ 2.68 +/- 0.25 (mean +/- SD) log10 pfu/cell.
Chou-Talalay analysis of the combination of ReoT3D with cisplatin, gemcitabine, or vinblastine demonstrated strong synergistic effects on cell killing, but only in cell lines that were sensitive to these compounds. In contrast, the combination of ReoT3D and paclitaxel was invariably synergistic in all cell lines tested, regardless of their levels of sensitivity to either agent.
Treatment of NSCLC cell lines with the ReoT3D-paclitaxel combination resulted in increased poly (ADP-ribose) polymerase cleavage and caspase activity compared to single therapy, indicating enhanced apoptosis induction in dually treated NSCLC cells. NSCLC cells treated with the ReoT3D-paclitaxel combination showed increased proportions of mitotic and apoptoticcells, and a more pronounced level of caspase-3 activation was demonstrated in mitotically arrested cells.
Conclusions: These data suggest that the oncolytic activity of ReoT3D can be potentiated by taxanes and other chemotherapeutic agents, and that the ReoT3D-taxane combination most effectively achieves synergy through accelerated apoptosis triggered by prolonged mitotic arrest.
Oncolytics shares soar on cancer treatment trial news
Financial Post Published: Friday, October 02, 2009
OTTAWA - Shares of Calgary-based Oncolytics Biotech Inc. shot up Friday after the company announced it had reached an agreement with the U.S. Food and Drug Administration for the design of a Phase 3 trial involving its Reolysin cancer treatment.
"Oncolytics (ONC/TSX) is the first company to reach an agreement with the FDA on a Phase 3 trial design for an intravenously administered oncolytic virus under the SPA (special protocol assessment) process," Brad Thompson, chief executive of Oncolytics, said in a statement.
"This is an exciting step forward for our clinical program."
Shares of the Calgary-based firm rose as high as $4.10 in early morning trading in Toronto stock exchange, settling back to $3.70 by mid-afternoon.
The company said it will work with the FDA to develop trials to examine the effectiveness of its Reolysin treatment in combination with paclitaxel and carboplatin in patients with head and neck cancers, versus chemotherapy alone.
The main goal of the trial is to establish overall patient survival while secondary endpoints include response rates and safety and tolerability of Reolysin when used in combination.
The company said in a statement the study could eventually support a licence application submission for Reolysin, a virus that targets mostly solid-tumour cancers that have a tendency to spread, or metastasize, such as in head and neck tumours.
In previous tests, "the treatment combination has increased the response rate several fold compared to historical outcomes," the company said.
11/10/09
Excitement is growing among Canadian scientists that certain viruses might be used to shrink or even destroy cancer cells, a leading authority in cancer research told a Sarnia audience Monday. "We're seeing dramatic results. This is one of those times to stay tuned, folks. We're really, really excited," said Michael Wosnick, vice-president of research with the Canadian Cancer Society and scientific director of the newly-established Canadian Cancer Society Research Institute.
Dalhousie Medical School researcher Patrick Lee earlier this year used a common virus to kill breast cancer stem cells. Previous trials using mice showed astonishing results, with a benign virus causing lung tumours to disappear in weeks. This year, clinical trials started on people and the results so far have been dramatic, Wosnick said.
"This is a place where Canada has been a world leader," he said. "Canada excels at clinical trials and a number of researchers across the country are now involved in oncolytic viruses that literally burst open cancer cells."
Numerous strains of viruses are being tested on various tumours, he said.
But it's too early to know if the viruses provide longterm cures or if there are significant side effects, he added.
Speaking at a volunteer and donor appreciation event for the Canadian Cancer Society's Lambton County Unit, Wosnick showed before-and-after slides of mouse tumours and a human tumour taken during the trials. In both cases, the cancers disappeared in a few weeks and did not attack healthy cells.
......
Phase I/II trial of oncolytic reovirus (Reolysin) in combination with carboplatin/paclitaxel in patients (pts) with advanced solid cancers.
E. Karapanagiotou, H. S. Pandha, G. Hall, J. Chester, A. Melcher, M. Coffey, J. de Bono, M. E. Gore, C. M. Nutting, K. J. Harrington; The Royal Marsden Hospital NHS Foundation Trust, London, United Kingdom; University of Surrey, Guildford, United Kingdom; Leeds Institute of Molecular Medicine, Leeds, United Kingdom; Oncolytics Biotech Inc., Calgary, AB, Canada Abstract: Background: Reolysin, a wild type reovirus (Dearing strain), replicates preferentially in Ras-activated cancer cells. Preclinical data have demonstrated synergistic tumor kill when reolysin is combined with standard chemotherapies including platinum agents and taxanes, justifying the clinical evaluation of this drug combination. Methods: Pts were initially treated in an open-label, dose-escalating, phase I trial and received iv reolysin, d1-5, iv carboplatin (AUC5), d1, and paclitaxel (175mg/m2), d1, qw3. Reolysin was administered at a starting dose of 3x109 TCID50 and then increased to 1x1010 and 3x1010 TCID50 in cohorts of 3 pts. Primary endpoints for the dose escalation trial were to determine the maximum tolerated dose, dose limiting toxicity (DLT) and to recommend a dose for phase II studies. Secondary endpoints were to evaluate pharmacokinetics, immune response and anti-tumour activity. The primary endpoint for the phase II expansion cohort in head and neck (H&N) pts is to characterize response rate. Results:17 heavily pre-treated pts (11 M, median age 55 yrs) with advanced cancer: H&N (10), melanoma (4), peritoneal/endometrial cancer (2), and sarcoma (1) have received 82 cycles of treatment to date; 4 pts are still on study. There were no DLTs in the dose escalation. Toxicities were mainly grade 1 and 2 and included: nausea, fatigue, vomiting, myalgia, fever, neutropenia, lymphopenia, thrombocytopenia and hypotension. This combination resulted in a blunting of antiviral immune response as compared to monotherapy virus. Response rates in 15 evaluable patients were partial response (PR) (4 pts), stable disease (SD) (6 pts) and progressive disease (5 pts). Of note, all PRs and 4/5 SDs were in H&N disease. Conclusions:The combination of reolysin and carboplatin/paclitaxel was well tolerated and resulted in disease control in the majority of pts. Significant responses in refractory H&N pts recommended this combination for phase II evaluation. Enrollment is ongoing and randomized studies are planned.
Tranilast inhibits the growth and metastasis of mammary carcinoma.
Chakrabarti R, Subramaniam V, Abdalla S, Jothy S, Prud'homme GJ.
Department of Laboratory Medicine and Li Ka Shing Knowledge Institute, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Tranilast (N-[3,4-dimethoxycinnamonyl]-anthranilic acid) is a drug of low toxicity that is orally administered, and has been used clinically in Japan as an antiallergic and antifibrotic agent. Its antifibrotic effect is thought to depend on the inhibition of transforming growth factor-beta (TGF-beta). It has also been shown to exert antitumor effects, but its mode of action is unclear. Here, we explored the antitumor effects of tranilast in vitro and in vivo. Tranilast inhibited the proliferation of several tumor cell lines including mouse mammary carcinoma (4T1), rat mammary carcinoma stem cell (LA7), and human breast carcinoma (MDA-MB-231 and MCF-7). Tranilast blocked cell-cycle progression in vitro. In the highly metastatic 4T1 cell line, tranilast inhibited phospho-Smad2 generation, consistent with a blockade of TGF-beta signaling. It also inhibited the activation of MAP kinases (extracellularly regulated kinase 1 and 2 and JNK), which have been linked to TGF-beta-dependent epithelial-to-mesenchymal transition and, indeed, it blocked epithelial-to-mesenchymal transition. Although tranilast only partially inhibited TGF-beta production by 4T1 tumor cells, it potently inhibited the production of TGF-beta, interferon-gamma, IL-6, IL-10, and IL-17 by lymphoid cells, suggesting a general anti-inflammatory activity. In vivo, female BALB/c mice were inoculated with syngeneic 4T1 cells in mammary fat pads and treated with tranilast by gavage. Tranilast reduced (>50%) the growth of the primary tumor. However, its effects on metastasis were more striking, with more than 90% reduction of metastases in the lungs and no metastasis in the liver. Thus, tranilast has potential activity as an antimetastatic agent in breast cancer.
Tranilast suppresses prostate cancer growth and osteoclast differentiation in vivo and in vitro.
Sato S, Takahashi S, Asamoto M, Naiki T, Naiki-Ito A, Asai K, Shirai T.
Department of Experimental Pathology and Tumor Biology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.
BACKGROUND: In bone metastatic sites, prostate cancer cells proliferate on interacting with osteoclasts. Tranilast, which is used for an antiallergic drug, has been shown to inhibit growth of several cancers and stromal cells. The present study was conducted to assess suppressive effects of Tranilast on prostate cancer growth and osteoclast differentiation in vivo and in vitro. METHODS: In vivo, rat prostate cancer tissue was transplanted onto cranial bones of F344 rats and Tranilast was given for 9 days at doses of 0, 200, or 400 mg/kg/day. In vitro, human prostate cancer cell lines, LNCaP, PC3, and DU145, the rat prostate cancer cell line, PLS-10, and rat bone marrow cells were similarly treated with the agent. RESULTS: In vivo, tumor volumes were significantly decreased in the high dose group. While cell proliferation did not appear to be affected, apoptosis was induced and tumor necrosis was apparent. Cranial bone defects were decreased in the high dose group. In vitro, cell proliferation rates of all four cell lines were reduced by Tranilast and increased apoptosis was observed in LNCaP and PLS-10. In addition, Tranilast significantly reduced osteoclast differentiation of rat bone marrow cells. Western blot analysis of PLS-10 and LNCaP revealed that phospho-GSK3beta was up-regulated and phospho-Akt was down-regulated. CONCLUSIONS: Tranilast here suppressed rat prostate cancer growth and osteoclast differentiation. Growth of human prostate cancer cells was also inhibited. Thus, this agent deserves consideration as a candidate for conventional therapy of bone metastatic prostate cancer. Prostate (c) 2009 Wiley-Liss, Inc.
PMID: 19790239 [PubMed - as supplied by publisher]
Cancer develops when cells known as cancer stem cells begin to divide in an uncontrolled manner. Researchers from the University of Michigan Comprehensive Cancer Center have identified roles for the gene PTEN, which is already well known for its ability to suppress tumor growth, and for several pathways linked to PTEN in the growth of cells that give rise to breast cancer. The work, published in this week's issue of the open-access journal PLoS Biology, also reports that a drug that interferes with the activity of one of these pathways leads to a 90 percent decrease in the number of cells able to form tumors in mice.
PTEN is the most frequently inactivated tumor suppressor gene in several cancers, including breast cancer, where it is inactivated in about 40 percent of patients. PTEN inactivation is associated with poor patient outcomes, aggressive tumor growth, and resistance to chemotherapy and current targeted therapies.
Researchers first deleted PTEN from tumor cells grown in cell culture and from tumors in mice, and found an increase in the number cells able to form new tumors, which suggests that PTEN influences the cancer stem cell population. They also looked at pathways associated with PTEN and reported that the activity of the PI3-K/Akt pathway also regulates the size of the tumor-forming cell population by activating the Wnt pathway, another pathway previously implicated in multiple cancer types.
"Although there has been considerable progress in identifying cancer stem cells in a variety of tumor types, the pathways that drive the transformation of these cells are not well understood," says lead study author Hasan Korkaya, D.V.M., Ph.D., a research investigator in internal medicine at the University of Michigan Medical School.
Stem cells in breast cancer represent fewer than 5 percent of the cells in a tumor but are believed to be responsible for fueling a tumor's growth and spread. Researchers believe that the ultimate cure of cancer will require killing these cancer stem cells.
In the current study, researchers looked at a drug called perifosine, which inhibits the Akt pathway. Tumors in mice were treated with perifosine or docetaxel, a standard chemotherapy drug. The docetaxel alone treatment showed no effect on the number of tumor-forming cells, but the addition of perifosine reduced the tumor-forming cell population by up to 90 percent. Additionally, cells treated with perifosine - either with or without docetaxel - were less likely to form tumors when reintroduced into mice when compared to cells treated with docetaxel alone. These results suggest that perifosine specifically targets the breast cancer stem cell population.
"This is most exciting since perifosine and other drugs that target this pathway are currently in clinical development. If cancer stem cells do contribute to tumor relapse, then adding drugs that target these cells may help to make our current therapies more effective," says study senior author Max S. Wicha, M.D., Distinguished Professor of Oncology and director of the University of Michigan Comprehensive Cancer Center.
Funding: This work was funded by the National Institutes of Health (NIH) grants CA129765 and CA101860, by the Taubman Institute, and in part by the University of Michigan Cancer Center NIH support grant 5 P 30 CA46592. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests statement: MSW holds equity in and is a scientific consultant for OncoMed Pharmaceuticals.
Citation: "Regulation of Mammary Stem/Progenitor Cells by PTEN/Akt/b-Catenin Signaling."
Korkaya H, Paulson A, Charafe-Jauffret E, Ginestier C, Brown M, et al. (2009) PLoS Biol 7(6): e1000121. doi:10.1371/journal.pbio.1000121
PERIFOSINE
To date, over 1,800 patients have been treated with KRX-0401 in trials conducted both in the United States and Europe. Its safety profile is distinctly different from that of most cytotoxic agents. KRX-0401 does not appear to cause flu-like symptoms, thrombocytopenia (decrease in platelets that may result in bleeding) or alopecia (hair loss); all of these toxicities occur frequently with many of the currently available treatments for cancer. The main side effects of KRX-0401 are nausea, vomiting, diarrhea and fatigue, but these are generally well-managed particularly at lower daily doses (50 mg or 100 mg) that have induced tumor regression. Responses have been seen with both daily and weekly regimens. At the doses studied, the daily regimens were better tolerated.
Seven Phase 1 single agent studies of KRX-0401 have been completed; three in Europe by Zentaris and four in the United States by the NCI, a department of the National Institutes of Health, or NIH, as part of a Cooperative Research and Development Agreement, or CRADA, and by us. These trials demonstrated that KRX-0401 can be safely given to humans with a manageable toxicity profile. The dose limiting toxicity in the Phase 1 studies was gastrointestinal: nausea, vomiting and diarrhea.
Thirteen Phase 1/2 studies of KRX-0401 in combination with other drugs have been conducted by Keryx. Agents that have been included in these combinations include gemcitabine, paclitaxel, docetaxel, prednisone, doxorubicin, capecitabine, pemetrexed, irinotecan, Doxil® (doxorubicin HCl liposome injection), trastuzumab, various endocrine therapies, imatinib, bortezomib, lenalidomide, sorafenib, and sunitinib. KRX-0401 has generally been well tolerated when used as a low daily dose (50 mg or 100 mg) in combination with these approved agents. KRX-0401 has also been studied in combination with radiotherapy without evidence of increased toxicity.
The NCI has completed a number of Phase 2 clinical trials studying KRX-0401 as a single agent, including studies in prostate, breast, head and neck and pancreatic cancers, as well as melanoma and sarcomas. In total, nine NCI clinical trials have been conducted across these six tumor types.
KRX-0401 has also been evaluated in ten Phase 2 clinical studies conducted by Keryx evaluating the single agent activity in various tumor types where patients have progressed on standard treatments. Clinical trials where responses have been reported have been conducted in patients with renal cell carcinoma, advanced brain tumors, soft-tissue sarcomas, hepatocellular carcinoma, as well as in hematologic malignancies including multiple myeloma and Waldenstrom's macroglobulinemia. As illustrated in the previous NCI trials, the lower daily doses (50 mg or 100 mg) have been better tolerated than the intermittent higher doses.
For information on KRX-0401 (Perifosine) clinical trials which are open and recruiting patients, please click here
1: PLoS Biol. 2009 Jun 2;7(6):e1000121. Epub 2009 Jun 2.Links
Regulation of mammary stem/progenitor cells by PTEN/Akt/beta-catenin signaling.
Korkaya H, Paulson A, Charafe-Jauffret E, Ginestier C, Brown M, Dutcher J, Clouthier SG, Wicha MS.
Comprehensive Cancer Center, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA. hkorkaya@med.umich.edu
Recent evidence suggests that many malignancies, including breast cancer, are driven by a cellular subcomponent that displays stem cell-like properties. The protein phosphatase and tensin homolog (PTEN) is inactivated in a wide range of human cancers, an alteration that is associated with a poor prognosis. Because PTEN has been reported to play a role in the maintenance of embryonic and tissue-specific stem cells, we investigated the role of the PTEN/Akt pathway in the regulation of normal and malignant mammary stem/progenitor cell populations. We demonstrate that activation of this pathway, via PTEN knockdown, enriches for normal and malignant human mammary stem/progenitor cells in vitro and in vivo. Knockdown of PTEN in normal human mammary epithelial cells enriches for the stem/progenitor cell compartment, generating atypical hyperplastic lesions in humanized NOD/SCID mice. Akt-driven stem/progenitor cell enrichment is mediated by activation of the Wnt/beta-catenin pathway through the phosphorylation of GSK3-beta. In contrast to chemotherapy, the Akt inhibitor perifosine is able to target the tumorigenic cell population in breast tumor xenografts. These studies demonstrate an important role for the PTEN/PI3-K/Akt/beta-catenin pathway in the regulation of normal and malignant stem/progenitor cell populations and suggest that agents that inhibit this pathway are able to effectively target tumorigenic breast cancer cells.
PMID: 19492080 [PubMed - in process
Inhibition of pulmonary metastasis in a human MT3 breast cancer xenograft model by dual liposomes preventing intravasal fibrin clot formation.
Wenzel J, Zeisig R, Haider W, Habedank S, Fichtner I.
Max-Delbrück-Center for Molecular Medicine Berlin-Buch, R.-Rössle-Strasse 10, 13122, Berlin, Germany, j.wenzel@mdc-berlin.de.
The process of metastasis formation in cancer is not completely understood and is the main reason cancer therapies fail. Previously, we showed that dual liposomes simultaneously containing the hemostatic inhibitor, dipyridamole and the anticancer drug, perifosine potently inhibited metastasis, causing a 90% reduction in the number of lung metastases in a murine experimental metastasis model. To gain deeper insight into the mechanisms leading to the inhibition of metastasis by these dual liposomes, in the present study, the development of metastases by MT3 breast cancer cells in a mouse xenograft model was analyzed in more detail with regard to tumor cell settlement and metastatic growth. We found that the development of lung metastases by MT3 tumor cells is essentially dependent on the formation of fibrin clots as a precondition for the pulmonary arrest of tumor cells and the subsequent intravascular expansion of micrometastases before their invasion into the surrounding tissue.
PMID: 19548083 [PubMed - as supplied by publisher
Targeting notch signaling and estrogen receptor pathways in human breast cancer stem cells
N. S. Luraguiz, T. Yong, H. Yin and A. Sun Feist Weiller Cancer Center, LSUHSC, Shreveport, LA 22066 Background: Breast cancer stem cells have been identified asESA+CD44+CD24-Lin- cells, which may account for disease relapseand metastasis. Deregulation in stem cell self-renewal pathwayssuch as Notch, Wnt and Hedgehog signaling have been implicatedin mammary transformation. In humans, high levels of Notch1are associated with reduced patient survival. Inhibition ofNotch signaling has been proposed as a potential strategy intreating breast cancer. Tamoxifen, a modulator of estrogen receptor(ER), is currently used for the treatment of both early andadvanced ER+ breast cancer. It is unclear whether ER+ breastcancers originate from ER+ or ER- mammary stem/progenitor cells.Here, we investigate the molecular mechanisms of Notch signalingand ER interaction in breast cancer stem cells, and evaluateNotch inhibition and estrogen antagonist in targeting breastcancer stem cells. Methods: CD44+CD24- breast cancer stem cellsare isolated by flow cytometry sorting of (1) human breast cancercell line MDA-MB-231, (2) primary cells from invasive breastcancer lesions and (3) primary cells from benign breast tissues.Real-time PCR is performed to determine the expression of stemcell genes including genes in Notch pathway. IHC is performedto determine the ER and PR status of the cells. Stem like andnon-stem like cells are treated with GSI (a Notch inhibitor)and tamoxifen. The effects of the treatments on cell proliferationand apoptosis are determined by BrdU and Tunnel Assays. Resultsand Conclusion: Previously we have shown that GSI alone effectivelyinduced apoptosis in ER- MDA-MB-231 cells. Tamoxifen alone hadsubstantial killing effects on ER+ MCF7 cells, but enhancedkilling in both cell types were observed when treatments werecombined. Stem like, non stem-like and unsorted cells were treatedwith GSI, tamoxifen and combination of GSI and tamoxifen. Proliferationwas determined at 24 and 72 hours of treatment by BrdU assay.Stem-like cells exhibited significant sensitivity to GSI killingIn addition, an enhanced effect was observed when GSI was combinedwith tamoxifen, suggesting that chemotherapy that targets bothNotch signaling and estrogen receptor pathways in breast cancerstem cells may be an effective strategy in treating breast cancer.
J Med Chem. 2009 Jun 11;52(11):3441-4. Novel orally bioavailable gamma-secretase inhibitors with excellent in vivo activity.
Keown LE, Collins I, Cooper LC, Harrison T, Madin A, Mistry J, Reilly M, Shaimi M, Welch CJ, Clarke EE, Lewis HD, Wrigley JD, Best JD, Murray F, Shearman MS.
Department of Medicinal Chemistry, Molecular and Cellular Neuroscience, and in Vivo Neuroscience, The Neuroscience Research Centre, Merck Sharp & Dohme Research Laboratories, Terlings Park, Harlow, Essex, UK. keown.linda@yahoo.co.uk
The development of potent gamma-secretase inhibitors having substituted heterocycles attached to a benzobicyclo[4.2.1]nonane core is described. This work led to the identification of [6S,9R,11R]-2',3',4',5,5',6,7,8,9,10-decahydro-2-(5-(4-fluorophenyl)-1-methylpyrazol-3-yl)-5'-(2,2,2-trifluoroethyl)spiro[6,9-methanobenzocyclooctene-11,3'-[1,2,5]thiadiazole] 1',1'-dioxide (16), which has excellent in vitro potency (0.06 nM) and which reduced amyloid-beta in APP-YAC mice with an ED(50) of 1 mg/kg (po). 16 had a good pharmacokinetic profile in three preclinical species.
PMID: 19432431 [PubMed - indexed for MEDLINE]
Exp Cell Res. 2009 Jul 15;315(12):2022-32. Epub 2009 Apr 22. Tamoxifen inhibits tumor cell invasion and metastasis in mouse melanoma through suppression of PKC/MEK/ERK and PKC/PI3K/Akt pathways.
Matsuoka H, Tsubaki M, Yamazoe Y, Ogaki M, Satou T, Itoh T, Kusunoki T, Nishida S.
Division of Pharmacotherapy, Kinki University School of Pharmacy, Kowakae, Higashi-Osaka 577-8502, Japan.
In melanoma, several signaling pathways are constitutively activated. Among these, the protein kinase C (PKC) signaling pathways are activated through multiple signal transduction molecules and appear to play major roles in melanoma progression. Recently, it has been reported that tamoxifen, an anti-estrogen reagent, inhibits PKC signaling in estrogen-negative and estrogen-independent cancer cell lines. Thus, we investigated whether tamoxifen inhibited tumor cell invasion and metastasis in mouse melanoma cell line B16BL6. Tamoxifen significantly inhibited lung metastasis, cell migration, and invasion at concentrations that did not show anti-proliferative effects on B16BL6 cells. Tamoxifen also inhibited the mRNA expressions and protein activities of matrix metalloproteinases (MMPs). Furthermore, tamoxifen suppressed phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt through the inhibition of PKCalpha and PKCdelta phosphorylation. However, other signal transduction factor, such as p38 mitogen-activated protein kinase (p38MAPK) was unaffected. The results indicate that tamoxifen suppresses the PKC/mitogen-activated protein kinase kinase (MEK)/ERK and PKC/phosphatidylinositol-3 kinase (PI3K)/Akt pathways, thereby inhibiting B16BL6 cell migration, invasion, and metastasis. Moreover, tamoxifen markedly inhibited not only developing but also clinically evident metastasis. These findings suggest that tamoxifen has potential clinical applications for the treatment of tumor cell metastasis.
PMID: 19393235 [PubMed - indexed for MEDLINE]
Anticancer Drugs. 2009 Sep;20(8):723-35. The antipsychotic drug chlorpromazine enhances the cytotoxic effect of tamoxifen in tamoxifen-sensitive and tamoxifen-resistant human breast cancer cells.
Yde CW, Clausen MP, Bennetzen MV, Lykkesfeldt AE, Mouritsen OG, Guerra B.
Department of Biochemistry and Molecular Biology, Institute of Cancer Biology, Danish Cancer Society, Copenhagen, Denmark.
Tamoxifen resistance is a major clinical problem in the treatment of estrogen receptor alpha-positive breast tumors. It is, at present, unclear what exactly causes tamoxifen resistance. For decades, chlorpromazine has been used for treating psychotic diseases, such as schizophrenia. However, the compound is now also recognized as a multitargeting drug with diverse potential applications, for example, it has antiproliferative properties and it can reverse resistance toward antibiotics in bacteria. Furthermore, chlorpromazine can reverse multidrug resistance caused by overexpression of P-glycoprotein in cancer cells. In this study, we have investigated the effect of chlorpromazine on tamoxifen response of human breast cancer cells. We found that chlorpromazine worked synergistically together with tamoxifen with respect to reduction of cell growth and metabolic activity, both in the antiestrogen-sensitive breast cancer cell line, MCF-7, and in a tamoxifen-resistant cell line, established from the MCF-7 cells. Tamoxifen-sensitive and tamoxifen-resistant cells were killed equally well by combined treatment with chlorpromazine and tamoxifen. This synergistic effect could be prevented by addition of estrogen, suggesting that chlorpromazine enhances the effect of tamoxifen through an estrogen receptor-mediated mechanism. To investigate this putative mechanism, we applied biophysical techniques to simple model membranes in the form of unilamellar liposomes of well-defined composition and found that chlorpromazine interacts strongly with lipid bilayers of different composition leading to increased permeability. This implies that chlorpromazine can change influx properties of membranes hence suggesting that chlorpromazine may be a promising chemosensitizing compound for enhancing the cytotoxic effect of tamoxifen.
Tumor-initiating cells of HER2-positive carcinoma cell lines express the highest oncoprotein levels and are sensitive to trastuzumab.
Magnifico A, Albano L, Campaner S, Delia D, Castiglioni F, Gasparini P, Sozzi G, Fontanella E, Menard S, Tagliabue E.
Molecular Biology Unit, Department of Experimental Oncology, IRCCS Foundation: National Cancer Institute, Milan, Italy.
PURPOSE: The existence of tumor-initiating cells in breast cancer has profound implications for cancer therapy. In this study, we investigated the sensitivity of tumor-initiating cells isolated from human epidermal growth factor receptor type 2 (HER2)-overexpressing carcinoma cell lines to trastuzumab, a compound used for the targeted therapy of breast cancer. EXPERIMENTAL DESIGN: Spheres were analyzed by indirect immunofluorescence for HER2 cell surface expression and by real-time PCR for HER2 mRNA expression in the presence or absence of the Notch1 signaling inhibitor (GSI) or Notch1 small interfering RNA. Xenografts of HER2-overexpressing breast tumor cells were treated with trastuzumab or doxorubicin. The sphere-forming efficiency (SFE) and serial transplantability of tumors were assessed. RESULTS: In HER2-overexpressing carcinoma cell lines, cells with tumor-initiating cell properties presented increased HER2 levels compared with the bulk cell population without modification in HER2 gene amplification. HER2 levels were controlled by Notch1 signaling, as shown by the reduction of HER2 cell surface expression and lower SFE following gamma-secretase inhibition or Notch1 specific silencing. We also show that trastuzumab was able to effectively target tumor-initiating cells of HER2-positive carcinoma cell lines, as indicated by the significant decrease in SFE and the loss of serial transplantability, following treatment of HER2-overexpressing xenotransplants. CONCLUSIONS: Here, we provide evidence for the therapeutic efficacy of trastuzumab in debulking and in targeting tumor-initiating cells of HER2-overexpressing tumors. We also propose that Notch signaling regulates HER2 expression, thereby representing a critical survival pathway of tumor-initiating cells.
PMID: 19276287
Oncogene. 2008 Oct 16;27(47):6120-30. Epub 2008 Jun 30. HER2 regulates the mammary stem/progenitor cell population driving tumorigenesis and invasion.
Korkaya H, Paulson A, Iovino F, Wicha MS.
Department of Internal Medicine, Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA. hkorkaya@med.umich.edu
The cancer stem cell hypothesis proposes that cancers arise in stem/progenitor cells through disregulation of self-renewal pathways generating tumors, which are driven by a component of 'tumor-initiating cells' retaining stem cell properties. The HER2 gene is amplified in 20-30% of human breast cancers and has been implicated in mammary tumorigenesis as well as in mediating aggressive tumor growth and metastasis. We demonstrate that HER2 overexpression drives mammary carcinogenesis, tumor growth and invasion through its effects on normal and malignant mammary stem cells. HER2 overexpression in normal mammary epithelial cells (NMEC) increases the proportion of stem/progenitor cells as demonstrated by in vitro mammosphere assays and the expression of stem cell marker aldehyde dehydrogenase (ALDH) as well as by generation of hyperplastic lesions in humanized fat pads of NOD (nucleotide-binding oligomerization domain)/SCID (severe combined immunodeficient) mice. Overexpression of HER2 in a series of breast carcinoma cell lines increases the ALDH-expressing 'cancer stem cell' population which displays increased expression of stem cell regulatory genes, increased invasion in vitro and increased tumorigenesis in NOD/SCID mice. The effects of HER2 overexpression on breast cancer stem cells are blocked by trastuzumab in sensitive, but not resistant, cell lines, an effect mediated by the PI3-kinase/Akt pathway. These studies provide support for the cancer stem cell hypothesis by suggesting that the effects of HER2 amplification on carcinogenesis, tumorigenesis and invasion may be due to its effects on normal and malignant mammary stem/progenitor cells. Furthermore, the clinical efficacy of trastuzumab may relate to its ability to target the cancer stem cell population in HER2-amplified tumors.
PMID: 18591932 [PubMed - indexed for MEDLINE]
Tumor-Initiating Cells of HER2-Positive Carcinoma Cell Lines Express the Highest Oncoprotein Levels and Are Sensitive to Trastuzumab
Authors' Affiliation:1Molecular Biology Unit, 2Molecular Cell Cycle Control Unit, and 3Molecular-Cytogenetics Unit, Department of Experimental Oncology, IRCCS Foundation: National Cancer Institute, and 4Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
Requests for reprints:
Elda Tagliabue, Molecular Biology Unit, Department of Experimental Oncology, National Cancer Institute, Foundation IRCCS, Via Venezian 1, 20133 Milan, Italy. Phone: 390223903013; Fax: 390223903073; E-mail: elda.tagliabue@istitutotumori.mi.it.
Abstract
Purpose: The existence of tumor-initiating cells in breast cancer has profound implications for cancer therapy. In this study, we investigated the sensitivity of tumor-initiating cells isolated from human epidermal growth factor receptor type 2 (HER2)-overexpressing carcinoma cell lines to trastuzumab, a compound used for the targeted therapy of breast cancer. Experimental Design: Spheres were analyzed by indirect immunofluorescence for HER2 cell surface expression and by real-time PCR for HER2 mRNA expression in the presence or absence of the Notch1 signaling inhibitor (GSI) or Notch1 small interfering RNA. Xenografts of HER2-overexpressing breast tumor cells were treated with trastuzumab or doxorubicin. The sphere-forming efficiency (SFE) and serial transplantability of tumors were assessed. Results:In HER2-overexpressing carcinoma cell lines, cells with tumor-initiating cell properties presented increased HER2 levels compared with the bulk cell population without modification in HER2 gene amplification. HER2 levels were controlled by Notch1 signaling, as shown by the reduction of HER2 cell surface expression and lower SFE following γ-secretase inhibition or Notch1 specific silencing. We also show that trastuzumab was able to effectively target tumor-initiating cells of HER2-positive carcinoma cell lines, as indicated by the significant decrease in SFE and the loss of serial transplantability, following treatment of HER2-overexpressing xenotransplants. Conclusions: Here, we provide evidence for the therapeutic efficacy of trastuzumab in debulking and in targeting tumor-initiating cells of HER2-overexpressing tumors. We also propose that Notch signaling regulates HER2 expression, thereby representing a critical survival pathway of tumor-initiating cells.
Expression of p95HER2, a truncated form of the HER2 receptor, and response to anti-HER2 therapies in breast cancer.
Scaltriti M, Rojo F, Ocaña A, Anido J, Guzman M, Cortes J, Di Cosimo S, Matias-Guiu X, Ramon y Cajal S, Arribas J, Baselga J.
Medical Oncology Program, Medical Oncology Department, Vall d'Hebron University Hospital and Research Institute, Barcelona 08035, Spain.
BACKGROUND: Women with HER2-overexpressing breast cancers have poor prognosis, and many are resistant to the HER2 monoclonal antibody trastuzumab. A subgroup of HER2-overexpressing tumors also express p95HER2, an amino terminally truncated receptor that has kinase activity. Because p95HER2 cannot bind to trastuzumab but should be responsive to the HER2 tyrosine kinase inhibitor lapatinib, we compared the sensitivity of tumors expressing p95HER2 and tumors expressing the full-length HER2 receptor to these agents. METHODS: MCF-7 and T47D breast cancer cells were stably transfected with either full-length HER2 or p95HER2. We studied the effects of trastuzumab and lapatinib on receptor signaling, cell proliferation, and the growth of xenograft tumors. A paraffin-based immunofluorescence assay was developed to study the association between p95HER2 expression and sensitivity to trastuzumab in patients with advanced breast cancer. All statistical tests were two-sided. RESULTS: Treatment of p95HER2-expressing cells with lapatinib inhibited p95HER2 phosphorylation, reduced downstream phosphorylation of Akt and mitogen-activated protein kinases, inhibited cell growth (MCF-7p95HER2 clones, lapatinib versus control, mean growth inhibition = 57.6% versus 22.6%, difference = 35%, 95% confidence interval [CI] = 22.5% to 47.3%; P<.001; T47Dp95HER2 clones, lapatinib versus control, mean growth inhibition = 36.8% versus 20%, difference = 16.8%, 95% CI = 11.3% to 22.3%, P<.001), and inhibited growth of MCF-7p95HER2 xenograft tumors (lapatinib versus control, mean = 288.8 versus 435 mm3, difference = 146.2 mm3, CI = 73.8 to 218.5 mm3, P = .002). By contrast, treatment with trastuzumab had no effect on any of these parameters. Of 46 patients with metastatic breast cancer who were treated with trastuzumab, only one of nine patients (11.1%) expressing p95HER2 responded to trastuzumab (with a partial response), whereas 19 of the 37 patients (51.4%) with tumors expressing full-length HER2 achieved either a complete (five patients) or a partial (14 patients) response (P = .029). CONCLUSIONS: Breast tumors that express p95HER2 are resistant to trastuzumab and may require alternative or additional anti-HER2-targeting strategies.
PMID: 17440164
U-M researchers link pathway to breast cancer stem cells
Drug that inhibits this pathway shown to reduce stem cell population
added 6/01/09Ann Arbor - A gene well known to stop or suppress cancer plays a role in cancer stem cells, according to a new study from the University of Michigan Comprehensive Cancer Center. The researchers found that several pathways linked to the gene, called PTEN, also affected the growth of breast cancer stem cells.
Further, by using a drug that interferes with that pathway, the researchers produced an up to 90 percent decrease in the number of cancer stem cells within a tumor.
The study appears in the June issue of PLoS Biology, a journal from the Public Library of Science.
PTEN is the most frequently inactivated tumor suppressor gene in several cancers, including breast cancer, where it is inactivated in about 40 percent of patients. PTEN is linked to poor outcomes and is associated with aggressive cancers resistant to chemotherapy and current targeted therapies.
The U-M researchers deleted PTEN in tumors grown in cell cultures and in mice, and found an increase in the number of stem cells. They also looked at pathways associated with PTEN and reported that a pathway called PI3-K/Akt regulated the cancer stem cell population by activating another stem cell pathway, Wnt, which is also implicated in multiple cancer types.
"Although there has been considerable progress in identifying cancer stem cells in a variety of tumor types, the pathways that drive the transformation of these cells are not well understood," says lead study author Hasan Korkaya, D.V.M., Ph.D., research investigator in internal medicine at the U-M Medical School.
Researchers at U-M were the first to identify stem cells in breast cancer. These cells represent fewer than 5 percent of the cells in a tumor but are believed to be responsible for fueling a tumor’s growth and spread. Researchers believe that the ultimate cure of cancer will require killing these cancer stem cells.
In the current study, researchers looked at a drug called perifosine, which inhibits the Akt pathway. Tumors in mice were treated with perifosine or docetaxel, a standard chemotherapy drug. The docetaxel alone showed no effect on the number of cancer stem cells in the tumor. But adding perifosine reduced the cancer stem cell population by up to 90 percent.
What's more, the cells treated with perifosine – either with or without docetaxel – were less likely to grow a secondary tumor, compared to the cells treated with just docetaxel.
"This is most exciting since perifosine and other drugs that target this pathway are currently in clinical development. If cancer stem cells do contribute to tumor relapse, then adding drugs that target these cells may help to make our current therapies more effective," says study senior author Max S. Wicha, M.D., Distinguished Professor of Oncology and director of the U-M Comprehensive Cancer Center.
1: PLoS Biol. 2009 Jun 2;7(6):e1000121. Epub 2009 Jun 2. Links
Regulation of mammary stem/progenitor cells by PTEN/Akt/beta-catenin signaling.
Korkaya H, Paulson A, Charafe-Jauffret E, Ginestier C, Brown M, Dutcher J, Clouthier SG, Wicha MS.
Comprehensive Cancer Center, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA. hkorkaya@med.umich.edu
Recent evidence suggests that many malignancies, including breast cancer, are driven by a cellular subcomponent that displays stem cell-like properties. The protein phosphatase and tensin homolog (PTEN) is inactivated in a wide range of human cancers, an alteration that is associated with a poor prognosis. Because PTEN has been reported to play a role in the maintenance of embryonic and tissue-specific stem cells, we investigated the role of the PTEN/Akt pathway in the regulation of normal and malignant mammary stem/progenitor cell populations. We demonstrate that activation of this pathway, via PTEN knockdown, enriches for normal and malignant human mammary stem/progenitor cells in vitro and in vivo. Knockdown of PTEN in normal human mammary epithelial cells enriches for the stem/progenitor cell compartment, generating atypical hyperplastic lesions in humanized NOD/SCID mice. Akt-driven stem/progenitor cell enrichment is mediated by activation of the Wnt/beta-catenin pathway through the phosphorylation of GSK3-beta. In contrast to chemotherapy, the Akt inhibitor perifosine is able to target the tumorigenic cell population in breast tumor xenografts. These studies demonstrate an important role for the PTEN/PI3-K/Akt/beta-catenin pathway in the regulation of normal and malignant stem/progenitor cell populations and suggest that agents that inhibit this pathway are able to effectively target tumorigenic breast cancer cells.
PMID: 19492080 [PubMed - in process]
Akt enzyme: new therapeutic target in cancer and diabetes?
Cseh A, Szebeni B, Szalay B, Vásárhelyi B.
Semmelweis Egyetem, Altalános Orvostudományi Kar I. Gyermekgyógyászati Klinika Budapest Bókay u. 54. 1083, Hungary. sceharon@gmail.com
Alteration of apoptotic processes plays a central role in the development and progression of several chronic disorders. Proteins responsible for the regulation of apoptosis are therapeutic targets; these include the Akt enzyme. Akt enzyme is expressed in most cell types. Akt activation is regulated by growth factors, insulin, and also environmental factors as altered oxygen tension and high temperature. Akt is a central regulator of cellular metabolism and survival. Akt function is reportedly altered in some disorders. An increased activity of Akt has been described in prostate, breast, colon, and pancreatic cancer, as well as in hematological malignancies. Akt is also a factor in the pathomechanism of diabetes as it determines beta-cell apoptosis of Langerhans islets and insulin sensitivity of the cells. Several studies revealed that some of the marketed drugs including statins, thiazolidinediones and ACE inhibitors modulate Akt activity. There are efforts to develop specific Akt inhibitors that may improve the efficacy of chemotherapy. Triciribine and perifosine are two Akt inhibitors in developmental phase 1 and 2 that may improve survival in breast cancer, pancreas cancer, gastrointestinal stroma tumor, sarcoma and melanoma, and in hematological malignancy.
PMID: 19218147 [PubMed - indexed for MEDLINE]
The induction of autophagy by gamma-radiation contributes to the radioresistance of glioma stem cells.
Lomonaco SL, Finniss S, Xiang C, Decarvalho A, Umansky F, Kalkanis SN, Mikkelsen T, Brodie C.
William and Karen Davidson Laboratory of Cell Signaling and Tumorigenesis, Department of Neurosurgery, Hermelin Brain Tumor Center, Henry Ford Hospital, Detroit, MI.
Malignant gliomas are characterized by a short median survival which is largely impacted by the resistance of these tumors tochemo- and radiotherapy. Recent studies suggest that a small subpopulation of cancer stem cells, which are highly resistant to gamma-radiation, has the capacity to repopulate the tumors and contribute to their malignant progression. gamma-radiation activates the process of autophagy and inhibition of this process increases the radiosensitivity of glioma cells; however, the role of autophagy in the resistance of glioma stem cells (GSCs) to radiation has not been yet reported. In this study we examined the induction of autophagy by gamma-radiation in CD133+ GSCs. Irradiation of CD133+ cells induced autophagy within 24-48 hr and slightly decreased the viability of the cells. gamma-radiation induced a larger degree of autophagy in the CD133+ cells as compared with CD133- cells and the CD133+ cells expressed higher levels of the autophagy-related proteins LC3, ATG5 and ATG12. The autophagy inhibitor bafilomycin A1 and silencing of ATG5 and beclin1 sensitized the CD133+ cells to gamma-radiation and significantly decreased the viability of the irradiated cells and their ability to form neurospheres. Collectively, these results indicate that the induction of autophagy contributes to the radioresistance of these cells and autophagy inhibitors may be employed to increase the sensitivity of CD133+ GSCs to gamma-radiation. (c) 2009 UICC.
PMID: 19431142 [PubMed - as supplied by publisher
Humanized immunotoxins: A new generation of immunotoxins for targeted cancer therapy.
Mathew M, Verma RS.
Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
Chemotherapy, radiation, and surgery are the conventional treatment modalities for cancer. The success achieved with these approaches has been limited due to several factors like chemoresistance to drugs, non-specificity leading to peripheral toxicity, and non-resectable tumors. To combat these problems, the concept of targeted therapy using immunotoxins was developed. Immunotoxins are chimeric proteins with a cell-selective ligand chemically linked or genetically fused to a toxin moiety and can target cancer cells overexpressing tumor-associated antigens, membrane receptors, or carbohydrate antigens. Ligands for these receptors or monoclonal antibodies or single chain variable fragments directed against these antigens are fused with bacterial or plant toxins and are made use of as immunotoxins. Pseudomonas exotoxin, anthrax toxin, and diphtheria toxin are the commonly used bacterial toxins. Ricin, saporin, gelonin, and poke weed antiviral protein are the plant toxins utilized in immunotoxin constructs. Several such fusion proteins are in clinical trials, and denileukin difitox is a FDA-approved fusion protein. In spite of the promise shown by bacterial- and plant toxin-based chimeric proteins, their clinical application is hampered by several factors like immunogenicity of the toxin moiety and non-specific toxicity leading to vascular leak syndrome. In order to overcome these problems, a novel generation of immunotoxins in which the cytotoxic moiety is an endogenous protein of human origin like proapoptotic protein or RNase has been developed. This review summarizes the advances in this new class of fusion protein and the future directions to be explored. (Cancer Sci 2009).
PMID: 19459847 [PubMed - as supplied by publisher]
HER-2, Notch, and Breast Cancer Stem Cells: Targeting an Axis of Evil
Hasan Korkaya and Max S. WichaAuthors' Affiliation: University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan Requests for reprints: Max S. Wicha, Department of Internal Medicine/Oncology, Comprehensive Cancer Center, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0015. Phone: 734-647-9923; Fax: 734-647-9480; E-mail: mwicha@med.umich.edu. Abstract
Increasing evidence indicates that tumor-initiating (cancerstem) cells may contribute to treatment resistance and relapse,suggesting that improved clinical outcome will require effectivetargeting of this cell population. Recent studies suggest thatthe remarkable clinical efficacy of trastuzumab may relate toits ability to target cancer stem cell populations.
Intrinsic resistance of tumorigenic breast cancer cells to chemotherapy.
Li X, Lewis MT, Huang J, Gutierrez C, Osborne CK, Wu MF, Hilsenbeck SG, Pavlick A, Zhang X, Chamness GC, Wong H, Rosen J, Chang JC.
Breast Center at Baylor College of Medicine, 1 Baylor Plaza BCM 600, TX 77030, USA.
BACKGROUND: Tumorigenic breast cancer cells that express high levels of CD44 and low or undetectable levels of CD24 (CD44(>)/CD24(>/low)) may be resistant to chemotherapy and therefore responsible for cancer relapse. These tumorigenic cancer cells can be isolated from breast cancer biopsies and propagated as mammospheres in vitro. In this study, we aimed to test directly in human breast cancers the effect of conventional chemotherapy or lapatinib (an epidermal growth factor receptor [EGFR]/HER2 pathway inhibitor) on this tumorigenic CD44(>) and CD24(>/low) cell population. METHODS: Paired breast cancer core biopsies were obtained from patients with primary breast cancer before and after 12 weeks of treatment with neoadjuvant chemotherapy (n = 31) or, for patients with HER2-positive tumors, before and after 6 weeks of treatment with the EGFR/HER2 inhibitor lapatinib (n = 21). Single-cell suspensions established from these biopsies were stained with antibodies against CD24, CD44, and lineage markers and analyzed by flow cytometry. The potential of cells from biopsy samples taken before and after treatment to form mammospheres in culture was compared. All statistical tests were two-sided. RESULTS: Chemotherapy treatment increased the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 12 weeks, 4.7%, 95% confidence interval [CI] = 3.5% to 5.9%, vs 13.6%, 95% CI = 10.9% to 16.3%; P < .001) and increased mammosphere formation efficiency (MSFE) (mean at baseline vs 12 weeks, 13.3%, 95% CI = 6.0% to 20.6%, vs 53.2%, 95% CI = 42.4% to 64.0%; P < .001). Conversely, lapatinib treatment of patients with HER2-positive tumors led to a non-statistically significant decrease in the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 6 weeks, 10.0%, 95% CI = 7.2% to 12.8%, vs 7.5%, 95% CI = 4.1% to 10.9%) and a statistically non-significant decrease in MSFE (mean at baseline vs 6 weeks, 16.1%, 95% CI = 8.7% to 23.5%, vs 10.8%, 95% CI = 4.0% to 17.6%). CONCLUSION: These studies provide clinical evidence for a subpopulation of chemotherapy-resistant breast cancer-initiating cells. Lapatinib did not lead to an increase in these tumorigenic cells, and, in combination with conventional therapy, specific pathway inhibitors may provide a therapeutic strategy for eliminating these cells to decrease recurrence and improve long-term survival.
PMID: 18445819 [PubMed - indexed for MEDLINE]
News What are the clinical implications of breast-cancer stem cells?
Kathryn Senior
PII S1470-2045(08)70141-4
DOI 10.1016/S1470-2045(08)70141-4
The number of breast-cancer stem cells expressing the CD44+/CD24-/low marker decreased in women with primary breast cancer after treatment with lapatinib, reported researchers at the 6th European Breast Cancer Conference (Berlin, Germany; April 15–19, 2008).
“The activity of lapatinib, an epidermal growth factor receptor (EGFR)/ERBB2 tyrosine-kinase inhibitor, suggests that targeting specific signalling pathways responsible for self renewal of these cells could provide a therapeutic strategy for eliminating breast-cancer stem cells”, says Jenny Chang (Baylor College of Medicine, Houston, TX, USA) co-author on the lapatinib study. Max Wicha (University of Michigan, Ann Arbor, MI, USA) agrees: “this is consistent with our findings that ERBB2 is an important regulator of the breast-cancer stem-cell phenotype”…
Adult Stem Cells From Bone Marrow Made To Kill Metastatic Lung Cancer Cells In Mice
ScienceDaily (May 22, 2009) — Researchers in London have demonstrated the ability of adult stem cells from bone marrow (mesenchymal stem cells, or MSCs) to deliver a cancer-killing protein to tumors. The genetically engineered stem cells are able to home to the cancer cells, both in culture and in mouse models, and deliver TNF-related apoptosis-inducing ligand (TRAIL), destroying the tumor cells while sparing normal cells.
The research will be presented on May 19, at the American Thoracic Society's 105th International Conference in San Diego. "Present oncological therapies are limited by host toxicity," said Michael Loebinger, M.D., M.A, who, along with S. M. Janes, M.D., Ph.D., conducted the research at the Centre for Respiratory Research at the University College of London. "They are also limited by cancer resistance and may not destroy cancer stem cells."
With these experiments, the investigators combined two disparate areas of research that they believed held promise for treating cancer. Studies had shown that MSCs can be used as vectors to deliver anti-tumor therapy, while other studies found that TRAIL killed cancer cells, but not normal cells.
For their experiments, Drs. Loebinger and Janes identified those cells likely to be resistant to therapies (cancer cells that have characteristics of stem cells) and found that they were just as likely to be destroyed as tumor cells by this novel therapy.
In culture, the stem cells caused lung, squamous, breast and cervical cancer cells to die (all p< 0.01), even at low stem cell/tumor cell ratios (1:16).
In mice, the researchers showed that the stem cells could reduce the growth of subcutaneous breast tumors by approximately 80 percent (p< .0001). The stem cells could also be injected intravenously as therapy for mice with lung metastases and could eliminate lung metastases in 38 percent of mice compared to control mice, all of which still had metastases (p=0.03).
It is the first study to intravenously introduce MSCs that have been genetically modified to deliver TRAIL. Drs. Loebinger and Janes chose the breast cancer cells for both models because in their in vitro experiments, the MSCs "demonstrated a particularly strong homing to breast cancer cells."
"Breast cancer tumors are a good model of metastases," added Dr. Loebinger, "but our plan is to test the engineered stem cells with other models, including lung cancer."
While not fully understood, Dr. Loebinger added, the homing of the engineered cells appears to be a characteristic of MSCs themselves.
The authors conclude that, "this is the first study to demonstrate a significant reduction in tumor burden with inducible TRAIL-expressing MSCs in a well-controlled and specifically directed therapy."
They believe that human trials of TRAIL-expressing MSCs could begin in two or three years.
April 18, 2008 — Results from a small clinical trial of 45 patients with locally advanced breast cancer suggests that the novel agent lapatinib (Tykerb, GlaxoSmithKline) has an effect on tumor-causing breast cancer stem cells. "We saw significant tumor regression after 6 weeks with single-agent lapatinib," Angel Rodriguez, MD, from the Baylor College of Medicine, in Houston, Texas, reported yesterday at the 6th European Breast Cancer Conference (EBCC) in Berlin, Germany.
Lapatinib is available in the United States but not yet in Europe. In the United States, lapatinib is indicated for use in combination with capecitabine in advanced or metastatic breast cancer overexpressing HER-2 in women who have already been treated with an anthracycline, a taxane, and trastuzumab. The drug is expected to be approved in Europe soon; the European Medicines Agency issued a positive opinion in December 2007 for use of the drug in advanced or metastatic HER-2 breast cancer.
In the current study, lapatinib was given at a much earlier disease stage than specified in its licensed indication. Dr. Rodriguez and colleagues used lapatinib in a neoadjuvant setting for locally advanced cancer, and gave the drug as a single agent for 6 weeks, followed by a combination of weekly trastuzumab and 3-weekly docetaxel for 12 weeks before primary surgery.
A core biopsy taken after the 6 weeks of lapatinib therapy showed significant tumor regression, the researchers reported. Bidimensional tumor measurements showed a median decrease of 60.8%. In addition, there was a decrease in the tumorigenic CD44+/CD24–/low breast cancer cells (considered to be stem cells), from 10.6% to 4.7%, and a reduced self-renewal capacity as measured by mammosphere formation assays (reduced from 30 to 15 mammosphere/10,000 cells; P = .01). The researchers had previously found that the tumorigenic CD44+/CD24–/low cells were resistant to conventional chemotherapy. "Indeed, residual cancers that were exposed to such chemotherapy showed an increase in the tumor-causing cells and enhanced tumor initiation by the formation of mammospheres (small tumors that form when tumor-causing cells are cultured in a test tube), which reflect the capacity of the cells to self-renew. So we were excited to see that the results with lapatinib were different," Dr. Rodriguez commented in a statement.
Analysis of surgically removed tissue showed a pathological complete response rate of 63% (16/25) after lapatinib and trastuzumab/decetaxel therapy, a rate that was "much higher than expected," the researchers told the meeting.
"Contrary to conventional chemotherapy, human breast cancer specimens obtained from this prospective in vivo study have demonstrated for the first time that lapatinib decreases tumorigenic breast cancer stem cells in the primary breast cancers of women receiving neoadjuvant treatment," Dr. Rodriguez and colleagues concluded.
"This indicates that the stem cells themselves should be the specific target," Dr. Rodriguez commented, "rather than a broad-brush approach, in which cells are killed indiscriminately. Targeting the stem cells may be more effective and could also prevent some of the unpleasant side effects associated with conventional chemotherapy."
Asked to comment on these findings, Dr. Emiel Rutgers, MD, PhD, from the Netherlands Cancer Institute and Antoni van Leeuwenhoek Hospital, in Amsterdam, who chaired the EBCC meeting, said: "If this is true — and it needs to be confirmed — then this is a bonus." The contention here is that such a response to just 6 weeks of lapatinib monotherapy — which wasn't expected — is due to the very basic and aggressive cancer stem cells being 'switched off'," he commented. "However, one of the weak points in this research is that we talk about cancer stem cells, but we don't really know where they are," Dr. Rutgers told Medscape Oncology in an interview. "There is a lot of work supporting this concept, but if you ask me where the stem cell is in a tumor, well that's not so easy.... It's all conceptual. But it's a nice concept and a lot of research fits in with this concept, so there must be something true in it."
The response seen to lapatinib alone bodes well for the ongoing ALTTO study involving 8000 women, Dr. Rutgers commented. This study is comparing lapatinib with trastuzumab (Herceptin, Roche), both together and alone, in the adjuvant setting. However, the group in this study that involves monotherapy with lapatinib has been criticized, and some doctors have been reluctant to recruit women into this trial because they believe that there isn't enough evidence that lapatinib alone is effective. "So this latest bit of information will really help us to go forward with the ALTTO trial," Dr. Rutgers said.
6th European Breast Cancer Conference (EBCC): Abstract 204. Presented April 17, 2008.
Monitoring circulating epithelial tumour cells (CETC) to gauge therapy: in patients with disease progression after trastuzumab persisting CETC can be eliminated by combined lapatinib treatment.
Camara O, Jörke C, Hammer U, Egbe A, Rabenstein C, Runnebaum IB, Hoeffken K, Pachmann K.
Women's Hospital, Friedrich Schiller University, Bachstr. 18, 07740, Jena, Germany.
BACKGROUND: In breast cancers, the gene for the growth factor receptor HER2 can be amplified leading to increased aggressiveness and metastasis formation. The monoclonal antibody trastuzumab prolongs relapse-free survival highly significantly but eventually many patients relapse. METHOD: In this study, CETC were monitored using the Maintrac method during adjuvant trastuzumab treatment and during subsequent treatment with capecitabine/lapatinib. RESULTS: In one patient, trastuzumab led to marginal reduction in CETC with disease progress. The combination of capecitabine/lapatinib was preliminarily capable to eliminate all CETC, however, CETC reappeared. The second patient received adjuvant taxane together with trastuzumab and 1 year of further trastuzumab during which CETC increased. After stopping trastuzumab skin metastases occurred. Capecitabine/lapatinib led to complete CETC elimination with stable disease. CONCLUSIONS: In patients with lack of CETC reduction in spite of trastuzumab treatment correlated with disease progression the combination of capecitabine/lapatinib highly efficiently led to rapid elimination of CETC warranting further monitoring during such studies.
Updated: Friday, 29 May 2009, 8:57 PM EDT
Published : Friday, 29 May 2009, 8:52 PM EDT
(NCI) - A new drug combination tested in mice may target the cells responsible for driving some pancreatic tumors. The combination of gemcitabine and the experimental drug tigatuzumab eliminated populations of cancer stem cells and reduced tumor growth in a mouse model of pancreatic cancer, researchers from the Johns Hopkins Sidney Kimmel Cancer Center reported at the AACR annual meeting.
The results provide a rationale for testing the promising combination in patients with this deadly disease, Dr. Rajesh Kumar NV and his colleagues concluded.
Cancer stem cells are thought to self renew while giving rise to tumors, and they may resist conventional treatments. The researchers found that human pancreatic cancer stem cells overexpress a protein called death receptor-5 (DR-5), which is involved in programmed cell death (apoptosis). The protein is also the target of tigatuzumab, a humanized monoclonal antibody also known as CS-1008.
To evaluate the drug’s effects on these important cells, mice were given tigatuzumab alone, gemcitabine alone, or a combination. Although gemcitabine reduced tumor size, it increased levels of pancreatic cancer stem cells (as defined by the protein markers ALDH, CD24, and CD44), and all of the tumors recurred. The combination treatment, however, led to long-term remissions in half of the treated mice.
In addition, cancer stem cells were eliminated in mice that received tigatuzumab plus gemcitabine, which is the first-line treatment for patients with advanced pancreatic cancer. “It appears that tigatuzumab may be one of the first monoclonal antibodies to target cancer stem cells,” said Dr. Kumar NV. The drug is being tested in a phase II clinical trial with patients who have inoperable, untreated pancreatic cancer.
Combination Therapy Targets Pancreatic Cancer Stem Cells
A new drug combination tested in mice may target the cells responsible for driving some pancreatic tumors. The combination of gemcitabine and the experimental drug tigatuzumab eliminated populations of cancer stem cells and reduced tumor growth in a mouse model of pancreatic cancer, researchers from the Johns Hopkins Sidney Kimmel Cancer Center reported at the AACR annual meeting.
The results provide a rationale for testing the promising combination in patients with this deadly disease, Dr. Rajesh Kumar NV and his colleagues concluded.
Cancer stem cells are thought to self renew while giving rise to tumors, and they may resist conventional treatments. The researchers found that human pancreatic cancer stem cells overexpress a protein called death receptor-5 (DR-5), which is involved in programmed cell death (apoptosis). The protein is also the target of tigatuzumab, a humanized monoclonal antibody also known as CS-1008.
To evaluate the drug’s effects on these important cells, mice were given tigatuzumab alone, gemcitabine alone, or a combination. Although gemcitabine reduced tumor size, it increased levels of pancreatic cancer stem cells (as defined by the protein markers ALDH, CD24, and CD44), and all of the tumors recurred. The combination treatment, however, led to long-term remissions in half of the treated mice.
In addition, cancer stem cells were eliminated in mice that received tigatuzumab plus gemcitabine, which is the first-line treatment for patients with advanced pancreatic cancer. “It appears that tigatuzumab may be one of the first monoclonal antibodies to target cancer stem cells,” said Dr. Kumar NV. The drug is being tested in a phase II clinical trial with patients who have inoperable, untreated pancreatic cancer.
Chuthapisith S et al. - Review presents the evidence for the involvement of cancer stem cells (CSCs) in carcinogenesis, tumour invasion and metastases, and resistance to various forms of therapies, including chemotherapy. What are CSCs?
Concepts of CSCs arose from the observations of the capacity to and comparability of self-renewal between stem cells and cancer cells
A minority of tumor cells that are able to self renew and differentiate into a new tumor cell are termed CSCs
Role of CSCs in breast cancer chemoresistance:
CSCs have a high level of ATP binding cassette (ABC) transporters that protect these cells from drug damage
These cells remain quiescent in G-null phase
They are later induced by different stimuli to differentiate into new mature chemoresistant tumor cells
Strategies to overcome chemoresistant breast cancer by targeting breast cancer stem cells:
Traditional approach of switching to another drug does not work
CSCs may be eliminated by selectively targeted therapies against various self-renewal signalling pathways including the Notch, Shh, BMI-1 and Wnt signalling pathways
Targeting ABC transporter proteins may be another approach
Biological therapy with monoclonal antibodies targeted against specific cellular surface molecules or receptors should be considered
Targeting at the apoptotic pathway could be an attractive and therapeutically beneficial option
Histone deacetylase inhibitors as a new weapon in the arsenal of differentiation therapies of cancer.
Botrugno OA, Santoro F, Minucci S.
Department of Experimental Oncology, European Institute of Oncology, Milan, Italy.
Absent or altered differentiation is one of the major features of cancer cells. Histone deacetylases (HDACs) play a central role in the epigenetic regulation of gene expression. Aberrant activity of HDACs has been documented in several types of cancers, leading to the development of HDAC inhibitors (HDACi) as anti-tumor drugs. In vitro and in vivo experimental evidences show that HDACi are able to resume the process of maturation in undifferentiated cancer cells, justifying their introduction as differentiating agents in several clinical trials. Modulation of cell fate by HDACi is observed at several levels, including the stem cell compartment: HDACi can act both on cancer stem cells, and with the rest of the tumor cell mass, leading to complex biological outputs. As a note of caution, when used as single agent, HDACi show only a moderate and limited biological response, which is augmented in combinatorial therapies with drugs designed against other epigenetic targets. The optimal employment of these molecules may be therefore in combination with other epigenetic drugs acting against the set of enzymes responsible for the set-up and maintenance of epigenetic information.
PMID: 19345000
J Mammary Gland Biol Neoplasia. 2009 Mar;14(1):45-54. Epub 2009 Feb 28. Resistance to endocrine therapy: are breast cancer stem cells the culprits?
"A common theme of many investigations into CSCs is that they have inherent resistance to chemo and radiotherapy. This is proposed to be due to mechanisms such as more efficient DNA damage checkpoints and survival pathways compared to more differentiated tumor
cell populations."
"Enhanced interaction between estrogen receptor signalling and growth factor tyrosine kinase pathways such as EGFR, HER2/erbB2 and IGFR mediates resistance to endocrine therapy"
"HDAC inhibitors are being used in a number of on going clinical trials including a phase II trial evaluating vorinostat in ER positive patients with metastatic breast cancer who failed prior aromatase inhibitor therapy and up to three chemotherapy regimes [95]. A report of preliminary findings presented at ASCO 2008 showed that out of the 17 enrolled patients 21% had a partial response and 29% had stable disease after treatment with vorinostat 400 mg daily for 3 of 4 weeks and tamoxifen 20 mg daily,
continuously. These findings suggest that the addition of an HDAC inhibitor to tamoxifen in patients who have failed prior aromatase inhibitors or adjuvant tamoxifen may restore hormone sensitivity."
Clinical and biological effects of valproic acid as a histone deacetylase inhibitor on tumor and surrogate tissues: phase I/II trial of valproic acid and epirubicin/FEC.
Munster P, Marchion D, Bicaku E, Lacevic M, Kim J, Centeno B, Daud A, Neuger A, Minton S, Sullivan D.
Division of Hematology Oncology, University of California, San Francisco, Divisadero, San Francisco, California 94143-1711, USA. pmunster@medicine.ucsf.edu
PURPOSE: The aim was to study the biological and molecular effects of the histone deacetylase (HDAC) inhibitor, valproic acid, in patients with solid tumor malignancies. EXPERIMENTAL DESIGN: A phase I dose escalation of valproic acid given on days 1 to 3 followed by epirubicin (day 3) was followed by a dose expansion of valproic acid combined with 5-fluorouracil, epirubicin, and cyclophosphamide (FEC100). Pharmacodynamic and pharmacokinetic studies entailed valproic acid and epirubicin plasma levels and their interaction, the effects of valproic acid on histone acetylation in peripheral blood mononuclear cells (PBMC) and tumor cells at baseline and day 3, and baseline expression of HDAC2 and HDAC6 as therapeutic targets. RESULTS: Forty-four patients were enrolled in the phase I part, with a disease-specific cohort expansion of 15 breast cancer patients (median age, 55 years; range, 28-66 years) receiving 120 mg/kg/day valproic acid followed by FEC100. Partial responses were seen in 9 of 41 (22%) patients during the phase I part. Objective responses were seen in 9 of 14 (64%) evaluable patients at the dose expansion with a median number of 6 administered cycles. Predominant toxicities were valproic acid-associated somnolence and epirubicin-induced myelosuppression. Valproic acid plasma levels were associated with short-term, reversible depletion of WBC and neutrophils within 48 hours. Histone acetylation in tumor samples and in PBMCs correlated with valproic acid levels and was further linked to baseline HDAC2 but not to HDAC6 expression. CONCLUSION: Valproic acid is a clinically relevant HDAC inhibitor, and PBMCs may serve as a surrogate for tumor histone acetylation in solid tumor malignancies. HDAC2 should be further considered as a relevant therapeutic target.
PMID: 19318486
Troglitazone inhibits histone deacetylase activity in breast cancer cells.
Davies GF, Ross AR, Arnason TG, Juurlink BH, Harkness TA.
University of Saskatchewan, Department of Anatomy and Cell Biology, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
We previously demonstrated that the PPARgamma agonist Troglitazone (TRG), a potent antiproliferative agent, in combination with the anthracycline antibiotic Doxorubicin (DOX), is an effective killer of multiple drug resistant (MDR) human cancer cells. Cell killing was accompanied by increased global histone H3 acetylation. Presently, we investigated the epigenetic and cell killing effects of TRG in estrogen receptor (ER) positive MCF7 breast cancer cells. MCF7 cells were treated with the Thiazolidinediones (TZDs) TRG and Ciglitazone (CIG), the non-TZD PPARgamma agonist 15PGJ2, and the histone deacetylase inhibitors (HDACi's) Trichostatin A (TSA), sodium butyrate and PXD101. Using MTT cell viability assays, Western analyzes and mass spectrometry, we showed a dose-dependent increase in cell killing in TRG and HDACi treated cells, that was associated with increased H3 lysine 9 (H3K9) and H3K23 acetylation, H2AX and H3S10 phosphorylation, and H3K79 mono- and di-methylation. These effects were mediated through an ER independent pathway. Using HDAC activity assays, TRG inhibited HDAC activity in cells and in cell lysates, similar to that observed with TSA. Furthermore, TRG and TSA induced a slower migrating HDAC1 species that was refractory to HDAC2 associations. Lastly, TRG and the HDACi's decreased total and phosphorylated AKT levels. These findings suggest that TRG's mode of killing may involve downregulation of PI3K signaling through HDAC inhibition, leading to increased global histone post-translational modifications.
PMID: 19699029 [PubMed - as supplied by publisher]
Rezulin (troglitazone)
Parke-Davis/Warner Lambert agree to FDA's request to withdraw Rezulin from the market. FDA asked Parke-Davis/Warner Lambert to withdraw Rezulin after a review of recent safety data on Rezulin and two similar drugs, Avandia (rosiglitazone) and Actos (pioglitazone), showed that Rezulin is more toxic to the liver than the other two drugs. Data to date show that Avandia and Actos, both approved in the past year, offer the same benefits as Rezulin without the same risk.
[March 21, 2000 - News Release - FDA]
The antitumor histone deacetylase inhibitor suberoylanilide hydroxamic acidexhibits antiinflammatory properties via suppression of cytokines
*Italfarmaco, SpA., 20092 Cinisello Balsamo, Italy; â€*Istituto Mario Negri, 20157 Milan, Italy; University of Brescia, 25123 Brescia, Italy; and ‡University of Colorado Health Sciences Center, Denver, CO 80262
Contributed by Charles A. Dinarello
Abstract
Suberoylanilide hydroxamic acid (SAHA) is a hydroxamic acid-containing hybrid polar molecule; SAHA specifically binds to and inhibits the activity of histone deacetylase. Although SAHA, like other inhibitors of histone deacetylase, exhibits antitumor effects by increasing expression of genes regulating tumor survival, we found that SAHA reduces the production of proinflammatory cytokines in vivo and in vitro. A single oral administration of SAHA to mice dose-dependently reduced circulating TNF-α, IL-1-β, IL-6, and IFN-γ induced by lipopolysaccharide (LPS). Administration of SAHA also reduced hepatic cellular injury in mice following i.v. injection of Con A. SAHA inhibited nitric oxide release in mouse macrophages stimulated by the combination of TNF-α plus IFN-γ. Human peripheral blood mononuclear cells stimulated with LPS in the presence of SAHA released less TNF-α, IL-1-β, IL-12, and IFN-γ (50% reduction at 100–200 nM). The production of IFN-γ stimulated by IL-18 plus IL-12 was also inhibited by SAHA (85% at 200 nM). However, SAHA did not affect LPS-induced synthesis of the IL-1-β precursor, the IL-1 receptor antagonist, or the chemokine IL-8. In addition, IFN-γ induced by anti-CD3 was not suppressed by SAHA. Steady-state mRNA levels for LPS-induced TNF-α and IFN-γ in peripheral blood mononuclear cells were markedly decreased, whereas IL-8 and IL-1-β mRNA levels were unaffected. Because SAHA exhibits antiinflammatory properties in vivo and in vitro, inhibitors of histone deacetylase may stimulate the expression of genes that control the synthesis of cytokines and nitric oxide or hyperacetylate other targets.
Clin Cancer Res. 2010 Apr 13. [Epub ahead of print] Sulforaphane, a Dietary Component of Broccoli/Broccoli Sprouts, Inhibits Breast Cancer Stem Cells.
Li Y, Zhang T, Korkaya H, Liu S, Lee HF, Newman B, Yu Y, Clouthier SG, Schwartz SJ, Wicha MS, Sun D.
Authors' Affiliations: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan and Comprehensive Cancer Center, Department of Internal Medicine, University of Michigan; and Department of Food Science and Technology, The Ohio State University, Columbus, Ohio. Abstract
PURPOSE: The existence of cancer stem cells (CSCs) in breast cancer has profound implications for cancer prevention. In this study, we evaluated sulforaphane, a natural compound derived from broccoli/broccoli sprouts, for its efficacy to inhibit breast CSCs and its potential mechanism. EXPERIMENTAL DESIGN: Aldefluor assay and mammosphere formation assay were used to evaluate the effect of sulforaphane on breast CSCs in vitro. A nonobese diabetic/severe combined immunodeficient xenograft model was used to determine whether sulforaphane could target breast CSCs in vivo, as assessed by Aldefluor assay, and tumor growth upon cell reimplantation in secondary mice. The potential mechanism was investigated using Western blotting analysis and beta-catenin reporter assay. RESULTS: Sulforaphane (1-5 mumol/L) decreased aldehyde dehydrogenase-positive cell population by 65% to 80% in human breast cancer cells (P < 0.01) and reduced the size and number of primary mammospheres by 8- to 125-fold and 45% to 75% (P < 0.01), respectively. Daily injection with 50 mg/kg sulforaphane for 2 weeks reduced aldehyde dehydrogenase-positive cells by >50% in nonobese diabetic/severe combined immunodeficient xenograft tumors (P = 0.003). Sulforaphane eliminated breast CSCs in vivo, thereby abrogating tumor growth after the reimplantation of primary tumor cells into the secondary mice (P < 0.01). Western blotting analysis and beta-catenin reporter assay showed that sulforaphane downregulated the Wnt/beta-catenin self-renewal pathway. CONCLUSIONS: Sulforaphane inhibits breast CSCs and downregulates the Wnt/beta-catenin self-renewal pathway. These findings support the use of sulforaphane for the chemoprevention of breast cancer stem cells and warrant further clinical evaluation. Clin Cancer Res; 16(9); OF1-11. (c)2010 AACR.
PMID: 20388854 [PubMed - as supplied by publisher]
Environ Mol Mutagen. 2009 Apr;50(3):213-21. Modulation of histone deacetylase activity by dietary isothiocyanates and allyl sulfides: studies with sulforaphane and garlic organosulfur compounds.
Nian H, Delage B, Ho E, Dashwood RH.
Linus Pauling Institute, Oregon State University, Corvallis, Oregon 97331-6512, USA.
Histone deacetylase (HDAC) inhibitors reactivate epigenetically-silenced genes in cancer cells, triggering cell cycle arrest and apoptosis. Recent evidence suggests that dietary constituents can act as HDAC inhibitors, such as the isothiocyanates found in cruciferous vegetables and the allyl compounds present in garlic. Broccoli sprouts are a rich source of sulforaphane (SFN), an isothiocyanate that is metabolized via the mercapturic acid pathway and inhibits HDAC activity in human colon, prostate, and breast cancer cells. In mouse preclinical models, SFN inhibited HDAC activity and induced histone hyperacetylation coincident with tumor suppression. Inhibition of HDAC activity also was observed in circulating peripheral blood mononuclear cells obtained from people who consumed a single serving of broccoli sprouts. Garlic organosulfur compounds can be metabolized to allyl mercaptan (AM), a competitive HDAC inhibitor that induced rapid and sustained histone hyperacetylation in human colon cancer cells. Inhibition of HDAC activity by AM was associated with increased histone acetylation and Sp3 transcription factor binding to the promoter region of the P21WAF1 gene, resulting in elevated p21 protein expression and cell cycle arrest. Collectively, the results from these studies, and others reviewed herein, provide new insights into the relationships between reversible histone modifications, diet, and cancer chemoprevention.
PMID: 19197985 [PubMed - indexed for MEDLINE]PMCID: PMC2701665Free PMC Article
System 
PERIFOSINE
A new drug combination tested in mice may target the cells responsible for driving some pancreatic tumors. The combination of 
Linear Mode
