Journal of Clinical Oncology, 2008 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 26, No 15S (May 20 Supplement), 2008: 22066
© 2008
American Society of Clinical Oncology
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 as
ESA+CD44+CD24-Lin- cells, which may account for disease relapse
and metastasis. Deregulation in stem cell self-renewal pathways
such as Notch, Wnt and Hedgehog signaling have been implicated
in mammary transformation. In humans, high levels of Notch1
are associated with reduced patient survival. Inhibition of
Notch signaling has been proposed as a potential strategy in
treating breast cancer. Tamoxifen, a modulator of estrogen receptor
(ER), is currently used for the treatment of both early and
advanced ER+ breast cancer.
It is unclear whether ER+ breast cancers originate from ER+ or ER- mammary stem/progenitor cells. Here, we investigate the molecular mechanisms of Notch signaling
and ER interaction in breast cancer stem cells, and evaluate
Notch inhibition and estrogen antagonist in targeting breast
cancer stem cells.
Methods: CD44+CD24- breast cancer stem cells
are isolated by flow cytometry sorting of (1) human breast cancer
cell line MDA-MB-231, (2) primary cells from invasive breast
cancer lesions and (3) primary cells from benign breast tissues.
Real-time PCR is performed to determine the expression of stem
cell genes including genes in Notch pathway. IHC is performed
to determine the ER and PR status of the cells. Stem like and
non-stem like cells are treated with GSI (a Notch inhibitor)
and tamoxifen. The effects of the treatments on cell proliferation
and apoptosis are determined by BrdU and Tunnel Assays.
Results and Conclusion: Previously we have shown that GSI alone effectively
induced apoptosis in ER- MDA-MB-231 cells. Tamoxifen alone had
substantial killing effects on ER+ MCF7 cells, but enhanced
killing in both cell types were observed when treatments were
combined. Stem like, non stem-like and unsorted cells were treated
with GSI, tamoxifen and combination of GSI and tamoxifen. Proliferation
was determined at 24 and 72 hours of treatment by BrdU assay.
Stem-like cells exhibited significant sensitivity to GSI killing In addition, an enhanced effect was observed when GSI was combined with tamoxifen, suggesting that chemotherapy that targets both
Notch signaling and estrogen receptor pathways in breast cancer
stem 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.
PMID: 19584708 [PubMed - indexed for MEDLINE]