Why Are The Trials Not Done?

[R.B.]

This is an exellent article which helps explain the aromatase inhibitors.

The STAGGERING bit for me was the straight line graph between COXs and aromatase. "B, Correlation of aromatase (CYP19) gene expression with COX-1 and COX-2 gene expression in human breast tissue specimens."

http://edrv.endojournals.org/cgi/con...ll/26/3/331/F4

For those who have been following my journey into the world of fats, or who are better informed than me (and I am amateur who not so long ago new nothing on this subject) it will not have escaped your attention that COX 2 is a product of arachnidonic acid which is a product of linoleic acid omega six which occurs in high quantities in vegetable oils (50-70% of fats in many of the commonly used cheap oils).

The human body as I understand is unable to manifacture omega six products from scratch. It has to have the raw material in omega six from plants, meat fats, eggs etc.

Plant and seed oils were scarce before mechanisation and a new factor in the human diet and in general terms the source of current, historically unprecedented imbalances in the omega threes and sixes, and represent historically unprecedented intakes of omega six.

In essence less omega six should equate to less COX 2 making material.

As an adjunct and preventative this would seem to me to be a good starting point, to see if this saved the need for drugs that block the effect of too much COX which is from my limited knowledge all this effort is being put.

I am sure that there will be some this does not help, and am not suggesting drugs and research is not necessary, (I am amazed by the work progress effort and acheivement in better understanding of the the way we work, and in medicine) but if there is a simple opportunity to mitigate the occurence and impact of this dreadful disease through diet should it not be taken with alacrity, and women not put unnecessarily through one more life changing nightmare than possible.

The more I read the more I find it hard to beleive that those in the industry can be blind to these simple potential opportunities for the significant betterment of public health and reduction of suffering.

The means exist to determine with certainty if what appears to be a strong probability, that excess omega six is leading to the eicosanoid pathway on the omega six side going into hyperdrive, and in consequence a magor factor in the increase in western diseases including BC, is indeed fact.

Fat tissue samples breast, abdominal, gluteal, gene array for relevant known markers, outcomes - what is so difficult about that - it has already been done in whole or in part but not in sufficient depth to be authoritative.


WHY ARE THESE TRIALS TO DETERMINE IF EXCESS OMEGA SIX IN THE DIET IS RESPONSIBLE FOR A PART OF THIS SUFFERING NOT DONE?


RB










http://edrv.endojournals.org/cgi/content/full/26/3/331

ABSTRACTS

Aromatase Inhibitors in the Treatment of Breast Cancer
Robert W. Brueggemeier, John C. Hackett and Edgar S. Diaz-Cruz

Medicinal Chemistry and Pharmacognosy, College of Pharmacy, and Hormones and Cancer Program, Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210

Correspondence: Address all correspondence and requests for reprints to: Dr. Robert W. Brueggemeier, Professor and Dean, College of Pharmacy, The Ohio State University, 500 West 12th Avenue, Columbus, Ohio 43210-1291. E-mail: Brueggemeier.1@osu.edu


Abstract
Top
Abstract
I. Introduction
II. Aromatase and Estrogen...
III. Development of Aromatase...
IV. Aromatase Inhibitors in...
V. Conclusions
References

Estradiol, the most potent endogenous estrogen, is biosynthesized from androgens by the cytochrome P450 enzyme complex called aromatase. Aromatase is present in breast tissue, and intratumoral aromatase is the source of local estrogen production in breast cancer tissues. Inhibition of aromatase is an important approach for reducing growth-stimulatory effects of estrogens in estrogen-dependent breast cancer. Steroidal inhibitors that have been developed to date build upon the basic androstenedione nucleus and incorporate chemical substituents at varying positions on the steroid. Nonsteroidal aromatase inhibitors can be divided into three classes: aminoglutethimide-like molecules, imidazole/triazole derivatives, and flavonoid analogs. Mechanism-based aromatase inhibitors are steroidal inhibitors that mimic the substrate, are converted by the enzyme to a reactive intermediate, and result in the inactivation of aromatase. Both steroidal and nonsteroidal aromatase inhibitors have shown clinical efficacy in the treatment of breast cancer. The potent and selective third-generation aromatase inhibitors, anastrozole, letrozole, and exemestane, were introduced into the market as endocrine therapy in postmenopausal patients failing antiestrogen therapy alone or multiple hormonal therapies. These agents are currently approved as first-line therapy for the treatment of postmenopausal women with metastatic estrogen-dependent breast cancer. Several clinical studies of aromatase inhibitors are currently focusing on the use of these agents in the adjuvant setting for the treatment of early breast cancer. Use of an aromatase inhibitor as initial therapy or after treatment with tamoxifen is now recommended as adjuvant hormonal therapy for a postmenopausal woman with hormone-dependent breast cancer.

I. Introduction ..................



......................C. Aromatase in breast cancer tissues
Aromatase is found in breast tissue, and the importance of intratumoral aromatase and local estrogen production is being unraveled (6, 19, 20). Aromatase has been measured in the stromal cell component of normal breast and breast tumors, but the enzyme has also been detected in the breast epithelial cells in vitro (5, 8, 20, 21, 22). Furthermore, expression of aromatase is highest in or near breast tumor sites (8, 20). The exact cellular location(s) of aromatase must await more rigorous analysis by several laboratories with a new monoclonal antibody now being developed and evaluated (23).

The increased expression of aromatase cytochrome P450arom observed in breast cancer tissues is associated with a switch in the major promoter region used in gene expression, with promoter PII being the predominant promoter used in breast cancer tissues (24). As a result of the use of the alternate promoter, the regulation of estrogen biosynthesis switches from one controlled primarily by glucocorticoids and cytokines to a promoter regulated through cAMP-mediated pathways (24). Prostaglandin E2 (PGE2) increases intracellular cAMP levels and stimulates estrogen biosynthesis (24), whereas other autocrine factors such as IL-1ß do not appear to act via PGE2 (25).

Local production of PGE2 via the cyclooxygenase isozymes (constitutive COX-1 isozyme and inducible COX-2 isozyme) can influence estrogen biosynthesis and estrogen-dependent breast cancer. This biochemical mechanism may explain epidemiological observations of the beneficial effects of nonsteroidal antiinflammatory drugs (NSAIDs) on breast cancer (26, 27, 28, 29). Investigations using human breast cancer patient specimens demonstrated a strong linear correlation between CYP19 expression and the sum of COX-1 and COX-2 expression (30). Gene expression analysis for CYP19, COX-1, and COX-2 were performed in 20 human breast cancer specimens and in five normal control breast tissue samples. A positive correlation was observed between CYP19 expression and the greater extent of breast cancer cellularity (Fig. 4AGo), in agreement with literature reports showing that aromatase levels were higher in tumors than in normal tissue. Furthermore, a positive linear correlation was observed between COX-2 expression breast cancer cellularity in each sample. Linear regression analysis using a bivariate model shows a strong linear association between CYP19 expression and the sum of COX-1 and COX-2 expression (Fig. 4BGo). Similar correlations between CYP19 expression and COX-2 expression in breast cancer patient specimens have been confirmed in other laboratories (31). This significant relationship between the aromatase and COX enzyme systems suggests that autocrine and paracrine mechanisms may be involved in hormone-dependent breast cancer development via growth stimulation from local estrogen biosynthesis. In human breast stromal cells, PGE2 acts via two G protein-coupled receptors, EP1 and EP2 receptors, to stimulate aromatase gene expression via protein kinase A and protein kinase C signaling pathways (32). NSAIDs and COX-1- and COX-2-selective inhibitors produce dose-dependent decreases in aromatase activity in breast cancer tissues (Fig. 5Go) (33, 34). Real time PCR analysis of aromatase gene expression showed a significant decrease in mRNA levels by these agents, and the effect of COX inhibitors on aromatase expression occurs through suppression at the tissue-specific promoters PI.3, PI.4, and PII. This significant relationship between the aromatase and COX enzyme systems suggests that autocrine and paracrine mechanisms may be involved in hormone-dependent breast cancer development via growth stimulation from local estrogen biosynthesis (Fig. 6Go).



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FIG. 4. Aromatase, COX-1, and COX-2 gene expression in breast cancer patients. A, Expression of aromatase CYP19 ({blacktriangleup}), COX-1 (•), and COX-2 ({blacksquare}) gene expression in human breast tissue specimens. B, Correlation of aromatase (CYP19) gene expression with COX-1 and COX-2 gene expression in human breast tissue specimens.




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FIG. 5. Effect of NSAIDs and COX-specific inhibitors on aromatase enzyme activity. A, SK-BR-3 cells were treated with indomethacin ({circ}), piroxicam (•), ibuprofen ({blacksquare}), or SC-560 ({diamondsuit}), and aromatase activity was measured using the tritiated water release assay. B, SK-BR-3 cells were treated with NS-398 ({diamondsuit}), nimesulide ({circ}), SC-58125 ({blacksquare}), celecoxib (•), or niflumic acid ({square}), and aromatase activity was measured using the tritiated water release assay.

http://edrv.endojournals.org/content...525810004.jpeg



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FIG. 6. Model of autocrine and paracrine pathways of aromatase and COXs in hormone-dependent breast cancer. E2, Estradiol; T, testosterone; ER, estrogen receptor; PTK, protein tyrosine kinase.



http://edrv.endojournals.org/cgi/con...ll/26/3/331/F5..............



AND SOME OTHER TRIALS......


http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum




1: Postepy Biochem. 2005;51(4):430-9.
Related Articles, Links


[Aromatase--key enzyme of estrogen biosynthesis]

[Article in Polish]

Milczarek R, Klimek J.

Department of Pharmaceutical Biochemistry, Medical University of Gdansk, 1 Debinki St., 80-211 Gdansk, Poland. rysmil@amg.gda.pl

Estrogens control a large range pivotal life functions as reproductive development and fertility, bone growth and sexual behavior. Aromatase is a key enzyme of estrogen biosynthesis. The property, structure and reaction mechanism of aromatase as well as detailed structure of human aromatase cytochrome P450 gene (CYP19) was discussed in this article. It was pointed that unique human CYP19 gene expression results from presence of many tissue specific promoters and alternative splicing. The molecular mechanism of control aromatase cytochrome P450 gene expression in various species ovaries, testes and human adipose tissue and placenta was discussed in details. Because of a very important role of estrogen in breast cancer a molecular base of aberrant expression CYP19 gene in breast tumor and adipose tissue proximal to breast tumor and potential possibility of pharmacological silencing of this gene expression was discussed in the article.

PMID: 16676578 [PubMed - in process]



http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum



1: J Steroid Biochem Mol Biol. 2005 May;95(1-5):129-36. Related Articles, Links


Translational studies on aromatase, cyclooxygenases, and enzyme inhibitors in breast cancer.

Brueggemeier RW, Diaz-Cruz ES, Li PK, Sugimoto Y, Lin YC, Shapiro CL.

College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA. brueggemeier.1@osu.edu

Aromatase expression and enzyme activity in breast cancer patients is greater in or near the tumor tissue compared with the normal breast tissue. Regulation of aromatase expression in human tissues is quite complex, involving alternative promoter sites that provide tissue-specific control. Previous studies in our laboratories suggested a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Our hypothesis is that higher levels of COX expression result in higher levels of prostaglandin E2 (PGE2), which in turn increases CYP19 expression through increases in intracellular cyclic AMP levels. This biochemical mechanism may explain the beneficial effects of non-steroidal anti-inflammatory drugs (NSAIDs) on reducing the risks of breast cancer. The effects of NSAIDs (ibuprofen, piroxicam, and indomethacin), a COX-1 selective inhibitor (SC-560), and COX-2 selective inhibitors (celecoxib, niflumic acid, nimesulide, NS-398, and SC-58125) on aromatase activity and CYP19 expression were investigated in breast cancer cell culture systems. Dose-dependent decreases in aromatase activity were observed following treatment with an NSAID or COX inhibitor, with the most effective agents being COX selective inhibitors. Real time PCR analysis of aromatase gene expression showed a significant decrease in mRNA levels in treated cells when compared to vehicle control. These results suggest that the effect of COX inhibitors on aromatase occurs at the transcriptional level. To further probe these interactions, short interfering RNAs (siRNA) were designed against either human CYP19 mRNA or human COX-2 mRNA. Treatment of breast cancer cells with aromatase siRNAs suppressed CYP19 mRNA and aromatase enzyme activity. Finally, treatment with COX-2 siRNAs downregulated the expression of COX-2 mRNA; furthermore, the siCOX-2-mediated suppression of COX-2 also resulted in suppression of aromatase mRNA. In summary, pharmacological regulation of aromatase and cyclooxygenases can act locally in an autocrine fashion to decrease the biosynthesis of estrogen and may provide additional therapy options for patients with hormone-dependent breast cancer.

PMID: 15964185 [PubMed - indexed for MEDLINE]


http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum



1: Anticancer Agents Med Chem. 2006 May;6(3):221-32. Related Articles, Links


Interrelationships between cyclooxygenases and aromatase: unraveling the relevance of cyclooxygenase inhibitors in breast cancer.

Diaz-Cruz ES, Brueggemeier RW.

Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy,The Ohio State University, Columbus, Ohio 43210, USA. Brueggemeier.1@osu.edu.

Breast cancer is the most common cancer among women, and ranks second among cancer deaths in women. Approximately 60% of all breast cancer patients have hormone-dependent breast cancer, which contains estrogen receptors and requires estrogen for tumor growth. Estradiol is biosynthesized from androgens by the cytochrome P450 enzyme complex called aromatase. Aromatase is found in several tissues in the body and aromatase (CYP19) gene expression is regulated in a tissue-specific manner via use of alternative promoters. Aromatase transcript expression and activity in breast tumor tissue is greater than that in the normal breast tissue, and prostaglandins can increase CYP19 expression and aromatase activity in breast cancer cells. Cyclooxygenase (COX) is a key enzyme in the production of prostaglandins. Studies have shown higher levels of COX-2 isoform in breast cancer tissue when compared to normal breast tissue, and this is accompanied by high concentrations of prostaglandin E(2) (PGE(2)). Previous studies suggest a strong association between CYP19 gene expression and the expression of COX genes. While studies have shown that nonsteroidal anti-inflammatory drugs (NSAIDs) have beneficial effects on breast cancer, the mechanism by which this occurs is still unclear. Studies have shown that COX inhibitors decrease aromatase activity in breast cancer cells and this effect starts at the transcriptional level. Real time PCR data shows that this molecular mechanism involves promoters I.4 and II, the promoters involved in the development of breast cancer. High levels of COX-2 expression result in higher levels of prostaglandin E(2) (PGE(2)), which in turn increases CYP19 expression through increases in intracellular cyclic AMP levels and activation of promoter II. Thus, PGE(2) produced via COX may act locally in paracrine and autocrine fashion to increase the biosynthesis of estrogen by aromatase in hormone-dependent breast cancer development.

PMID: 16712450 [PubMed - in process]