Here's another example of how genistein acts an antiestrogen, (which in this case is a good one). But the point being, genistein is in so many phytoestrogens, SOY isoflavones, Fenugreek, PM etc. (crazy, huh?). 
Genistein in the presence of 17beta-estradiol inhibits proliferation of ERbeta breast cancer cells.
A significant decrease in cell proliferation was seen in MDA-MB-231 cells at low concentrations of genistein in the presence of 17beta-estradiol, as compared to genistein alone. In T47D cells, which are known to have a predominance of ERalpha over ERbeta, genistein showed a biphasic cell proliferative response both in the presence and absence of 17beta-estradiol.
CONCLUSIONS:
Our results suggest that in cells with a predominance of ERalpha, genistein acts as an agonist to ERalpha, and in cells with ERbeta alone, genistein most likely acts as an antiestrogen. Our results also suggest that genistein could be useful as a chemotherapeutic agent in premenopausal women with breast cancer of the ERalpha-negative and ERbeta-positive type.
http://www.ncbi.nlm.nih.gov/pubmed/19556829
If anybody is bored,
and wants to do some research 
here's 185 possible ways to improve upon the estrogen receptor binding process, (Could be some new hope in there). 
and of course there's always new paythways to discover. (Ah well, it was a thought). (yup, I know)....there are studies confirming genistein may promote breast cancer too. Seen here:
The binding database
http://www.bindingdb.org/bind/ByPubMed_server.jsp?target=Estrogen%20Receptor%20(ER-alpha)
(Great site)
Genistein in the presence of 17beta-estradiol inhibits proliferation of ERbeta breast cancer cells.
A significant decrease in cell proliferation was seen in MDA-MB-231 cells at low concentrations of genistein in the presence of 17beta-estradiol, as compared to genistein alone. In T47D cells, which are known to have a predominance of ERalpha over ERbeta, genistein showed a biphasic cell proliferative response both in the presence and absence of 17beta-estradiol.
CONCLUSIONS:
Our results suggest that in cells with a predominance of ERalpha, genistein acts as an agonist to ERalpha, and in cells with ERbeta alone, genistein most likely acts as an antiestrogen. Our results also suggest that genistein could be useful as a chemotherapeutic agent in premenopausal women with breast cancer of the ERalpha-negative and ERbeta-positive type.
http://www.ncbi.nlm.nih.gov/pubmed/19556829
If anybody is bored,
and wants to do some research here's 185 possible ways to improve upon the estrogen receptor binding process, (Could be some new hope in there). and of course there's always new paythways to discover. (Ah well, it was a thought). (yup, I know)....there are studies confirming genistein may promote breast cancer too. Seen here: (20-08-2014, 12:26 AM)Lotus Wrote:(19-08-2014, 10:08 PM)Lotus Wrote: Everyone should read this about Genistein, (one of phytoestrogens in PM and other products).
Also note that increased consumption of soy products reduces plasma concentrations of estradiol.
Genistein: does it prevent or promote breast cancer?
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1638285/pdf/envhper00309-0057.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1638285/?page=1
From pg. 702 Possible Anti-Estrogenic Effects of Genistein
Genistein has significant estrogenic properties in both in vitro and in vivomodels (Table1). Genistein binds to the estrogen receptor(ER), although its binding affinity is several-fold weaker than that of estradiol(30). Genistein can also activate a number of estrogen-responsive genes in vitro, including pS2 and c-fos (18,31). Furthermore, when administered at low doses, genistein stimulates the growth of ER-positive(ER+) breast cancer cells (18-20). Findings in other tissue systems support the estrogenicity of genistein. For example, genistein is uterotrophic in a variety of species, resulting in impaired reproductive activity and increases inuterine wet weights.
Phytoestrogens and diseases of the prostate gland.
In particular, soya contains the isoflavone genistein, a compound with many properties which could influence both endocrine and growth factor signalling pathways.
http://www.ncbi.nlm.nih.gov/pubmed/?term=%5B10%5D%09+K%2C+Griffiths%2C+L.+Denis%2C+A.+Turkes%2C+et+al.%2C+“Phytoestrogens+and+Diseases+of+the+Prostate+Gland%2C”+Baillieres+Clinical+Endocrinology+Metabolism%2C+Vol.+12%2C+No.+4%2C+1998%2C+pp.+625-647.+doi%3A10.1016%2FS0950-351X(98)80008-6
The binding database
http://www.bindingdb.org/bind/ByPubMed_server.jsp?target=Estrogen%20Receptor%20(ER-alpha)
(Great site)
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