The role of soy on breast cancer risk and survival

[Barbara2]

http://ww5.komen.org/Content.aspx?id...id=emklmar10:5

[Rich66]

A message that keeps getting lost is how this issue plays out differently in ER+/HER2+ BC. And the fact that HER2 and ER status can change should keep this an area of caution.



Carcinogenesis. 2010 Jan 12. [Epub ahead of print]
Genistein Induces Enhanced Growth Promotion in ER Positive/erbB-2 Overexpressing Breast Cancers by ER-erbB-2 crosstalk and p27/kip1 Downregulation.

Yang X, Yang S, McKimmey C, Liu B, Edgerton S, Bales W, Archer L, Thor AD.
Department of Pathology, University of Oklahoma Health Sciences Center.
Genistein is a major isoflavone with known hormonal and tyrosine kinase modulating activities. Genistein has been shown to promote the growth of estrogen receptor (ER) positive MCF-7 cells. In ER negative/erbB-2 overexpressing cells, genistein has been shown to inhibit cell growth through its tyrosine kinase inhibitor activity. The effects of genistein on cell growth and tamoxifen response in ER positive/erbB-2 altered breast cancers (known as luminal type B and noted in approximately 10-20% of breast cancers) have not been well explored. Using erbB-2 transfected ER+ MCF-7 cells, we found that genistein induced enhanced cellular proliferation and tamoxifen resistance when compared to control MCF-7 cells. These responses were accompanied by increased phosphorylation of ERalpha and ER signaling, without increase in ER protein levels. Genistein treated MCF-7/erbB-2 cells also showed enhanced activation/phosphorylation of erbB-2, Akt and MAPK/Erk. Blockade of the PI3K and/or MAPK pathways abrogated genistein induced growth promotion, suggesting that genistein effects involve both critical signaling pathways. We also found that p27/kip1 was markedly downregulated in genistein treated MCF-7/erbB-2 cells. Overexpression of p27/kip1 attenuated genistein mediated growth promotion.



In aggregate, our data suggest that the concomitant co-expression of ER and erbB-2 makes breast cancers particularly susceptible to the growth promoting effects of genistein across a wide range of doses. The underlying mechanisms involve enhanced ER-erbB-2 crosstalk and p27/kip1 downregulation.

PMID: 20067990 [PubMed - as supplied by publisher]

[Laurel]

Thanks for the reminder, Rich, from a triple pos gal.

[Rich66]

Um hmm. How's that coffee embargo going, miss triple pos? Still working the superstition angle?

[v-ness]

i'm willing to bet there are a thousand other dietary reasons why women in less industrialized areas of Asia are getting less breast cancer than us in the U.S. and none of it has to do with how much soy they're eating. a couple chapters into the book 'ANTI-cancer' is all it took (not that i care to eat soy anyway). valerie

[ElaineM]

There is something to be said about Asian women and soy. They eat much more of it than most Western women. Studies have been done on Asian women who moved to the West and switched to a Western diet. I think that study determined that Asian women started getting more cancer after they changed to a Western diet.
As far as I am concerned I do everything in moderation.
I became a vegetarian, so I don't eat anything with a face, and that includes chicken. I get all my protein from vegetable sources like various kinds of beans, grains, vegetables and small amounts of soy products. However, I do eat yoghurt and an occassional egg.
I lost weight on a vegetarian diet, especially after I reduced the amount of cheese I eat. My estrogen levels did not increase. They decreased. I read that estrogen can be stored in body fat. After the weight loss there was less fat to store the estrogen in my body. My cholesterol also decreased without medications.
There is still room for improvement in my diet, so I try to make adjustments whenever I can.