Effects of soy isoflavones on 17beta-estradiol-induced proliferation of MCF-7 breast cancer cells.
Based on the results of in vitro-experiments in practically estrogen-free media and in the absence of estrogen-beta receptors, soy isoflavones have been suspected to enhance proliferation of MCF-7 breast cancer cells. In this study the effects of soy isoflavones on MCF-7 cells were investigated in the presence and absence of estrogen, directly and in a metabolized form by testing sera of postmenopausal women supplemented with isoflavones. First, three concentrations of isoflavones (0.1, 1 and 10 mumol/l) were tested at increasing levels of 17-beta-estradiol (<10 pM, 50, 100 and 500 pM). Next, blood sera from women supplemented for two weeks either with 200mg isoflavones or with 2 mg 17-beta-estradiol per day, or the combination of both were investigated in an MCF-7 cell proliferation assay. Further, the samples were screened for changes in gene expression patterns of the MCF-7 cells with Gene Chip arrays. Only at unphysiologically low estrogen levels isoflavones led to minor proliferation-enhancing effects. In contrast, at estradiol levels of >20 pM, isoflavones both tested directly and indirectly (metabolized) revealed significant anti-proliferative effects as well as in the proliferation and the gene chip assay. These findings emphasize the reported advantageous properties of isoflavones for postmenopausal women.
Center of Private Clinic and Clinical Studies MED 19, Armbrustergasse 1, Vienna, Austria.
Marianne
M
Imhof
Sylvia
S
Molzer
Martin
M
Imhof
D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology*; D017698:Postmenopause; D013025:Glycine max / Q000737:chemistry
D004967:Estrogens; D007529:Isoflavones; D004958:Estradiol