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.
Imhof
Marianne
M
Center of Private Clinic and Clinical Studies MED 19, Armbrustergasse 1, Vienna, Austria.
Molzer
Sylvia
S
Imhof
Martin
M
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