Effects of phytoestrogens on the activity and growth of primary breast cancer cells ex vivo

Aim To explore the ex vivo effects of phytoestrogens on primary human breast cancer cells. Methods Breast cancer cells were obtained from patients who underwent primary breast cancer surgery, which were treated with 10(-8) M 17 beta-estradiol (E-2), one of three phytoestrogens (genistein, resveratrol and quercetin, 10(-7) M), and a combination of E-2 and one of the three phytoestrogens for 48 h. These cells were then extracted for viability and apoptosis assay. The proteins involved in the proliferative and apoptotic pathways were evaluated by western blot analysis. Results Human breast cancer cell viability was inhibited by all phytoestrogens but induced by E-2 with or without phytoestrogen. Apoptotic cells, as well as the proteins involved in apoptotic pathway and estrogen receptor (ER) beta, were significantly increased in the cells treated with phytoestrogen alone. The use of E-2 with or without a phytoestrogen revealed completely opposite results. The proteins involved in the proliferative pathway and ER alpha expression were all increased in the cultures with E-2 with or without phytoestrogens. Conclusion In the presence of E-2, these phytoestrogens lose the effects of suppressing breast cancer cells; contrastingly, induce growth stimulatory effects by inhibiting apoptosis and stimulating proliferation in primary breast cancer cells. Thus, the effects of phytoestrogens on breast cancer should be considered as E-2 still present in breast cancer tissue.