Synergistic Effect of Bioactive Anticarcinogens from Soybean on Anti-Proliferative Activity in MDA-MB-231 and MCF-7 Human Breast Cancer Cells In Vitro

Consumption of soybean products has been implicated in the prevention of breast cancer. This study provides insights into the anti-proliferative activity of 12 anticarcinogens from soybean by single or two-way combination treatment against MCF-7 and MDA-MB-231 human breast cancer cells. Results showed that genistein, daidzein, glycitein, genistin and dainzin showed stronger anti-proliferative activity against MCF-7 cells with EC50 values of 66.98 +/- 4.87 mu M, 130.14 +/- 2.10 mu M, 190.67 +/- 5.65 mu M, 72.82 +/- 2.66 mu M and 179.21 +/- 6.37 mu M, respectively. There is a synergistic effect of combination treatment of genistin plus daidzin in MCF-7 cells with combination index at inhibition of 50% (CI50) of 0.89 +/- 0.12. Genistein, glycitein, genistin and beta-sitosterol were demonstrated to have a stronger anti-proliferative activity against MDA-MB-231 cells with EC50 values of 93.75 +/- 5.15 mu M, 142.67 +/- 5.88 mu M, 127.82 +/- 4.70 mu M and 196.28 +/- 4.45 mu M. The synergistic effect was observed in the mixture of genistein plus genistin, genistein plus beta-sitosterol or beta-sitosterol plus genistin with CI50 values of 0.56 +/- 0.13, 0.54 +/- 0.20 and 0.45 +/- 0.12, respectively. These bioactive anticarcinogens were able to inhibit invasion and migration of breast cancer cells and the combination treatments enhanced the inhibitory effect. Regulation of PI3K/Akt/mTORpathway seems to be the main mechanisms involved in the anticancer activity.