Genistein targets only proliferating but not quiescent cells: Potential therapeutic significance in breast cancer

Phytochemicals are biologically active secondary plant metabolites that could mimic biological activities. In this study genistein isoflavone, a phytochemical present in soy was investigated to determine its effect on the growth of human breast cancer cell line GI-101 and normal breast epithelial cells in vitro. The cells were exposed to varying concentrations of genistein isoflavone for 24 and 48 hour time periods and the effect was determined using post-treatment assays: MTT and Trypan Blue for cell viability; LDH assay for cytotoxicity; Rhodamine 123/Propidium Iodide and Ethidium Bromide/Acridine Orange assays for treatment-induced apoptosis and FAM Poly caspase assay for mechanism of action. The overall results revealed that genistein inhibited cell growth and proliferation through apoptosis in the cells in both time and dose-dependent manner. Normal breast epithelial cells were not significantly affected by genistein at the corresponding dosages. Based on the results obtained, it was concluded that genistein isoflavone could offer therapeutic efficacy in human breast carcinoma without significantly affecting the normal breast epithelial cells.