Induction of apoptosis in breast cancer cells MDA-MB-231 by genistein

Breast cancer is the most common cancer among American women, whereas Asian women, who consume a traditional diet high in soy products, have a relativ ely low incidence, Genistein is a prominent isoflavonoid in soy products an d has been proposed as the agent responsible for lowering the rate of breas t cancer in Asian women. We investigated the effects of genistein on cell g rowth and apoptosis-related gene expression in breast cancer cells MDA-MB-2 31. We found upregulation of Bar and p21(WAF1) expressions and downregulati on of Bcl-2 and p53 expression in genistein-treated cells. Furthermore, DNA ladder formation, CPP32 activation, and PARP cleavage were observed after treatment with genistein, indicating apoptotic cell deaths. Flow cytometry with 7-amino actinomycin D staining showed that the number of apoptotic cel ls increased with longer treatment of genistein. From these results, we con clude that genistein inhibits the growth of MDA-MB-231 breast cancer cells, regulates the expression of apoptosis-related genes, and induces apoptosis through a p53-independent pathway. The up-regulation of Bar and p21(WAF1) may be the molecular mechanisms by which genistein induces apoptosis, howev er, further definitive studies are needed. These results suggest that genis tein may be a potentially effective chemopreventive or therapeutic agent ag ainst breast cancer.