Differential effect of genistein on transforming growth factor beta 1 expression in normal and malignant mammary epithelial cells.

Our present study demonstrates that the isoflavone genistein exerts a differential response in normal and malignant breast epithelial cells. The addition of genistein results in a dose-dependent increase in TGF-beta 1 mRNA expression in normal human mammary epithelial cells (HMEC) but not in tumor-derived MCF-7 cells. Genistein inhibits the growth and also causes an increase in apoptosis of HMEC. The increased expression of TGF-beta 1 may contribute to the growth inhibitory as well as apoptotic effects of genistein on HMEC.