Indolol-3-cabinol and genistein inhibit growth of human uterine leiomyoma cells

Abstract

Indole-3-carbinol (I3C) is a phytochemical that has been documented in numerous epidemiological and preclinical studies to possess preventive properties of mammary cancer. I3C is also promising agents for the prevention of estrogen-enhanced cancers. Genistein is one of the predominant isoflavones found in soy, and it has been documented that it produces cell cycle arrest and apoptosis in a variety of cells. The purpose of this study was to determine whether I3C can enhance the inhibitory effect of genistein on a human uterine leiomyoma cells. The effect of I3C and genistein on cell proliferation and cell cycle progression was examined in the human uterine leiomyoma cells. MTS reduction assay was carried out to determine the viability of human uterine leiomyoma cells. Cell cycle analysis for I3C and genistein treated human uterine leiomyoma cells was done by Fluorescent activated cell sorter analysis. Western blot analysis was done using anti-p27, anti-p21, anti-p53, anti-cyclin E, anti-cyclin A, anti-cyclin D1, anti-cyclin B1, and anti CDK2 antibodies to detect the presence and expression of these proteins in the treatment with I3C and genistein. I3C and genistein induced growth inhibition in a dose dependent manner, treatment with 100 ㎛ol/L I3C and 100 ㎛ol/L genisten blocked 60% cell growth. FACS results showed that treatment with the I3C and genistein increased the percentage of cells in G2/M phase. From Western blot analysis it revealed I3C and genistein induced the expression of p53, p21, and p27 increasing. Reduced expression of cyclin B1 and cyclin E were detected in treatment with I3C and genistein. The expression levels of these proteins correlate with G2/M cell cycle arrest. Activation of caspase pathway and fragmentation of PARP did not take place. These results demonstrate that I3C enhances genistein-mediated uterine leiomyoma cell growth inhibition through the cell cycle arrest at G2/M phase by decreasing the production of cyclin B1. Because of the synergistic effect of I3C and genistein, the potential exists for the prophylactic or therapeutic efficacy of lower concentrations of each phytochemical when used in combination.