Induction of apoptosis in MCF-7 cells by indole-3-carbinol is independent of p53 and bax.

The anticancer activity of indole-3-carbinol and the possible mechanisms involved were explored in human breast cancer cell lines MCF-7 and T47D. Treatment with indole-3-carbinol suppressed the growth of MCF-7 and T47D cells. MCF-7 cells were more sensitive to indole-3-carbinol than T47D cells. The growth suppression caused by indole-3-carbinol was found to be partially involved in its ability to induce apoptosis (programmed cell death) in MCF-7 cells. Western blot analysis demonstrated that wild-type p53 was not induced after treatment of MCF-7 cells with indole-3-carbinol. Northern blot analysis showed that treatment of MCF-7 cells with indole-3-carbinol did not affect the expression of bax gene (one of the death genes). In the tissue culture medium, indole-3-carbinol was found to be partially converted to 3,3'-diindolylmethane. The experiments indicated that indole-3-carbinol suppressed MCF-7 cell growth in part by induction of apoptosis which was independent of p53 and bax expression and that the effect caused by indole-3-carbinol was partially due to its conversion to a more potent compound, 3,3'-diindolylmethane, in vitro.