Differential effects of broccoli bioactives on growth of human prostate and ovarian cancer cells at physiologically relevant doses

Abstract

The broccoli-derived bioactives sulforaphane (SF) and indole-3-carbinol (I3C) have been shown to inhibit growth of human prostate and ovarian cancer cells through multiple mechanisms, including induction of apoptosis and cell cycle arrest, increased chemosensitization, and reduced hormone responsiveness. However, most studies were conducted using concentrations that may not be reached in the plasma after oral administration. Exposure of human prostate LNCaP and ovarian OVCAR-3 cells to physiologically relevant doses of SF (1.25 – 5.0 μM) resulted in a dose-dependent inhibition of cell growth. In contrast, I3C (0.125 – 0.5 μM) did not affect cell growth. Combination treatment of SF and I3C at a ratio reflective of that in broccoli extract did not result in greater inhibition of cell growth than SF alone. These results support a hypothesis that SF, but not I3C, when provided in the diet as broccoli, slows prostatic and ovarian tumor growth. Supported by a grant from USDA/NRI 2009-02961.