Molecular effects of soy phytoalexin glyceollins in human prostate cancer cells LNCaP.

Glyceollins are soy-derived phytoalexins that have been proposed to be candidate cancer preventive compounds. The effect of the glyceollins on prostate cancer is unknown. The present study examined the molecular effects of soy phytoalexin, glyceollins, on human prostate cancer cell LNCaP to further elucidate its potential effects on prostate cancer prevention. We found that the glyceollins inhibited LNCaP cell growth similar to that of the soy isoflavone genistein. The growth inhibitory effects of the glyceollins appeared to be due to an inhibition of G1/S progression and correlated with an up-regulation of cyclin-dependent kinase inhibitor 1 A and B mRNA and protein levels. By contrast, genistein only up-regulates cyclin-dependent kinase inhibitor 1A. In addition, glyceollin treatments led to down-regulated mRNA levels for androgen responsive genes. In contrast to genistein, this effect of glyceollins on androgen responsive genes appeared to be mediated through modulation of an estrogen- but not androgen-mediated pathway. Hence, the glyceollins exerted multiple effects on LNCaP cells that may be considered cancer preventive and the mechanisms of action appeared to be different from other soy-derived phytochemicals.