Plant compounds protect from prostate cancer via an ER.αdependent mechanism

Prostate cancer risk may be reduced by consuming components of plants with antioxidant (polyphenols) or estrogenic(isoflavones) activity. The transgenic adenoma of the mouse prostate (TRAMP) model mimics the human disease. We crossed TRAMP mice with estrogen receptor alpha knockout (ERαKO) mice to generate ERα/TRAMP, or wildtype (WT)/TRAMP. Trial 1 mice were fed an AIN93G casein diet with or without 250 mg genistein/kg. After 5 months cancer was inhibited by genistein but only in WT/TRAMP. Trial 2 diets contained mixtures of 7 pure compounds; Diet 1: curcumin, resveratrol and EGCG; Diet 2: genistein, baicalein, apigenin and quercetin; Diet 3: all 7 compounds and Diet 4: casein. The plant compound mixtures (Diets 1, 2 and 3) inhibited cancer compared to casein but only in the WT/TRAMP mice. In Trial 3 we used only WT/TRAMP mice fed casein or a mixture of 7 herbs: tumeric, yucca root, sencha leaves, Novasoy, gingko biloba, chamomile, and saw palmetto. Cancer was inhibited in mice fed the herb mixture compared to casein. Hence, plant polyphenols and isoflavones protect from prostate cancer via an ERα-dependent mechanism.