17α-Estradiol and Genistein Inhibit High Fat Diet Induced Prostate Gene Expression and Prostate Growth in the Rat

Purpose: High dietary fat and low phytoestrogen intake are associated with prostate cancer development and progression. Our previous study showed that exposure to a high fat diet significantly increased prostate 5 alpha-reductase-2 mRNA and prostate growth in the rat. In the current experiments we determined the effects of genistein and 17 alpha-estradiol on the modulation of dietary fat induced prostate 5 alpha-reductase-2 and insulin-like growth factor-1 gene expression, and prostate growth. Materials and Methods: At weaning male ACI/Seg rats (Harlan (R) Sprague-Dawley (R)) were fed a low or a high fat diet, with or without genistein or 17 alpha-estradiol for 2, 4 or 10 weeks. The prostate was dissected and weighed. We determined the levels of prostate 5 alpha-reductase-2 mRNA, insulin-like growth factor-1 mRNA, dihydrotestosterone, and plasma insulin-like growth factor-1, dihydrotestosterone and testosterone. Results: Two-week exposure to a high fat diet significantly increased prostate insulin-like growth factor-1 mRNA without significant changes in plasma insulin-like growth factor-1, which was blocked by genistein and 17 alpha-estradiol. Genistein but not 17 alpha-estradiol also inhibited prostate 5 alpha-reductase-2 mRNA and intraprostatic dihydrotestosterone induced by the high fat diet at 2 weeks. Genistein and 17 alpha-estradiol completely blocked high fat diet induced prostate growth at 10 weeks of dietary treatment. However, neither genistein nor 17 alpha-estradiol had any significant effect when co-administered with the low fat diet. Conclusions: Results indicate that genistein and 17 alpha-estradiol can inhibit dietary fat induced changes in prostate 5 alpha-reductase-2 and insulin-like growth factor-1 gene expression, and prostate growth in the rat. This may be beneficial to prevent dietary fat associated prostate diseases such as prostate cancer.