Resveratrol, a natural polyphenolic phytochemical, has been reported to act as an antioxidant and provide anticancer activities. We hypothesized that resveratrol would exert a chemopreventive effect against prostate cancer via regulation of sex steroid receptor and growth factor signaling pathways. In the current study, Transgenic Adenocarcinoma Mouse Prostate males were fed resveratrol (625 mg resveratrol per kg AIN-76A diet) or phytoestrogen-free, control diet (AIN-76A) starting at 5 weeks of age. Mechanisms of action and histopathology studies were conducted at 12 and 28 weeks of age, respectively. Resveratrol in the diet significantly reduced the incidence of poorly differentiated prostatic adenocarcinoma by 7.7-fold. In the dorsolateral prostate, resveratrol significantly inhibited cell proliferation, increased androgen receptor, estrogen receptor-beta, and insulin-like growth factor-1 receptor, and significantly decreased insulin-like growth factor (IGF)-1 and phospho-extracellular regulating kinase 1 (phospho-ERK 1). In the ventral prostate, resveratrol significantly reduced cell proliferation and phospho-ERKs 1 and 2, but did not significantly alter insulin-like growth factor-1 receptor and IGF-1. Serum total testosterone, free testosterone, estradiol, dihydrotestosterone and sex hormone-binding globulin (SHBG) concentrations and Simian Virus-40 large T antigen expression in the prostate were not altered in resveratrol-treated mice. Total resveratrol concentration in the blood serum of 12-week-old mice treated for 3 weeks with 625 mg resveratrol per kg diet was 52 +/- 18 nM. The decrease in cell proliferation and the potent growth factor, IGF-1, the down-regulation of downstream effectors, phospho-ERKs 1 and 2 and the increase in the putative tumor suppressor, estrogen receptor-beta, provide a biochemical basis for resveratrol suppressing prostate cancer development.

The attenuation of the AR, the down-regulation of potent growth factor IGF-1, modulation of inflammation biomarkers, and decrease in the MAPK signaling may contribute to the reduction in cell proliferation and induction of apoptosis and hence provide a biochemical basis for EGCG suppressing PCa without toxicity.

Background Chemoprevention utilizing dietary agents is an effective means to slow the development of prostate cancer. We evaluated the potential additive and synergistic effects of genistein and resveratrol for suppressing prostate cancer in the Simian Virus-40 T-antigen (SV-40 Tag) targeted probasin promoter rat model, a transgenic model of spontaneously developing prostate cancer. Methods Rats were fed genistein or resveratrol (250 mg/kg AIN-76A diet) alone and in combination, and a low dose combination (83 mg genistein + 83 mg resveratrol/kg diet). Histopathology and mechanisms of action studies were conducted at 30 and 12 weeks of age, respectively. Results Genistein, resveratrol, and the high dose combination treatments suppressed prostate cancer. The low dose combination did not elicit protection against prostate cancer and was most likely below the effective dose for causing significant histopathological changes. Total genistein and resveratrol concentrations in the blood reached 2160 and 211 nM, respectively in rats exposed to the single treatments. Polyphenol treatments decreased cell proliferation and insulin-like growth factor-1 (IGF-1) protein expression in the prostate. In addition, genistein as a single agent induced apoptosis and decreased steroid receptor coactivator-3 (SRC-3) in the ventral prostate (VP). Conclusions Genistein and resveratrol, alone and in combination, suppress prostate cancer development in the SV-40 Tag model. Regulation of SRC-3 and growth factor signaling proteins are consistent with these nutritional polyphenols reducing cell proliferation and increasing apoptosis in the prostate.

Background: Prostate cancer is the second most frequently diagnosed cancer in men. Animal models that closely mimic clinical disease in humans are invaluable tools in the fight against prostate cancer. Recently, a Simian Virus-40 T-antigen (SV-40 Tag) targeted probasin promoter rat model was developed. This model, however, has not been extensively characterized; hence we have investigated the ontogeny of prostate cancer and determined the role of sex steroid receptor and insulin-like growth factor-1 (IGF-1) signaling proteins in the novel SV-40 Tag rat.

No abstract