Selective estrogen receptor modulators regulate stromal proliferation in human benign prostatic hyperplasia by multiple beneficial mechanisms--action of two new agents.

The existing drugs for benign prostatic hyperplasia (BPH) are partially effective with undesirable side-effects; hence new agents acting by different mechanism(s) are required as supplements. Modulation of estrogen receptor signaling using selective estrogen receptor modulators (SERMs) offers an alternative approach for BPH management. Using human BPH-derived stromal cells and tissue explants in culture we evaluated two SERMs, DL-2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2 H-1-benzopyran (BP) and Ormeloxifene (Orm) in comparison to Tamoxifen (Tam) and 4-hydroxytamoxifen (OHT). BP, OHT and Tam were more effective than Orm in reducing stromal cell proliferation of human BPH. BP was either equipotent or more effective than OHT and Tam in increasing estrogen receptor(ER)-ß, TGFß1, Fas and FasL, and in decreasing ER-α, AR, EGF-R and IGF-I expressions in BPH stromal cells. BP, Tam and Orm (1.0 mg/Kg) reduced rat prostate weights by almost same extent as Finasteride (Fin, 5.0 mg/Kg); however combination treatment (SERM+Fin) was more effective. BP was exceptionally efficient in reducing IGF-1 and cleaving PARP while combination treatments more effectively increased bax:bcl-2 ratio. Fin reduced acinar diameter and prostatic DHT level but increased testosterone, estradiol (E(2)) and E(2)/T+DHT ratio. SERMs, especially BP, reduced epithelial cell height drastically without significantly altering steroid hormone levels and E(2)/T+DHT ratio. Combination treatment reduced both acinar diameter and epithelial cell height with modest increase in E(2), T and E(2)/T+DHT. The study reveals the potential of SERMs per se for BPH management, and more effectively in combination with a 5α-reductase inhibitor. BP appears promising for further evaluation as a drug candidate for BPH and prostate cancer.

Synergistic chemoprotective mechanisms of dietary phytoestrogens in a select combination against prostate cancer.

Combination of dietary phytoestrogens with diverse molecular mechanisms may enhance their anticancer efficacy at physiological concentrations, as evidenced in epidemiological studies. A select combination of three dietary phytoestrogens containing 8.33 µM each of genistein (G), quercetin (Q) and biochanin A (B) was found to be more potent in inhibiting the growth of androgen-responsive prostate cancer cells (LNCaP) as well as DU-145 and PC-3 prostate cancer cells in vitro than either 25 µM of G, B or Q or 12.5+12.5 µM of G+Q, Q+B or G+B. Subsequent mechanistic studies in PC-3 cells indicated that the action of phytoestrogens was mediated both through estrogen receptor (ER)-dependent and ER-independent pathways as potent estrogen antagonist ICI-182780 (ICI, 5 µM) could not completely mask the synergistic anticancer effects, which were sustained appreciably in presence of ICI. G+Q+B combination was significantly more effective than individual compounds or their double combinations in increasing ER-ß, bax (mRNA expression); phospho-JNK, bax (protein levels); and in decreasing bcl-2, cyclin E, c-myc (mRNA expression); phospho-AKT, phospho-ERK, bcl-2, proliferating cell nuclear antigen (protein levels) in PC-3 cells. Phytoestrogens also synergistically stimulated caspase-3 activity. Our findings suggest that selectively combining anticancer phytoestrogens could significantly increase the efficacy of individual components resulting in improved efficacy at physiologically achievable concentrations. The combination mechanism of multiple anticancer phytochemicals may be indicative of the potential of some vegetarian diet components to elicit chemopreventive effects against prostate cancer at their physiologically achievable concentrations, in vivo.