Phytoestrogens Inhibiting Androgen Receptor Signal and Prostate Cancer Cell Proliferation

• Published in: Chemical research in Chinese universities 2013-10, Vol.29 (5), p.911-916
• Main Authors: Wu, Jing, Liu, Shu, Shen, Xiao-yan, Yang, Nan-yang, Liu, Ying, Tsuji, Ichiro, Yamamura, Takaki, Li, Jiang, Li, Xiao-meng
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Inorganic Chemistry; LNCaP细胞; Organic Chemistry; Physical Chemistry; 信号功能; 免疫印迹分析; 免疫荧光分析; 前列腺癌; 植物雌激素; 细胞增殖; 雄激素受体
• ISSN: 1005-9040; 2210-3171
• DOI: 10.1007/s40242-013-3123-6

The androgen receptor（AR） signaling activated by dihydrotestosterone（DHT） plays critical roles in pros- tate cancer development and progression. Phytoestrogens, which are diphenolic compounds with estrogen and an- ti-estrogen effects, can bind to estrogen receptors. However, their function on AR signaling has not been fully eluci- dated. In this study, dual-luciferase reporter assay, immunobloting, docking system test, MTT assay, immunofluores- cence and chromatin immunoprecipitation（ChlP） assays were employed to examine the potential effects of three phytoestrogens（genistein, daidzein, flavone） on DHT-activated prostate specific antigen（PSA） activation, cell proli- feration and AR transactivation in lymph node carcinoma of prostate（LNCaP） cells. Phytoestrogens were detected to down-regulate DHT-activated AR-mediated PSA promoter transactivation by dual-luciferase reporter system. Fur- thermore, three phytoestrogens, especially genistein, were demonstrated to significantly decrease AR-activated PSA protein expression by Western blotting analysis. MTT experiment proves that phytoestrogens, especially genistein, remarkably inhibits the DHT-indueed cell proliferation in LNCaP cells. To provide reasonable explanations for expe- rimental phenomena mentioned above, we did docking system test and detected phytoestrogens to share the same AR-binding site with DHT. To further prove the competition between phytoestrogen and DHT on AR binding, we examined the effects of phytoestrogens on DHT-activated AR nuclear translocation and immunofluorescence analysis which confirms that phytoestrogens, especially genistein, inhibit DHT-activated androgen receptor nuclear transloca- tion. Results from ChIP show that phytoestrogens down-regulate DHT-induces AR binding to the androgen response elements（AREs, including AREI, AREII, and AREIII） in PSA promoter. Genistein remarkably down-regulates AR, binding to the AREI located in -250---39 bp and AREIII in --4170---3978 bp in the presence of DHT. In general, three phytoestrogens were identified to inhibit DHT-AR binding by competitively binding to AR and inhibit AR-mediated transactivation. And genistein shows the strongest effects among three phytoestrogens. Our findings confirm that phytoestrogens are AR antagonist in the regulation of AR-related PSA activation and cell proliferation, which provides valuable insights into the treatment of prostate cancer.