278 Androgen receptor positive stromal cells regulate prostate cancer proliferation through noncanonical Wnt signaling

Abstract

INTRODUCTION AND OBJECTIVES: The Wnt signaling pathway (canonical and non-canonical) regulates crucial aspects of embryonic development. Previously, we have reported that non-canonical Wnt members promote proliferation of cancer cells by increasing secretion of growth factors and expression of cancer related genes. We have also demonstrated that Wnt5a is predominantly expressed in prostatic stromal cells and plays a key role in stromalepithelial communication and in the development of prostate cancer. The purpose of this study is to reveal the relation between the noncanonical Wnt signaling and AR signaling on prostate. METHODS: Prostate tissue samples were obtained from patients undergoing radical prostatectomy or cystectomy for prostate and bladder cancer respectively. Cells, representing the cancer, stromal from around the cancer, as well as epithelium and stromal from pathologically normal tissues were isolated by laser capture microdissection Stromal cells (WPMY1 and PrSC) were cultured with DHT ligand and protein. The mRNA levels of Wnt5a, AR, and PSA were determined in both sample types. Wnt5a-knockdown in WPMY1 cells (shWnt5a) along with a vector control (shCTL) was performed and effects on growth evaluated by MTT assay. The cells were co-cultured with PC3 cells, and the mRNA expression of AR was evaluated. A DNA fragment upstream of the Wnt5a gene was inserted into pGL4.17 a vector and the luciferase activity representing Wnt5a inductionby DHT was measured. RESULTS: Wnt5a mRNA expression was prediminanly in the stromal cells of the human prostate samples and the expression levels observed were in proportion to PSA mRNA expression levels. DHT increased production of AR as well as PSA and Wnt5a mRNA expression in both WPMY1 and PrSC cells. Wnt5 knockdown decreased the proliferation of WPMY1cells by 50% compared to shCTR. Co-culture of PC3 cells and WPMY1shWnt5a formed fewer and smaller sized colonies than co-culture of PC3 cells and WPMY1shCTR. AR and PSA mRNA expression levels were remarkably lower in WPMY1shWnt5a than in the control. DHT ligand dramatically increased the luciferase activity of Wnt5a promoter in WPMY1 cells. CONCLUSIONS: The AR is expressed not only in prostatic epithelium but also prostatic stromal as measured by their response to DHT. In stromal cells, The studies presented here demonstrated an interplay between AR signaling and Wnt5a that appears to modulate the proliferation of prostate cancer cells providing further support for the importance of Wnt5a in the regulation of prostate cancer.