Abstract 1934: MicroRNA-383 located in frequently deleted chromosomal locus 8p22 regulates prostate cancer stem cell marker CD44

Abstract

Abstract A major genomic alteration in prostate cancer (PCa) is frequent loss of chromosome (chr) 8p with a common region of loss of heterozygosity (LOH) at chr8p22 locus. Genomic studies implicate this locus in the initiation of clinically significant PCa and with progression to metastatic disease. However, the genes within this region have not been fully characterized to date. Here we demonstrate for the first time that a microRNA component of this region -miR-383- is frequently downregulated in prostate cancer, plays a critical role in determining tumor initiating potential and is involved in prostate cancer metastasis via direct regulation of CD44, a ubiquitous marker of PCa tumor initiating cells (TICs)/ stem cells. Expression analyses of miR-383 in PCa clinical tissues established that low miR-383 expression is associated with poor prognosis. Functional data suggests that miR-383 regulates PCa tumor initiating/ stem-like cells via CD44 regulation. Ectopic expression of miR-383 inhibited tumor initiating capacity of CD44+ PCa cells. Also, ‘anti-metastatic’ effects of ectopic miR-383 expression were observed in a PCa experimental metastasis model. In view of our results, we propose that frequent loss of miR-383 at chr8p22 region leads to tumor initiation and prostate cancer metastasis. Thus, we have identified a novel finding that associates a long observed genomic alteration to PCa stemness and metastasis. Our data suggests that restoration of miR-383 expression may be an effective therapeutic modality against PCa relapse and metastasis. Importantly, we identified miR-383 as a novel PCa diagnostic biomarker with potential that outperforms that of serum PSA. Citation Format: Nathan Bucay, Kiran Sekhon, Varahram Shahryari, Yozo Mitsui, Guoren Deng, Z. Laura Tabatabai, Shahana Majid, Soichiro Yamamura, Rajvir Dahiya, Yuichiro Tanaka, Sharanjot Saini. MicroRNA-383 located in frequently deleted chromosomal locus 8p22 regulates prostate cancer stem cell marker CD44. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1934.