MicroRNA (miR) dysregulation alters cancer-associated gene expression, which contributes to cancer pathogenesis. For example, miR-186 over expression lead to enhanced proliferation and migration in pancreatic cancer cell models. However, the role of miR-186 in prostate cancer (PCa) remains controversial. Previously, miR-186-5p was up-regulated in PCa patient serum (stage III/IV) compared to controls. Furthermore, miR-186-5p was up-regulated in metastatic PCa (PC-3, MDA PCa 2b, LNCaP) relative to normal prostate epithelial cells (RWPE1). We hypothesized miR-186 inhibition will reduce aggressive PCa using metastatic cell models. To test this, we evaluated whether miR-186-5p inhibition would reduce aggressive PCa behavior and overexpression induce malignant transformation in normal cells. Cell proliferation (BrdU incorporation), invasion (reduced growth factor matrigel), colony formation (soft agar) and cell death (trypan blue exclusion) were examined in miR-186-5p inhibited PCa cells (PC-3, MDA PCa 2b) and overexpressed RWPE1 cells. Aberrant gene expression was evaluated in stable PC-3 and RWPE1 cells to identify miR-186 candidate targets via microarray and qRT-PCR analyses using published reports, miR databases and statistical filtering (FDR p-value ≤ 0.05 and ±1.2 fold change). MiR-186-5p inhibition reduced proliferation (27-46%) in PCa (PC-3, MDA PCa 2b), cellular invasion (66%) in PC-3 cells and anchorage independent growth (28-64%) in PC-3 cells and post-DHT (10 nM) treatment in MDA PCa 2b cells. Over 2,343 genes were differentially expressed in stably miR-186 inhibited PC-3 and overexpressed RWPE1 cells relative to controls. Out of 23 selected candidates, AKAP12 gene and protein was up-regulated in miR-186-5p inhibited PC-3 cells. MiR-186-5p overexpression decreased AKAP12 protein in HEK 293T cells. Additional in vitro as well as in vivo studies are needed to further elucidate the role of additional targets in PCa. Ultimately, the identification of novel biomarkers may improve detection and effective treatment of aggressive PCa.