MiR-194 inhibits cell proliferation and invasion via repression of RAP2B in bladder cancer.

Bladder cancer is the 7th most common cancer type in the world, and microRNAs (miRNAs) play important roles in cancer progression. In the present study, we investigated the roles and molecular mechanisms of miR-194 in bladder cancer. The results demonstrated that the expression level of miR-194 is significantly down-regulated in bladder cancer cell lines and clinical tissues. Overexpression of miR-194 inhibited cell proliferation and invasion in J82 and T24 cells. Further mechanistic study showed that overexpression of miR1-94 induced G0/G1 phase arrest as well as apoptosis in J82 and T24 cells. In addition, by using bioinformatics tool (Targetscan), RAP2B is found to be a target of miR-194, and miR-194 down-regulates the expression level of RAP2B via directly targeting its 3'UTR. Knockdown of RAP2B also inhibited cell proliferation and invasion in J28 cells. More importantly, restoration of RAP2B activity rescued the inhibitory effects of miR-194 on cell proliferation and invasion in J82 cells. Further analysis of bladder cancer clinical samples showed that miR-194 is inversely correlated with RAP2B. Collectively, our study may implicate that miR-194 plays an important role in the regulation of bladder cancer progression. In summary, our study may implicate that miR-194 acts as a tumor suppressor and plays an important role in the regulation of bladder cancer progression.