miR-451 inhibits invasion and proliferation of bladder cancer by regulating EMT.

MicroRNAs (miRNAs) have recently been reported play a crucial role in some tumors. In order to investigate the association of miR-451 with bladder cancer, we investigate the expression of miR-451 in bladder cancer tissues and its role in biological behavior of T24, 5637 and J28 bladder cancer cell lines. Quantitative RT-PCR results showed miR-451 was significantly down-regulated in bladder cancer tissues and paracancerous tissues compared with normal bladder tissues. miR-451 expression was significantly associated with histological differentiation degree and TNM stage. Over-expression of miR-451 was established by transfecting miR-451 mimics into T24, 5637 and J28 cells, and its effects on the biological behavior of bladder cancer were studied using transwell assay, migration assay, adhesion assay, MTT and flow cytometry. Results indicated over-expression of miR-451 significantly inhibited cell proliferation, migration, invasion and induced apoptosis of the bladder cancer cells. Furthermore, we investigated the expression level of EMT related proteins in transfected 5637 cells by western blot. Results shown E-cadherin was up-regulated more significantly than N-cadherin, vimentin and Snail. N-cadherin and vimentin were up-regulated significantly when miR-451 was inhibited in miR-451 inhibitor group, however, no significant changes in mimics group. In conclusion, miR451 should be a tumor-suppressing gene in bladder cancer. miR-451 could maintain the bladder tumor cells in epithelial phenotype, inhibit EMT process, thereby reducing the invasion and migration of tumor cells.