MicroRNA-449a acts as a tumor suppressor in human bladder cancer through the regulation of pocket proteins.

Frequent downregulation of microRNA-449a (miR-449a) was detected in 14 human bladder cancer tissues. The restoration of miR-449a inhibited cell growth and induced G1-phase arrest in T24 and 5637 human bladder cancer cells. CDK6 and CDC25a were downregulated after miR-449a treatment, resulting in the functional accumulation of the pocket proteins Rb and p130. The growth of T24 tumor xenografts was suppressed by exogenous miR-449a, and the nuclear proliferation antigen Ki-67 was downregulated in miR-449a-treated tumors. These results suggest a tumor-suppressive role for miR-449a in human bladder cancer.