CDK3 is a major target of miR-150 in cell proliferation and anti-cancer effect.

MiR-150, a member of small non-coding RNAs, has been proven to dysregulate in different types of tumor and bear on carcinogenesis and cancer prognosis by regulating the expression of a series of gene including utrophin. Given that utrophin can compensate for dystrophin's absence and be regarded as a promising therapeutic target for Duchenne Muscular Dystrophy (DMD), we further detected the deep role of miR-150 in dystrophic muscle. Using a range of bioinformatic, molecular and cell biology techniques, we declared that miR-150 directly targets cyclin-dependent kinase 3 (CDK3) and leads to the regulation of CDK3 gene expression in both muscle-derived and non-muscle cells. The results indicated the expression of miR-150 was upregulated in mdx muscle and closely related to the lower level of CDK3. Transient transfection of miR-150 into cultured C2C12 cells led to significant decrease in cell proliferation, which is partly mediated via the 3'-UTRs of CDK3 mRNA. Targeting of CDK3 could also play a role, at least in part, in the anti-cancer activity suggested for miR-150 in previous studies. Consistently, the analysis of tumor and matched normal lung tissues indicates that miR-150 downregulation in lung tumors correlates with higher CDK3 levels. In addition, miR-150 transfection experiments with cancer-derived cell lines reveal that miR-150-mediated CDK3 suppression directly induces to growth inhibition. Collectively, our results highlight a novel activity for CDK3 in myoblast cell proliferation and confirm CDK3 as a key target that further enhances the tumor suppressor function proposed for miR-150.