MiR-211 is epigenetically regulated by DNMT1 mediated methylation and inhibits EMT of melanoma cells by targeting RAB22A.

MiR-211 has strong inhibitive effects on melanoma cell growth, invasion and metastasis. However, how it is downregulated and whether other genes are involved its downstream regulation in melanoma are not clear. In this study, we firstly verified the expression of miR-211 in melanoma cell lines and observed that its downregulation is associated with increased DNMT1 expression. By performing qRT-PCR and MSP analysis, we confirmed that DNMT1 is negatively correlated with miR-211 expression and can modulate DNA methylation in the promoter region of miR-211. By performing bioinformatics analysis, we found that RAB22A is a possible target of miR-211, which has two broadly conversed binding sites with miR-211 in the 3'UTR. Following dual luciferase assay, qRT-PCR and western blot analysis confirmed the direct binding between miR-211 and RAB22A and the suppressive effect of miR-211 on RAB22A expression. Knockdown of RAB22A increased epithelial properties and impaired mesenchymal properties of the melanoma cells, suggesting that miR-211 modulates epithelial mesenchymal transition (EMT) of melanoma cells via downregulating RAB22A. In summary, the present study firstly demonstrated that DNMT1 mediated promoter methylation is a mechanism of miRNA suppression in melanoma and revealed a new tumor suppressor role of the miR-211 by targeting RAB22A in melanoma. The DNMT1/miR-211/RAB22A axis provides a novel insight into the pathogenesis of melanoma, particularly in the EMT process.