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Oncotarget

KDM4B-mediated epigenetic silencing of miRNA-615-5p augments RAB24 to facilitate malignancy of hepatoma cells.


PMID 27487123

Abstract

Emerging evidence indicates that dysregulation of microRNAs (miRNAs) contributes to hepatocellular carcinoma (HCC) tumorigenesis and development. Here, we found that miR-615-5p was obviously downregulated in HCC. Furthermore, the deficiency of demethylase KDM4B stimulated the CpG methylation of miR-615-5p promoter and then decreased the miR-615-5p expression. The Ras-related protein RAB24 was found to be downregulated by miR-615-5p. The low level of miR-615-5p increased the expression of RAB24 and facilitated HCC growth and metastasis in vitro and in vivo. Moreover, miR-615-5p suppresses HCC cell growth by influencing cell cycle progression and apoptosis. Downregulation of miR-615-5p and upregulation of RAB24 promotes the epithelial-mesenchymal transition (EMT), adhesion and vasculogenic mimicry (VM) of HCC cells, all of which contribute to cell motility and metastasis. Thus, miR-615-5p, who is downregulated by KDM4B-mediated hypermethylation in its promoter, functions as a tumor suppressor by inhibiting RAB24 expression in HCC. In conclusion, our findings characterize miR-615-5p as an important epigenetically silenced miRNA involved in the Rab-Ras pathway in hepatocellular carcinoma and expand our understanding of the molecular mechanism underlying hepatocarcinogenesis and metastasis.