PKC‐alpha mediated induction of miR‐101 in human hepatoma cells

Abstract

Protein Kinase C (PKC) is a serine/threonine kinase that involved in controlling of many cellular processes such as cell proliferation and differentiation. We have shown previously that TPA (12‐O‐tetradecanoylphorbol 13‐acetate) induces cell cycle arrest in G0/G1 phase in human hepatoma HepG2 cells. In this study, we examined TPA regulated miRNA expression profile in human hepatoma HepG2 cells. Six miRNA were identified as putative tumor suppressor genes since there both are induced by TPA and are also down regulated in human hepatoma tissues. Among six miRNA, miR‐101 has been intensively studied recently. MiR101 targets two subunits of PRC2 complex, enhancer of zeste homolog 2 (EZH2) and EED, and was shown to play negative role in cell growth in human prostate, breast and liver cancers. We showed that TPA not only up regulated miR‐101 expression, but also reduced protein level of EZH2, EED and H3K27me3 in HepG2 cells. Using lenti‐virus‐mediated shRNA to knockdown endogenous PKC‐alpha expression, we observed that TPA induced growth arrest, elevation of miR‐101 and reduction of EZH2, EED and H3K27me3 proteins were all PKC‐alpha dependent. Therefore, we proposed that PKC‐alpha mediated miRNA expression may play an important role in carcinogenesis of human hepatoma.