miR-522 contributes to cell proliferation of hepatocellular carcinoma by targeting DKK1 and SFRP2.

The morbidity and mortality of hepatocellular carcinoma (HCC) is very high, finding new therapeutic targets are critical for HCC treatment. miR-522 has been demonstrated to be upregulated in HCC tissues, but its role in HCC progression remains to be elucidated. In this report, we found miR-522 was upregulated in HCC cells and tissues, miR-522 overexpression promoted cell proliferation, colony formation, and cell cycle progression, whereas knockdown of miR-522 reduced these effects. We also analyzed the expression of several key cell cycle regulatory proteins and found overexpression of miR-522-inhibited cell cycle inhibitors p21 and p27 expression and enhanced cyclin D1 expression and the level of Rb phosphorylation, vice versa. These suggested miR-522-accelerated G1/S transition. DKK1 (dickkopf-1) and SFRP2 (secreted frizzled-related protein 2) were the targets of miR-522, their expression was inversely with miR-522 in HCC tissues. DKK1 and SFRP2 the antagonists of Wnt signaling, suggesting miR-522-promoted HCC progression through activating Wnt signaling. miR-522 might be a valuable target for HCC therapy.