MicroRNA-769-5p contributes to the proliferation, migration and invasion of hepatocellular carcinoma cells by attenuating RYBP.

Hepatocellular carcinoma (HCC) is the commonest primary liver cancer with highly aggressive features. MicroRNAs (miRNAs) are demonstrated to play important roles in the tumorigenesis and progression of HCC. miR-769-5p is a recently identified cancer-associated miRNA. But, the expression level of miR-769-5p and its function in HCC are unexplored. In this study, we found that miR-769-5p expression was obviously increased in HCC samples compared to adjacent noncancerous liver tissues. Additionally, we revealed that miR-769-5p was over-expressed in HCC cells as compared with LO2 cells. Notably, HCC tissues from patients with tumor size ≥5 cm, venous infiltration and advanced tumor stages showed higher levels of miR-769-5p compared to those from corresponding controls. Interestingly, our data indicated that HCC patients highly expressing miR-769-5p had significant shorter survivals. Next, functional experiments verified that miR-769-5p knockdown markedly suppressed HCC cell proliferation, migration and invasion. Conversely, ectopic expression of miR-769-5p promoted these biological behaviors of Hep3B cells. Furthermore, depletion of miR-769-5p repressed the growth and metastasis of HCCLM3 cells in vivo. Importantly, miR-769-5p inversely modulated RING1 and YY1 binding protein (RYBP) by directly binding to 3' untranslated region (UTR) in HCC cells. The expression of RYBP mRNA was down-regulated in HCC tissues and negatively correlated with miR-769-5p level. RYBP overexpression remarkably inhibited the proliferation, migration and invasion of HCCLM3 cells. Accordingly, knockdown of RYBP partially abolished miR-769-5p silencing-induced tumor suppressive effects on HCCLM3 cells. In summary, our study revealed the up-regulated expression of miR-769-5p, which contributed to HCC progression possibly by targeting RYBP.

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