Abstract: Background and purpose: This study aimed to investigate the expression, cellular functions and mechanisms of miR-509-3p in hepatocellular carcinoma (HCC). Methods: miR-509-3p was detected by real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) in an independent validation sample cohort of 46 HCC tissues, 3 HCC cell lines and one normal liver cell line. Transwell assay was performed to evaluate the effect of miR-509-3p on metastasis in HCC cells. Western blot was performed to evaluate the relationship between miR-509-3p and matrix metalloproteinases (MMPs) associated with epithelial-mesenchymal transition (EMT). Results: miR-509-3p was highly expressed in HCC tissues and HCC cell lines. In vitro functional experiments showed that the inhibition of mir-509-3p decreased the metastatic ability of HCC cells. Western blot analysis confirmed that mir-509- 3p negatively regulated the protein level of MMP-9 and MMP-2. Conclusion: This study shows that mir-509-3p promotes EMT in HCC cells through specific signaling pathway and molecular mechanisms.

Key words: Hepatocellular carcinoma, MicroRNA, Tumor invasion, Metastasis