Circular RNA CircEPB41L2 Functions as Tumor Suppressor in Hepatocellular Carcinoma Through Sponging miR-590-5p

Circular RNAs (circRNAs) could interact with miRNAs to regulate gene expression, participating in hepatocellular carcinoma (HCC) initiation and development. This work aimed to determine the potential function and molecular mechanism of circEPB41L2 (hsa_circ_0077837) during HCC progression.

The expression of circEPB41L2 in HCC tissues and HCC cell lines was quantified using real-time quantitative PCR (qRT-PCR). CCK-8 assays and colony formation assays were utilized to detect the proliferation of HCC cells. Wound healing assay and transwell assay were performed to determine the capability of migration and invasion for HCC cells. Western blot was conducted to determine gene expression on protein levels. The effect of circEPB41L2 on HCC in vivo was investigated via xenograft experiment. Interaction between circEPB41L2 and miR-590-5p was predicted through bioinformatics methods and confirmed via luciferase reporter assay.

Extensive analysis of circRNA profiles in tumor and matched para-tumor tissues collected from 61 HCC patients identified that circEPB41L2 was significantly down-regulated in HCC, which was further confirmed in another HCC group by qRT-PCR analysis. The clinicopathological analysis revealed that down-regulation of circEPB41L2 was negatively associated with tumor size, vascular invasion and alpha-fetoprotein, while positively correlated with HCC prognosis. The biological function experiments showed that overexpression of circEPB41L2 could obviously inhibit the proliferation and metastasis of HCC cells in vitro, while knockdown of circEPB41L2 induced opposite results. Moreover, we also found that circEPB41L2 inhibited HCC migration and invasion though EMT signaling pathway. Similarly, overexpression of circEPB41L2 can also significantly inhibit the proliferation of HCC cells in vivo. Bioinformatic analysis and luciferase reporter assay revealed that circEPB41L2 interacts directly with miR-590-5p and the corresponding biological functions were also verified in miRNA rescue experiments.

Our results suggest that circEPB41L2 might function as a tumor suppressor during HCC progression by sponging miR-590-5p.