Objective: Many aberrantly expressed circular RNAs (circRNAs) play important roles in the development and progression of hepatocellular carcinoma (HCC). However, the exact function of circ_0001175 in HCC cells is unknown. Our study aimed to investigate the expression characteristics of circ_0001175 in HCC and its effects on the proliferation, migration and invasion of HCC cells, and to explore the potential mechanism.
Materials and Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were carried out to detect circ_0001175, microRNA-130a-5p (miR-130a-5p) and sorting nexin 5 (SNX5)  expressions in HCC tissues and cells; cell counting kit-8 (CCK-8), BrdU and Transwell assays were conducted to detect the proliferation, migration and invasion of HCC cells. A lung metastasis model in nude mice was used to examine the effect of circ_0001175 on the metastasis of HCC cells in vivo. Bioinformatics prediction, luciferase reporter gene experiment, Ago2-RIP experiment and RNA pull-down assay were adopted to identify the binding relationships among circ_0001175, miR-130a-5p and SNX5 .
Results: Circ_0001175 and SNX5  expressions were up-regulated in HCC tissues and cell lines, while miR-130a-5p expression was down-regulated. Abnormal expressions of circ_0001175, miR-130a-5p and SNX5 were associated with poor clinicopathological features of HCC patients; circ_0001175 facilitated HCC cell proliferation, migration and invasion in vitro and promoted lung metastasis in vivo; miR-130a-5p inhibited the above malignant biological behaviors of HCC cells, and it could reverse the function of circ_0001175. SNX5  was identified as a target gene of miR-130a-5p, and circ_0001175 could sponge miR-130a-5p and up-regulate the expression of SNX5  in HCC cells.
Conclusion: Circ_0001175 is highly expressed in HCC and facilitates HCC progression through regulating miR-130a-5p/SNX5  axis.
Keywords: circ_0001175, miR-130a-5p, HCC, proliferation, metastasis