Circ_0000517 Contributes to Hepatocellular Carcinoma Progression by Upregulating TXNDC5 via Sponging miR-1296-5p

Background: Circular RNAs (circRNAs) function as essential regulators in diverse human cancers, including hepatocellular carcinoma (HCC). However, the function of circ_0000517 in HCC was unknown. We aimed to explore the roles and mechanisms of circ_0000517 in HCC. Materials and Methods: The levels of circ_0000517, RPPH1 mRNA and microRNA-1296-5p (miR-1296-5p) were measured using quantitative real-time polymerase chain reaction (qRTPCR). The characteristics of circ_0000517 were explored by RNase R digestion and actinomycin D assays. Cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell cycle process and cell apoptosis were analyzed by flow cytometry analysis. The function of circ_0000517 in vivo was explored by a murine xenograft model. The association between miR-1296-5p and circ_0000517 or thioredoxin domain containing 5 (TXNDC5) was determined by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The protein level of TXNDC5 was detected by Western blot assay. Results: Circ_0000517 was upregulated in HCC tissues and cells. Silencing of circ_0000517 suppressed HCC cell viability and colony formation and promoted cell cycle arrest and apoptosis in vitro and hampered tumor growth in vivo. MiR-1296-5p was a target of circ_0000517 and the effects of circ_0000517 silencing on HCC cell viability, cell cycle, colony formation and apoptosis were abolished by miR-1296-5p inhibition. TXNDC5 functioned as a target gene of miR-1296-5p, and the inhibitory effect of miR-1296-5p on HCC cell progression was rescued by TXNDC5 overexpression. Moreover, circ_0000517 promoted TXNDC5 expression via targeting miR-1296-5p. Conclusion: Circ_0000517 accelerated HCC progression by upregulating TXNDC5 through sponging miR-1296-5p.