Background: Recent studies reported that circular RNAs (circRNAs) exert essential functions in hepatocellular carcinoma (HCC) progression. However, the expression profile and function of circular RNA PVT1 (circPVT1) in HCC are not fully addressed. Thus, we aimed to probe into the function of circPVT1 in HCC development.
Methods: The levels of circPVT1, microRNA-377 (miR-377) and transcripts encoding tripartite motif containing 23 (TRIM23 ) were determined by qRT-PCR. The stability and localization of circPVT1 were examined by RNase R digestion assay and subcellular fraction assay, respectively. Cell proliferation and apoptosis were evaluated by MTT assay and flow cytometry analysis, respectively. The relationship between miR-377 and circPVT1 or TRIM23  was determined by dual-luciferase reporter assay and RNA immunoprecipitation (RIP). The protein expression of TRIM23  was measured by Western blot. The glycolysis level was assessed by specific kits and Seahorse Extracellular Flux Analyzer XF96. The function of circPVT1 in vivo was investigated in a murine xenograft model.
Results: CircPVT1 and TRIM23  levels were elevated, while miR-377 was decreased in HCC. CircPVT1 knockdown restrained proliferation and glycolysis, but enhanced apoptosis in HCC cells. CircPVT1 could bind to miR-377 and inhibition of miR-377 restored circPVT1 knockdown-mediated effect on HCC cells. TRIM23  was certified as a target of miR-377, and TRIM23  upregulation overturned the influence of miR-377 upregulation or circPVT1 silence on HCC progression. Moreover, circPVT1 knockdown restrained tumor growth in HCC in vivo.
Conclusion: CircPVT1 aggravated the progression of HCC by upregulating TRIM23  via sponging miR-377.
Keywords: hepatocellular carcinoma, circPVT1, miR-377, TRIM23