High-throughput circular RNA sequencing reveals the profiles of circular RNA in non-cirrhotic hepatocellular carcinoma

Background Liver cirrhosis is a well-known risk factor for hepatocellular carcinoma (HCC). However, some HCC cases can also originate from non-cirrhotic livers. The aim of this study was to identify key circular RNAs (circRNAs) associated with the tumorigenesis of non-cirrhotic liver disease. Methods The differently expressed circRNAs between non-cirrhotic and cirrhotic HCCs were assessed with use of high-throughput circRNAs sequencing and validated with quantitative reverse transcription polymerase chain reaction (qRT-PCR). Potential biological functions of these dysregulated circRNAs were predicted with use of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. A circRNA-miRNA-mRNA regulation network was constructed as achieved with use of miRanda software and visualized using Cytoscape software. Biological functions of the four most prominent dysregulated circRNAs identified were confirmed by in vitro experiments. Moreover, possible translations of these dysregulated circRNAs were also predicted. Results A total of 393 dysregulated circRNAs were identified between non-cirrhotic and cirrhotic HCC, including 213 that were significantly up-regulated and 180 significantly down-regulated circRNAs. Expression levels of the six most prominent dysregulated circRNAs were further validated using qRT-PCR. Many tumor related miRNAs were involved in the circRNA-miRNA-mRNA networks, including miR-182-5p, miR-561-3p, miR-125a-5p, miR-145, miR-23b-3p and miR-30e-3p, and downstream mRNAs of dysregulated circRNAs were significantly related with biological processes involved in the progression of tumors, including proliferation, migration, differentiation, and focal adhesion. Results from the in vitro experiments demonstrated that the most prominent dysregulated circRNAs exerted notable effects upon the proliferation and migration of HCC cells. Finally, we also identified 19 dysregulated circRNAs having potential for the coding of functional peptides. Conclusion The results of this present study indicate that circRNAs may play important roles in tumorigenesis of non-cirrhotic HCC. Such findings provide some novel insights and pave the way for the development of future studies directed at investigating the initiation and treatment of HCC.