Abstract:Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs, with a closed circular structure formed through the back-splicing of linear RNAs. CircRNAs widely exist in eukaryotic cells and can be detected in many types of body fluid samples, presenting with stable structure, highly conserved and specific expression, and are important regulators of tumors. CircRNAs exert a "sponge action" mainly by adsorbing microRNAs (miRNAs) or RNA binding proteins (RBPs) to regulate the expression of downstream target genes, and play important role in a variety of diseases, especially in tumors. They are involved in many biological processes such as proliferation, migration, invasion, cell cycle, apoptosis, epithelial-mesenchymal transformation and signaling pathway of tumor cells. Recent studies have shown that circRNAs have critical regulatory functions affecting the occurrence and development of hepatocellular carcinoma (HCC), and they are expected to become the diagnostic biomarkers and therapeutic targets of HCC. Here, the authors address the research progress of the roles of circRNAs in the initiation and progression of HCC.