Circular RNAs in hepatocellular carcinoma: Biomarkers, functions and mechanisms

Hepatocellular carcinoma (HCC), a leading cause of cancer-related death with high invasive and metastatic potential, has a low survival rate. To improve the survival and quality of life in HCC patients, it is urgently needed to explore novel biomarkers for early diagnosis and prognosis of HCC, as well as therapeutic strategies. Circular RNAs (circRNAs) are a class of highly conserved, stable and abundant non-coding RNAs (ncRNAs) that can regulate gene expression at transcriptional or post-transcriptional levels. Recently, some circRNAs are identified to be potential biomarkers for HCC diagnosis and prognosis. Furthermore, some circRNAs are found to play oncogenic or suppressive roles in HCC progression by regulating various biological processes, including cell proliferation, migration, invasion and metastasis, epithelial-mesenchymal transition (EMT), as well as apoptosis. In this review, we summarize recent findings of deregulated circRNAs, their functions and molecular mechanisms in HCC, and discuss their potential roles as diagnostic biomarkers, prognostic biomarkers, as well as therapeutic targets for HCC.