MicroRNAs and liver disease: viral hepatitis, liver fibrosis and hepatocellular carcinoma.

MicroRNAs (miRNAs), a type of highly conserved small non-coding RNAs with an average length of 22 nucleotides, may serve as major regulators of gene expression and indispensable components of cellular gene expression networks. They have critical roles in normal biological processes and have been linked to many tumours, including hepatocellular carcinoma (HCC). HCC is the fifth most common malignancy and the third leading cause of cancer-related death worldwide. Viral hepatitis, caused by infection with hepatitis B or C viruses (HBV or HCV), can increase the risk of HCC and contributes to a significant disease burden around the world. Because of the variety of molecular alterations that may arise during the development and progression of HCC, standard of care and treatment for patients with HCC remains unsatisfactory. MiRNAs have been shown to participate in the pathogenesis of both HBV and HCV. In addition to a role in pathogenesis, miRNAs have significant clinical value in the early diagnosis of HCC since they are present in the blood and can be used as diagnostic markers and potential targets for specific systemic treatment.