Identification of microRNAs specifically expressed in hepatitis C virus-associated hepatocellular carcinoma

Although several studies have investigated the association of miRNAs with hepatocellular carcinoma (HCC), the data published so far are not concordant. A reason for these discrepancies may be the fact that most studies used the nontumorous tissue surrounding the HCC lesion as a control, which is almost invariably affected by cirrhosis or chronic hepatitis, as well as other pathological conditions such as hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Moreover, HCC is often analyzed as a single group regardless of the different viral etiologies. The miRNAs differentially expressed in HCV-related HCC were investigated by comparing the tumorous tissues to a wide range of liver specimens, including healthy livers obtained from liver donors and patients who underwent liver resection for angioma, in addition to tissues from various acute and chronic liver diseases, including HCV-related cirrhosis not associated with HCC, HCV-related cirrhosis associated with HCC and HBV-associated acute liver failure. The whole set of 2,226 human miRNAs were examined, including 1,121 pre-miRNAs and 1,105 mature miRNAs, available in a microarray platform. Stringent statistical methods were applied to reduce the risk of false discoveries to less than 1%. These data identified 18 miRNAs exclusively expressed in HCV-associated HCC, characterized by high specificity and selectivity versus all other liver diseases and healthy conditions and connected into a regulatory network pivoting on p53, phosphatase and tensin homolog and all-trans retinoic acid signaling.