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To identify proteins that could be molecular targets for diagnosis and treatment of hepatitis C virus-related hepatocellular carcinoma (HCV-related HCC), we used a proteomic approach to analyze protein expression in samples of human liver. Twenty-six pairs of tumorous and corresponding nontumorous liver samples from patients with HCV-related HCC and six normal liver samples were analyzed by two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry. One of the numerous spots that showed stronger intensity in tumorous than in nontumorous samples was identified as alpha enolase, a key enzyme in the glycolytic pathway. Expression of this protein increased with tumor dedifferentiation and was significantly higher in poorly differentiated HCC than in well-differentiated HCC. This pattern was reproduced by immunoblot analysis and immunohistochemistry. Expression of alpha enolase also correlated positively with tumor size and venous invasion. These results suggest that alpha enolase is one of the candidates for biomarkers for tumor progression that deserves further investigation in HCV-related HCC.

Hepatocellular carcinoma (HCC) is a major cause of death in Japan. It has been suggested that hepatitis C virus (HCV) plays an important role in hepatocarcinogenesis, because of high incidence among the patients. To understand the mechanism of hepatocarcinogenesis after HCV infection, we performed a comparative study on the protein profiles between tumorous and nontumorous specimens from the patients infected with HCV by means of two-dimensional electrophoresis. Eleven spots were decreased in HCC tissues from over 50% of the patients. Eight proteins out of 11 spots were identified using peptide mass fingerprinting with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry. These proteins were liver type aldolase, tropomyosin beta-chain, ketohexokinase, enoyl-CoA hydratase, albumin, smoothelin, ferritin light chain, and arginase 1. The intensity of enoyl-CoA hydratase, tropomyosin beta-chain, ketohexokinase, liver type aldolase, and arginase 1 was significantly different (p < 0.05). The decrease of 8 proteins was characteristic in HCC. We will discuss the implication of these proteins for the loss of function of hepatocytes and for the possibility of carcinogenesis of HCV-related HCC.

Using oligonucleotide microarray data of 45 hepatocellular carcinoma (HCC) samples, we evaluated gene expression in hepatitis B virus-positive and hepatitis C virus-positive HCCs (HBV-and HCV-HCCs) for an association with liver cirrhosis (LC). In all, 89 genes were expressed differentially between HBV-HCCs associated with LC and those not associated with LC. Among them, tumors from LC patients showed significantly lower expression levels of 72 genes and significantly higher levels of 17 genes than the levels found in tumors from non-LC patients. The former included genes responsible for signal transduction, transcription, metabolism, and cell growth. The latter included a tumor suppressor gene and a cell-growth-related gene. Only eight genes were expressed differentially between HCV-HCCs associated with and without LC. Our findings provide as a framework for clarifying the role of LC in HBV-and HCVrelated hepatocarcinogenesis.