Detection of hepatitis B virus x transcripts in human hepatocellular carcinoma tissues

Background: The hepatitis B virus (HBV) or hepatitis C virus (HCV) sequences were frequently detected in hepatocellular carcinoma (HCC) tissues by the method of polymerase chain reaction (PCR). However, the expression levels of HBV and HCV in HCC tissues remain to be documented. This study evaluates the mRNA expression levels of those virus sequences in the human HCC tissues through Northern blot hybridization. Methods: We performed Northern blot hybridization to identify the HBV x mRNA and HCV RNA in HCC tissues of 14 cases excised at Chiba University Hospital. Results: The HBV x transcripts could be identified in the tumor tissues from all three serum HBsAg-positive cases and two cases among 11 HBsAg-negative patients. One HBsAg-negative case showed the most intensive signal in those five cases. However, HCV RNA could not be identified by this method. The HBV x gene transcript is predicted to have a size of about 0.7 kb; however, the molecular weight of HBV x specific mRNA is not consistent and is distributed between approximately 2.0 and 9.0 kb. The hybridization signal intensity is also variable according to the cases. Conclusion: These observations suggest that HBV x gene may be transcribed with flanking cellular sequences and the carcinogenic activity may be different according to the expressed levels. The identification of HBV x transcripts in HCC tissues on the Northern blot level also suggests that HBV x mRNA expression might be significant and concerned with the development of human HCC even in HBsAg-negative cases. (C) 1997 Academic Press.