Increased expression of transforming growth factor α after transfection of a human hepatoblastoma cell line with the hepatitis B virus

Abstract

The expression of transforming growth factor a (TGF-α) was examined in a human hepatoblastoma cell line. Hep G2, which does not contain hepatitis B virus (HBV) DNA, and in the cell line 2.2.15, which was formed by the transfection of Hep G2 cells with the complete HBV DNA, to study the possibility that HBV and TGF-α could function as co-factors in hepatocarcinogenesis. Northern blot hybridization of RNA extracted from these cell lines, with densitometric analysis, revealed expression of the TGF-α gene in the transfected cells at a level three times higher than in the nontransfected cells. Staining of the cells using a monoclonal antibody to TGF-α and the avidin-biotin-peroxidase immunohistochemical method revealed a much higher intensity of TGF-α staining in the transfected cell line. These findings show that the presence of HBV DNA appears to cause a significant up-regulation of the TGF-α gene. This effect on the TGF-α gene may be a mechanism by which HBV contributes to the etiology of hepatocellular carcinoma in some patients.