Transformation of NIH/3T3 cells by DNA from a human hepatoma cell line with integrated hepatitis B virus DNA

We have studied by means of DNA-mediated gene transfer the transforming activity of the DNA of the human hepatoma cell line HCC-M, which contains genomes of hepatitis B virus (HBV) in integrated form. DNA from HCC-M induced transformed foci on transfection of NIH/3T3 cells. DNAs from primary transformants were capable of inducing secondary transformants. Most of the DNAs of these transformants were demonstrated to contain both human repetitive sequences and HBV DNA, indicating that the transformants had incorporated exogenous human DNA and HBV DNA as well. These results suggest that transformation occurs as the result of the transfer of oncogene which might be closely associated with HBV genome.