Stability of HBV DNA in cell lines and nude mouse-passaged tissues derived from human hepatocellular carcinoma

Human hepatitis B virus (HBV) infection has been closely linked to the occurrence of hepatocellular carcinoma (HCC). Hepatoma cell lines and nude mouse-passaged hepatoma tissues were used in this report to study the HBV DNA status in these cells after passage. DNA was extracted from seven hepatoma cell lines and three nude mouse passaged HCC lines. Southern blot hybridization technique was performed with either cloned HBV whole genome or subgenomic DNA fragments as probes to analyze the presence of HBV DNA. Integration of HBV DNA fragments was detected in one mouse passaged tissue, R. Hybridization with HBV subgenomic DNA revealed that there were some DNA rearrangements of the integrated HBV DNA in R. However, the integrated HBV DNA could not be detected in the cell line derived from R after in vitro cultivation for 2 years. Both episomal form and integrated HBV DNA were detected in a cell line NTU-h3. Episomal form HBV DNA ih NTU-h3 changed after several passages. HBV DNA in NTU-h3 was unstable after in vitro cultivation. Therefore, we concluded that the presence of HBV DNA might not be essential for the maintenance of the tumorigenicity of hepatoma and the nude mouse system was more stable for maintaining HBV DNA in HCC.