Relationship between c-myc gene protein, nucleic acids and hepatitis B virus expression in hepatoma cell lines and their corresponding tumors in nude mice.

myc gene protein--a 62,000 molecular weight protein (p62c-myc)--was localized in the nuclei of a human hepatoblastoma cell line (HepG2) and its corresponding tumors in nude mice but not in the mouse liver cells using immunoenzymatic and immunogold techniques. Double staining revealed that myc protein and nucleic acids are mutually exclusive and that myc protein is located in the nucleoplasm. Immunoelectron microscopic observation confirmed that the myc protein is part of the nuclear sap. To study the relationship between myc protein and hepatitis B virus (HBV) marker expression, we have utilized the cell line HepG2 transfected with the HBV genome as well as the corresponding tumors induced in nude mice. HBsAg- and HBcAg-positive cells were not always associated with over-expression of myc gene protein suggesting that HBV expression is not required for increased expression of myc gene protein.