Tumor necrosis factor-alpha induces a kappa B sequence-specific DNA-binding protein in human hepatoblastoma HepG2 cells.

Tumor necrosis factor-alpha is an inducer of acute-phase protein synthesis in liver cells. The mechanism by which tumor necrosis factor-alpha alters gene expression in these cells is largely unknown. In this study, we demonstrate that tumor necrosis factor-alpha stimulates human immunodeficiency virus-1 long terminal repeat-promoted gene expression in the human hepatoblastoma HepG2 cell line and increased binding of trans-activating factors to kappa B (kappa B) DNA sequences. In contrast to lymphocytic cells where the nuclear factors recognizing the kappa B sequences are activated by both tumor necrosis factor-alpha and phorbol-12-myristate-13-acetate through a posttranslational mechanism, in HepG2 cells phorbol-12-myristate-13-acetate does not activate these factor(s), and de novo protein synthesis seems to be required in HepG2 cells for gene activation by tumor necrosis factor-alpha.