Hepatitis C virus core protein is necessary for the maintenance of immortalized human hepatocytes.

Hepatitis C virus (HCV) core protein has many intriguing properties and plays an important role in cell growth regulation. We have recently shown that the HCV core protein from genotype 1a promotes primary human hepatocytes to an immortalized phenotype. Here, we investigated whether the presence of core protein is necessary for maintenance of the immortalized hepatocytes and investigated its consequences on cellular gene expression. The introduction of an antisense orientation of the core gene into immortalized hepatocytes led to the onset of cell death. Further analysis suggested that cell death occurred through apoptosis associated with the activation of tumor suppressor pathways. Antisense core gene expression in immortalized hepatocytes increased p53 expression at both the mRNA and the protein levels. A decreased telomere length and reduced c-myc protein expression were also observed in hepatocytes when the antisense core gene was introduced. Results from these studies suggested that modulation of cell cycle regulatory genes by repression of core protein expression is responsible for reversion of the immortalized phenotype of the hepatocytes. Thus, targeted inhibition may contribute to the development of new therapeutic modalities for prevention of HCV core protein function.