Suppression of serum starvation-induced apoptosis by hepatitis C virus core protein.

Hepatitis C virus (HCV) core protein either enhances or inhibits apoptosis depending on the apoptosis-inducing stimuli and cell conditions. In this paper we studied possible effect of HCV core protein on apoptosis induced by serum starvation. NIH3T3 cells stably expressing HCV core protein were more resistant to serum starvation-induced apoptosis than were the non-expressing control. Neither p53, p21Waf1 nor Bax was detectably induced after serum starvation, irrespective of HCV core protein expression, suggesting that the observed apoptosis is p53-independent. Serum starvation-induced apoptosis was partially inhibited by SB203580, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, in the non-expressing control, but not in HCV core protein-expressing cells. Moreover, activation of p38 MAP kinase after serum starvation, as measured by the amount of its phosphorylated form, was inhibited in HCV core protein-expressing cells. Our results suggest that HCV core protein inhibits serum starvation-induced apoptosis through inhibition of p38 MAP kinase activation.