Hepatitis B virus X protein modulates peroxisome proliferator-activated receptor γ through protein–protein interaction

Ligand activation of peroxisome proliferator-activated receptor γ (PPARγ) has been reported to induce growth inhibition and apoptosis in various cancers including hepatocellular carcinoma (HCC). However, the effect of hepatitis B virus X protein (HBx) on PPARγ activation has not been characterized in hepatitis B virus (HBV)-associated HCC. Herein, we demonstrated that HBx counteracted growth inhibition caused by PPARγ ligand in HBx-associated HCC cells. We found that HBx bound to DNA binding domain of PPARγ and HBx/PPARγ interaction blocked nuclear localization and binding to recognition site of PPARγ. HBx significantly suppressed a PPARγ-mediated transactivation. These results suggest that HBx modulates PPARγ function through protein–protein interaction.ope