Expression of HBx protein in hepatitis B virus-infected intrahepatic cholangiocarcinoma

BACKGROUND: Hepatitis B virus (HBV) is an etiological factor of intrahepatic cholangiocarcinoma (ICC), but the pathogenic mechanisms remain unclear. This study aimed to investigate the expression and possible role of HBx, an HBV- encoded potentially oncogenic protein, in HBV-infected ICC. METHODS: Tissue samples were obtained from 54 specimens of HBV-infected ICC. Forty-four specimens were of peripheral type and 10 hilar type. Formalin-fixed, paraffin-embedded sections of the specimens were immunohistochemically stained for HBx and p53. RESULTS: HBx expression was found in 70.4% (38/54) of the specimens, and it was more frequently seen in the peripheral type than in the hilar type (79.5% vs 30.0%, P=0.002). All three well-differentiated ICCs expressed HBx, whereas 76.9% (30/39) moderately-differentiated and 41.7% (5/12) poorly-differentiated ICCs had HBx expression (P=0.033). Patients with HBx expression had a significantly higher prevalence of elevated serum alpha-fetoprotein (P=0.033). p53 protein expression was found in 18 of 54 cases (33.3%), and was not correlated with that of HBx. CONCLUSIONS: HBx may contribute to the pathogenesis of ICC, particularly the peripheral type. p53 abnormality may not play a significant role in HBx-mediated oncogenicity during ICC carcinogenesis.