OBJECTIVETo detect the expression of HBV X gene (HBx mRNA) in extrahepatic biliary tract carcinomas and the adjacent non-cancerous tissues, and to analyzed the relationship between HBV infection and incidence of biliary tract carcinomas, thereby to elucidate the possible role of HBx in the carcinogenesis of biliary tract.

METHODSThe plasmid pSPX46 was digested by appropriate restriction enzyme. HBx fragment was obtained through gel extraction kit. The digoxigenin-labeled DNA probes for HBx mRNA were prepared by a random prime technique. The expression of HBx mRNA was detected in formalin-fixed- paraffin-embedded specimens from 71 cases of biliary tract carcinomas and 39 specimens of non-cancerous tissues adjacent to cancer by in situ hybridization. The correlations between HBx mRNA expression and clinicopathological parameters were statistically analysed in 71 cases of biliary duct carcinomas.

RESULTSForty-three of 71 malignant specimens had detectable HBx mRNA expression with a positive rate being 61%. Only 7 of 39 specimens of non-cancerous tissues adjacent to cancer had weak HBx mRNA expression, with a positive rate being 18%, and all these positive signals were found in the hyperplastic biliary epithelium. No significant correlation was found between HBx mRNA expression and clinicopathological parameters, but a strong positive correlation was found between HBx mRNA and protein expression.

CONCLUSIONThere is a high frequency of HBx mRNA expression in extrahepatic biliary tract carcinomas. HBV infection and its gene integration might play a role to certain extent in the development of biliary tract carcinomas.