ABSTRACT
<p><b>OBJECTIVES</b>To study the phenomena of hepatitis B virus (HBV) integration into the tissues of hilar cholangiocarcinoma (HCCA) and to identify the integration sites in the host genome.</p><p><b>METHODS</b>Ten fresh HCCA samples were collected from the tissues by surgical ablation, 1 normal hilar bile duct sample selected as control. Cellular DNA were extracted by Wizard SV Genomic DNA Purification System. PCR-derived assay (HBV-Alu-PCR) was employed to amplify the viral-host junctions which contain the HBV sequence and the adjacent cellular flanking sequences. The PCR products were purified and subjected to sequencing by ABI-3730XL Auto DNA Analyzer. The sequence analysis of viral-host junctions was performed by DNASIS MAX 3.0 bioinformatics software. The insertion sites between viral and cellular sequences were identified through homology comparison using NCBI BLAST and MapViewer search.</p><p><b>RESULTS</b>In 10 HCCA samples, 5 were demonstrated to have HBV integration fragments with total 6 inserted sites identified. Sequence analysis from viral-host junction showed that HBV X gene inserted into host genome at random distribution with truncated fragments. HBV integration recurrently targeted the unknown region in upstream of CXXC finger protein-1 (CpG-binding protein) gene (4 cases). p53 tumor suppressor gene was also found at the integration site.</p><p><b>CONCLUSIONS</b>There is high integration rate of HBV DNA into cellular genome of HCCA. HBV integration is found frequently into or close to cancer-related genes. The findings demonstrate that HBV infection might have association with the pathogenesis of HCCA.</p>