A chromosome 17:7 translocation is associated with a hepatitis B virus DNA integration in human hepatocellular carcinoma DNA

Abstract

Chronic hepatitis B virus infection is often associated with major structural rearrangements of both the integrated viral DNA and the associated cellular sequences. We present here the structure of a single-copy hepatitis B virus insert cloned from human hepatocellular carcinoma DNA recently reported to encode a novel transcriptional trans-activator function. The hepatitis B virus portion of the clone consists of two colinear fragments covering the X gene with its promoter and enhancer (nucleotides 717 to 1796) and a 3' truncated pre-S/S gene (nucleotides 2703 to 423). The lack of the entire pre-C/C gene caused a fusion of the 3' end of the X gene with sequences upstream from the pre-S gene. The structure of the integrated viral DNA fragments suggests insertion of hepatitis B virus replication intermediates into cellular DNA and subsequent recombination between these primary integrations to generate the final structure of the clone. The 5' and 3' cellular flanking sequences mapped to the centromeric alpha-satellite DNA of chromosome 17 and to the short arm of chromosome 7 (p14-pter), respectively, indicating that chromosomal translocation was associated with the hepatitis B virus DNA integration. Because this is the fourth case reported in which hepatitis B virus-associated rearrangements have affected chromosome 17, it is conceivable that a loss of important cellular genes (such as the p53 antioncogene on chromosome 17) may be a crucial step in hepatitis B virus-related hepatocarcinogenesis.