Characterization of the genotype and integration patterns of hepatitis B virus in early‐ and late‐onset hepatocellular carcinoma

Abstract

Early-onset hepatocellular carcinoma (HCC) accounts for 15%-20% of total HCC cases in Asia, and the incidence is increasing. The low frequency of cirrhosis and poor prognosis of early-onset HCC suggests that its mechanisms may differ from late-onset HCC. Although hepatitis B virus (HBV) infection is epidemiologically associated with HCC, the role of HBV in early-onset HCC remains poorly understood. Here, we report a comparative study of HBV subgenotypes and integration in early-( £ 30) and late-onset (70) HBV-associated HCC using a novel high-throughput viral integration detection method. We report that HBV B2 is predominantly present in early-onset HCC. HBV integration is a common phenomenon, both in early-and late-onset HCC, which favors integrating into human repeat regions. Moreover, we found a breakpoint in 8q24 located between c-Myc and plasmocytoma variant translocation 1 (PVT1), which was detected in 12.4% (14 of 113) of early-onset HCCs, but only 1.4% (2 of 145) in lateonset HCCs. HBV integrating this site results in c-MYC, PVT1, and microRNA-1204 overexpression in tumors, thereby potentially contributing to the development of earlyonset HCC. Conclusion: HBV genotype and integration patterns may be distinct in early-onset HCC. Our results may shed light on HCC risk factors in young HBV carriers. Further studies are needed to elucidate at which time in tumor development this integration event occurs and whether it plays an important, causative role in HCC development or progression. (HEPATOLOGY 2015;61:1821-1831 H epatocellular carcinoma (HCC) is a common solid tumor and the third leading cause of cancer death worldwide.1 Hepatitis B virus (HBV) is a major etiological agent in China, Southeast Asia, and sub-Saharan Africa, and individuals with chronic HBV infection are at increased risk of developing HCC, particularly those with chronic liver disease and cirrhosis.2 Average age at onset of HBVassociated HCC is 50 years 3,4 ; thus, the recommendations advise HCC screening for Asian male HBV patients older than 40 and Asian female HBV patients older than 50.5 Nonetheless, incidence of HCC in patients younger than 40, especially in high-risk populations, is relatively high. 6,7 Recent studies have reported a significant prevalence and worse prognosis in early-onset HCC patients, 8,9 suggesting that there Abbreviations: ALB, albumin; bp, base pairs; DR1/2, direct repeat 1 and 2; FN1, fibronectin 1; GATM, glycine amidinotransferase; gDNA, genomic DNA; HBV, hepatitis B virus; Hbx, HBV x gene; HCC, hepatocellular carcinoma; HIVID, high-throughput viral integration detection; kb, kilobase; LC, liver cirrhosis; LINE, long interspersed nuclear elements; miR, microRNA; MLL4, myeloid/lymphoid or mixed-lineage leukemia 4; PVT1, plasmocytoma variant translocation 1; RT-PCR, reverse-transcription polymerase chain reaction; SINE, short interspersed nuclear elements; ST18, suppression of tumorigenicity 18; STAT1, signal transducer and activator of transcription 1; SYT12, synaptotagmin XII; TERT, telomerase reverse transc...

Hepatitis B virus genotypes: epidemiological and clinical relevance in Asia

“…Mechanisms for early-onset (B30 years) HCC may be different from those for late-onset (C70 years) HCC, given the low frequency of liver cirrhosis and poor prognosis in the former. In a comparative study of HBV sub-genotypes and HBV-associated HCC from Shanghai, China, Yan et al found that HBV sub-genotype B2 was predominant in early-onset HCC (mostly without cirrhosis), while C2 was more frequently seen in late-onset HCC [46]. However, in a community-based study from mainland China, HCC-associated mutations were more frequently found in young patients infected with genotype C than in those with genotype B, indicating genotype C might be more apt to cause LC and HCC with increasing age [47].…”

HBV DNA Integration: Molecular Mechanisms and Clinical Implications

“…HBV shows significant enrichment of integration near fragile sites, repetitive regions, CpG islands, and telomeres in tumours compared to non-tumour tissue [84,94]. Over half of the integration events were located in intergenic regions within the chromosomes of the human genome and in repeat sequences such as LINEs, short interspersed nuclear elements, or simple repeats (microsatellites) [94]. Furthermore, chromosomal rearrangements and copy number variations were associated with a large fraction of HBV-related HCCs [43,80], but this can be highly variable [95,96].…”

c-MYC—Making Liver Sick: Role of c-MYC in Hepatic Cell Function, Homeostasis and Disease

“…HBV integration is a common phenomenon, even in early-onset HCC, but the conditions between early- and late-onset diseases are rather different. A breakpoint between c-MYC and plasmacytoma variant translocation 1 ( PVT1) , located in the 8q24 gene desert, is frequently detected in early-onset HCC, resulting in overexpression of c-MYC in tumors [103,104]. However, the stage in tumor development when this integration occurs, and how important it may be for HCC, is currently unknown.…”