Analysis of HBV Genome Integration in Patients With HBV-Previously Infected NBNC-HCC

The incidence of non-B non-C hepatocellular carcinoma (NBNC-HCC), which is negative for Hepatitis B surface antigen and Hepatitis C virus antibodies, is on the rise. Relatively higher numbers of NBNC-HCC patients are Hepatitis B core antibody (HBcAb) positive, suggesting that previous HBV infection may play a role in NBNC-HCC development, though the exact mechanisms are unclear. This study aimed to investigate whether HBV genomes are integrated into the host genome of HBcAb-positive NBNC-HCC cases and how these integrations may contribute to cancer development and progression.

HBV detection PCR using HBV-specific primers on DNA extracted from HBcAb-positive NBNC-HCC tissue samples was performed. Positive samples were further examined for HBV integration sites using Viral DNA-Capture sequencing Approach. Additionally, Hepatitis B core-related antigen (HBcrAg) serum levels were measured to assess whether they could be predictive for HBV detection PCR results.

Among 90 HBcAb-positive NBNC-HCC samples, HBV genome amplification was detected in 19 samples, and differences in HBcrAg status were observed according to HBV detection PCR results. Eighteen of these samples showed HBV integration. The HBV genome was integrated near the TERT gene in 7 samples, resulting in significantly increased TERT mRNA levels, in the KMT2B gene (3 samples), and downstream of the LOC441666 gene (2 samples).

The integration sites we identified in our samples have been previously reported in HBV-related HCC, suggesting that HBV integration may also contribute to hepatocarcinogenesis in HBcAb-positive NBNC-HCC. Furthermore, HBcrAg could serve as a potential, noninvasive marker for detecting the HBV genome in these cases.