Molecular mechanisms of viral hepatitis induced hepatocellular carcinoma.

Chronic infection with viral hepatitis affects half a billion individuals worldwide and can lead to cirrhosis, cancer, and liver failure. Liver cancer is the third leading cause of cancer-associated mortality, of which hepatocellular carcinoma (HCC) represents 90% of all primary liver cancers. Solid tumors like HCC are complex and have heterogeneous tumor genomic profiles contributing to complexity in diagnosis and management. Chronic infection with hepatitis B virus (HBV), hepatitis delta virus (HDV), and hepatitis C virus (HCV) are the greatest etiological risk factors for HCC. Due to the significant role of chronic viral infection in HCC development, it is important to investigate direct (viral associated) and indirect (immune-associated) mechanisms involved in the pathogenesis of HCC. Common mechanisms used by HBV, HCV, and HDV that drive hepatocarcinogenesis include persistent liver inflammation with an impaired antiviral immune response, immune and viral protein-mediated oxidative stress, and deregulation of cellular signaling pathways by viral proteins. DNA integration to promote genome instability is a feature of HBV infection, and metabolic reprogramming leading to steatosis is driven by HCV infection. The current review aims to provide a brief overview of HBV, HCV and HDV molecular biology, and highlight specific viral-associated oncogenic mechanisms and common molecular pathways deregulated in HCC, and current as well as emerging treatments for HCC.

Oncogenic HBV variants and integration are present in hepatic and lymphoid cells derived from chronic HBV patients.

The hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC), partly driven by viral integration and specific oncogenic HBV variants. However, the biological significance of HBV genomes within lymphoid cells (i.e., peripheral blood mononuclear cells, PBMCs) is unclear. Here, we collected available plasma, PBMC, liver, and tumor from 52 chronic HBV (CHB) carriers: 32 with HCC, 19 without HCC, and one with dendritic cell sarcoma, DCS. Using highly sensitive sequencing techniques, next generation sequencing, and AluPCR, we demonstrate that viral genomes (i.e., HBV DNA, RNA, and cccDNA), oncogenic variants, and HBV-host integration are often found in all sample types collected from 52 patients (including lymphoid cells and a DCS tumor). Viral integration was recurrently identified (n = 90 such hits) in genes associated with oncogenic consequences in lymphoid and liver cells. Further, HBV genomes increased in PBMCs derived from 7 additional (treated or untreated) CHB carriers after extracellular mitogen stimulation. Our study shows novel HBV molecular data and replication not only liver, but also within 63.8% of lymphoid cells analysed (including a representative lymphoid cell malignancy), that was enhanced in ex vivo stimulated PBMC.

Hepatitis B virus (HBV) genome detection and genotyping in virally suppressed patients using nested polymerase chain reaction-based Sanger sequencing.

Hepatitis B virus (HBV) genotypes have important clinical implications. Current genotyping methods are less sensitive in patients with ultra-low HBV viral load. We report a highly sensitive and specific nested polymerase chain reaction (PCR) assay for genotyping patient HBV. Total DNA derived from plasma of 14 (HBsAg+ and/or HBsAg-) HBcAb+ patients was used for HBV-specific nested PCRs targeting the preC/C, X/BCP/preC, and surface regions. All patients were treated with long-term nucleos(t)ide analogues (NAs), and 12/14 have undetectable viremia (clinical PCR: sensitivity >10 IU/mL). Surface amplicons were sequenced, aligned with reference genomes, and used in phylogenetic tree construction to determine genotype. HBV DNA was detected in 14/14, including 3 occult (HBsAg-/HBcAb+) cases. Genotypes identified were 6/14 B, 6/14 C, and 2/14 D. This assay in virologically suppressed patients may be useful for future studies requiring genotype prior to assessment of immunomodulatory and/or direct acting anti-viral therapeutics in patients on potent NAs.