HBV Integration Induces Complex Interactions between Host and Viral Genomic Functions at the Insertion Site

Impact of HBV Integration on Hepatocellular Carcinoma After Long-Term Antiviral Therapy

Purpose

Few studies have reported the integrated characteristics of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) after long-term antiviral therapy. This study aimed to investigate the HBV integration features in HBV-HCC patients who had undergone long-term antiviral therapy, evaluate their impact on clinical indicators, and analyze the potential mechanisms involved.

Patients and Methods

We utilized genome-wide association study (GWAS) to analyze liver cancer tissues and detect the presence of HBV integration. Seventeen patients with HBV integration were included in the integration (Int) group, while the remaining five patients were included in the non-integration (N-int) group. Clinical indicators were regularly monitored and compared between the two groups. The characteristics of HBV integration patterns were analyzed, and differences between the groups were explored at the chromosome and genomic levels.

Results

After long-term antiviral therapy, although the frequency of HBV integration in HBV-HCC was reduced, residual HBV integration still accelerated the development of HCC. It affected the diagnosis, treatment, and prognosis of patients. HBV integration events led to changes in chromosome structure, which were closely related to HCC. Novel fusion genes were detected at a high frequency and had the potential to be specific detection sites for HBV-HCC.

Conclusion

HBV integration events are synergistically involved in the human genome and HBV, which can lead to chromosome structural instability, gene rearrangement events closely related to HCC production, and the formation of new specific fusion genes.

Novel Approaches to Inhibition of HBsAg Expression from cccDNA and Chromosomal Integrants: A Review

Hepatitis B virus (HBV) is a widely prevalent liver infection that can cause acute or chronic hepatitis. Although current treatment modalities are highly effective in the suppression of viral levels, they cannot eliminate the virus or achieve definitive cure. This is a consequence of the complex nature of HBV-host interactions. Major challenges to achieving sustained viral suppression include the presence of a high viral burden from the HBV DNA and hepatitis B surface antigen (HBsAg), the presence of reservoirs for HBV replication and antigen production, and the HBV-impaired innate and adaptive immune response of the host. Those therapeutic methods include cell entry inhibitors, HBsAg inhibitors, gene editing approaches, immune-targeting therapies and direct inhibitors of covalently closed circular DNA (cccDNA). Novel approaches that target these key mechanisms are now being studied in preclinical and clinical phases. In this review article, we provide a comprehensive review on mechanisms by which HBV escapes elimination from current treatments, and highlight new agents to achieve a definitive HBV cure.

Comprehensive Analysis of TRIM Family Genes in Hepatitis Virus B-Related Hepatoma Carcinoma

Background: As significant components of E3 ligases, the tripartite motif (TRIM) proteins participate in various biological processes and facilitate the development of several diseases. Nevertheless, the correlations of TIRMs with hepatitis B virus (HBV)-positive hepatoma carcinoma (HCC) are not well elaborated.

Methods: The expression profile of TRIM genes in HBV-associated HCC and related clinical information were extracted from the Cancer Genome Atla (TCGA) database and the International Cancer Genome Consortium (ICGC) database. Dependent on the ConsensusPathDB and STRING databases, the gene ontology, Reactome pathways, and protein-protein interaction were assessed. Relied on TIMER 2.0 database, the relationship of the TRIMs with immune infiltration was investigated. Using multivariate analysis and Kaplan Meier analysis, the association between TRIM genes and the prognostic value was examined.

Results: A total of 17 TRIM genes, including TRIM16, TRIM17, and TRIM31 with fold change no less than 1.5, were discovered to upregulate in HBV-associated HCC in both TCGA and ICGC cohorts. Relied on gene enrichment analysis, the identified TRIMs were observed to not only be related to the interferon and cytokine signaling but also linked to the adaptive immune system. Particularly, the co-expression patterns of identified TRIMs with other E3 ligase genes and many innate immune genes that are associated with Toll-like receptor signaling, apoptosis, and SUMOylation. Besides, some of identified TRIM expressions were also linked to the infiltration levels of T cells and B cells. Additionally, several TRIM genes were associated with various clinical factors and relevant to the poor survival of HBV-associated HCC.

Conclusion: Our findings could deepen our understanding of TRIMs and their correlations with HBV-associated HCC. Furthermore, some of these TRIMs may be utilized as new prognostic markers of HBV-related HCC prognosis, or act as potential molecular targets for the disease.

Inflammatory Gene Expression Associates with Hepatitis B Virus cccDNA- but Not Integrant-Derived Transcripts in HBeAg Negative Disease

Chronic hepatitis B virus (HBV) infection is a global health problem that presents as a spectrum of liver disease, reflecting an interplay between the virus and the host immune system. HBV genomes exist as episomal covalently closed circular DNA (cccDNA) or chromosomal integrants. The relative contribution of these genomes to the viral transcriptome in chronic hepatitis B (CHB) is not well-understood. We developed a qPCR method to estimate the abundance of HBV cccDNA- and integrant-derived viral transcripts and applied this to a cohort of patients diagnosed with CHB in the HBe antigen negative phase of disease. We noted a variable pattern of HBV transcripts from both DNA templates, with preS1/S2 mRNAs predominating and a significant association between increasing age and the expression of integrant-derived mRNAs, but not with inflammatory status. In contrast, cccDNA-derived transcripts were associated with markers of liver inflammation. Analysis of the inflammatory hepatic transcriptome identified 24 genes significantly associated with cccDNA transcriptional activity. Our study uncovers an immune gene signature that associates with HBV cccDNA transcription and increases our understanding of viral persistence.

Hepatitis B virus DNA integration as a novel biomarker of hepatitis B virus-mediated pathogenetic properties and a barrier to the current strategies for hepatitis B virus cure

Chronic infection with Hepatitis B Virus (HBV) is a major cause of liver-related morbidity and mortality worldwide. HBV-DNA integration into the human genome is recognized as a frequent event occurring during the early phases of HBV infection and characterizing the entire course of HBV natural history. The development of refined molecular biology technologies sheds new light on the functional implications of HBV-DNA integration into the human genome, including its role in the progression of HBV-related pathogenesis and in triggering the establishment of pro-oncogenic mechanisms, promoting the development of hepatocellular carcinoma. The present review provides an updated and comprehensive overview of the current body of knowledge on HBV-DNA integration, focusing on the molecular mechanisms underlying HBV-DNA integration and its occurrence throughout the different phases characterizing the natural history of HBV infection. Furthermore, here we discuss the main clinical implications of HBV integration as a biomarker of HBV-related pathogenesis, particularly in reference to hepatocarcinogenesis, and how integration may act as a barrier to the achievement of HBV cure with current and novel antiviral therapies. Overall, a more refined insight into the mechanisms and functionality of HBV integration is paramount, since it can potentially inform the design of ad hoc diagnostic tools with the ability to reveal HBV integration events perturbating relevant intracellular pathways and for identifying novel therapeutic strategies targeting alterations directly related to HBV integration.

Mechanisms of DNA Methylation in Virus-Host Interaction in Hepatitis B Infection: Pathogenesis and Oncogenetic Properties

Hepatitis B virus (HBV), the well-studied oncovirus that contributes to the majority of hepatocellular carcinomas (HCC) worldwide, can cause a severe inflammatory microenvironment leading to genetic and epigenetic changes in hepatocyte clones. HBV replication contributes to the regulation of DNA methyltransferase gene expression, particularly by X protein (HBx), and subsequent methylation changes may lead to abnormal transcription activation of adjacent genes and genomic instability. Undoubtedly, the altered expression of these genes has been known to cause diverse aspects of infected hepatocytes, including apoptosis, proliferation, reactive oxygen species (ROS) accumulation, and immune responses. Additionally, pollutant-induced DNA methylation changes and aberrant methylation of imprinted genes in hepatocytes also complicate the process of tumorigenesis. Meanwhile, hepatocytes also contribute to epigenetic modification of the viral genome to affect HBV replication or viral protein production. Meanwhile, methylation levels of HBV integrants and surrounding host regions also play crucial roles in their ability to produce viral proteins in affected hepatocytes. Both host and viral changes can provide novel insights into tumorigenesis, individualized responses to therapeutic intervention, disease progress, and early diagnosis. As such, DNA methylation-mediated epigenetic silencing of cancer-related genes and viral replication is a compelling therapeutic goal to reduce morbidity and mortality from liver cancer caused by chronic HBV infection. In this review, we summarize the most recent research on aberrant DNA methylation associated with HBV infection, which is involved in HCC development, and provide an outlook on the future direction of the research.