Analysis of hepatitis B virus X gene (HBx) mutants in tissues of patients suffered from hepatocellular carcinoma in China

Aldo-keto reductase family 1 member B10 is regulated by nucleos(t)ide analogues for chronic hepatitis B

The number of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) patients persists even under nucleos(t)ide analogues (NAs) treatment. Aldo-keto reductase family 1 member B10 (AKR1B10) expression has been reported in advanced chronic liver diseases as well as cancer tissues. We observed an association between related to HCC incidence and serum AKR1B10 by analyzing patients under treatment with NAs. Serum AKR1B10 levels measured by ELISA were higher in HCC cases under NA treatment compared with non-HCC cases and were associated with lamivudine- and adefovir pivoxil-, but not entecavir- or tenofovir alafenamide-treated cases. The latter drugs did not increase AKR1B10 values even in HCC cases, suggesting that they influence the reduction of AKR1B10 in any cases. This analysis was supported by in-vitro examination, which showed reduced AKR1B10 expression by entecavir and tenofovir via immunofluorescence staining. In conclusion there was a relationship between HBV-related HCC incidence and AKR1B10 under nucleos(t)ide analogues, especially in the use of lamivudine and adefovir pivoxil, but entecavir and tenofovir had suppressive effects of AKR1B10.

Whole genome analysis of hepatitis B virus before and during long-term therapy in chronic infected patients: Molecular characterization, impact on treatment and liver disease progression

Hepatitis B virus (HBV) infection remains a serious public health concern worldwide despite the availability of an efficient vaccine and the major improvements in antiviral treatments. The aim of the present study is to analyze the mutational profile of the HBV whole genome in ETV non-responder chronic HBV patients, in order to investigate antiviral drug resistance, immune escape, and liver disease progression to Liver Cirrhosis (LC) or Hepatocellular Carcinoma (HCC). Blood samples were collected from five chronic hepatitis B patients. For each patient, two plasma samples were collected, before and during the treatment. Whole genome sequencing was performed using Sanger technology. Phylogenetic analysis comparing the studied sequences with reference ones was used for genotyping. The mutational profile was analyzed by comparison with the reference sequence M32138. Genotyping showed that the studied strains belong to subgenotypes D1, D7, and D8. The mutational analysis showed high genetic variability. In the RT region of the polymerase gene, 28 amino acid (aa) mutations were detected. The most significant mutations were the pattern rtL180M + rtS202G + rtM204V, which confer treatment resistance. In the S gene, 35 mutations were detected namely sP120T, sT126S, sG130R, sY134F, sS193L, sI195M, and sL216stop were previously described to lead to vaccine, immunotherapy, and/or diagnosis escape. In the C gene, 34 mutations were found. In particular, cG1764A, cC1766G/T, cT1768A, and cC1773T in the BCP; cG1896A and cG1899A in the precore region and cT12S, cE64D, cA80T, and cP130Q in the core region were associated with disease progression to LC and/or HCC. Other mutations were associated with viral replication increase including cT1753V, cG1764A/T, cC1766G/T, cT1768A, and cC1788G in the BCP as well as cG1896A and cG1899A in the precore region. In the X gene, 30 aa substitutions were detected, of which substitutions xT36D, xP46S, xA47T, xI88F, xA102V, xI127T, xK130M, xV131I, and xF132Y were previously described to lead to LC and/or HCC disease progression. In conclusion, our results show high genetic variability in the long-term treatment of chronic HBV patients causing several effects. This could contribute to guiding national efforts to optimize relevant HBV treatment management in order to achieve the global hepatitis elimination goal by 2030.

Novel X gene point mutations in chronic hepatitis B and HBV related cirrhotic patients

INTRODUCTION

HBx is a multifunctional modulator viral protein with key roles in various biological processes such as signal transduction, transcription, proliferation, and cell apoptosis. Also, HBx has an important role in the progression of cirrhosis and hepatocellular carcinoma (HCC). This study aimed to determine mutations in X gene, enhancer II (EnhII), and basal core promoter (BCP) of genotype D of Hepatitis B Virus (HBV) in cirrhotic and chronic HBV patients.

MATERIAL AND METHODS

This cross-sectional study was performed on 68 cases with chronic HBV (cHBV) and 50 cases with HBV related cirrhosis. Serum samples were obtained for genomic DNA extraction. Semi-nested PCR was used to amplify the HBx region. Point mutations in the HBx region were detected by sequencing.

RESULT

Novel mutations were detected, including C1491G, C1500T, G1613T, and G1658T in the N-terminal of the X gene. The frequency of C1481T/G1479A, T1498C, C1500T, G1512A, A1635T, C1678T, A1727T, and A1762T/ G1764A/ C1773T was significantly higher in cirrhotic patients compared to chronically HBV infected ones. A higher rate of A1635T, C1678T, A1727T, A1762T, G1764A, and C1773T was observed in cirrhotic patients.

CONCLUSION

Our findings showed that the frequency of mutations in the basal-core promoter, enhancer II, and regulatory region of the HBx gene was more seen in cirrhotic patients than in chronic HBV cases. Novel mutations were detected in the HBx gene, causing amino acid substitutions; however, the clinical impact of these novel mutations is yet to be cleared.

Viral Hepatitis and Hepatocellular Carcinoma: State of the Art

Viral hepatitis is one of the main causes leading to hepatocellular carcinoma (HCC). The continued rise in incidence of HCC suggests additional factors following infection may be involved. This review examines recent studies investigating the molecular mechanisms of chronic hepatitis and its association with hepatocarcinogenesis. Hepatitis B virus patients with genotype C display an aggressive disease course leading to HCC more than other genotypes. Furthermore, hepatitis B excretory antigen (HBeAg) seems to be a more sensitive predictive tumor marker exhibiting a six-fold higher relative risk in patients with positive HBsAg and HBeAg than those with HBsAg only. Single or combined mutations of viral genome can predict HCC development in up to 80% of patients. Several mutations in HBx-gene are related with higher HCC incidence. Overexpression of the core protein in HCV leads to hepatocellular lipid accumulation associated with oncogenesis. Reduced number and decreased functionality of natural killer cells in chronic HCV individuals dysregulate their surveillance function in tumor and viral cells resulting in HCC. Furthermore, high T-cell immunoglobulin and mucin 3 levels supress CD8+ T-cells, which lead to immunological dysregulation. Hepatitis D promotes HCC development indirectly via modifications to innate immunity, epigenetic alterations and production of reactive oxygen species with the LHDAg being the most highly associated with HCC development. Summarizing the results, HBV and HCV infection represent the most associated forms of viral hepatitis causing HCC. Further studies are warranted to further improve the prediction of high-risk patients and development of targeted therapeutics preventing the transition from hepatic inflammation–fibrosis to cancer.

Hepatitis B virus X gene mutants emerge during antiviral therapy and increase cccDNA levels to compensate for replication suppression

BACKGROUND

Hepatitis B virus (HBV) X gene (HBx) mutants can develop during the natural course of chronic HBV infection. However, little is known about whether the emergence of HBx mutants during long-term antiviral therapy is an adaptation of HBV to antiviral stress. This study was to identify HBx mutants that emerged in patients experiencing Lamivudine resistance or suboptimal treatment.

METHODS

Forty-six Lamivudine-resistant patients and 46 patients with suboptimal treatment responses to Entecavir were enrolled in this study. HBx mutants were identified by sequence analysis and their roles in the HBV replication cycle were characterized.

RESULTS

We show that deletion/truncation/insertion mutations were only detected in the Lamivudine resistance group, while synonymous mutations were found in both groups. Follow-up analyses revealed that five patients in the Lamivudine group developed hepatocellular carcinoma, while patients in the Entecavir group did not. These mutants were characterized by a significant decrease in transactivation of the pre-S1 promoter, and varying effects on transactivation of the X promoter. Co-transfection of HBx-mutant plasmid and HBV replication-competent clone into HepG2 cells resulted in increased nuclear-to-cytoplamic HBV core antigen, HBV-DNA ratios, and nuclear covalently closed circular DNA (cccDNA). Antiviral drug sensitivity assays revealed that these mutants exhibited a compensatory effect to counteract antiviral drug suppression, resulting in elevated secretory HBV-DNA levels.

CONCLUSIONS

Our study demonstrates that HBx mutants can emerge during Lamivudine or Entecavir therapy. These mutants exhibit altered transactivation of the HBV pre-S1 and X promoters, leading to increased cccDNA levels to compensate for replication suppression.

Nanocarrier-mediated antioxidant delivery for liver diseases

Liver is the principal detoxifying organ and metabolizes various compounds that produce free radicals (FR) constantly. To maintain the oxidative/antioxidative balance in the liver, antioxidants would scavenge FR by preventing tissue damage through FR formation, scavenging, or by enhancing their decomposition. The disruption of this balance therefore leads to oxidative stress and in turn leads to the onset of various diseases. Supplying the liver with exogeneous antioxidants is an effective way to recreate the oxidative/antioxidative balance in the liver homeostasis. Nevertheless, due to the short half-life and instability of antioxidants in circulation, the methodology for delivering antioxidants to the liver needs to be improved. Nanocarrier mediated delivery of antioxidants proved to be an ingenious way to safely and efficiently deliver a high payload of antioxidants into the liver for circumventing liver diseases. The objective of this review is to provide an overview of the role of reactive oxygen species (oxidant) and ROS scavengers (antioxidant) in liver diseases. Subsequently, current nanocarrier mediated antioxidant delivery methods for liver diseases are discussed.

The novel HBx mutation F30V correlates with hepatocellular carcinoma in vivo, reduces hepatitis B virus replicative efficiency and enhances anti-apoptotic activity of HBx N terminus in vitro

OBJECTIVE

We aimed to investigate HBx genetic elements correlated with hepatitis B virus (HBV) -related hepatocellular carcinoma (HCC) and their impact on (a) HBV replicative efficiency, (b) HBx binding to circular covalently closed DNA (cccDNA), (c) apoptosis and cell-cycle progression, and (d) HBx structural stability.

METHODS

This study included 123 individuals chronically infected with HBV: 27 with HCC (77.9% (21/27) genotype D; 22.1% (6/27) genotype A) and 96 without HCC (75% (72/96) genotype D; 25.0% (24/96) genotype A). HepG2 cells were transfected by wild-type or mutated linear HBV genome to assess pre-genomic RNA (pgRNA) and core-associated HBV-DNA levels, HBx-binding onto cccDNA by chromatin immunoprecipitation-based quantitative assay, and rate of apoptosis and cell-cycle progression by cytofluorimetry.

RESULTS

F30V was the only HBx mutation correlated with HCC (18.5% (5/27) in HCC patients versus 1.0% (1/96) in non-HCC patients, p 0.002); a result confirmed by multivariate analysis. In vitro, F30V determined a 40% and 60% reduction in pgRNA and core-associated HBV-DNA compared with wild-type (p <0.05), in parallel with a significant decrease of HBx binding to cccDNA and decreased HBx stability. F30V also decreased the percentage of apoptotic cells compared with wild-type (14.8 ± 6.8% versus 19.1 ± 10.1%, p <0.01, without affecting cell-cycle progression) and increased the probability of HBx-Ser-31 being phosphorylated by PI3K-Akt kinase (known to promote anti-apoptotic activity).

CONCLUSIONS

F30V was closely correlated with HBV-induced HCC in vivo, reduced HBV replicative efficiency by affecting HBx-binding to cccDNA and increased anti-apoptotic HBx activity in vitro. This suggests that F30V (although hampering HBV's replicative capacity) may promote hepatocyte survival, so potentially allowing persistent production of viral progeny and initiating HBV-driven hepatocarcinogenesis. Investigation of viral genetic markers associated with HCC is crucial to identify those patients at higher risk of HCC, who hence deserve intensive liver monitoring and/or early anti-HBV therapy.

Host and Viral Genetic Variation in HBV-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the second leading cause of cancer deaths globally. The high prevalence of HCC is due in part to the high prevalence of chronic HBV infection and the high mortality rate is due to the lack of biomarkers for early detection and limited treatment options for late stage HCC. The observed individual variance in development of HCC is attributable to differences in HBV genotype and mutations, host predisposing germline genetic variations, the acquisition of tumor-specific somatic mutations, as well as environmental factors. HBV genotype C and mutations in the preS, basic core promoter (BCP) or HBx regions are associated with an increased risk of HCC. Genome-wide association studies have identified common polymorphisms in KIF1B, HLA-DQ, STAT4, and GRIK1 with altered risk of HBV-related HCC. HBV integration into growth control genes (such as TERT), pro-oncogenic genes, or tumor suppressor genes and the oncogenic activity of truncated HBx promote hepatocarcinogenesis. Somatic mutations in the TERT promoter and classic cancer signaling pathways, including Wnt (CTNNB1), cell cycle regulation (TP53), and epigenetic modification (ARID2 and MLL4) are frequently detected in hepatic tumor tissues. The identification of HBV and host variation associated with tumor initiation and progression has clinical utility for improving early diagnosis and prognosis; whereas the identification of somatic mutations driving tumorigenesis hold promise to inform precision treatment for HCC patients.

Serum Wisteria floribunda agglutinin-positive Mac-2 binding protein predicts hepatocellular carcinoma incidence and recurrence in nucleos(t)ide analogue therapy for chronic hepatitis B

BACKGROUND

Hepatocellular carcinoma (HCC) occurs in chronic hepatitis B (CH-B) patients even after treatment with nucleos(t)ide analogues (NAs) by a mechanism involving an association between the oncogenic factors of integrated HBV and liver fibrosis. An association has been demonstrated between advanced chronic liver disease and elevated levels of Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA(+)-M2BP), a recently discovered serum liver fibrosis marker. Moreover, hepatitis B core-related antigen (HBcrAg) reflects intracellular HBV protein production and its relationship with liver carcinogenesis has been reported. This study aimed to determine whether the incidence and recurrence of HBV-related liver cancer could be predicted using these serum markers.

METHODS

We evaluated 141 CH-B cases treated for more than 1 year with NAs. We compared 17 HCC cases with 124 non-HCC cases and evaluated serum WFA(+)-M2BP, HBV markers including HBcrAg, and other clinical factors. We also evaluated 71 CH-B-related HCC cases who started or continued NAs and compared the incidence and recurrence of HCC after successful cancer treatment.

RESULTS

Multivariate analysis showed that the incidence of HCC was significantly associated with higher histological stage and grade before NA treatment and with WFA(+)-M2BP and HBcrAg positivity during NA treatment. The cumulative incidence of HCC was strongly associated with higher WFA(+)-M2BP levels and HBcrAg positivity. HCC recurrence after anti-cancer therapy was also significantly associated with higher WFA(+)-M2BP levels compared with those in cases without recurrence during follow-up.

CONCLUSION

Serum WFA(+)-M2BP and HBcrAg are useful diagnostic tests for predicting the development and recurrence of HBV-related HCC during NA treatment.

Hepatitis B virus (HBV) X gene mutations and their association with liver disease progression in HBV-infected patients

Hepatitis B virus (HBV) is one of the most widespread human pathogens causing chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). This study investigated the clinical impact of single and combinational mutations in HBx gene on the pathogenesis of HCC during progressive stages of liver disease. The patients were categorized into inactive HBV carriers, active carriers, cirrhosis and HCC groups based on disease severity. Male sex, age > 50 years, and high serum alanine aminotransferase level were associated with risk of progressive liver disease. I127T, V131I, and F132Y/I/R mutations showed a significant increasing trend associated with the disease progression to HCC. H94Y and K130M mutations were also significantly associated with severe liver disease. One double mutation (K130M+V131I) and two triple mutations (I127T+K130M+V131L and K130M+V131I+F132Y) were observed, with significant rising prevalence through progressive clinical phases of liver disease to HCC. Several single and combinational mutations in HBx correlating with severity and progressive clinical phases of HBV infection were identified. The mutational combinations may have a synergistic effect in accelerating the progression to HCC. These specific patterns of HBx mutations can be useful in predicting the clinical outcome of HBV-infected patients and may serve as early markers of high risk of developing HCC.

USP16 Downregulation by Carboxyl-terminal Truncated HBx Promotes the Growth of Hepatocellular Carcinoma Cells

Hepatitis B virus (HBV) infection is a major factor that contributes to the development of hepatocellular carcinoma (HCC). HBV X protein (HBx) has been shown to accelerate HCC progression by promoting tumour growth and metastasis. In the clinic, carboxyl-terminal truncated HBx (Ct-HBx) proteins are frequently present in HCC tumour tissues, but not in non-tumorous tissues. In this study, we analysed deubiquitinase expression profiles in cells with or without ectopic expression of the Ct-HBx proteins and observed that the expression of ubiquitin specific peptidase 16 (USP16) was substantially inhibited by Ct-HBx proteins. Liver tumour cells with forced down-regulation of USP16 exhibited increased capabilities for colony formation and tumour growth in vivo. In addition, USP16 inhibition promoted stem-like properties in tumour cells, as evidenced by their spheroid formation and chemo-responsiveness. Furthermore, ectopic expression of USP16 in tumour cells significantly abrogated the tumour promoting activities of the Ct-HBx proteins (HBxΔ35), leading to decreased tumour cell viability and tumour growth. In human HCCs, USP16 was frequently downregulated, and the decreased expression of USP16 was correlated with high tumour stages and poor differentiation status. Taken together, our study suggests that USP16 downregulation is a critical event in Ct-HBx-mediated promotion of HCC tumorigenicity and malignancy.

Carboxyl-terminal truncated HBx contributes to invasion and metastasis via deregulating metastasis suppressors in hepatocellular carcinoma

Hepatitis B virus (HBV) X protein (HBx), a trans-regulator, is frequently expressed in truncated form without carboxyl-terminus in hepatocellular carcinoma (HCC), but its functional mechanisms are not fully defined. In this report, we investigated frequency of this natural HBx mutant in HCCs and its functional significance. In 102 HBV-infected patients with HCC, C-terminal truncation of HBx, in contrast to full-length HBx, were more prevalent in tumors (70.6%) rather than adjacent non-tumorous tissues (29.4%) (p = 0.0032). Furthermore, two naturally-occurring HBx variants (HBxΔ31), which have 31 amino acids (aa) deleted (codons 123-125/124-126) at C-terminus were identified in tumors and found that the presence of HBxΔ31 significantly correlated with intrahepatic metastasis. We also show that over-expression of HBxΔ31 enhanced hepatoma cell invasion in vitro and metastasis in vivo compared to full-length HBx. Interestingly, HBxΔ31 exerts this function via down-regulating Maspin, RhoGDIα and CAPZB, a set of putative metastasis-suppressors in HCC, in part, by enhancing the binding of transcriptional repressor, myc-associated zinc finger protein (MAZ) to the promoters through physical association with MAZ. Notably, these HBxΔ31-repressed proteins were also significantly lower expression in a subset of HCC tissues with C-terminal HBx truncation than the adjacent non-tumorous tissues, highlighting the clinical significance of this novel HBxΔ31-driven metastatic molecular cascade. Our data suggest that C-terminal truncation of HBx, particularly breakpoints at 124aa, plays a role in enhancing hepatoma cell invasion and metastasis by deregulating a set of metastasis-suppressors partially through MAZ, thus uncovering a novel mechanism for the progression of HBV-associated hepatocarcinogenesis.

A novel mutant 10Ala/Arg together with mutant 144Ser/Arg of hepatitis B virus X protein involved in hepatitis B virus-related hepatocarcinogenesis in HepG2 cell lines

Hepatitis B virus (HBV) infection-related hepatocellular carcinoma (HCC) represents a major health problem worldwide. HBV X (HBx) protein is the most common open reading frame that may undergo mutations, resulting in the development of HCC. This study aimed to determine specific HBx mutations that differentiate the central- and para-tumor tissues, and identify their association with HCC development. HBx gene from HCC tumor and para-tumor tissues of 47 HCC patients was amplified, sequenced and statistically analyzed. A novel combination of 2 mutations at residues 10 and 144 was identified which might play a significant role in HCC development. Expression vectors carrying HBx with the specific mutations were constructed and transfected into HepG2 and p53-null HepG2 cells. Compared to wild type (WT) and single mutation of HBx at residue 10 or 144, the 10/144 double mutations strongly up-regulated p21 expression and prolonged G1/S transition in WT- and p53-null HepG2 cells. Apoptosis was also inhibited by HBx harboring 10/44 double-mutation. Binding of 10/144 double-mutant HBx to p53 was lower than WT HBx. Conclusively, the 10/144 double mutation of HBx might play a crucial role in HCC formation.

Oncogenic potential of hepatitis B virus encoded proteins

Due to the limited treatment options hepatocellular carcinoma (HCC) is one of the leading causes of cancer related death, and hepatitis B virus (HBV) infection is the major risk factor for development of HCC worldwide. HCC is typically preceded by chronic inflammation, but may also develop in the absence of liver disease on the basis of HBV infection and even when virus replication is controlled by antivirals. In this situation, HBV antigen expression persists and direct oncogenic effects of HBV are integration of the viral DNA into the host genome as well as direct effects of viral proteins. These factors have to be taken into account in order to personalize HCC surveillance in CHB and unravel novel therapeutic approaches.

Key role of hepatitis B virus mutation in chronic hepatitis B development to hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). The HBV mutations, which include point mutation, deletion, insertion and truncation mutation of HBV gene in 4 open reading frames (S, C, P, X), are closely associated with HCC pathogenesis. Some mutations accumulated during chronic HBV infection could be regarded as a biomarker to predict the occurrence of HCC. The detection of the mutations in clinical practice could be helpful for defining better preventive and therapeutic strategies and, moreover, predicting the progression of liver disease.

The direct and indirect roles of HBV in liver cancer: prospective markers for HCC screening and potential therapeutic targets

Chronic hepatitis B virus (HBV) infection remains the number one risk factor for hepatocellular carcinoma (HCC), accounting for more than 600 000 deaths/year. Despite highly effective antiviral treatment options, chronic hepatitis B (CHB), subsequent end-stage liver disease and HCC development remain a major challenge worldwide. In CHB, liver damage is mainly caused by the influx of immune cells and destruction of infected hepatocytes, causing necro-inflammation. Treatment with nucleoside/nucleotide analogues can effectively suppress HBV replication in patients with CHB and thus decrease the risk for HCC development. Nevertheless, the risk of HCC in treated patients showing sufficient suppression of HBV DNA replication is significantly higher than in patients with inactive CHB, regardless of the presence of baseline liver cirrhosis, suggesting direct, long-lasting, predisposing effects of HBV. Direct oncogenic effects of HBV include integration in the host genome, leading to deletions, cis/trans-activation, translocations, the production of fusion transcripts and generalized genomic instability, as well as pleiotropic effects of viral transcripts (HBsAg and HBx). Analysis of these viral factors in active surveillance may allow early identification of high-risk patients, and their integration into a molecular classification of HCC subtypes might help in the development of novel therapeutic approaches.

Hepatitis B virus, HBx mutants and their role in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of death induced by cancer in the modern world and majority of the cases are related to chronic hepatitis B virus (HBV) infection. HBV-encoded X protein (HBx) is known to play a pivotal role in the pathogenesis of viral induced HCC. HBx is a multifunctional protein of 17 kDa which modulates several cellular processes by direct or indirect interaction with a repertoire of host factors resulting in HCC. HBX might interfere with several cellular processes such as oxidative stress, DNA repair, signal transduction, transcription, protein degradation, cell cycle progression and apoptosis. A number of reports have indicated that HBx is one of the most common viral ORFs that is often integrated into the host genome and its sequence variants play a crucial role in HCC. By mutational or deletion analysis it was shown that carboxy terminal of HBx has a likely role in protein-protein interactions, transcriptional transactivation, DNA repair, cell, signaling and pathogenesis of HCC. The accumulated evidence thus far suggests that it is difficult to understand the mechanistic nature of HBx associated HCC, and HBx mediated transcriptional transactivation and signaling pathways may be a major determinant. This article addresses the role of HBx in the development of HCC with particular emphasis on HBx mutants and their putative targets.

The oncogenic role of hepatitis B virus

The hepatitis B virus (HBV) is a small enveloped DNA virus that causes acute and chronic hepatitis. HBV infection is a world health problem, with 350 million chronically infected people at increased risk of developing liver disease and hepatocellular carcinoma (HCC). HBV has been classified among human tumor viruses by virtue of a robust epidemiologic association between chronic HBV carriage and HCC occurrence. In the absence of cytopathic effect in infected hepatocytes, the oncogenic role of HBV might involve a combination of direct and indirect effects of the virus during the multistep process of liver carcinogenesis. Liver inflammation and hepatocyte proliferation driven by host immune responses are recognized driving forces of liver cell transformation. Genetic and epigenetic alterations can also result from viral DNA integration into host chromosomes and from prolonged expression of viral gene products. Notably, the transcriptional regulatory protein HBx encoded by the X gene is endowed with tumor promoter activity. HBx has pleiotropic activities and plays a major role in HBV pathogenesis and in liver carcinogenesis. Because hepatic tumors carry a dismal prognosis, there is urgent need to develop early diagnostic markers of HCC and effective therapies against chronic hepatitis B. Deciphering the oncogenic mechanisms that underlie HBV-related tumorigenesis might help developing adapted therapeutic strategies.