Effect of combined mutations in the enhancer II and basal core promoter of hepatitis B virus on development of hepatocellular carcinoma in Qidong, China

Genetic diversity in enhancer II region of HBV genotype D and its association with advanced liver diseases

Background

Hepatitis B Virus (HBV) is one of the most common human infectious agents, and the mutations in its genome may cause chronic hepatitis (CH), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). This study was designed to characterize the enhancer-II (Enh-II) region of X gene in HBV positive patients to assess the association of such mutations with CH, LC, and HCC.

Methods

HBV positive samples (N = 200) with patients’ demographic and clinical data were collected from different regions of Khyber Pakhtunkhwa (KP), Pakistan. The Enh-II region of the HBx gene was sequenced and zanalyzed for polymorphism associated with advanced liver disease. Univariate and logistic regression analyses were performed to evaluate potent mutations associated with a risk for LC and HCC.

Results

HBV Enh-II region sequences analysis revealed 25 different mutations. The highest frequency of mutations S101F (62.2%), A102V/R/G/I (56.25%), M103L/A (68.75%)were found in HCC, followed in LC and CH patients as 57.1%, 42.8%, 28.52% 16%, 15.2% and 18.4% respectively. H94 deletion in the α-box of the Enh-II region, associated with a high risk of HCC was found in half of the HCC patients. This deletion was present in 28.5% of LC and 6.5% of CH patients. Importantly, the high frequency of some notable mutations such as E109A/Y, A110S/K, Y111D/E, and F112L was first time reported in the entire study population. The frequencies of these mutations were high in HCC (43.75%, 37.5%, 50% and 43.75% respectively) as compared to LC (14.28%, 14.28%, 28.2% and 42.8%) and CH patients (12.8%, 15.2%, 16.8% and 16% respectively).

Conclusion

Mutations associated with LC and HCC are prevalent in the Enh-II region in Pakistani HBV isolates. The mutations found are alarming in CH patients as these may progress to LC and HCC in a large number of patients.

Locus 5p13.1 may be associated with the selection of cancer-related HBV core promoter mutations

Background: The basal core promoter (BCP) double mutations (A1762T and G1764A) of hepatitis B virus (HBV) have been reported to be an aetiological factor of hepatocellular carcinoma (HCC). What distinguishes the subset of HBV carriers in whom these mutations are selected? Methods: A genome-wide association study (GWAS) was carried out on 218 asymptomatic HBsAg carriers infected with HBV with BCP double mutations and 191 controls infected with HBV with the wild type BCP. The highest ranking nucleotide polymorphisms (SNPs) were validated with other study subjects, 203 cases and 181 controls. The expression of the gene nearest a SNP found to be significant was examined using RT-PCR. Results: Forty-five candidate SNPs were identified in the GWAS. Three SNPs were found to be associated with the selection of HBV BCP double mutations in the replication stage, including rs7717457 at 5p13.1, rs670011 at 17q21.2, rs2071611 at 6p22.2. Especially, rs7717457 (P= 4.57×10^-5 combined P) reached the potential GWAS significance level. The expression of gene complement component 7 (C7), nearest to SNP rs7717457, differed significantly between the case and control groups (t=2.045, P=0.04), suggesting that SNP rs7717457 was associated with the expression of its nearest gene. Conclusions: SNP rs7717457 is associated with the selection of HBV BCP double mutations, providing an important clue to understanding the mechanisms of oncogenesis of HBV BCP double mutations.

Pre-S deletions of hepatitis B virus predict recurrence of hepatocellular carcinoma after curative resection

The relationship between hepatitis B virus (HBV) and the prognosis of hepatocellular carcinoma (HCC) after surgery remains uncertain. A retrospective cohort study was performed to evaluate the impact of pre-S deletions, T1762/A1764, and A1896 mutations on prognosis of HCC after curative resection. A total of 113 patients with positive serum HBV DNA (>200 IU/mL) who had underwent curative resection of pathologically proven HCC were recruited to determine the risk factors affecting the prognosis.The median follow-up time was 36.5 months and recurrence was detected in 67 patients (59.3%). The cumulative recurrence rates and overall survival rates at 1-, 3-, and 5-year after curative resection were 18.0%, 49.7%, 70.3%, and 93.7%, 61.0%, 42.5%, respectively. Patients with pre-S deletions showed significantly higher recurrence rates compared with those with wild type infection (HR: 1.822, P = .018), but not related with a significantly poor survival (HR: 1.388, P = .235). Subgroup analysis indicated that the patients with type III deletion had significant higher tumor recurrence rates than other deletion types (HR: 2.211, 95% confidence intervals [CI]: 1.008-4.846, P = .048). Multivariate analysis revealed that pre-S deletion, tumor size >3 cm in diameter, and the presence of microvascular invasion were independent risk factors for tumor recurrence. HBV pre-S deletions were found to be clustered primarily in the 5' end of pre-S2 region and were more often found between amino acids 120 and 142 of the pre-S2 domain. The domains most frequently potentially involved were the transactivator domain in pre-S2 and polymerized human serum albumin binding site.Our cohort showed that pre-S deletions at the time of resection could predict tumor recurrence in HCC patients after curative resection.

Hepatocellular carcinoma-associated single-nucleotide variants and deletions identified by the use of genome-wide high-throughput analysis of hepatitis B virus

This study investigated hepatitis B virus (HBV) single-nucleotide variants (SNVs) and deletion mutations linked with hepatocellular carcinoma (HCC). Ninety-three HCC patients and 108 non-HCC patients were enrolled for HBV genome-wide next-generation sequencing (NGS) analysis. A systematic literature review and a meta-analysis were performed to validate NGS-defined HCC-associated SNVs and deletions. The experimental results identified 60 NGS-defined HCC-associated SNVs, including 41 novel SNVs, and their pathogenic frequencies. Each SNV was specific for either genotype B (n = 24) or genotype C (n = 34), except for nt53C, which was present in both genotypes. The pathogenic frequencies of these HCC-associated SNVs showed a distinct U-shaped distribution pattern. According to the meta-analysis and literature review, 167 HBV variants from 109 publications were categorized into four levels (A-D) of supporting evidence that they are associated with HCC. The proportion of NGS-defined HCC-associated SNVs among these HBV variants declined significantly from 75% of 12 HCC-associated variants by meta-analysis (Level A) to 0% of 10 HCC-unassociated variants by meta-analysis (Level D) (P < 0.0001). PreS deletions were significantly associated with HCC, in terms of deletion index, for both genotypes B (P = 0.030) and C (P = 0.049). For genotype C, preS deletions involving a specific fragment (nt2977-3013) were significantly associated with HCC (HCC versus non-HCC, 6/34 versus 0/32, P = 0.025). Meta-analysis of preS deletions showed significant association with HCC (summary odds ratio 3.0; 95% confidence interval 2.3-3.9). Transfection of Huh7 cells showed that all of the five novel NGS-defined HCC-associated SNVs in the small surface region influenced hepatocarcinogenesis pathways, including endoplasmic reticulum-stress and DNA repair systems, as shown by microarray, real-time polymerase chain reaction and western blot analysis. Their carcinogenic mechanisms are worthy of further research. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The virological aspects of hepatitis B

Human hepatitis B virus (HBV) is a hepatotropic virus that is responsible for a significant burden of disease, causing liver disease and hepatocellular carcinoma. It is a small DNA virus with a replication strategy that is similar to that of a retrovirus. HBV is prone to mutagenesis and under the influence of diverse selection pressures, has evolved into a pool of quasispecies, genotypes and mutants, which confers a significant survival advantage. The genome is small, circular, and compact but has a complex replication strategy. The viral life cycle involves the formation of a covalently closed circular DNA (cccDNA), which is organized into a minichromosome that is the template for the synthesis of viral mRNA. HBV DNA (double-stranded linear form) can also integrate into the host genome, ensuring lifelong persistence of the virus. To date, despite great advances in therapeutics, once HBV is chronically established, it is incurable. This is by virtue of many aspects of its virological structure and viral life cycle. In this review, we aim to discuss important aspects of the virology of HBV with a focus on clinical implications.

The association between hepatitis B mutants and hepatocellular carcinoma: A meta-analysis

BACKGROUND

More and more studies focus on the relationship between hepatitis B virus (HBV) basal core promoter/precore (BCP/PC) mutations, but it remains controvercial, we conducted a meta-analysis to investigate the features of hepatitis B virus basal core promoter/precore mutations on the progression of hepatocellular carcinoma (HCC).

METHODS

A comprehensive search was conducted for articles published between January 1, 2005 and December 31, 2015 using the following databases: PubMed, Embase, Cochrane Library, Wanfang, and China National Knowledge Infrastructure. Medical subject heading terms were prioritized in setting the search strategy. Search terms included ("hepatitis B virus"), ("mutation or mutations or mutant"), and ("hepatocellular carcinoma" or "liver cancer" or hepatoma). A meta-analysis of pooled results from case-control studies examined the association between mutations G1896A, A1762T, G1764A, and A1762T/G1764A and the risk of HCC.

RESULTS

We included 29 articles for analysis and found that G1896A (summary odds ratios [OR] = 2.04, 95% confidence interval [CI] = 1.41-2.95), A1762T (summary OR = 3.96, 95% CI = 1.98-7.92), G1764A (summary OR = 3.48, 95% CI = 1.99-6.09), and A1762T/G1764A (summary OR = 3.96, 95% CI = 2.77-5.65) are each associated with a statistically significant increase in the risk of HCC.

CONCLUSION

In summary, we found that G1896A, A1762T, G1764A, and A1762T/G1764A are associated with an increased risk of HCC.

X region mutations of hepatitis B virus related to clinical severity

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

Naturally occurring basal core promoter A1762T/G1764A dual mutations increase the risk of HBV-related hepatocellular carcinoma: a meta-analysis

Basal core promoter (BCP) A1762T/G1764A dual mutations in hepatocarcinogenesis remain controversial. Published studies up to June 1, 2015 investigating the frequency of A1762T/G1764A dual mutations from chronic hepatitis B virus (HBV) infection, including hepatocellular carcinoma (HCC), were systematically identified. A total of 10,240 patients with chronic HBV infection, including 3729 HCC cases, were included in 52 identified studies. HCC patients had a higher frequency of BCP A1762T/G1764A dual mutations compared with asymptomatic HBsAg carriers (ASC) and patients with chronic hepatitis B (CHB) and liver cirrhosis (LC) (OR = 5.59, P < 0.00001; OR = 2.87, P < 0.00001; OR = 1.55, P = 0.02, respectively). No statistically significant difference was observed in the frequency of A1762T/G1764A dual mutations in cirrhotic HCC versus non-cirrhotic HCC patients (OR = 2.06, P = 0.05). Chronic HBV-infected patients and HCC patients with genotype B had a significantly lower risk of A1762T/G1764A dual mutations compared with patients with genotype C (OR = 0.30, P < 0.0001 and OR = 0.34, P = 0.04, respectively). In HBV genotype C subjects, A1762T/G1764A dual mutations contributed to significantly higher risk for HCC developing compared with non-mutation ones (OR = 3.47, P < 0.00001). In conclusion, A1762T/G1764A dual mutations increase the risk of HBV-related hepatocellular carcinoma, particularly in an HBV genotype C population, even without progression to cirrhosis.

Hepatitis B virus genotype, mutations, human leukocyte antigen polymorphisms and their interactions in hepatocellular carcinoma: a multi-centre case-control study

Three genome-wide association studies (GWAS) have been conducted on the genetic susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), two of which consistently identified tagging single nucleotide polymorphisms (SNPs) around HLA-DQ/DR. In contrast, large multi-centre association studies between HBV genotype, mutations and the risk of HCC are relatively rare, and their interactions with host variants are even less. We performed a multi-centre study of 1,507 HBV-related HCC cases and 1,560 HBV persistent carriers as controls to evaluate the effects of HBV genotype, mutations, GWAS-identified HLA-DQ/DR SNPs (rs9272105 and rs9275319) and their interactions on HCC risk. We found HBV genotype C was more frequent in HBV-related HCC. And 11 HBV hotspot mutations were independently and significantly associated with HCC risk. We also detected significant interactions of rs9272105 with both the HBV genotype and mutations. Through stepwise regression analysis, HBV genotype, the 11 mutations, HLA-DQ/DR SNPs, and the interaction of rs9272105 with mutation A1752G were all entered into the HCC prediction model, and the area under the curve for the panel including the HLA-DQ/DR SNPs, HBV genotype and mutations was 0.840. The HBV genotype, the mutations and the HLA-DQ/DR SNPs may serve as biomarkers for the surveillance of HBV persistent carriers.

Quantitative evaluation of hepatitis B virus mutations and hepatocellular carcinoma risk: a meta-analysis of prospective studies

BACKGROUND

The temporal relationship between hepatitis B virus (HBV) mutations and hepatocellular carcinoma (HCC) remains unclear.

METHODS

We conducted a meta-analysis including cohort and nested case-control studies to prospectively examine the HCC risk associated with common variants of HBV in the PreS, Enhancer II, basal core promoter (BCP) and precore regions. Pertinent studies were identified by searching PubMed, Web of Science and the Chinese Biological Medicine databases through to November 2014. Study-specific risk estimates were combined using fixed or random effects models depending on whether significant heterogeneity was detected.

RESULTS

Twenty prospective studies were identified, which included 8 cohort and 12 nested case-control studies. There was an increased risk of HCC associated with any PreS mutations with a pooled relative risk (RR) of 3.82 [95% confidence interval (CI): 2.59-5.61]. The pooled-RR for PreS deletion was 3.98 (95% CI: 2.28-6.95), which was higher than that of PreS2 start codon mutation (pooled-RR=2.63, 95% CI: 1.30-5.34). C1653T in Enhancer II was significantly associated with HCC risk (pooled-RR=1.83; 95% CI: 1.21-2.76). For mutations in BCP, statistically significant pooled-RRs of HCC were obtained for T1753V (pooled-RR=2.09; 95% CI: 1.49-2.94) and A1762T/G1764A double mutations (pooled-RR=3.11; 95% CI: 2.08-4.64). No statistically significant association with HCC risk was observed for G1896A in the precore region (pooled-RR=0.77; 95% CI: 0.47-1.26).

CONCLUSIONS

This study demonstrated that PreS mutations, C1653T, T1753V, and A1762T/G1764A, were associated with an increased risk of HCC. Clinical practices concerning the HCC risk prediction and diagnosis may wish to focus on patients with these mutations.

Novel point and combo-mutations in the genome of hepatitis B virus-genotype D: characterization and impact on liver disease progression to hepatocellular carcinoma

Background

The contribution of chronic hepatitis B virus (HBV) infection in the pathogenesis of hepatocellular carcinoma (HCC) through progressive stages of liver fibrosis is exacerbated by the acquisition of naturally occurring mutations in its genome. This study has investigated the prevalence of single and combo mutations in the genome of HBV-genotype D from treatment naïve Indian patients of progressive liver disease stages and assessed their impact on the disease progression to HCC.

Methods

The mutation profile was determined from the sequence analysis of the full-length HBV genome and compared with the reference HBV sequences. SPSS 16.0 and R software were used to delineate their statistical significance in predicting HCC occurrence.

Results

Age was identified as associated risk factor for HCC development in chronic hepatitis B (CHB) patients (p≤0.01). Beyond the classical mutations in basal core promoter (BCP) (A1762T/G1764A) and precore (G1862T), persistence of progressively accumulated mutations in enhancer-I, surface, HBx and core were showed significant association to liver disease progression. BCP_T1753C, core_T147C, surface_L213I had contributed significantly in the disease progression to HCC (p<0.05) in HBeAg positive patients whereas precore_T1858C, core_I116L, core_P130Q and preS1_S98T in HBeAg negative patients. Furthermore, the effect of individual mutation was magnified by the combination with A1762T/G1764A in HCC pathogenesis. Multivariate risk analysis had confirmed that core_P130Q [OR 20.71, 95% CI (1.64–261.77), p = 0.019] in B cell epitope and core_T147C [OR 14.58, 95% CI (1.17–181.76), p = 0.037] in CTL epitope were two independent predictors of HCC in HBeAg positive and negative patients respectively.

Conclusions

Thus distinct pattern of mutations distributed across the entire HBV genome may be useful in predicting HCC in high-risk CHB patients and pattern of mutational combinations may exert greater impact on HCC risk prediction more accurately than point mutations and hence these predictors may support the existing surveillance strategies in proper management of the patients.

Association of hepatitis B virus pre-S deletions with the development of hepatocellular carcinoma in Qidong, China

Background/Aim

To investigate the roles of mutations in pre-S and S regions of hepatitis B virus (HBV) on the progression of hepatocellular carcinoma (HCC) in Qidong, China.

Methods

We conducted an age matched case-control study within a cohort of 2387 male HBV carriers who were recruited from August, 1996. The HBV DNA sequence in pre-S/S regions was successfully determined in 96 HCC cases and 97 control subjects. In addition, a consecutive series of samples from 11 HCC cases were employed to evaluate the pre-S deletion patterns before and after the occurrence of HCC.

Results

After adjustment for age, history of cigarette smoking and alcohol consumption, HBeAg positivity, pre-S deletions, pre-S2 start codon mutations, and T53C mutation were significantly associated with HCC, showing adjusted odds ratios (ORs) from 1.914 to 3.199. HCC patients also had a lower frequency of T31C mutation in pre-S2 gene, compared with control subjects (0.524; 95% CI 0.280-0.982). HBV pre-S deletions were clustered mainly in the 5′ end of pre-S2 region. Multivariate analysis showed that pre-S deletions and pre-S2 start codon mutations were independent risk factors for HCC. The OR (95% CI) were 2.434 (1.063–5.573) and 3.065 (1.099–8.547), respectively. The longitudinal observation indicated that the pre-S deletion mutations were not acquired at the beginning of HBV infection, but that the mutations occurred during the long course of liver disease.

Conclusion

Pre-S deletions and pre-S2 start codon mutations were independently associated with the development of HCC. The results also provided direct evidence that pre-S deletion mutations were not acquired from the beginning of infection but arose de novo during the progression of liver disease.