Human cytidine deaminases facilitate hepatitis B virus evolution and link inflammation and hepatocellular carcinoma

Progress in understanding of relationship between inflammation and tumors

Over the past decade, there has been clear evidence that inflammation plays a key role in tumorigenesis. Tumor extrinsic inflammation is caused by many factors, including bacterial and viral infections, autoimmune diseases, obesity, smoking, excessive alcohol consumption, etc., all of which can increase cancer risk and stimulate malignant progression. Conversely, inflammation inherent in cancer or caused by cancer can be triggered by cancer-initiating mutations and can promote malignant progression through recruitment and activation of inflammatory cells. Both exogenous and endogenous inflammation can lead to immunosuppression, thus providing a preferred opportunity for tumor development. Studies have confirmed that chronic inflammation is involved in various steps of tumorigenesis, including cell transformation, promotion, survival, prolifer-ation, invasion, angiogenesis, and metastasis. Recent research has shed new light on the molecular and cellular circuits between inflammation and cancer. Two pathways have been preliminarily identified: Intrinsic and extrinsic. In the intrinsic pathway, genetic events leading to tumors initiate the expression of inflammatory related programs and guide the construction of the inflammatory microenvironment. In the extrinsic pathway, inflammatory conditions promote the development of cancer. This article reviews the recent progress in the understanding of the relationship between inflammation and tumors.

HLA-DR genetic polymorphisms and hepatitis B virus mutations affect the risk of hepatocellular carcinoma in Han Chinese population

BACKGROUND

Human leucocyte antigen (HLA)-DR plays a crucial role in the immune response against hepatitis B virus (HBV). We aimed to investigate the associations of HLA-DR single nucleotide polymorphisms (SNPs) with the generation of hepatocellular carcinoma (HCC)-related HBV mutations. The effects of HLA-DR SNPs and their interactions with HBV mutations on HCC risks were also determined.

METHODS

Five HLA-DR SNPs (rs3135363, rs9268644, rs35445101, rs24755213, and rs984778) were genotyped in 792 healthy controls, 586 chronic hepatitis B (CHB) patients, 536 liver cirrhosis (LC) patients, and 1500 HCC patients using quantitative PCR. Sanger sequencing was used to identify the HBV mutations. Logistic regression model was performed to evaluate the association of HLA-DR SNPs with HCC risk and the frequencies of HCC-related HBV mutations.

RESULTS

The variant genotypes at rs3135363, rs9268644, rs35445101, rs24755213, and rs984778 were associated with decreased HCC risks. In genotype C HBV-infected subjects, variant genotypes of these SNPs were associated with decreased frequencies of HCC-related HBV mutations such as C1653T, T1674C/G, G1719T, T1753A/C, A1762T/G1764A, A1846T, G1896A, G1899A, and preS deletion. AG genotype at rs3135363, CA genotype at rs9268644, and AG genotype at rs24755213 reduced the generation of T1753A/C and G1896A in genotype B HBV-infected subjects, respectively. In addition, the interactions of rs3135363, rs9268644, rs24755213 with C1653T, T1753A/C, A1846T, and G1896A decreased the risks of HCC.

CONCLUSIONS

HLA-DR genetic polymorphisms might predispose the host to immunoselection of HCC-related HBV mutations and affect the HCC risks possibly through interacting with HBV mutations.

Genomic Characterization Revealed PM2.5-Associated Mutational Signatures in Lung Cancer Including Activation of APOBEC3B

Fine particulate matter (PM_2.5) exposure causes DNA mutations and abnormal gene expression leading to lung cancer, but the detailed mechanisms remain unknown. Here, analysis of genomic and transcriptomic changes upon a PM_2.5 exposure-induced human bronchial epithelial cell-based malignant transformed cell model in vitro showed that PM_2.5 exposure led to APOBEC mutational signatures and transcriptional activation of APOBEC3B along with other potential oncogenes. Moreover, by analyzing mutational profiles of 1117 non-small cell lung cancers (NSCLCs) from patients across four different geographic regions, we observed a significantly higher prevalence of APOBEC mutational signatures in non-smoking NSCLCs than smoking in the Chinese cohorts, but this difference was not observed in TCGA or Singapore cohorts. We further validated this association by showing that the PM_2.5 exposure-induced transcriptional pattern was significantly enriched in Chinese NSCLC patients compared with other geographic regions. Finally, our results showed that PM_2.5 exposure activated the DNA damage repair pathway. Overall, here we report a previously uncharacterized association between PM_2.5 and APOBEC activation, revealing a potential molecular mechanism of PM_2.5 exposure and lung cancer.

Potential Role of the Fragile Histidine Triad in Cancer Evo-Dev

Cancer development follows an evolutionary pattern of "mutation-selection-adaptation" detailed by Cancer Evolution and Development (Cancer Evo-Dev), a theory that represents a process of accumulating somatic mutations due to the imbalance between the mutation-promoting force and the mutation-repairing force and retro-differentiation of the mutant cells to cancer initiation cells in a chronic inflammatory microenvironment. The fragile histidine triad (FHIT) gene is a tumor suppressor gene whose expression is often reduced or inactivated in precancerous lesions during chronic inflammation or virus-induced replicative stress. Here, we summarize evidence regarding the mechanisms by which the FHIT is inactivated in cancer, including the loss of heterozygosity and the promoter methylation, and characterizes the role of the FHIT in bridging macroevolution and microevolution and in facilitating retro-differentiation during cancer evolution and development. It is suggested that decreased FHIT expression is involved in several critical steps of Cancer Evo-Dev. Future research needs to focus on the role and mechanisms of the FHIT in promoting the transformation of pre-cancerous lesions into cancer.

APOBEC3B is overexpressed in cervical cancer and promotes the proliferation of cervical cancer cells through apoptosis, cell cycle, and p53 pathway

Objective

APOBEC3B (A3B), a member of the APOBEC family of cytidine deaminases, has been gradually regarded as a key cancerous regulator. However, its expression and mechanism in cervical cancer (CC) have not been fully elucidated. This study was to investigate its expression pattern and potential mechanism on the cell cycle, as well as HPV oncogenes in CC.

Methods

Data from The Cancer Genome Atlas (TCGA) and Gene Expression (GEO) were used to indicate the mRNA expression pattern of A3B in cervical cancer. Western blot assay was used to detect A3B levels in SiHa and Hela cell lines. Immunohistochemistry (IHC) was used to explore A3B protein abundance and sublocation in cervical cancer as well as normal cervical tissues. Based on the Protein atlas (www.proteinatlas.org), A3B expression in the SiHa cell line is lower than in the HeLa cell line. Therefore, the SiHa cell line was used for A3B gene overexpression experiments while the HeLa cell line was used for knockdown experiments. Flow cytometry analysis was used to detect cell apoptosis. Biological function and cancer-related pathways of A3B were conducted using bioinformatics analysis.

Results

A3B mRNA was significantly overexpressed in cervical cancer in TCGA-cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), GSE67522, and GSE7803. A3B was more highly expressed in cervical cancers than in high-grade squamous intraepithelial lesions and normal controls. A3B expression was found to be progressively activated during cervical cancer development. IHC results showed that A3B was significantly higher in cervical cancer tissues than in normal cervical tissues. A3B plasmid-mediated overexpression experiments and A3B siRNA-mediated knockdown experiments showed that A3B significantly promotes cell proliferation, migration, cell cycle, and chemoresistance in cervical cancer cells by the p53 pathway. GO and KEGG analyses showed that A3B expression was strikingly associated with cell proliferation, apoptosis, and immune-associated pathways.

Conclusions

Taken together, our study implies that A3B promotes cell proliferation, migration, and cell cycle and inhibits cancer cell apoptosis through the p53-mediated signaling pathway. Moreover, A3B could also contribute to chemoresistance in cervical cancer cells. It may be a potential diagnostic biomarker and therapeutic target for chemoresistant cervical cancers.

Cancer Evo-Dev: A Theory of Inflammation-Induced Oncogenesis

Chronic inflammation is a prerequisite for the development of cancers. Here, we present the framework of a novel theory termed as Cancer Evolution-Development (Cancer Evo-Dev) based on the current understanding of inflammation-related carcinogenesis, especially hepatocarcinogenesis induced by chronic infection with hepatitis B virus. The interaction between genetic predispositions and environmental exposures, such as viral infection, maintains chronic non-resolving inflammation. Pollution, metabolic syndrome, physical inactivity, ageing, and adverse psychosocial exposure also increase the risk of cancer via inducing chronic low-grade smoldering inflammation. Under the microenvironment of non-resolving inflammation, pro-inflammatory factors facilitate the generation of somatic mutations and viral mutations by inducing the imbalance between the mutagenic forces such as cytidine deaminases and mutation-correcting forces including uracil-DNA glycosylase. Most cells with somatic mutations and mutated viruses are eliminated in survival competition. Only a small percentage of mutated cells survive, adapt to the hostile environment, retro-differentiate, and function as cancer-initiating cells via altering signaling pathways. These cancer-initiating cells acquire stem-ness, reprogram metabolic patterns, and affect the microenvironment. The carcinogenic process follows the law of "mutation-selection-adaptation". Chronic physical activity reduces the levels of inflammation via upregulating the activity and numbers of NK cells and lymphocytes and lengthening leukocyte telomere; downregulating proinflammatory cytokines including interleukin-6 and senescent lymphocytes especially in aged population. Anti-inflammation medication reduces the occurrence and recurrence of cancers. Targeting cancer stemness signaling pathways might lead to cancer eradication. Cancer Evo-Dev not only helps understand the mechanisms by which inflammation promotes the development of cancers, but also lays the foundation for effective prophylaxis and targeted therapy of various cancers.

Compartmentalized evolution of hepatitis B virus contributes differently to the prognosis of hepatocellular carcinoma

Serum hepatitis B virus (HBV) mutations can predict hepatocellular carcinoma (HCC) occurrence. We aimed to clarify if HBV evolves synchronously in the sera, adjacent liver and tumors and predict HCC prognosis equally. A total of 203 HBV-positive HCC patients with radical hepatectomy in Shanghai, China, during 2011-15 were enrolled in this prospective study. Quasispecies complexity (QC) in HBV core promoter region was assessed using clone-based sequencing. We performed RNA sequencing on tumors and paired adjacent tissues of another 15 HCC patients and analyzed it with three public data sets containing 127 samples. HBV QC was positively correlated to APOBEC3s' expression level (r = 0.28, P < 0.001), higher in the adjacent tissues than in the tumors (P = 6.50e-3), and higher in early tumors than in advanced tumors (P = 0.039). The evolutionary distance between the sera-derived HBV strains and the tumor-derived ones was significantly longer than that between the sera-derived ones and the adjacent tissue-derived ones (P < 0.001). Multivariate Cox regression analyses indicated that high HBV QC in the sera predicted an unfavorable overall survival (P = 0.002) and recurrence-free survival (RFS; P = 0.004) in HCC, whereas, in the tumors, it predicted a favorable RFS (P < 0.001). APOBECs-related HBV mutations, including G1764A, were more frequent in the sera than in the adjacent tissues. High-frequent A1762T/G1764A in the sera predicted an unfavorable RFS (P < 0.001), whereas, in the tumors, it predicted a favorable RFS (P = 0.035). In conclusion, HBV evolves more advanced in the sera than in the tumors. HBV QC and A1762T/G1764A in the sera and tumors have contrary prognostic effects in HCC.

THERAPEUTIC OLIGONUCLEOTIDES, IMPURITIES, DEGRADANTS, AND THEIR CHARACTERIZATION BY MASS SPECTROMETRY

Oligonucleotides are an emerging class of drugs that are manufactured by solid-phase synthesis. As a chemical class, they have unique product-related impurities and degradants, characterization of which is an essential step in drug development. The synthesis cycle, impurities produced during the synthesis and degradation products are presented and discussed. The use of liquid chromatography combined with mass spectrometry for characterization and quantification of product-related impurities and degradants is reviewed. In addition, sequence determination of oligonucleotides by gas-phase fragmentation and indirect mass spectrometric methods is discussed. © 2019 John Wiley & Sons Ltd. Mass Spec Rev.

Multiple Roles for Hepatitis B and C Viruses and the Host in the Development of Hepatocellular Carcinoma

Chronic hepatitis B and C viral infections are major risk factors for hepatocellular carcinoma (HCC) in the United States and worldwide. Direct and indirect mechanisms of viral infection lead to the development of HCC. Chronic viral infection leads to inflammation and liver damage, culminating in cirrhosis, the penultimate step in the progression toward HCC. Host, viral, and environmental factors likely interact to promote oncogenesis. Clinical considerations include recommendations for screening for HCC in persons at risk, treatment with antivirals, and an emerging role for immunotherapy in HCC. We pose unanswered questions regarding HCC susceptibility and pathogenesis in the setting of chronic hepatitis B and C.

The genetic polymorphism down-regulating HLA-DRB1 enhancer activity facilitates HBV persistence, evolution and hepatocarcinogenesis in the Chinese Han population

Genetic predisposition of human leucocyte antigen (HLA)-DR has been linked to nonresponse to hepatitis B virus (HBV) vaccination. We sought to reveal their effects on chronic infection and evolution of HBV and development of hepatocellular carcinoma (HCC). Genetic polymorphisms at HLA-DR enhancer regions were genotyped in 4588 participants using quantitative PCR. HBV mutations were determined by sequencing. A dual-luciferase assay was applied to detect the enhancer activity. Associations between HLA-DR polymorphisms and postoperative prognosis were investigated in another cohort of 397 HBV-infected HCC patients. Variant alleles (rs3135395-T, rs3135338-C and rs477515-T) were significantly associated with a decreased risk of HBV persistence in Chinese patients. rs3135395-T, rs3135338-C, rs477515-T and rs2395178-G also significantly decreased HCC risk. rs3135395-T, rs477515-T and rs2395178-G were inversely associated with the generation of A1762T/G1764A, T1753V and C1653T, the HCC-risk HBV mutations. Multiplicative interactions of the variant genotypes with the HCC-risk HBV mutations were significantly associated with a decreased risk of HCC. In multivariate Cox analysis, rs477515-T independently predicted a favourable prognosis, with a hazard ratio of 0.48 (P = .002). The activity of the HLA-DRB1 enhancer with rs477515-T was significantly higher than that with rs477515-C. The activity of the HLA-DRB1 enhancer with rs477515-T and that with rs477515-C was significantly up-regulated by interferon-γ and interleukin-4, respectively. Interleukin-6 significantly inhibited the HLA-DRB1 enhancer activity, and this effect was more evident in those carrying rs477515-T. Polymorphisms predisposing to down-regulation of HLA-DR facilitate the Th1-to-Th2 transition and promote HCC development, possibly via selecting the HCC-risk HBV mutations. This can be transformed into specific prophylaxis of HCC.

GATA3 and APOBEC3B are prognostic markers in adrenocortical carcinoma and APOBEC3B is directly transcriptionally regulated by GATA3

Recent evidence has implicated APOBEC3B (Apolipoprotein B mRNA editing enzyme catalytic subunit 3B) as a source of mutations in breast, bladder, cervical, lung, head, and neck cancers. However, the role of APOBEC3B in adrenocortical carcinoma (ACC) and the mechanisms through which its expression is regulated in cancer are not fully understood. Here, we report that APOBEC3B is overexpressed in ACC and it regulates cell proliferation by inducing S phase arrest. We show high APOBEC3B expression is associated with a higher copy number gain/loss at chromosome 4 and 8 and TP53 mutation rate in ACC. GATA3 was identified as a positive regulator of APOBEC3B expression and directly binds the APOBEC3B promoter region. Both GATA3 and APOBEC3B expression levels were associated with patient survival. Our study provides novel insights into the function and regulation of APOBEC3B expression in addition to its known mutagenic ability.

Resveratrol inhibits tumor progression by down-regulation of NLRP3 in renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most common urologic malignant tumors. Current chemotherapy is not effective in RCC and results in some side effects. Resveratrol (RSV) has been reported to exert antitumor effects in some cancer cells; however the mechanism is not fully understood. Herein, we aimed to determine the anticancer effect of RSV on RCC and further explore the underlying molecular mechanism in this process. We found that RSV inhibited tumor cells proliferation, migration and invasion and increased apoptosis of RCC either in vivo or in vitro. RSV significantly down-regulated expressions of NLRP3 and its downstream genes. Inhibition of NLRP3 by NLRP3 small interfering RNA mimicked the effects of RSV on RCC cells. These results suggested that RSV could exert antitumor effect by depressing activity of NLRP3, and NLRP3 would be a promising clinical therapeutic strategy for RCC.

Differences in HBV Replication, APOBEC3 Family Expression, and Inflammatory Cytokine Levels Between Wild-Type HBV and Pre-core (G1896A) or Basal Core Promoter (A1762T/G1764A) Mutants

Background

Chronic hepatitis B virus (HBV) infection is the leading cause of hepatocellular carcinoma (HCC) world-wide. HBV variants, particularly the G1896A pre-core (PC) and A1762T/G1764A basal core promoter (BCP) mutations, are established risk factors for cirrhosis and HCC, but the molecular biological basis is unclear. We hypothesized that these variants result in differential HBV replication, APOBEC3 family expression, and cytokine/chemokine expression.

Methods

HepG2 cells were transfected with monomeric full-length containing wild-type, PC, or BCP HBV. Cells and supernatant were collected to analyze viral infection markers (i.e., HBsAg, HBeAg, HBV DNA, and RNA). Cellular APOBEC3 expression and activity was assessed by quantitative real-time (qRT)-PCR, immunoblot, differential DNA denaturation PCR, and sequencing. Cytokine/chemokines in the supernatant and in serum from 11 CHB carriers (4 non-cirrhotic; 7 cirrhotic and/or HCC) with predominantly wild-type, PC, or BCP variants were evaluated by Luminex.

Results

HBeAg expression was reduced in PC and BCP variants, and higher supernatant HBV DNA and HBV RNA levels were found with A1762T/G1764A vs. G1896A mutant (p < 0.05). Increased APOBEC3G protein levels in wild-type vs. mutant were not associated with HBV covalently closed circular DNA G-to-A hypermutations. Differences in cytokine/chemokine expression in culture supernatants, especially IL-13 were observed amongst the variants analyzed. Noticeable increases of numerous cytokines/chemokines, including IL-4 and IL-8, were observed in ex vivo serum collected from CHB carriers with PC mutant.

Conclusion

HBV sequence variation leads to differences in HBV protein production (HBeAg) and viral replication in addition to altered host innate antiviral restriction factor (APOBEC3) and cytokine/chemokine expression.

Correlation of APOBEC3G expression with liver function indexes of patients with chronic hepatitis B and comparison in chronic hepatitis B, liver cirrhosis and liver cancer

Correlation of APOBEC3G expression with liver function indexes of patients with chronic hepatitis B and its expression in chronic hepatitis B, liver cirrhosis and liver cancer were investigated to evaluated the significance of APOBEC3G. Fifty-eight patients with chronic hepatitis B were selected, including 20 cases of chronic hepatitis B, 19 cases of liver cirrhosis and 19 cases of liver cancer. Liver function indexes were detected and analyzed, and messenger ribonucleic acid (mRNA) and protein expression levels of APOBEC3G in liver tissues were detected via reverse transcription-polymerase chain reaction (RT-PCR), western blotting and immunohistochemistry, followed by correlation analysis. Certain liver function indexes had significant differences among the three groups of patients (P<0.05). Results of RT-PCR, Western blotting and immunohistochemistry confirmed that the content of APOBEC3G in liver tissues was the highest in patients with chronic hepatitis B, slightly lower in patients with liver cirrhosis and the lowest in patients with liver cancer. The content of APOBEC3G mRNA in liver tissues had a certain correlation with the content of alanine aminotransferase (ALT) (r² =0.34, P<0.05). Other liver function indexes had no significant correlations with APOBEC3G (P>0.05). APOBEC3G expression has a certain correlation with some liver function indexes of patients with chronic hepatitis B. There are significant differences in the expression level of APOBEC3G in patients with hepatitis, liver cirrhosis and liver cancer.

APOBEC3B interaction with PRC2 modulates microenvironment to promote HCC progression

OBJECTIVE

APOBEC3B (A3B), a cytidine deaminase acting as a contributor to the APOBEC mutation pattern in many kinds of tumours, is upregulated in patients with hepatocellular carcinoma (HCC). However, APOBEC mutation patterns are absent in HCC. The mechanism of how A3B affects HCC progression remains elusive.

DESIGN

A3B -promoter luciferase reporter and other techniques were applied to elucidate mechanisms of A3B upregulation in HCC. A3B overexpression and knockdown cell models, immunocompetent and immune-deficient mouse HCC model were conducted to investigate the influence of A3B on HCC progression. RNA-seq, flow cytometry and other techniques were conducted to analyse how A3B modulated the cytokine to enhance the recruitment of myeloid--derived suppressor cells (MDSCs) and tumour--associated macrophages (TAMs).

RESULTS

A3B upregulation through non-classical nuclear factor-κB (NF-κB)signalling promotes HCC growth in immunocompetent mice, associated with an increase of MDSCs, TAMs and programmed cell death1 (PD1) exprssed CD8⁺ T cells. A CCR2 antagonist suppressed TAMs and MDSCs infiltration and delayed tumour growth in A3B and A3B^E68Q/E255Q- expressing mouse tumours. Mechanistically, A3B upregulation in HCC depresses global H3K27me3 abundance via interaction with polycomb repressor complex 2 (PRC2) and reduces an occupancy of H3K27me3 on promoters of the chemokine CCL2 to recruit massive TAMs and MDSCs.

CONCLUSION

Our observations uncover a deaminase-independent role of the A3B in modulating the HCC microenvironment and demonstrate a proof for the concept of targeting A3B in HCC immunotherapy.

LncRNA FOXD2-AS1 as a competitive endogenous RNA against miR-150-5p reverses resistance to sorafenib in hepatocellular carcinoma

The current study elucidated the role of a long non-coding RNA (lncRNA), FOXD2-AS1, in the pathogenesis of hepatocellular carcinoma (HCC) and the regulatory mechanism underlying FOXD2-AS1/miR-150-5p/transmembrane protein 9 (TMEM9) signalling in HCC. Microarray analysis was used for preliminary screening of candidate lncRNAs in HCC tissues. qRT-PCR and Western blot analyses were used to detect the expression of FOXD2-AS1. Cell proliferation assays, luciferase assay and RNA immunoprecipitation were performed to examine the mechanism by which FOXD2-AS1 mediates sorafenib resistance in HCC cells. FOXD2-AS1 and TMEM9 were significantly decreased and miR-150-5p was increased in SR-HepG2 and SR-HUH7 cells compared with control parental cells. Overexpression of FOXD2-AS1 increased TMEM9 expression and overcame the resistance of SR-HepG2 and SR-HUH7 cells. Conversely, knockdown of FOXD2-AS1 decreased TMEM9 expression and increased the sensitivity of HepG2 and Huh7 cells to sorafenib. Our data also demonstrated that FOXD2-AS1 functioned as a sponge for miR-150-5p to modulate TMEM9 expression. Taken together, our findings revealed that FOXD2-AS1 is an important regulator of TMEM9 and contributed to sorafenib resistance. Thus, FOXD2-AS1 may serve as a therapeutic target against sorafenib resistance in HCC.

Genetic Polymorphisms Predisposing the Interleukin 6-Induced APOBEC3B-UNG Imbalance Increase HCC Risk via Promoting the Generation of APOBEC-Signature HBV Mutations

PURPOSE

APOBEC3-UNG imbalance contributes to hepatitis B virus (HBV) inhibition and somatic mutations. We aimed to explore the associations between hepatocellular carcinoma (HCC) risk and genetic polymorphisms predisposing the imbalance.Experimental Design: Genetic polymorphisms at APOBEC3 promoter and UNG enhancer regions were genotyped in 5,621 participants using quantitative PCR. HBV mutations (nt.1600-nt.1945, nt.2848-nt.155) were determined by Sanger sequencing. Dual-luciferase reporter assay was applied to detect the transcriptional activity. Effects of APOBEC3B/UNG SNPs and expression levels on HCC prognosis were evaluated with a cohort of 400 patients with HCC and public databases, respectively.

RESULTS

APOBEC3B rs2267401-G allele and UNG rs3890995-C allele significantly increased HCC risk. rs2267401-G allele was significantly associated with the generation of APOBEC-signature HBV mutation whose frequency consecutively increased from asymptomatic HBV carriers to patients with HCC. Multiplicative interaction of rs2267401-G allele with rs3890995-C allele increased HCC risk, with an adjusted OR (95% confidence interval) of 1.90 (1.34-2.81). rs2267401 T-to-G and rs3890995 T-to-C conferred increased activities of APOBEC3B promoter and UNG enhancer, respectively. IL6 significantly increased APOBEC3B promoter activity and inhibited UNG enhancer activity, and these effects were more evident in those carrying rs2267401-G and rs3890995-C, respectively. APOBEC3B rs2267401-GG genotype, higher APOBEC3B expression, and higher APOBEC3B/UNG expression ratio in HCCs indicated poor prognosis. APOBEC-signature somatic mutation predicts poor prognosis in HBV-free HCCs rather than in HBV-positive ones.

CONCLUSIONS

Polymorphic genotypes predisposing the APOBEC3B-UNG imbalance in IL6-presenting microenvironment promote HCC development, possibly via promoting the generation of high-risk HBV mutations. This can be transformed into specific prophylaxis of HBV-caused HCC.

Occurrence of APOBEC3G variations in West Indian HIV patients

The genetic variations in APOBEC3G gene are correlated with HIV disease progression. These variations differ in different ethnic groups. The prevalence of APOBEC3G (-90C/G, -571G/C) variations have not been studied in Indian population. Hence, we assessed the occurrence of APOBEC3G polymorphisms in HIV patients and its association with acquisition of HIV and disease progression. Polymorphisms in APOBEC3G were genotyped in a total of 153 HIV patients, naïve to ARV and 156 healthy controls by PCR-RFLP method. In single locus model, the frequency of distribution of APOBEC3G -90CG, -571 GC genotypes were higher in HIV patients as compared to healthy controls (57.5% vs. 50.0%, OR = 1.22; 17.0% vs. 12.8%, OR = 1.39). In double locus model, the dominant -571 GC + CC genotype was distributed at a much higher frequency in HIV patients as compared to healthy controls (18.3% vs. 14.1%, OR = 1.50). The frequency of APOBEC3G -571CC and CC + GC genotypes were higher in early HIV disease stage as compared to healthy controls (23.9% vs. 12.8%, OR = 2.23, P = 0.08; 28.3% vs. 14.1%, OR = 2.40, P = 0.04). APOBEC3G-571 GC and GC + CC genotypes were more prevalent in HIV patients consuming tobacco and alcohol as compared to non-users (22.7% vs. 15.3%, OR = 1.71, P = 0.56; 27.3% vs. 16.5%, OR = 1.90, P = 0.39 and 31.6% vs. 13.6%, OR = 2.31, P = 0.08; 36.8% vs14.8%, OR = 2.49, P = 0.04, respectively). In conclusion, APOBEC3G-571G/C polymorphism was associated with the early stage of HIV infection and could potentially influence HIV disease progression in alcohol users. The distribution of APOBEC3G polymorphisms and its haplotypes were not significantly different between HIV patients and healthy controls.

APOBEC3B up-regulation independently predicts ovarian cancer prognosis: a cohort study

Background

Ovarian cancer is a heterogeneous disease with a high degree of genomic instability, pro-/antitumor immunity and inflammation, and remains the most lethal gynecologic cancer worldwide. APOBEC3B, a member of the AID/APOBEC family, is part of the innate immune system which plays a key role in combating exogenous infection especially viral infection. Studies have shown that APOBEC3B expression is elevated in a variety of cancer tissues and cell lines, and plays a prominent role in the genesis and evolution of various cancers. However, the clinical relevance of APOBEC3B in ovarian cancer needs to be further investigated. The current study aimed to evaluate the predictive value of APOBEC3B in ovarian cancer clinical outcome, and to explore possible molecular mechanisms contributing to ovarian cancer progression.

Methods

The expression of APOBEC3B in biopsy tissue specimens from 88 ovarian cancer patients was examined using immunohistochemistry. In addition, ovarian cancer cell lines were transfected with APOBEC3B siRNA or pLenti-APOBEC3B construct. Western blotting and SRB assay were performed to explore the role of APOBEC3B in ovarian cancer.

Results

Patients were followed for a median of 74.77 months following the time of surgery. Forty-two patients had died, 5 had relapsed but were still alive at the end of study, and 41 patients remained alive and had no recurrence. Over-expression of APOBEC3B was associated with advanced FIGO stage and elevated CA125 (both p< 0.05). Univariate analysis result showed that histological subtype, FIGO stage, intravascular tumor thrombus, CA125 and APOBEC3B expression were associated with overall survival and disease-free survival of ovarian cancer patients. Multivariate analysis result showed that higher APOBEC3B expression were an independent prognostic factor to predict both worse overall survival (hazard ratio: 5.18, 95% confidence interval: 1.40–11.95, p= 0.003) and disease-free survival (hazard ratio: 4.23, 95% confidence interval: 1.60–11.17, p= 0.004) of ovarian cancer patients. Furthermore, knockdown of APOBEC3B expression in ovarian cancer cells caused an decrease in cell line viability.

Conclusions

APOBEC3B expression is an independent prognostic factor in ovarian cancer patients. Knockdown of APOBEC3B expression affects ovarian cancer viability.

Metavir and FIB-4 scores are associated with patient prognosis after curative hepatectomy in hepatitis B virus-related hepatocellular carcinoma: a retrospective cohort study at two centers in China

Although Metavir and Fibrosis-4 (FIB-4) scores are typically used to assess the severity of liver fibrosis, the relationship between these scores and patient outcome in hepatocellular carcinoma (HCC) is unclear. The aim of this study was to evaluate the prognostic value of the severity of hepatic fibrosis in HBV-related HCC patients after curative resection. We examined the prognostic roles of the Metavir and preoperative FIB-4 scores in 432 HBV-HCC patients who underwent curative resection at two different medical centers located in western (Chongqing) and eastern (Shanghai) China. In the testing set (n = 108), the Metavir, FIB-4, and combined Metavir/FIB-4 scores were predictive of overall survival (OS) and recurrence-free survival (RFS). Additionally, they were associated with several clinicopathologic variables. In the validation set (n = 324), the Metavir, FIB-4, and combined Metavir/FIB-4 scores were associated with poor prognosis in HCC patients after curative resection. Importantly, in the negative alpha-fetoprotein subgroup (≤ 20 ng/mL), the FIB-4 index (I vs. II) could discriminate between patient outcomes (high or low OS and RFS). Thus Metavir, preoperative FIB-4, and combined Metavir/FIB-4 scores are prognostic markers in HBV-HCC patients after curative hepatectomy.

APOBEC-mediated genomic alterations link immunity and viral infection during human papillomavirus-driven cervical carcinogenesis

Cervical cancer is one of the most frequently diagnosed cancers and is a major cause of death from gynecologic cancers worldwide; the cancer burden from cervical cancer is especially heavy in less developed countries. Most cases of cervical cancer are caused by persistent infection with carcinogenic human papillomavirus (HPV) genotypes 16 and 18. Non-resolving inflammation caused by HPV infection provides a microenvironment that facilitates cancer development. Molecular alterations during the process of HPV-induced carcinogenesis are characterized by DNA methylation within the HPV genome, promoter hypermethylation of tumor suppressor genes in the host genome, as well as genomic instability caused by viral DNA integrating into the host genome. Catalytic polypeptide-like apolipoprotein B mRNA editing enzymes (APOBECs) normally function as part of the innate immune system. APOBEC expression is stimulated upon viral infection and plays an important role in HPV-induced cervical cancer. APOBECs catalyze the deamination of cytosine bases in nucleic acids, which leads to a conversion of target cytosine (C) to uracil (U) and consequently a change in the single-stranded DNA/RNA sequence. APOBEC proteins mediate the complex interactions between HPV and the host genome and link immunity and viral infection during HPV-driven carcinogenesis. Understanding the effects of APOBECs in HPV-induced cervical carcinogenesis will enable the development of better tools for HPV infection control and personalized prevention and treatment strategies.

Association between polymorphisms of the APOBEC3G gene and chronic hepatitis B viral infection and hepatitis B virus-related hepatocellular carcinoma

AIM

To determine the relationship between five A3G gene single nucleotide polymorphisms and the incidence of hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC).

METHODS

This association study was designed as a retrospective study, including 657 patients with chronic HBV infection (CHB) and 299 healthy controls. All subjects were ethnic Han Chinese. Chronic HBV-infected patients recruited between 2012 and 2015 at The First Hospital of Jilin University (Changchun) were further classified into HBV-related HCC patients (n = 287) and non-HCC patients (n = 370). Frequency matching by age and sex was performed for each group. Human genomic DNA was extracted from whole blood. Gene polymorphisms were identified using a mass spectroscopic method.

RESULTS

There were no significant differences between the genotype and allele frequencies of the rs7291971, rs5757465 and rs5757463 A3G gene polymorphisms, and risk of CHB and HBV-related HCC. The AG genotype and G allele for rs8177832 were significantly related to a decreased risk of CHB (OR = 0.67, 95%CI: 0.47-0.96; OR = 0.69, 95%CI: 0.50-0.95, respectively) and HCC (OR = 0.53, 95%CI: 0.34-0.84; OR = 0.58, 95%CI: 0.39-0.87, respectively). A significant relationship was found between rs2011861 computed tomography, TT genotypes and increased risk of HCC (OR = 1.69, 95%CI: 1.02-2.80; OR = 1.82, 95%CI: 1.08-3.06, respectively). Haplotype analyses showed three protective and four risk haplotypes for HCC. Also, one protective haplotype was found against CHB.

CONCLUSION

This study indicates that the A3G rs8177832 polymorphism is associated with a decreased risk of CHB infection and HCC, while the rs2011861 polymorphism is associated with an increased risk of HCC.

Functions and Malfunctions of Mammalian DNA-Cytosine Deaminases

The AID/APOBEC family enzymes convert cytosines in single-stranded DNA to uracils, causing base substitutions and strand breaks. They are induced by cytokines produced during the body's inflammatory response to infections, and they help combat infections through diverse mechanisms. AID is essential for the maturation of antibodies and causes mutations and deletions in antibody genes through somatic hypermutation (SHM) and class-switch recombination (CSR) processes. One member of the APOBEC family, APOBEC1, edits mRNA for a protein involved in lipid transport. Members of the APOBEC3 subfamily in humans (APOBEC3A, APOBEC3B, APOBEC3C, APOBEC3D, APOBEC3F, APOBEC3G, and APOBEC3H) inhibit infections of viruses such as HIV-1, HBV, and HCV, and retrotransposition of endogenous retroelements through mutagenic and nonmutagenic mechanisms. There is emerging consensus that these enzymes can cause mutations in the cellular genome at replication forks or within transcription bubbles depending on the physiological state of the cell and the phase of the cell cycle during which they are expressed. We describe here the state of knowledge about the structures of these enzymes, regulation of their expression, and both the advantageous and deleterious consequences of their expression, including carcinogenesis. We highlight similarities among them and present a holistic view of their regulation and function.

Association of Hepatitis B Virus Covalently Closed Circular DNA and Human APOBEC3B in Hepatitis B Virus-Related Hepatocellular Carcinoma

Chronic Hepatitis B Virus (HBV) infections can progresses to liver cirrhosis and hepatocellular carcinoma (HCC). The HBV covalently-closed circular DNA cccDNA is a key to HBV persistence, and its degradation can be induced by the cellular deaminase APOBEC3. This study aimed to measure the distribution of intrahepatic cccDNA levels and evaluate the association between levels of cccDNA and APOBEC3 in HCC patients. Among 49 HCC patients, 35 matched cancerous and contiguous noncancerous liver tissues had detectable cccDNA, and the median intrahepatic cccDNA in the cancerous tissues (CT) was significantly lower than in the contiguous noncancerous tissues (CNCT) (p = 0.0033). RCA (rolling circle amplification), followed by 3D-PCR identified positive amplification in 27 matched HCC patients. Sequence analysis indicated G to A mutations accumulated to higher levels in CT samples compared to CNCT samples, and the dinucleotide context showed preferred editing in the GpA context. Among 7 APOBEC3 genes, APOBEC3B was the only one up-regulated in cancerous tissues both at the transcriptional and protein levels (p < 0.05). This implies APOBEC3B may contribute to cccDNA editing and subsequent degradation in cancerous tissues.

Cancer Evolution-Development: experience of hepatitis B virus-induced hepatocarcinogenesis

Here, we present the basic concept and theoretical framework of a scientific hypothesis called Cancer Evolution-Development ("Cancer Evo-Dev"), based on our recent studies of the molecular mechanisms by which chronic infection with the hepatitis B virus induces hepatocarcinogenesis, together with related advances in that field. Several aspects central to our hypothesis are presented: ■ Immune imbalance-caused by the interaction of genetic predispositions and environmental exposures such as viral infection-is responsible for the maintenance of chronic non-resolving inflammation. Non-resolving inflammation promotes the occurrence and progression of cancers, characterized by an evolutionary process of "mutation-selection-adaptation" for both viruses and host cells.■ Under a microenvironment of non-resolving inflammation, proinflammatory factors promote mutations in viral or host genomes by transactivation of the expression of cytidine deaminases and their analogues. Most cells with genomic mutations and mutated viruses are eliminated in the competition for survival in the inflammatory microenvironment. Only a small percentage of the mutated cells that alter their survival signal pathways and exhibit the characteristics of "stem-ness" can survive and function as cancer-initiating cells.■ Cancers generally develop with properties of "backward evolution" and "retro-differentiation," indicating the indispensability of stem-like signal pathways in the evolution and development of cancers. The hypothesis of Cancer Evo-Dev not only lays the theoretical foundation for understanding the mechanisms by which inflammation promotes the development of cancers, but also plays an important role in specific prophylaxis, prediction, early diagnosis, and targeted treatment of cancers.

Phosphatase and tensin homologue genetic polymorphisms and their interactions with viral mutations on the risk of hepatocellular carcinoma

Background:

Chronic hepatitis B virus (HBV) infection is the major cause of hepatocellular carcinoma (HCC). Some HBV mutants and dysregulation of phosphatase and tensin homolog (PTEN) may promote the development of HCC synergistically. We aimed to test the effects of PTEN genetic polymorphisms and their interactions with important HBV mutations on the development of HCC in HBV-infected subjects.

Methods:

Quantitative polymerase chain reaction was applied to genotype PTEN polymorphisms (rs1234220, rs2299939, rs1234213) in 1012 healthy controls, 302 natural clearance subjects, and 2011 chronic HBV-infected subjects including 1021 HCC patients. HBV mutations were determined by sequencing. The associations of PTEN polymorphisms and their interactions with HBV mutations with HCC risk were assessed using multivariate logistic regression analysis.

Results:

Rs1234220 C allele was significantly associated with HCC risk compared to healthy controls (adjusted odds ratio [AOR] = 1.35, 95% confidence interval [CI] = 1.07–1.69) and HCC-free HBV-infected subjects (AOR = 1.27, 95% CI = 1.01–1.57). rs1234220 C allele was significantly associated with increased frequencies of HCC-risk A1652G, C1673T, and C1730G mutations in genotype B HBV-infected subjects. Rs2299939 GT genotype was inversely associated with HCC risk in HBV-infected patients (AOR = 0.75, 95% CI = 0.62–0.92). The interaction of rs2299939 variant genotypes (GT+TT) with A3054T mutation significantly increased HCC risk (AOR = 2.41, 95% CI = 1.08–5.35); whereas its interaction with C3116T mutation significantly reduced HCC risk (AOR = 0.34, 95% CI = 0.18–0.66). These significant effects were only evident in males after stratification.

Conclusions:

PTEN polymorphisms and their interactions with HBV mutations may contribute to hepatocarcinogenesis in males. The host-virus interactions are important in identifying HBV-infected subjects who are more likely to develop HCC.

Associations between activation-induced cytidine deaminase/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like cytidine deaminase expression, hepatitis B virus (HBV) replication and HBV-associated liver disease (Review)

The hepatitis B virus (HBV) infection is a major risk factor in the development of chronic hepatitis (CH) and hepa-tocellular carcinoma (HCC). The activation-induced cytidine deaminase (AID)/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) family of cytidine deaminases is significant in innate immunity, as it restricts numerous viruses, including HBV, through hypermutation-dependent and -independent mechanisms. It is important to induce covalently closed circular (ccc)DNA degradation by interferon-α without causing side effects in the infected host cell. Furthermore, organisms possess multiple mechanisms to regulate the expression of AID/APOBECs, control their enzymatic activity and restrict their access to DNA or RNA substrates. Therefore, the AID/APOBECs present promising targets for preventing and treating viral infections. In addition, gene polymorphisms of the AID/APOBEC family may alter host susceptibility to HBV acquisition and CH disease progression. Through G-to-A hypermutation, AID/APOBECs also edit HBV DNA and facilitate the mutation of HBV DNA, which may assist the virus to evolve and potentially escape from the immune responses. The AID/APOBEC family and their associated editing patterns may also exert oncogenic activity. Understanding the effects of cytidine deaminases in CH virus-induced hepatocarcinogenesis may aid with developing efficient prophylactic and therapeutic strategies against HCC.

The APOBEC3B deletion polymorphism is associated with prevalence of hepatitis B virus, hepatitis C virus, Torque Teno virus, and Toxoplasma gondii co-infection among HIV-infected individuals

BACKGROUND

Data regarding the influence of the APOBEC3B deletion on infectious diseases remain limited and shown discrepancies.

OBJECTIVES

To characterize the APOBEC3B deletion polymorphism status and its association with prevalence of co-infection with blood-borne pathogens in Indonesian HIV-infected individuals.

MATERIALS AND METHODS

A total of 597 HIV-positive blood samples were tested for the hepatitis B virus (HBV), hepatitis C virus (HCV), Torque Teno virus (TTV), GB virus-C (GBV-C), and Toxoplasma gondii. Nucleic acid was extracted from plasma samples and used for the molecular detection of HIV RNA, HBV DNA, HCV RNA, TTV DNA, and GBV-C RNA, whereas HBsAg, anti-HCV, IgM and IgG anti-T. gondii were detected through serological testing. The APOBEC3B deletion polymorphism was genotyped by polymerase chain reaction (PCR).

RESULTS

The deletion genotype was associated with HCV viremia (p<0.001) as well as elevated IgG anti-T. gondii (adjusted OR [aOR]=3.4). The deletion genotype was also associated with decreased levels of HBsAg (aOR=0.03), and anti-HCV (aOR=0.1). D/D was frequently found in HIV-infected individuals with CD4+T cells<14% (aOR=5.8). The intact genotype was associated with a reduced likelihood of a CD4+T cell count<200 cells/μL (aOR=0.2) but a higher prevalence of TTV co-infection (aOR=8.6).

CONCLUSIONS

The APOBEC3B deletion polymorphism was found to be associated with HBV, HCV, TTV, and T. gondii co-infection in Indonesian HIV-infected individuals.

Somatic mutations, viral integration and epigenetic modification in the evolution of hepatitis B virus-induced hepatocellular carcinoma

Liver cancer in men is the second leading cause of cancer death and hepatocellular carcinoma (HCC) accounts for 70%-85% of the total liver cancer worldwide. Chronic infection with hepatitis B virus (HBV) is the major cause of HCC. Chronic, intermittently active inflammation provides “fertile field” for “mutation, selection, and adaptation” of HBV and the infected hepatocytes, a long-term evolutionary process during HBV-induced carcinogenesis. HBV mutations, which are positively selected by insufficient immunity, can promote and predict the occurrence of HCC. Recently, advanced sequencing technologies including whole genome sequencing, exome sequencing, and RNA sequencing provide opportunities to better under-stand the insight of how somatic mutations, structure variations, HBV integrations, and epigenetic modifications contribute to HCC development. Genomic variations of HCC caused by various etiological factors may be different, but the common driver mutations are important to elucidate the HCC evolutionary process. Genome-wide analyses of HBV integrations are helpful in clarifying the targeted genes of HBV in carcinogenesis and disease progression. RNA sequencing can identify key molecules whose expressions are epigenetically modified during HCC evolution. In this review, we summarized the current findings of next generation sequencings for HBV-HCC and proposed a theory framework of Cancer Evolution and Development based on the current knowledge of HBV-induced HCC to characterize and interpret evolutionary mechanisms of HCC and possible other cancers. Understanding the key viral and genomic variations involved in HCC evolution is essential for generating effective diagnostic, prognostic, and predictive biomarkers as well as therapeutic targets for the interventions of HBV-HCC.

Epithelium-Specific ETS (ESE)-1 upregulated GP73 expression in hepatocellular carcinoma cells

Background

Golgi protein-73 (GP73) is a Golgi transmembrane glycoprotein elevated in numerous liver diseases. Clinically, GP73 is strongly elevated in the serum of HCC patients and is thus regarded as a novel potential biomarker for HCC. However, the mechanism leading to GP73 dysregulation in liver diseases remains unknown.

Results

This study determined that epithelium-specific ETS (ESE)-1, an epithelium-specific transcription factor, and GP73 expressions were induced by IL-1β stimulation in vitro, and both were triggered during liver inflammation in vivo. In hepatocellular carcinoma cells, the overexpression of ESE-1 induced GP73 expression, whereas its knock-down did the opposite. Mechanistically, ESE-1 activated GP73 expression by directly binding to its promoter.

Conclusions

Our findings supported a novel paradigm for ESE-1 as a transcriptional mediator of GP73. This study provided a possible mechanism for GP73 upregulation in liver diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/2045-3701-4-76) contains supplementary material, which is available to authorized users.

Role of antiviral therapy in reducing recurrence and improving survival in hepatitis B virus-associated hepatocellular carcinoma following curative resection (Review)

Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related mortality worldwide, with the majority of cases associated with persistent hepatitis B virus (HBV) or hepatitis C virus infection. In particular, chronic HBV infection is a predominant risk factor for the development of HCC in Asian and African populations. Hepatic resection, liver transplantion and radiofrequency ablation are increasingly used for the curative treatment of HCC, however, the survival rate of HCC patients who have undergone curative resection remains unsatisfactory due to the high recurrence rate. HCC is a complex disease that is typically resistant to the most commonly used types of chemotherapy and radiotherapy; therefore, the development of novel treatment strategies is required to improve the survival rate of this disease. A high viral load of HBV DNA is the most important correctable risk factor for HCC recurrence, for example nucleos(t)ide analogs improve the outcome following curative resection of HBV-associated HCC, and interferon-α exhibits antitumor activity against various types of cancer via direct inhibitory effects on tumor cells, anti-angiogenesis, enhanced immunogenicity of tumors, immunomodulatory effects and liver dysfunction. In the present review, antiviral treatment for HBV-associated HCC is described as a strategy to reduce recurrence and improve survival.

APOBEC3G exerts tumor suppressive effects in human hepatocellular carcinoma

In this study, we collected 44 hepatitis B virus surface antigen positivity HBsAg (+) tumor and nontumor hepatocellular tissues from hepatocellular carcinoma (HCC) patients during hepatectomy, and quantified the APOBEC3G (A3G) mRNA by using a real-time PCR. Our results showed higher expression of A3G mRNA in the nontumor tissues than in the tumor tissues of the HBsAg (+) HCC patients. To further investigate this phenomenon, we constructed a pLV-A3G vector and transfected it into the human HCC cell line, Hep 3B. The results of an immunofluorescence analysis showed the overexpression of A3G in the cytoplasm. We then evaluated A3G cytotoxicity by using a cell viability assay (MTS assay), the results of which showed that Hep 3B cell viability was 88 and 58% after the transfection of pLV and pLV-A3G, respectively, indicating the growth inhibitory effects of A3G on Hep 3B cells. To further evaluate the tumor suppressive effects of A3G, we used a plastic pipette tip to scratch Hep 3B cells grown on a culture dish (to 70-80% confluence) after transfection with pLV-A3G. Our data indicated a ratio of wound closure of 100% in the control cells and in the pLV-expressing cells, compared with 43% in the pLV-A3G-overexpressing cells, 72 h after the wound scratch, as observed using phase-contrast microscopy. These results indicated that A3G inhibits wound healing in Hep 3B cells. Overall, our results suggest that A3G inhibits the growth of human hepatoma cells.

Systemic responses of BALB/c mice to Salmonella typhimurium infection

Salmonella typhimurium is a bacterial pathogen that poses a great threat to humans and animals. In order to discover hosts' responses to S. typhimurium infection, we collected and analyzed biofluids and organ tissues from mice which had ingested S. typhimurium. We employed (1)H NMR spectroscopy coupled with multivariate data analysis and immunological techniques. The results indicate that infection leads to a severe impact on mice spleen and ileum, which are characterized by splenomegaly and edematous villi, respectively. We found that increased levels of itaconic acid were correlated with the presence of splenomegaly during infection and may play an important role in Salmonella-containing vacuole acidification. In addition, metabonomic analyses of urine displayed the development of salmonellosis in mice, which is characterized by dynamic changes in energy metabolism. Furthermore, we found that the presence of S. typhimurium activated an anti-oxidative response in infected mice. We also observed changes in the gut microbial co-metabolites (hippurate, TMAO, TMA, methylamine). This investigation sheds much needed light on the host-pathogen interactions of S. typhimurium, providing further information to deepen our understanding of the long co-evolution process between hosts and infective bacteria.

Effect of functional nuclear factor-kappaB genetic polymorphisms on hepatitis B virus persistence and their interactions with viral mutations on the risk of hepatocellular carcinoma

BACKGROUND

Nonresolving inflammation and viral mutations are important in hepatitis B virus (HBV)-induced hepatocarcinogenesis. However, the effects of genetic polymorphisms affecting nuclear factor-kappaB (NF-κB) on HBV persistence and generation of hepatocellular carcinoma (HCC)-related HBV mutations remain unknown.

PATIENTS AND METHODS

rs28362491 (NFKB1 -94Ins > Del), rs2233406 (NFKBIA -826C > T), rs3138053 (NFKBIA -881A > G), and rs696 (NFKBIA +2758G > A) were genotyped in 1342 healthy controls, 327 HBV-clearance subjects, and 3976 HBV-positive subjects including 1495 HCC patients, using quantitative PCR. HBV mutations were determined by sequencing. The NFKBIA promoter activity was assessed by transient transfection. Multiplicative interactions of the polymorphisms and viral mutations were assessed by multivariate logistic regression.

RESULTS

Compared with HBV-clearance subjects, rs2233406 (CT versus CC) and rs3138053 (AG or AG + GG versus AA) significantly decreased HBV persistence, especially in the genotype B HBV-infected subjects. In the genotype C HBV-infected subjects, rs2233406 variant genotypes were significantly associated with an increased risk of HCC [CT versus CC: age-, gender-adjusted odds ratio (AOR), 1.33; 95% confidence interval (CI) 1.01-1.75 in training set and AOR, 1.59; 95% CI 1.01-2.52 in validation set] compared with HCC-free HBV-infected subjects and significantly increased the frequencies of HCC-related HBV mutations (A1762T/G1764A, T1753V, preS1 start codon mutation, and preS deletion); rs28362491 (Del/Del or Ins/Del + Del/Del versus Ins/Ins) significantly increased the frequency of A1762T/G1764A and reduced the frequency of preS2 start codon mutation. The variant genotypes impaired NFKBIA promoter activity in hepatic cells. The interaction of rs2233406 variant genotypes (CT + TT versus CC) with A1762T/G1764A significantly increased HCC risk in genotype C HBV-infected subjects, with AOR of 2.61 (95% CI 1.09-6.26).

CONCLUSION

Genetic polymorphisms improving NF-κB activity contribute to genotype B HBV clearance. The rs2233406 variant genotypes significantly increase HCC risk, possibly via facilitating immune selection of the HBV mutations. The host-virus interactions are important in identifying HBV-infected subjects who are more likely to develop HCC.

Virus-related liver cirrhosis: molecular basis and therapeutic options

Chronic infections with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) are the major causes of cirrhosis globally. It takes 10-20 years to progress from viral hepatitis to cirrhosis. Intermediately active hepatic inflammation caused by the infections contributes to the inflammation-necrosis-regeneration process, ultimately cirrhosis. CD8(+) T cells and NK cells cause liver damage via targeting the infected hepatocytes directly and releasing pro-inflammatory cytokine/chemokines. Hepatic stellate cells play an active role in fibrogenesis via secreting fibrosis-related factors. Under the inflammatory microenvironment, the viruses experience mutation-selection-adaptation to evade immune clearance. However, immune selection of some HBV mutations in the evolution towards cirrhosis seems different from that towards hepatocellular carcinoma. As viral replication is an important driving force of cirrhosis pathogenesis, antiviral treatment with nucleos(t)ide analogs is generally effective in halting the progression of cirrhosis, improving liver function and reducing the morbidity of decompensated cirrhosis caused by chronic HBV infection. Interferon-α plus ribavirin and/or the direct acting antivirals such as Vaniprevir are effective for compensated cirrhosis caused by chronic HCV infection. The standard of care for the treatment of HCV-related cirrhosis with interferon-α plus ribavirin should consider the genotypes of IL-28B. Understanding the mechanism of fibrogenesis and hepatocyte regeneration will facilitate the development of novel therapies for decompensated cirrhosis.