FAT4 loss initiates hepatocarcinogenesis through the switching of canonical to noncanonical WNT signaling pathways.

BACKGROUND: Mutation and downregulation of FAT atypical cadherin 4 (FAT4) are frequently detected in HCC, suggesting a tumor suppressor role of FAT4. However, the underlying molecular mechanism remains elusive. METHODS: CRISPR-Cas9 system was used to knockout FAT4 (FAT4-KO) in a normal human hepatic cell line L02 to investigate the impact of FAT4 loss on the development of HCC. RNA-sequencing and xenograft mouse model were used to study gene expression and tumorigenesis, respectively. The mechanistic basis of FAT4 loss on hepatocarcinogenesis was elucidated using in vitro experiments. RESULTS: We found that FAT4-KO disrupted cell-cell adhesion, induced epithelial-mesenchymal transition, and increased expression of extracellular matrix components. FAT4-KO is sufficient for tumor initiation in a xenograft mouse model. RNA-sequencing of FAT4-KO cells identified PAK6-mediated WNT/ß-catenin signaling to promote tumor growth. Suppression of PAK6 led to ß-catenin shuttling out of the nucleus for ubiquitin-dependent degradation and constrained tumor growth. Further, RNA-sequencing of amassed FAT4-KO cells identified activation of WNT5A and ROR2. The noncanonical WNT5A/ROR2 signaling has no effect on ß-catenin and its target genes (CCND1 and c-Myc) expression. Instead, we observed downregulation of receptors for WNT/ß-catenin signaling, suggesting the shifting of ß-catenin-dependent to ß-catenin-independent pathways as tumor progression depends on its receptor expression. Both PAK6 and WNT5A could induce the expression of extracellular matrix glycoprotein, laminin subunit alpha 4. Laminin subunit alpha 4 upregulation in HCC correlated with poor patient survival. CONCLUSIONS: Our data show that FAT4 loss is sufficient to drive HCC development through the switching of canonical to noncanonical Wingless-type signaling pathways. The findings may provide a mechanistic basis for an in-depth study of the two pathways in the early and late stages of HCC for precise treatment.

Hepatitis B virus X protein promotes hepatocarcinogenesis via the activation of HMGA2/STC2 signaling to counteract oxidative stress-induced cell death.

Chronic hepatitis B virus (HBV) infection can cause oxidative stress and induce cell death. The mechanisms by which cells overcome oxidative stress to survive remain largely unknown. Here, we used human sera, liver tissues and cell lines to study how HBV modulates cellular pathways to counteract oxidative stress-induced cell death. We found high-mobility group AT-hook 2 (HMGA2), an architectural transcription factor is upregulated in hepatocellular carcinoma (HCC) tissues and cell lines. Elevated serum HMGA2 is significantly associated with viral load in HBV carriers, and HBV-related HCC. We showed that HBV X protein (HBx) encoded by HBV-induced cell growth via HMGA2 activation. The growth-promoting effect is abolished when HMGA2 is suppressed. Ectopic HBx expression induced DNA damage and oxidative stress. HMGA2 silencing reduced oxidative stress in HBx-expressing cells. Cytoprotective stanniocalcin 2 (STC2) protein is a downstream target of HMGA2. Consistent with the findings in HMGA2, STC2 mRNA and protein expression are upregulated in HCC tissues. Elevated serum STC2 is also associated with viral load in HBV carriers, and HCC. STC2 is transcriptionally upregulated by HBx and HMGA2 to elicit cytoprotection against apoptosis. STC2 knockdown disrupted Bax/Bcl-2 balance that increased cytochrome c release, caspase 3/7 activity and apoptosis, and thus abolished the growth-promoting effect of HMGA2. Clinical relevance of HBx/HMGA2/STC2 signaling is evidenced by the significant correlation of serum HMGA2/STC2 in active HBV infection and HCC. These findings reveal a novel HBx regulatory HMGA2/STC2 pathway in counteracting reactive oxygen species-induced cell death. HMGA2 and STC2 may be therapeutic targets for prevention of hepatocarcinogenesis in chronic HBV infection.

Phenotypic Changes of PD-1 and GITR in T Cells Are Associated With Hepatitis B Surface Antigen Seroclearance.

BACKGROUND: Regulatory T cells (Tregs) possess hepatitis B virus (HBV)-specific immunoregulatory effects in chronic HBV infection. The role of Tregs in spontaneous seroclearance of hepatitis B surface antigen (HBsAg) remains to be determined. METHODS: We recruited treatment-naive chronic HBV patients achieving spontaneous HBsAg seroclearance (experimental group) and matched HBsAg-positive controls. Peripheral blood mononuclear cells were isolated using the Ficoll-Paque density gradient centrifugation method. The frequency of Tregs and inhibitory phenotypes and immunoregulatory cytokines of Tregs were detected by flow cytometry. RESULTS: Twenty-seven patients with HBsAg seroclearance (mean age: 52.40±6.00 y, 55.6% male) and 27 matched controls were recruited. Median HBsAg and HBV DNA levels in the control group were 2.80 (1.24 to 3.43) and 3.16 (1.68 to 3.85) log IU/mL, respectively. Mean frequencies of Tregs and expressions of FoxP3+ Tregs were comparable in both groups (both P>0.05). The mean expression of programmed death 1 (PD-1) and glucocorticoid-induced TNFR family-related gene (GITR) in total CD4+ T cells were significantly downregulated in the experimental group when compared with the control group (10.62% vs. 13.85%, P=0.003; 16.20% vs. 27.02%, P=0.002, respectively). When compared with the control group, PD-1+CD4+ Tregs expression in the experimental group was significantly downregulated (13.85% vs. 10.62%, P=0.003). A similar phenomenon was noted for GITR+CD8+ Tregs (20.16% vs. 14.08%, P=0.049). Intracellular cytokine productions showed no significant differences (all P>0.05). CONCLUSIONS: The reduced expression of PD-1 and GITR might attenuate the immunosuppressive capability of Tregs. Decreased expression on CD4+ T cells might represent an enhanced antiviral function, playing a role in initiating the "functional cure" of chronic HBV infection.

Tumor suppressive role of mitochondrial sirtuin 4 in induction of G2/M cell cycle arrest and apoptosis in hepatitis B virus-related hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is developed from uncontrolled cell growth after the malignant transformation of hepatocytes. The hepatitis B virus (HBV) X protein (HBx) has shown to induce cell cycle progression and hepatocarcinogenesis. A sub-fraction of HBx is localized in the mitochondria. Sirtuin 4 (SIRT4), a mitochondrial protein, has been demonstrated to play a tumor-suppressive role in many cancers, including HCC. However, little is known about the association between mitochondrial HBx and SIRT4 during hepatocarcinogenesis. We aimed to investigate the clinical significance and functional role of SIRT4 in HBV-related HCC. SIRT4 expression was significantly lower in the HCC tissues collected from 30 patients with HBV-related HCC than in normal liver tissues from control patients (p < 0.0001). TCGA data analysis indicated that SIRT4 expression was also lower in patients with HBV infection than in those without, and SIRT4 levels were positively associated with better patient survival. Similarly, HCC cell lines had lower SIRT4 expression than normal liver cell lines (all p < 0.01). Among the HCC cell lines, those harbored HBV had a lower SIRT4 expression than those without HBV (p < 0.0001). In vitro experiments revealed that stable HBx transfection suppressed SIRT4 expression in both HepG2 and Huh7 cells (both p < 0.001). Ectopic SIRT4 overexpression alone could induce cellular senescence through arresting cell-cycle progression at G2/M, and inducing cell apoptosis in HCC cells. Mechanistically, SIRT4 upregulated cell-cycle governing genes p16 and p21 protein expression, suppressed CyclinB1/Cdc2 and Cdc25c which normally induce cell-cycle progression, and suppressed survivin to induce apoptosis. Our findings demonstrate the interaction between HBV and SIRT4 in the context of HCC. SIRT4 involves in G2/M DNA damage checkpoint control and genomic stability in hepatocarcinogenesis, which could be targeted for future anticancer strategies.

HBV X protein mutations affect HBV transcription and association of histone-modifying enzymes with covalently closed circular DNA.

The hepatitis B X protein (HBx) plays a role in the epigenetic regulation of hepatitis B virus (HBV) replication. This study investigated the effects of HBx mutations on HBV transcription and the recruitment of HBx, histone acetyl-transferase P300 and histone deacetylase 1 (HDAC1) to circularized HBV DNA (which resembles covalently closed circular DNA [cccDNA]). Compared with wild type, majority of mutants had lower levels of intracellular HBV RNA (44-77% reduction) and secretory HBsAg (25-81% reduction), and 12 mutants had a reduction in intracellular encapsidated HBV DNA (33-64% reduction). Eight mutants with >70% reduction in HBV RNA and/or HBsAg were selected for chromatin immunoprecipitation analysis. Four HBx mutants with mutations in amino acid residues 55-60 and 121-126 had a lower degree of HBx-cccDNA association than wild type HBx (mean % input: 0.02-0.64% vs. 3.08% in wild type). A reduced association between cccDNA and P300 (mean % input: 0.69-1.81% vs. 3.48% in wild type) and an augmented association with HDAC1 (mean % input: 4.01-14.0% vs. 1.53% in wild type) were detected. HBx amino acid residues 55-60 and 121-126 may play an important role in HBV transcription regulation, via their impeded interaction with cccDNA and altered recruitment of histone modifying enzymes to cccDNA.

Targeted genomic profiling identifies frequent deleterious mutations in FAT4 and TP53 genes in HBV-associated hepatocellular carcinoma.

BACKGROUND: Hepatitis B virus (HBV) is the major risk factor for hepatocellular carcinoma (HCC). The molecular mechanisms underlying HBV-associated HCC pathogenesis is still unclear. Genetic alterations in cancer-related genes have been linked to many human cancers. Here, we aimed to explore genetic alterations in selected cancer-related genes in patients with HBV-associated HCC. METHODS: Targeted sequencing was used to analyze six cancer-related genes (PIK3CA, TP53, FAT4, IRF2, HNF4α and ARID1A) in eight pairs of HBV-associated HCC tumors and their adjacent non-tumor tissues. Sanger sequencing, quantitative PCR, Western-blotting and RNAi-mediated gene knockdown were used to further validate findings. RESULTS: Targeted sequencing revealed thirteen non-synonymous mutations, of which 9 (69%) were found in FAT4 and 4 (31%) were found in TP53 genes. Non-synonymous mutations were not found in PIK3CA, IRF2, HNF4α and ARID1A. Among these 13 non-synonymous mutations, 12 (8 in FAT4 and 4 in TP53) were predicted to have deleterious effect on protein function by in silico analysis. For TP53, Y220S, R249S and P250R non-synonymous mutations were solely identified in tumor tissues. Further expression profiling of FAT4 and TP53 on twenty-eight pairs of HCC tumor and non-tumor tissues confirmed significant downregulation of both genes in HCC tumors compared with their non-tumor counterparts (P < 0.001 and P < 0.01, respectively). Functional analysis using RNAi-mediated knockdown of FAT4 revealed an increased cancer cell growth and proliferation, suggesting the putative tumor suppressor role of FAT4 in HCC. CONCLUSIONS: This study highlights the importance of FAT4 and TP53 in HCC pathogenesis and identifies new genetic variants that may have potentials for development of precise therapy for HCC.

Role of hepatitis B core protein in HBV transcription and recruitment of histone acetyltransferases to cccDNA minichromosome.

The hepatitis B core protein (HBc) has been suggested to interact with covalently closed circular DNA (cccDNA) and regulate hepatitis B virus (HBV) transcription. However, direct evidence is lacking. We aimed to identify the specific HBc region(s) responsible for transcription regulation and its interaction with cccDNA. Seventeen mutants with mutations at the four arginine-rich clusters of the HBc carboxyl-terminal domain (CTD) were created. The effect of HBc mutations on the levels of HBV DNA, RNA, and hepatitis B surface antigen (HBsAg) were measured. The association of cccDNA with mutant HBc and histone acetyltransferases (HATs) was assessed by chromatin immunoprecipitation (ChIP). Compared with wild-type HBc, HBc mutants with mutations in clusters III and IV resulted in a significant reduction in HBV RNA levels (all P < 0.05). HBc arginine clusters III and IV mutants also had a significantly lower levels of intracellular HBV DNA (<5% of wild-type; P < 0.001) and HBsAg (<10% of wild-type; P < 0.0001). cccDNA-ChIP assay demonstrated that HBc clusters III and IV mutants had a smaller degree of association with cccDNA (P < 0.001). In the HBc mutants, the association between HATs with cccDNA were reduced. In conclusion, HBc-CTD arginine residues at clusters III and IV play an important role in the regulation of HBV transcription as well as subsequent replication steps, likely through the reduced interaction of HBc with cccDNA and reduced acetylation of cccDNA-bound histones. These findings may provide clues to the identification of novel therapeutic targets against HBV.

Deep sequencing analysis of quasispecies in the HBV pre-S region and its association with hepatocellular carcinoma.

BACKGROUND: The association between the evolution of hepatitis B virus (HBV) quasispecies and the development of hepatocellular carcinoma (HCC) is unknown. METHODS: We used deep sequencing to examine the dynamics of HBV quasispecies and their relationship to HCC development. Thirty-two chronic hepatitis B (CHB) patients with HCC (HCC group) and 32 matched CHB patients without HCC (controls) were recruited. Fourteen patients from each group had serial sera available up to 9 years before the time of the present study. Deep sequencing of the HBV pre-S regions was performed. HBV quasispecies complexity, diversity, and intrapatient prevalence of pre-S deletions/mutations were analyzed. RESULTS: Compared with control patients, HCC patients had a significant greater quasispecies complexity (p = 0.04 at the nucleotide level), greater diversity (p = 0.004 and 0.009 at the nucleotide level and the amino acid level respectively), and a trend of greater complexity at the amino acid level (p = 0.065). HCC patients had a higher intrapatient prevalence of pre-S deletions and point mutations (at codons 4, 27, and 167) compared with the control patients (all p < 0.05). Longitudinal observation in the sera of 14 HCC patients showed that quasispecies complexity (p = 0.027 and 0.024 at the nucleotide level and the amino acid level respectively) and diversity (p = 0.035 and 0.031 at the nucleotide level and the amino acid level respectively) increased as the disease progressed to HCC. CONCLUSIONS: Increased HBV quasispecies complexity and diversity in the pre-S region, probably reflecting enhanced virus-host interplay, was associated with disease progression from CHB to HCC.

Hepatitis B virus core-related antigen as a surrogate marker for covalently closed circular DNA.

BACKGROUND & AIMS: Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is a key to viral persistence in chronic hepatitis B infection. Serum hepatitis B core-related antigen (HBcrAg) is a novel marker for HBV disease. We aimed to determine whether HBcrAg could be a surrogate marker for intrahepatic cccDNA. METHODS: Three hundred and five liver biopsies and the corresponding sera collected from 138 nucleos(t)ide analogues-treated patients were analysed. 124 patients had paired liver biopsies at baseline and 1-year post-treatment, and 43 patients had a third biopsy after 6-12 years of treatment. Serum HBcrAg, HBV DNA and hepatitis B surface antigen (HBsAg), and intrahepatic HBV DNA and cccDNA were measured. RESULTS: HBcrAg strongly correlated with cccDNA (r=.70), intrahepatic total HBV DNA (r=.67) and serum HBV DNA (r=.69; all P<.0001). In the 130 samples with undetectable serum HBV DNA, HBcrAg was detectable in 101 (78%) samples, and HBcrAg levels still correlated positively with cccDNA (r=.42, P<.0001). At ≥6 years of therapy, the median logarithmic reduction in HBcrAg was 2.7 log kU/mL, which was comparable to the magnitude of reduction in cccDNA. Twenty-one patients had undetectable cccDNA after ≥6 years of treatment, in whom 15 (71%) had detectable HBcrAg (range: 1.2-537 kU/mL). CONCLUSIONS: Serum HBcrAg is a reliable surrogate marker for intrahepatic cccDNA. HBcrAg could be a very sensitive marker to reflect the cccDNA content and persistence of disease even with the cccDNA levels below the detection limit of assays.

Reduction of covalently closed circular DNA with long-term nucleos(t)ide analogue treatment in chronic hepatitis B.

BACKGROUND AND AIMS: Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA), a mini-chromosome essential for HBV replication, is supposed to be resistant to nucleos(t)ide analogue treatment. We investigated the effect of long-term nucleos(t)ide analogue treatment on cccDNA. METHODS: Among 129 patients who had been enrolled in previous international nucleos(t)ide analogue clinical trials and had liver biopsies at baseline and one year after treatment, we recruited 43 patients on long-term continuous treatment for 72 to 145months for a third liver biopsy. Serum HBV DNA, hepatitis B surface antigen (HBsAg) levels, total intrahepatic HBV DNA (ihHBV DNA), cccDNA, HBV pregenomic RNA (pgRNA) as well as histologic changes were examined. RESULTS: At the time of the third biopsy, serum HBV DNA levels were undetectable in all but one patient. The median levels of HBsAg, ihHBV DNA, and cccDNA were 2.88logIU/ml, 0.03copies/cell, and 0.01copies/cell, respectively. Compared to baseline levels, there was reduction of HBsAg levels by 0.54log (71.46%), ihHBV DNA levels by 2.81log (99.84%), and cccDNA levels by 2.94log (99.89%), with 49% having cccDNA levels below the detection limit. One patient had undetectable HBsAg. The median pgRNA level, measured only in the third biopsy, was 0.021copies/cell, with 40% of patients having undetectable pgRNA. CONCLUSIONS: Long-term nucleos(t)ide analogue treatment induced marked depletion of cccDNA in the majority of patients while serum HBsAg levels, though reduced, were detectable in all but one patient. Whether cccDNA depletion is sustained and associated with better patient outcome requires further study. LAY SUMMARY: It is generally presumed that a form of hepatitis B virus DNA, called covalently closed circular DNA (cccDNA), which hides inside the nuclei of liver cells of patients with chronic hepatitis B, cannot be reduced by antiviral treatment. The present study showed that with prolonged treatment (median period 126months), cccDNA can be markedly reduced, with 49% of liver biopsies having undetectable cccDNA. This suggests that viral replication capacity would be very low after prolonged antiviral treatment.

Interleukin-1ß increases the risk of gastric cancer through induction of aberrant DNA methylation in a mouse model.

Interleukin-1ß (IL-1ß) has a significant role in chronic gastric inflammation and manifestations of gastric diseases. The present study aimed to elucidate the specific role of IL-1ß in induction of DNA methylation using IL-1 receptor type 1 knockout (IL-1R1-/-) mice. In the present study, wild-type (WT) and IL-1R1-/- mice were injected with IL-1ß (5 µg/kg/day). Serum levels of IL-1ß, interleukin-6 (IL-6) and nitric oxide (NO) were measured by enzyme-linked immunosorbent or NO assays. E-cadherin (E-cad) methylation status and messenger (m)RNA expression of IL-1ß, IL-6, E-cad and inducible nitric oxide synthase (iNOS) were analyzed. Results from the present study indicated significantly higher IL-1ß mRNA expression (P<0.001) in WT mice compared with IL-1R1-/- mice. IL-1ß and IL-6 release was significantly increased in treated WT mice compared with IL-1R1-/- mice at 1 h, 4 h and 8 h (all P<0.005). IL-1ß release was only detected in WT mice following a second dose measured at day 3, week 1 and week 2 when compared with IL-1R1-/- mice. Promoter methylation of E-cad and a decrease in gene expression was observed in treated WT mice. mRNA expression of iNOS in WT mice was significantly increased at week 1 compared with IL-1R1-/- mice (P=0.0411). Furthermore, a significantly increased level of NO production was observed in treated WT mice (P<0.005 at 8 h and week 1; P<0.001 at 4 h and day 3) when compared with IL-1R1-/- mice. The present results indicated that IL-1ß was able to directly induce DNA methylation, which may link inflammation-induced epigenetic changes and the development of gastric diseases.

Hepatitis B virus full-length genomic mutations and quasispecies in hepatocellular carcinoma.

BACKGROUND AND AIM: Hepatitis B virus (HBV) full-length genomic mutations and quasispecies characteristics in hepatocellular carcinoma (HCC) were investigated. METHODS: Hepatitis B virus DNA was extracted from the tumor and non-tumor tissues of 16 HCC patients. Overlapping DNA fragments covering the entire HBV genome were amplified and sequenced. To study HBV sequence at the quasispecies level, the preS region was amplified and clonally sequenced. HBV mutation profiles, quasispecies complexity and diversity, and phylogenetic characteristics were assessed. RESULTS: Fourteen patients had full-length HBV amplification. Hot-spot mutations at HBx aa130-131 and pre-S deletions were detected in 13 (93%) and 6 (43%) patients, respectively. Deletions in the X/preC/C regions were more frequently detected in the tumor than in the non-tumor tissues (P = 0.031). Compared with the non-tumor tissues, the tumor tissues had a lower quasispecies complexity (P = 0.014 and 0.043, at the nucleotide and amino acid levels, respectively) and diversity (P = 0.048 and 0.022, at the nucleotide and amino acid levels, respectively). Phylogenetic analysis showed that HBV sequences derived from tumor and non-tumor tissues were separately clustered, suggesting the occurrence of compartmentalization, which was confirmed by the correlation coefficient testing on both the number and length of branches of viral populations (all P < 0.02). CONCLUSIONS: Hepatitis B virus mutation patterns in HCC tumor tissues and non-tumor tissues were different. HBV quasispecies within the preS region were compartmentalized, and tumor tissues had a lower genome complexity and diversity. Our study suggests HBV evolution is conditioned by the differential host cellular environment in HCC tumors.

Evolutionary Changes of Hepatitis B Virus Pre-S Mutations Prior to Development of Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Deletions/mutations in the hepatitis B virus (HBV) pre-S region have been associated with hepatocellular carcinoma (HCC). We aimed to study the evolutionary changes of pre-S mutations prior to HCC development. METHODS: We studied the HBV pre-S sequences at 1 to 10 years preceding diagnosis of HCC in 74 patients with HBV-related HCC (HCC group). 148 chronic hepatitis B patients matched for sex and age in 2:1 ratio, who had been followed up for at least 3 years without HCC (HCC-free group) were recruited as controls. 56 and 47 patients of HCC and HCC-free groups respectively had serially stored sera for longitudinally examination at 1-3 years, 4-6 years, 7-9 years and ≥10 years prior to the recruitment of the study. RESULTS: Compared to the HCC-free group, higher frequencies of pre-S deletions and point mutations (at 11 codons) were observed in the HCC group (p<0.05). Multiple logistic regression analysis showed that pre-S deletions, point mutations at codon 51 and 167 were independent factors associated with HCC. Longitudinal observation showed that pre-S deletions and most of the 11 HCC-associated pre-S point mutations existed at least 10 years before HCC development, and were more prevalent preceding HCC development in patients from HCC groups than HCC-free group. The number of HCC-associated pre-S point mutations increased over time preceding HCC development, and correlated positively with the time to HCC diagnosis (r = 0.220, p = 0.005). CONCLUSIONS: High prevalence and cumulative evolution of pre-S mutations preceding HCC development suggested a possible carcinogenic role of pre-S mutations and their potential application in HCC risk prediction.

Estradiol induces apoptosis via activation of miRNA-23a and p53: implication for gender difference in liver cancer development.

Estrogen (E2) has been suggested to have a protective role in attenuating hepatocellular carcinoma (HCC) development. miRNAs have great potential as biomarkers and therapeutic agents owing to their ability to control gene expression. However, little is known about the mechanism underlying the protective role of E2 in hepatocarcinogenesis and the effects of E2 on apoptotic miRNAs expression. Using miRNA PCR array, we found more than 2-fold alteration was observed in 25 upregulated and 10 downregulated apoptotic miRNAs in E2-treated cells. Among these miRNAs, we found expression of miR-23a was related to p53 functional status in the male-derived liver cell-lines. We demonstrated that E2 via ERα transcriptionally activated miR-23a and p53 expression, and thus enhanced p53 activation of miR-23a expression. Moreover, miR-23a expression correlated inversely with the expression of target gene X-linked inhibitor of apoptosis protein (XIAP), but positively with the caspase-3/7 activity. Decreasing of XIAP might contribute to caspase-3 activity and cell apoptosis. Taken together, our findings reveal a novel E2-signaling mechanism in regulating miRNAs expression for controlling apoptosis in liver cells. Delineating the role of E2 in regulating the activation of p53 and miR-23a, expression in HCC is crucial to the understanding of the sex difference observed in HCC.

Characterization of interleukin-1ß in Helicobacter pylori-induced gastric inflammation and DNA methylation in interleukin-1 receptor type 1 knockout (IL-1R1(-/-)) mice.

Helicobacter pylori infection induced interleukin-1ß (IL-1ß) production and is associated with aberrant DNA methylation and gastric diseases. Here, we investigated the role of IL-1ß in H. pylori-induced gastric inflammation and DNA methylation using IL-1 receptor type 1 knockout (IL-1R1(-/-)) mice, and compared the therapeutic efficacy of antimicrobial therapy with IL-1 receptor antagonist (IL-1ra). IL-1R1(-/-) and wild-type (WT) mice were infected with H. pylori for 16, 24 and 32 weeks. Infected WT mice at 24 weeks were given either antimicrobial therapy or IL-1ra. Comparing to the IL-1R1(-/-) mice, infected WT mice with functional IL-1ß signaling had higher gastritis scores, higher IL-1ß and iNOS mRNA expression, higher nitric oxide (NO) production and increased frequency of E-cadherin (E-cad) methylation at all the time points analyzed. IL-1ß release was significantly elevated in infected WT mice than normal controls at 16 weeks post-infection (p<0.005). Treatment of infected mice with antimicrobial therapy and IL-1ra significantly reduced the degree of gastritis (p<0.005; p<0.05, respectively), iNOS expression (p<0.0001; p<0.01, respectively) and NO production (both p<0.001) compared with untreated controls. Mice receiving antimicrobial therapy had significantly lower IL-1ß expression than untreated controls (p<0.0001). Both treatments reduced the incidence of E-cad methylation in infected mice compared with controls, however, no statistical significance was observed. There was no significant alteration of total DNA methyltransferase (DNMT) activity. These results demonstrated that IL-1ß played a crucial role in H. pylori-induced gastric inflammation and DNA methylation. H. pylori eradication and IL-1ra administration could ameliorate inflammatory stress.

Reduction of hepatitis B surface antigen and covalently closed circular DNA by nucleos(t)ide analogues of different potency.

BACKGROUND & AIMS: Few studies have investigated the effects of different nucleos(t)ide analogues against hepatitis B virus (HBV) on levels of covalently closed circular DNA (cccDNA) and hepatitis B surface antigen (HBsAg) in patients. We measured the magnitude of reduction of cccDNA and HBsAg by nucleos(t)ide analogue therapy and assessed the correlation between their reductions. METHODS: We recruited 124 patients who were treated with 1 of the 5 nucleos(t)ide analogues (lamivudine, adefovir, entecavir, telbivudine, or clevudine). All patients had undergone liver biopsy when treatment began (baseline) and 1 year later. The cccDNA and HBsAg levels were measured by real-time polymerase chain reaction and the Elecsys II HBsAg Assay, respectively. RESULTS: After 1 year of treatment, HBV in 7 patients had become resistant to the nucleos(t)ide analogue. The remaining 117 patients had an average reduction of approximately 0.2 log10 IU/mL in HBsAg, 5 log10 IU/mL in serum level of HBV DNA, 2 log10 copies/cell in intrahepatic total HBV DNA, and 1 log10 copies/cell in cccDNA. Although 88 of 117 patients (75%) had undetectable serum levels of HBV DNA (<12 IU/mL), all had detectable levels of HBsAg, and only 5 (4%) had undetectable levels of cccDNA. On treatment with nucleos(t)ide analogues, patients with greater reductions in levels of cccDNA had greater reductions in HBsAg, but these reductions did not reach statistically significant correlations. CONCLUSIONS: Although nucleos(t)ide analogues potently reduced serum levels of HBV DNA, the reduction of HBsAg and cccDNA was small. In short-term therapy, the magnitude of HBsAg reduction does not correlate with that of cccDNA reduction.

Helicobacter pylori induces promoter methylation of E-cadherin via interleukin-1ß activation of nitric oxide production in gastric cancer cells.

BACKGROUND: Helicobacter pylori infection causes gastric mucosal inflammatory responses, resulting in up-regulation of interleukin-1ß (IL-1ß) and overproduction of mutagenic nitric oxide (NO). The authors previously demonstrated that IL-1ß plays an important role in H. pylori-induced E-cadherin (E-cad) methylation. Here, they extend the study to investigate the downstream effect of IL-1ß on H. pylori-induced gastric inflammation and aberrant DNA methylation. METHODS: Human gastric cancer cell lines (MKN7, MKN74, and TMK-1) with and without pretreatment of IL-1 receptor antagonist (IL-1ra) were treated with IL-1ß or infected with H. pylori. Promoter methylation status of E-cad was examined by methylation-specific polymerase chain reaction (PCR). Expression of E-cad, inducible nitric oxide synthase (iNOS), and nuclear factor κB (NFκB) was assessed by quantitative reverse transcriptase PCR, Western blotting, or immunofluorescence. NO production and total DNA methyltransferase (DNMT) activity were assayed fluorometrically. RESULTS: Both IL-1ß treatment and H. pylori infection-induced E-cad methylation led to a decrease in E-cad expression at both mRNA and protein levels. Total DNMT enzymatic activity was significantly elevated in treated cells, accounting for the observed E-cad methylation induction. Increased expression of NFκB was accompanied by up-regulation of iNOS and production of NO in treated cells. Reversal of all these phenomena in cells pretreated with IL-1ra suggested H. pylori-induced E-cad methylation via IL-1ß stimulation of the NFκB transcriptional system, leading to activation of DNMT activity by NO production. CONCLUSIONS: These findings reveal a previously unknown effect of IL-1ß and NO on H. pylori-induced aberrant DNA methylation. This possible pathway indicates the role of NO in epigenetic modification that links inflammation to carcinogenesis.

Occult hepatitis B infection and HBV replicative activity in patients with cryptogenic cause of hepatocellular carcinoma.

UNLABELLED: We aimed to investigate the incidence of occult hepatitis B infection (OBI) in patients with "cryptogenic" hepatocellular carcinoma (HCC) and to study the HBV replicative activity in these patients. Tumorous and adjacent nontumorous liver tissues were obtained from 33 cryptogenic HCC patients and 28 HCC patients with identifiable causes (13 with chronic hepatitis B [CHB], six with chronic hepatitis C, and nine alcohol-related). OBI was identified by nested polymerase chain reaction (PCR). Intrahepatic HBV DNA, covalently closed circular DNA (cccDNA), and pregenomic RNA (pgRNA) were quantified by real-time PCR and reverse-transcription PCR (RT-PCR), respectively. OBI was identified in 24 (73%) cryptogenic HCC patients, one (17%) HCC patient with HCV, and five (56%) patients with alcohol-related HCC. In HCC patients with OBI, HBV DNA were detected in ≥2 HBV genomic regions more often in nontumorous tissues than in tumorous tissues (90% versus 57%, respectively; P = 0.007). Cryptogenic HCC patients with OBI had lower intrahepatic total HBV DNA levels than HCC patients with CHB (median: 0.010 versus 3.19 copies/cell, respectively; P < 0.0001). Only six (26%) cryptogenic HCC patients with OBI had detectable cccDNA (median: <0.0002 copies/cell), which was significantly lower than that of the CHB patients (median: 0.005 copies/cell; P < 0.0001). HBV pgRNA were detectable in 12 (52%) cryptogenic HCC patients with OBI (median: 0.0001 copies/cell), which was significantly lower than that of the CHB patients (median: 2.90 copies/cell; P < 0.001). CONCLUSION: 73% of patients with apparently unidentifiable causes for HCC were HBV-related. The detection rate was higher in nontumorous tissues than tumorous tissues. The low intrahepatic HBV DNA and pgRNA levels indicated that persistent viral replication and possibly HBV integration are the likely causes of HCC in OBI patients.

Semi-quantitative fluorescent PCR analysis identifies PRKAA1 on chromosome 5 as a potential candidate cancer gene of cervical cancer.

OBJECTIVE: Comparative genomic hybridization has frequently detected amplification of chromosome 5p in cervical cancer, but candidate cancer genes within the region are rarely known. Therefore, we pursued to identify potential candidate gene related to cervical cancer development. METHODS: A series of 128 cervical tumor samples were examined by semi-quantitative fluorescent differential PCR for copy number changes on three candidate genes (PRKAA1, CTNND2 and POLS) mapped to chromosome 5p and one gene (ERBIN) mapped to chromosome 5q12.3. The impact of gene copy number was later analyzed in relation to HPV infection, tumor stage or tumor radiosensitivity. RESULTS: DNA copy numbers of PRKAA1, CTNND2 and ERBIN were significantly different from normal controls (P < 0.05). DNA copy number changes did not correlate with HPV infection, tumor stages or tumor radiosensitivity. Using RT-PCR, PRKAA1 mRNA expression in seven tumor samples with known 5p amplification was amplified from 3- to 15-fold. Over-expression of PRKAA1 was further confirmed by immunohistochemical staining on 125 paraffin-embedded cervical cancer tissues. The expression level in cervical tumor was significantly higher than that in normal epithelium (P < 0.001). CONCLUSIONS: PRKAA1 gene codes for the catalytic alpha 1 subunit of the AMP-activated protein kinase which is an important cellular metabolic stress regulator. It might assist tumor cells growth under stress. Thus, PRKAA1 may be one of the potential candidate genes for cervical carcinogenesis.

Heparin increases human gastric carcinoma cell growth.

BACKGROUND: Heparin has been widely used to prevent cancer-associated thromboembolism in cancer patients. Recent evidence reveals that heparin could modulate cell proliferation in the stomach. The effect of heparin on gastric cancer growth, however, is unknown. The effect of heparin on the proliferation of a human gastric adenocarcinoma cell line, BGC-823, was investigated. MATERIALS AND METHODS: Cell proliferation was assessed by [3H]-thymidine incorporation. The expressions of several growth-related genes were determined by RT-PCR and Western blot. RESULTS: Heparin significantly increased cell proliferation in BGC-823 cancer cells by 15.5% at the dose of 0.2 microg/ml. Heparin also up-regulated c-Myc protein expression by 14.4%. In contrast, mRNA and protein levels of epidermal growth factor receptor (EGFR) were, respectively, down-regulated by 12.7% and 8.2% with no effect on cyclooxygenase-2 mRNA or protein expression. CONCLUSION: Our results suggest that heparin can promote the proliferation and up-regulation of c-Myc protein expression in gastric cancer cells.