Molecular biology of gastric cancer: Helicobacter infection and gastric adenocarcinoma: bacterial and host factors responsible for altered growth signaling

Differences in gastric microbiota and mucosal function between patients with chronic superficial gastritis and intestinal metaplasia

Chronic superficial gastritis (CSG) and intestinal metaplasia (IM) can further develop into gastric cancer, which seriously endangers the health of people all over the world. In this study, the differences in gastric microbiota between CSG patients and IM patients were detected by 16S rRNA gene sequencing. As the expression levels of mucin and CDX2 are closely related to IM, the expression differences of mucin (MUC2 and MUC5AC) and CDX2 in the gastric mucosa of CSG patients and IM patients were detected by Western blot and qRT-PCR. The results showed that both Faith_pd and Observed_species indexes of microbiota in the gastric juice of CSG patients were significantly higher than those of IM patients. At the genus level, Thermus and Anoxybacillus were dominant in the gastric juice of IM patients, and Helicobacter was dominant in the gastric juice of CSG patients. Non-metric multidimensional scaling (NMDS) demonstrated that the dispersion of samples in the CSG group is greater than that in the IM group, and some samples in the CSG group are clustered with samples in the IM group. The KEGG metabolic pathway difference analysis of gastric juice microbiota in CSG and IM patients revealed that the gastric juice microbiota in the CSG and IM patients were significantly enriched in the amino acid metabolism, carbohydrate metabolism, and metabolism of cofactors and vitamins, and the functional differences between the two groups were mainly concentrated in the bacterial secretion system (VirB1, VirB2, VirB3, VirD2, and VirD4). In conclusion, there are significant differences in gastric microbiota and mucosal function between the CSG and IM patients. Moreover, the results of this study may provide a new means for the detection of CSG and IM and a new direction for the prevention and treatment of CSG and IM.

Streptococcal bacterial components in cancer therapy

The incidence rate of cancer is steadily increasing all around the world, and there is an urgent need to develop novel and more effective treatment strategies. Recently, bacterial therapy has been investigated as a new approach to target cancer, and is becoming a serious option. Streptococcus strains are among the most common and well-studied virulent bacteria that cause a variety of human infections. Everyone has experienced a sore throat during their lifetime, or has been asymptomatically colonized by streptococci. The ability of Streptococcus bacteria to fight cancer was discovered more than 100 years ago, and over the years has undergone clinical trials, but the mechanism is not yet completely understood. Recently, several animal models and human clinical trials have been reported. Streptococcal strains can have an intrinsic anti-tumor activity, or can activate the host immune system to fight the tumor. Bacteria can selectively accumulate and proliferate in the hypoxic regions of solid tumors. Moreover, the bacteria can be genetically engineered to secrete toxins or enzymes that can specifically attack the tumors.

Overview of Gene Expression Analysis in Gastric Disease Infected with Helicobacter pylori: CLDN1 and MMP9 Could Be Biomarkers for Early Diagnosis of Gastric Cancer

Chronic Helicobacter pylori infection produces several lesions in the human stomach, which can progress to chronic atrophic gastritis and gastric cancer. To date, there is very little information on gene expression in chronic atrophic gastritis and its relationship with progression to gastric cancer. In this study, we performed a gene expression analysis during chronic atrophic gastritis in order to identify possible biomarkers that allow an early diagnosis of gastric cancer. We studied biopsies from patients with chronic atrophic gastritis and gastric cancer. The biopsies were analyzed by a gene expression microarray and corroborated by qPCR and validated through immunohistochemistry. Our results revealed that gene expression profiles in patients with chronic atrophic gastritis showed molecular changes of the gastric mucosa, leading to gastric cancer. The gene expression profiles of CLDN1, CLDN7, OLFM4, C-MYC and MMP9 were more notable from the chronic atrophic gastritis. The gene expression patterns observed in this study allowed the identification of CLDN1 and MMP9 proteins as promising biomarkers of early stages of gastric cancer development.

Helicobacter pylori CagA elicits BRCAness to induce genome instability that may underlie bacterial gastric carcinogenesis

Infection with CagA-producing Helicobacter pylori plays a causative role in the development of gastric cancer. Upon delivery into gastric epithelial cells, CagA deregulates prooncogenic phosphatase SHP2 while inhibiting polarity-regulating kinase PAR1b through complex formation. Here, we show that CagA/PAR1b interaction subverts nuclear translocation of BRCA1 by inhibiting PAR1b-mediated BRCA1 phosphorylation. It hereby induces BRCAness that promotes DNA double-strand breaks (DSBs) while disabling error-free homologous recombination-mediated DNA repair. The CagA/PAR1b interaction also stimulates Hippo signaling that circumvents apoptosis of DNA-damaged cells, giving cells time to repair DSBs through error-prone mechanisms. The DSB-activated p53-p21^Cip1 axis inhibits proliferation of CagA-delivered cells, but the inhibition can be overcome by p53 inactivation. Indeed, sequential pulses of CagA in TP53-mutant cells drove somatic mutation with BRCAness-associated genetic signatures. Expansion of CagA-delivered cells with BRCAness-mediated genome instability, from which CagA-independent cancer-predisposing cells arise, provides a plausible "hit-and-run mechanism" of H. pylori CagA for gastric carcinogenesis.

Association between the microbiota and women's cancers - Cause or consequences?

Breast, ovarian and uterine cancers are the most common neoplasms among women. Several mechanisms may be involved in oncogenesis and these include environmental and genetic factors. Bacteria may affect the development of some cancers, with bacterial components, their products and metabolites interacting with susceptible tissues. Commensalism and dysbiosis are important potential mechanisms involved in oncogenesis, and an effective strategy for diagnosis and treatment is required. The purpose of this review was to analyze the complex associations between these cancers in women, and the microbiota, specifically bacterial microbes. However, several cancers have an increased prevalence among individuals with HIV and HPV so the relationship between viral infections and malignancies in women is also referred to. We described how different phylum of bacteria, particularly in the gut, mammary tissue and vaginal microbiome may be involved in carcinogenesis; and we discuss the potential pathways involved: (I), that lead to cell proliferation, (II), immune system perturbation, (III), cell metabolic changes (e.g., hormonal factors), and (IV), DNA damage. Studies investigating the differences between the composition of the bacterial microbiota of healthy women compared to that present in various conditions, and the clinical trials are summarized for the few studies that have addressed the microbiota and related conditions, are also reviewed.

Gastric cancer: genome damaged by bugs

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. The role of the microorganisms in gastric tumorigenesis attracts much attention in recent years. These microorganisms include bacteria, virus, and fungi. Among them, Helicobacter pylori (H. pylori) infection is by far the most important risk factor for GC development, with special reference to the early-onset cases. H. pylori targets multiple cellular components by utilizing various virulence factors to modulate the host proliferation, apoptosis, migration, and inflammatory response. Epstein–Barr virus (EBV) serves as another major risk factor in gastric carcinogenesis. The virus protein, EBER noncoding RNA, and EBV miRNAs contribute to the tumorigenesis by modulating host genome methylation and gene expression. In this review, we summarized the related reports about the colonized microorganism in the stomach and discussed their specific roles in gastric tumorigenesis. Meanwhile, we highlighted the therapeutic significance of eradicating the microorganisms in GC treatment.

Functional polymorphisms in NR3C1 are associated with gastric cancer risk in Chinese population

Recently promoter of NR3C1 has been found to be high methylated in gastric cancer tissues which might be involved in the initiation of gastric carcinoma development. To test whether the variants in NR3C1 could modify the risk of gastric cancer, we evaluated the association between four SNPs (rs6194, rs12521436, rs33388 and rs4912913) in NR3C1 and gastric cancer risk in a case-control study with 1,113 gastric cancer cases and 1,848 cancer-free controls in a Chinese population. We found a significant association between rs4912913 and gastric cancer risk (OR=1.18, 95%CI=1.05-1.33, P=5.49×10⁻³). We also observed that the A-allele of rs12521436 and rs33388 were significantly associated with a decreased risk of gastric cancer (OR=0.84, 95%CI=0.76-0.94, P=2.78×10⁻³; OR=0.85, 95%CI=0.75-0.97; P=0.018). Finally, we made a joint effect analysis of rs12521436, rs33388 and rs4912913 on risk of gastric cancer (P_Trend=2.83×10⁻⁵). These findings indicate that the variants rs4912913, rs33388 and rs12521436 of NR3C1 may contribute to gastric cancer susceptibility.

Combination of Interleukin 1 Polymorphism and Helicobacter pylori Infection: an Increased Risk of Gastric Cancer in Pakistani Population

Helicobacter pylori is one of the major risk factors involved in the development ofgastritis and gastric cancer (GC). H. pylori infection leads to increased production of pro-inflammatory cytokines by the host. Carriage of specific polymorphisms in cytokine genes may be associated with host susceptibility to the development of GC. We investigated the role of host genetic factors including polymorphisms of IL-1B and IL-1RN in correlation with gastritis and GC in H. pylori infected Pakistani population. A total of 230 gastritis cases and 100 GC cases were genotyped for IL 1B-511 and IL-1RN penta-allelic variable number of tandem repeats (VNTRs). A combination of IL-1B-511*T and IL-1RN*2 alleles (OR 19.064; 95% CI 2.319-156.7; p = 0.001) in H. pylori infected individuals had markedly increased risk of GC development. In Pakistani population, an increased risk of GC development is associated with the carriage of IL-1B-511*T and IL-1RN*2 alleles. Synergistic effect of H. pylori infection and IL-1B-511*T/IL-1RN*2 genotypes was also observed in association with significantly higher risk of developing GC. Further prospective and large scale studies are needed to establish the clinical impact of these findings.

Mouse models for gastric cancer: Matching models to biological questions

Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in late-stage diagnosis, at which point there are limited treatment options. Even when treated successfully, gastric cancer patients have a high risk of tumor recurrence and acquired drug resistance. It is vital to gain a better understanding of the molecular mechanisms underlying gastric cancer pathogenesis to facilitate the design of new-targeted therapies that may improve patient survival. A number of chemically and genetically engineered mouse models of gastric cancer have provided significant insight into the contribution of genetic and environmental factors to disease onset and progression. This review outlines the strengths and limitations of current mouse models of gastric cancer and their relevance to the pre-clinical development of new therapeutics.

Mouse models of gastric carcinogenesis

Gastric cancer is one of the most common cancers in the world. Animal models have been used to elucidate the details of the molecular mechanisms of various cancers. However, most inbred strains of mice have resistance to gastric carcinogenesis. Helicobacter infection and carcinogen treatment have been used to establish mouse models that exhibit phenotypes similar to those of human gastric cancer. A large number of transgenic and knockout mouse models of gastric cancer have been developed using genetic engineering. A combination of carcinogens and gene manipulation has been applied to facilitate development of advanced gastric cancer; however, it is rare for mouse models of gastric cancer to show aggressive, metastatic phenotypes required for preclinical studies. Here, we review current mouse models of gastric carcinogenesis and provide our perspectives on future developments in this field.

Positive association between Interleukin-8 -251A > T polymorphism and susceptibility to gastric carcinogenesis: a meta-analysis

Backgrounds

The associations between the polymorphisms of interleukin-8 (IL-8) gene and gastric carcinogenesis have been extensively investigated in recent years. However, the results remain conflicting rather than conclusive.

Methods

A meta-analysis of 18 eligible studies was performed to evaluate the association of IL-8 -251A > T polymorphism with risk of gastric carcinogenesis. A systematic literature search of MEDLINE, Embase, and Web of Science, CNKI databases was conducted. Statistical analysis was performed by using the Revman 5.1 software and the Stata 12.0 software.

Results

Of the 293 unique studies identified using our search criteria, 18 studies fulfilled our inclusion criteria and were included in the meta-analysis. These studies cumulatively reported 5,321 cases and 6,465 controls. The combined results based on all studies showed that the IL-8 -251A > T polymorphism was associated with the risk of gastric carciongenesis (A vs. T: OR: 1.14 [1.02, 1.26], P = 0.02), especially gastric cancer (A vs. T: OR: 1.15 [1.03, 1.29], P = 0.02), but not associated with the risk of precancerous lesion (A vs. T: OR: 1.09 [0.99, 1.20], P = 0.08). Analysis stratified by ethnicity may seem that IL-8 -251A > T polymorphism was susceptible to gastric cancer in Asian population, but not in Caucasian population.

Conclusions

Our meta-analysis results provide evidence that IL-8 -251A > T polymorphism is significantly associated with increased risk of gastric carcinogenesis in Asian population, particularly in gastric cancer. Further large and well-designed studies are required to confirm this conclusion.

The Effect of Helicobacter pylori on Epidermal Growth Factor Receptor-Induced Signal Transduction and the Preventive Effect of Celecoxib in Gastric Cancer Cells

Background/Aims

Helicobacter pylori infection induces cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) overexpression, and these factors may engage in cross-talk. The aim of the present study was to evaluate the effect of H. pylori on EGFR signaling pathways and to determine whether celecoxib has an inhibitory effect on this pathway.

Methods

The AGS cell line was cocultured with H. pylori G27 and the isogenic cagE- mutant. The expression of COX-2, EGFR, heparin binding-epidermal growth factor (HB-EGF), and transforming growth factor-β (TGF-β) was measured by real time-polymerase chain reaction (RT-PCR). Next, Western blot analyses of COX-2, EGFR, total Akt, phosphorylated Akt (pAkt), and phosphorylated glycogen synthase kinase-3β (pGSK3β) were performed after incubating H. pylori-treated AGS cells for 24 hours with various concentrations of celecoxib (0, 10, 20, and 30 µmol/L).

Results

H. pylori infection upregulated the mRNA levels of COX-2, EGFR, HB-EGF, and TGF-β, as detected by RT-PCR. However, AGS cells treated with cagE- mutants, which have a defective type IV secretion system, did not exhibit EGFR upregulation. Celecoxib had inhibitory effects on the H. pylori-induced overexpression of COX-2 (p=0.015), EGFR (p=0.025), pAkt (p=0.025), and pGSK3β (p=0.029) by Western blot analysis.

Conclusions

H. pylori with an intact type IV secretion system activated the COX-2 and EGFR-Akt pathways in the AGS cell line. As celecoxib exhibited inhibitory effects on the EGFR signaling pathway, the cross-talk of COX-2 and EGFR likely mediates H. pylori-induced gastric cancer.

Impact of methylenetetrahydrofolate reductase C677T polymorphism on the risk of gastric cancer and its interaction with Helicobacter pylori infection

BACKGROUND

Attempts for early detection of gastric cancer have recently focused on host's genetic susceptibility factors and gene-environment interactions. We have, herein, studied the association of MTHFR C677T single nucleotide polymorphism (SNP) and its interaction with Helicobacter pylori infection, smoking, age and gender on the risk of gastric cancer among an Iranian population.

METHODS

Gastric cancer patients (n = 450) and cancer-free controls (n = 780) were studied for serum H. pylori-specific IgG antibodies by ELISA and MTHFR C677T polymorphism (SNP) by PCR-RFLP. Demographic and life style data were collected through patient interviews. Unconditional logistic regression model estimated odds ratio (OR) and the corresponding 95% confidence intervals (CI).

RESULTS

The interactions of MTHFR genotype with H. pylori infection (P = 0.03), age (P = 0.049) and gender (P = 0.007) were statistically significant. Accordingly, MTHFR C677T carriers who were also positive for H. pylori infection exhibited 80% (OR = 1.8, 95% CI = 1.0-2.9) significant excess risk of non-cardia gastric cancer. Furthermore, subjects over the age of 50 or female subjects carrying MTHFR C677T SNP showed 40 (OR = 1.4, 95% CI = 1.0-2.0) and 100 (OR = 2.0, 95% CI = 1.2-3.2) percent increased risk of gastric cancer, respectively.

CONCLUSION

MTHFR C677T SNP seems to increase the risk of gastric cancer and the effect is significantly inflated by interactions with H. pylori infection, age and gender.

Prostaglandin reductase 2 modulates ROS-mediated cell death and tumor transformation of gastric cancer cells and is associated with higher mortality in gastric cancer patients

Various prostanoids and peroxisome proliferator-activated receptor γ (PPARγ) ligands play an important role in gastric cancer. Previously, we demonstrated that prostaglandin reductase 2 (PTGR2) catalyzes the reduction of the PPARγ ligand 15-keto-PGE(2) into 13,14-dihydro-15-keto-PGE(2). Here, we present functional data and clinical relevance for the role of PTGR2 in gastric cancer. Using lentiviral technology in AGS and SNU-16 gastric cancer cell lines, we either down-regulated or overexpressed PTGR2. In vitro analysis showed that PTGR2 knockdown resulted in decreased proliferation rate and colony formation, and in vivo xenograft models showed slower growth of tumors. Mechanistically, PTGR2 knockdown induced cell death, altered mitochondrial function, and increased reactive oxygen species production, which led to activation of ERK1/2 and caspase 3, with increased Bcl-2 and suppressed Bax expression. PTGR2 overexpression showed the opposite outcomes. Clinically, immunopathological staining showed strong PTGR2 expression in the gastric tumor portion, relative to nearby nontumor portions, and its expression negatively correlated with survival of patients with intestinal-type gastric cancer. Finally, in contrast to PTGR2-overexpressing cells, PTGR2-knockdown cells were more sensitive to cisplatin and 5-fluorouracil. Taken together, our findings not only provide functional and mechanistic evidence of the involvement of PTGR2 in gastric cancer, but also provide clinical observations affirming the significance of PTGR2 in gastric cancer and suggesting that PTGR2-target based therapy is worth further evaluation.

Mouse models of gastric cancer

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

Reduced FAF1 Expression and Helicobacter Infection: Correlations with Clinicopathological Features in Gastric Cancer

Background. This study aimed to investigate possible associations between FAF1 expression and aspects of gastric cancer, in particular its clinical characteristics and Helicobacter infection. Materials and Methods. RT-PCR and immunohistochemistry were used to analyze expression of FAF1 mRNA and protein in 40 gastric cancer patients. H. pylori infection was detected by three staining protocols. Results. The expression level of FAF1 mRNA was significantly lower in gastric cancer tissue than in normal gastric mucosa from the same patient (P < 0.05). FAF1 mRNA expression was significantly lower in stage IV gastric cancer than in stage I+II or IIIA+IIIB (P = 0.004) and also significantly lower in gastric cancer with distant metastasis. FAF1 mRNA expression was higher in well-differentiated cancer than in poorly-differentiated cancer (0.39 ± 0.06 versus 0.19 ± 0.06, t = 9.966, P < 0.01). FAF1 protein was detected in 15 of 40 (37.5%) cancerous tissue samples and in 29 of 40 (72.5%) corresponding normal tissue samples (P < 0.01). FAF1 mRNA expression was lower in H. pylori-positive cancerous tissue samples than in H. pylori-negative ones (P < 0.05). Conclusions. Downregulation of FAF1 expression may be related to the carcinogenesis and progression of gastric cancer, and H. pylori infection during gastric carcinogenesis may downregulate FAF1 expression.

Down-regulation of FUT3 and FUT5 by shRNA alters Lewis antigens expression and reduces the adhesion capacities of gastric cancer cells

BACKGROUND

Lewis antigens are fucosylated glycoconjugates involved in the development of several pathologies. The adhesion of sialyl-Lewis antigens to E-selectin is a key step in the development of metastasis and the glycosidic component of CD44 plays a key role in the binding to hyaluronic acid, a component of the extracellular matrix associated to tumor development and invasion. Fucosyltransferases are enzymes that add fucose to precursor glycan structures: FUT3 and FUT5 catalyze the addition of fucose to the α1-3,4 position and are detected in epithelial cells. In this study, we have analyzed the effects of silencing FUT3, FUT5 or FUT3/FUT5, in two gastric cancer cell lines, in the expression of Lewis antigens and in the adhesive and migratory capacities of the cells.

METHODS

FUT3, FUT5 and FUT3/FUT5 were down-regulated using lentiviral delivery of shRNAs in MKN45 and GP220 gastric cancer cells.

RESULTS

In the infected cells, decreased levels of FUT3 and FUT5 mRNA detected by quantitative RT-PCR; and lower levels of sialyl-Lewis antigens, evaluated by flow cytometry, were observed. The adhesion to endothelial cells trough the binding to E-selectin, and the binding to hyaluronic acid were reduced in the shFUT3, shFUT5 and shFUT3/FUT5, whereas the levels of CD44, analyzed by western blot, did not change.

GENERAL SIGNIFICANCE

The down-regulation of FUT3, FUT5 and FUT3/FUT5 reduces the expression of sialyl-Lewis antigens and the adhesion and binding capacities of gastric cancer cells; and allows to identify the specific α1-3,4 fucosyltransferases implicated in the Lewis antigens synthesis in this cellular model.

A new cyclo-oxygenase-2 gene variant in the Han Chinese population is associated with an increased risk of gastric carcinoma

BACKGROUND AND OBJECTIVE

Cyclo-oxygenase-2 (COX-2, also known as prostaglandin synthase 2) influences carcinogenesis through regulation of angiogenesis, apoptosis, and cytokine expression. COX-2 is encoded by the gene PTGS2. Several studies have suggested that PTGS2 single-nucleotide polymorphisms (SNPs) are involved in gastrointestinal carcinogenesis. In this study, we observed the PTGS2 Val511Ala (5939T/C) polymorphism in the Chinese population for the first time, and investigated whether this polymorphism might contribute to gastric cancer in a case-control study conducted in the Gansu province of China, a high-risk area for gastric cancer.

METHODS

We determined the genotypes of 110 gastric cancer patients and 138 controls using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis. Data were statistically analyzed using a chi-squared test and a logistic regression model.

RESULTS AND CONCLUSION

In our analysis, PTGS2 5939C allele carriers were at increased risk of gastric cancer (odds ratio [OR] 1.742; 95% confidence interval [CI] 1.009, 3.005; p = 0.045). We also found an interaction between Helicobacter pylori infection, a family history of gastric cancer, and presence of the 5939C allele. This study further indicated that H. pylori-positive status and family history jointly contribute to a higher risk of gastric cancer.

Origins of injection-site sarcomas in cats: the possible role of chronic inflammation-a review

The etiology of feline injection-site sarcomas remains obscure. Sarcomas and other tumors are known to be associated with viral infections in humans and other animals, including cats. However, the available evidence suggests that this is not the case with feline injection-site sarcomas. These tumors have more in common with sarcomas noted in experimental studies with laboratory animals where foreign materials such as glass, plastics, and metal are the causal agent. Tumors arising with these agents are associated with chronic inflammation at the injection or implantation sites. Similar tumors have been observed, albeit infrequently, at microchip implantation sites, and these also are associated with chronic inflammation. It is suggested that injection-site sarcomas in cats may arise at the administration site as a result of chronic inflammation, possibly provoked by adjuvant materials, with subsequent DNA damage, cellular transformation, and clonal expansion. However, more fundamental research is required to elucidate the mechanisms involved.

Phenotypic Differences of Gastric Cancer according to the Helicobacter pylori Infection in Korean Patients

Purpose

Infection with Helicobacter pylori is an important risk factor for gastric cancer in humans. We compared the clinicopathologic features of gastric cancer patients based on H. pylori infection.

Materials and Methods

We prospectively studied 155 patients who had gastric cancer and underwent gastrectomies in 1 hospital in Korea. We examined H. pylori infections using the rapid urease test (RUT) with gastrectomy specimens and collected clinical and pathologic data.

Results

The number of H. pylori infections based on the RUT was 137 (88%). The H. pylori-negative group was significantly associated with AGC and tumor histology. H. pylori infection was significantly correlated with type I/IIa in EGC and type III/IV/V in AGC. AGC was significantly correlated with larger tumor size, lymphatic invasion, perineural invasion, and H. pylori infection based on univariate and multivariate analyses.

Conclusions

We report the prevalence of H. pylori based on the RUT in gastric cancer patients. H. pylori infection influences the tumor histology, progression, and growth type of gastric cancer.

Analysis of translocation of the CagA protein and induction of a scattering phenotype in AGS cells infected with Helicobacter pylori

OBJECTIVE

To investigate whether the presence of structured CagA proteins in Western- and Eastern-type Helicobacter pylori (H. pylori) induces different incidences of gastric diseases.

METHODS

CagA and phosphorylated CagA were expressed in AGS gastric epithelial cells infected with wild type and mutant strains. The ability of individual CagA was determined by immunoprecipitation and Western blot assay. Morphological changes of these cells were observed under microscope to evaluate the appearance of elongation hummingbird phenotype.

RESULTS

The sizes of CagA proteins in different strains were different, and no phosphorylated CagA proteins were detected in wild-type strains. Meanwhile, the kinetics of CagA status in AGS infected with H. pylori was detected. The molecular weight of phosphorylated CagA with the same size of CagA proteins in H. pylori was different in infections with different wild-type strains. CagA and phosphorylated CagA increased in a time-dependent manner after the infection. The hummingbird phenotype with H. pylori for time-course was observed under microscope. Instead of HPK5 strain, the wild-type 26695 strain induced hummingbird phenotype in a time-dependent manner.

CONCLUSION

Translocation and phosphorylation of CagA are necessary, but not sufficient, for the induction of hummingbird phenotype in AGS cells.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

GG genotype of cyclin D1 G870A polymorphism is associated with non-cardiac gastric cancer in a high-risk region of China

OBJECTIVE

Cyclin D1 (CCND1) is a regulatory protein involved in the cell cycle of both normal and neoplastic cells. Polymorphism of this gene at codon 242 in exon 4 (A870G) has an impact on the risk of several human cancers. The purpose of this study was to study the relation between the CCND1 A870G gene polymorphism and the risk of non-cardiac gastric cancer in a Chinese population.

MATERIAL AND METHODS

The study population consisted of 159 patients with non-cardiac gastric cancer and 162 cancer-free controls. CCND1 870A/G polymorphism was genotyped by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay and sequencing.

RESULTS

CCND1 genotype distribution among the patients was significantly different from that among controls; AA (odds ratio (OR)=0.348, 95% CI: 0.163-0.742) and GA (OR=0.715, 95% CI: 0.506-1.012) genotypes were significantly lower in the gastric cancer patients than in the controls when subjects with the GG genotype served as the reference category. In other words, the risk of gastric cancer for subjects with the GG genotype was 2.8 times that of subjects with the AA genotype, and 1.4 times that of subjects with the GA genotype. Furthermore, in the stratification analyses, the risk of GG genotype was more evident in subjects >or=60 years of age and those positive for Helicobacter pylori (H. pylori) infection.

CONCLUSIONS

The CCND1870 GG genotype is associated with an increased risk for non-cardiac gastric cancer in patients in a high-risk area of China. Larger studies with multiple polymorphisms are needed to verify this finding and the function of this polymorphism needs to be further investigated.

The Role of PPARgamma Receptors and Leukotriene B(4) Receptors in Mediating the Effects of LY293111 in Pancreatic Cancer

Pancreatic cancer is a devastating disease in which current therapies are inadequate. Separate lines of research have identified the 5-lipoxygenase/leukotriene B(4) receptor pathway and the PPARgamma pathway as potential targets for prevention or treatment of this disease. LY293111 was originally designed as a potent leukotriene B(4) receptor antagonist for treatment of inflammatory conditions. LY293111 was also known to have inhibitory effects on 5-lipoxygenase, which is upstream of the production of leukotrienes. LY293111 was shown to have potent anticancer effects in pancreatic cancer and several other solid malignancies, where it caused cell cycle arrest and marked apoptosis. Subsequently, it came to light that LY293111 exhibited PPARgamma agonist activity in addition to its effects on the 5-lipoxygenase pathway. This raises the question of which of the two targets is of greatest importance with regard to the anticancer effects of this agent. The evidence to date is not conclusive, but suggests that the effects of LY293111 may be mediated by both LTB(4) receptors and PPARgamma.

Helicobacter pylori suppresses glycogen synthase kinase 3beta to promote beta-catenin activity

The human pathogen Helicobacter pylori influences cell adhesion, proliferation, and apoptosis and is involved in gastric adenocarcinoma formation. In our study we analyzed the impact of H. pylori infection on the regulation of beta-catenin, which plays a central role in both cell adhesion and tumorigenesis. Infection of Madin-Darby canine kidney cells with H. pylori led to suppression of Ser/Thr phosphorylation and ubiquitin-dependent degradation of beta-catenin and to up-regulation of lymphoid enhancer-binding factor/T cell factor (LEF/TCF)-dependent transcription. The impaired Ser/Thr phosphorylation of beta-catenin was accompanied by an increase of glycogen synthase kinase 3beta phosphorylation. Inhibition of Akt kinase, an up-stream regulator of glycogen synthase kinase 3, by a specific inhibitor Akti-1/2 or depletion of Akt with siRNA restored Ser/Thr phosphorylation of beta-catenin. We conclude that glycogen synthase kinase 3beta activity exerts an important role in beta-catenin regulation and LEF/TCF transactivation in H. pylori-infected Madin-Darby canine kidney cells.

Meta-analysis of different test indicators: Helicobacter pylori infection and the risk of colorectal cancer

BACKGROUND AND AIMS

Recent studies have demonstrated the relationship between Helicobacter pylori infection and the risk of colorectal carcinoma. However, the results of these studies remain controversial as the studies were relatively small in size and partially differed in designs, and so we reviewed the published studies and carried out a meta-analysis to further explore this relationship.

MATERIALS AND METHODS

We performed an extensive systematic review to find all the published case-control studies up to Jan. 2007 using electronic searching, hand searching, and reference lists of retrieved articles. Odds ratio (OR) was employed to evaluate the relationship of H. pylori infection and risk of colorectal cancer. Summary estimates were obtained using random effect models according to the result of a statistical test for heterogeneity across the studies. The presence of possible publication bias was assessed using different statistical approaches.

RESULTS

Thirteen studies were included, and summary OR 1.49 (95% confidence interval [CI] 1.17-1.91) was estimated for the association between H. pylori infection and colorectal cancer. Summary OR 1.56 (95% CI 1.14-2.14) was estimated for the association between immunoglobulin G antibody and colorectal cancer risk. By trimming and filling, the number of inputted studies was zero, and summary OR was still 1.49 (95% CI 1.17-1.91). The graphical funnel plot appeared asymmetrical, but there was no statistical evidence of publication bias. The method of fail-safe suggested that the effect of publication bias was small.

CONCLUSION

Current evidence, though limited, suggests that there is a possible increase in risk of colorectal cancer because of H. pylori infection.

Phytoceuticals: mighty but ignored weapons against Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection causes peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas, for which the pathogenesis of chronic gastric inflammation prevails and provides the pathogenic basis. Since the role of H. pylori infection is promoting carcinogenesis rather than acting as a direct carcinogen, as several publications show, eradication alone cannot be the right answer for preventing H. pylori-associated gastric cancer. Therefore, a non-antimicrobial approach has been suggested to attain microbe-associated cancer prevention through controlling H. pylori-related chronic inflammatory processes and mediators responsible for carcinogenesis. Phytoceutical is a term for plant products that are active on biological systems. Phytoceuticals such as Korean red ginseng, green tea, red wine, flavonoids, broccoli sprouts, garlic, probiotics and flavonoids are known to inhibit H. pylori colonization, decrease gastric inflammation by inhibiting cytokine and chemokine release, and repress precancerous changes by inhibiting nuclear factor-kappa B DNA binding, inducing profuse levels of apoptosis and inhibiting mutagenesis. Even though further unsolved issues are awaited before phytoceuticals are accepted as a standard treatment for H. pylori infection, phytoceuticals can be a mighty weapon for either suppressing or modulating the disease-associated footprints of H. pylori infection.

Epstein-Barr virus is associated with gastric carcinoma: The question is what is the significance?

AIM: To examine the possible role of the Epstein-Barr Virus (EBV) in the development of gastric adenocarcinoma (GC). It is unclear whether EBV is involved in GC development or is a consequence of gastric inflammation secondary to immunosuppressive treatments.

METHODS: A systematic review was carried out of all published observational studies on the temporal association between EBV and GC, with a view to determine a causal relationship.

RESULTS: The present study showed that the worldwide crude prevalence of EBV in gastric adenocarcinoma was 8.29%. The prevalence varied from 7.08% for intestinal type and 9.82% for diffuse type of GC. It was observed that Western and Central Asian countries had a significantly higher frequency of EBV positive cases compared to South-Eastern countries. America had the highest EBV-GC prevalence whereas Europe had the lowest.

CONCLUSION: The present review has demonstrated a high prevalence of EBV in gastric adenocarcinoma. However, studies designed to assess a temporal relationship and histological association using sensitive techniques should be carried out to establish the role of EBV in GC carcinogenesis.

Translational research in gastric malignancy

This article discusses recent advances in gastric cancer research that have improved treatment and outcomes of gastric malignancy, or have the potential to do so. The significance of Helicobacter pylori infection and eradication, immunology, host genetics, proto-oncogenes, and epigenetic alterations in gastric cancer are discussed. Abnormal signaling through growth factor pathways (tyrosine kinases and gastrointestinal peptides) presents ample opportunities for therapeutic intervention that are currently being tested in clinical trials. Drugs targeting abnormal epigenetic changes, such as DNA hypermethylation and histone deacetylation, are also on the horizon, although most of this research is still in the preclinical phase. The potential prognostic implications of genetics and immunology in gastric cancer prognosis are also reviewed.

Oxidative DNA damage in gastric cancer: CagA status and OGG1 gene polymorphism

Oxidative DNA damage is thought to play an important part in the pathogenesis of H. pylori-induced mucosal damage. 8-OHdG is a sensitive marker of DNA oxidation and is repaired by a polymorphic glycosylase (OGG1) more effectively than by OGG1-Cys(326). The aims of this study were to ascertain the respective roles of H. pylori, cagA status and OGG1 polymorphism in determining 8-OHdG levels in benign and premalignant stomach diseases and in gastric cancer (GC). The study involved 50 GC patients (for whom both neoplastic tissue and surrounding mucosa were available), 35 with intestinal metaplasia and atrophy (IMA) and 43 controls. H. pylori and cagA status were determined by histology and polymerase chain reaction for urease and cagA. 8-OHdG was assayed using HPLC with an electrochemical detector (HPLC-ED). The OGG1 1245C-->G transversion was identified using RFLP analyses. 8-OHdG levels were significantly higher in GC, with no differences in relation to H. pylori or cagA status. OGG1 polymorphism was documented in 34% of GC (15 Ser/Cys, 2 Cys/Cys). OGG1 1245C-->G polymorphism was detected in 54% of IMA patients, but only 16% of controls (p = 0.0004) and coincided with significantly higher 8-OHdG levels. In the multivariate analysis, 8-OHdG levels were predicted by histotype and OGG1 status. OGG1 1245C-->G polymorphism was common in both GC and IMA, but very rare in controls, and correlated more closely with 8-OHdG levels than do H. pylori infection or cagA status.

Crystallization and preliminary crystallographic analysis of decameric and monomeric forms of C49S mutant thioredoxin-dependent AhpC from Helicobacter pylori

Cys49Ser mutant Helicobacter pylori alkyl hydroperoxide reductase (C49S HpAhpC) was purified under reducing conditions in monomeric and decameric forms. The monomeric form was crystallized by the hanging-drop vapour-diffusion method. The crystals diffracted to 2.25 A resolution and belonged to space group C2, with unit-cell parameters a = 245.8, b = 140.7, c = 189.5 A, beta = 127 degrees , and contained 20 molecules in the asymmetric unit. A crystal of the decameric form was obtained by the microbatch crystallization method and diffracted to 2.8 A resolution. It belonged to space group C222, with unit-cell parameters a = 257.5, b = 417.5, c = 95.6 A. The structure of the monomeric form of C49S HpAhpC has been solved by the molecular-replacement method.

Genetic susceptibility to chronic hepatitis is inherited codominantly in Helicobacter hepaticus-infected AB6F1 and B6AF1 hybrid male mice, and progression to hepatocellular carcinoma is linked to hepatic expression of lipogenic genes and immune function-associated networks

Helicobacter hepaticus causes hepatitis in susceptible strains of mice. Previous studies indicated that A/JCr mice are susceptible and C57BL/6NCr mice are resistant to H. hepaticus-induced hepatitis. We used F1 hybrid mice derived from A/J and C57BL/6 matings to investigate their phenotype and determine their hepatic gene expression profile in response to H. hepaticus infection. F1 hybrid mice, as well as parental A/J and C57BL/6 mice, were divided equally into control and H. hepaticus-infected groups and euthanized at 18 months postinoculation. Hepatic lesions were evaluated histologically and the differential hepatic gene expression in F1 mice was determined by microarray-based global gene expression profiling analysis. H. hepaticus-infected parental strains including A/J and C57BL/6 mice, as well as F1 mice, developed significant hepatitis. Overall, hepatocellular carcinomas or dysplastic liver lesions were observed in 69% of H. hepaticus-infected F1 male mice and H. hepaticus was isolated from hepatic tissues of all F1 mice with liver tumors. Liver tumors, characterized by hepatic steatosis, developed in livers with high hepatitis scores. To identify gene expression specific to H. hepaticus-induced hepatitis and progression to hepatocellular carcinoma in F1 mice, a method using comparative group transcriptome analysis was utilized. The canonical pathway most significantly enriched was immunological disease. Fatty acid synthase and steaoryl-coenzyme A desaturase, the two rate-limiting enzymes in lipogenesis, were upregulated in neoplastic relative to dysplastic livers. This study suggests a synergistic interaction between hepatic steatosis and infectious hepatitis leading to hepatocellular carcinoma. The use of AB6F1 and B6AF1 mice, as well as genetically engineered mice, on a C57BL/6 background will allow studies investigating the role of chronic microbial hepatitis and steatohepatitis in the pathogenesis of liver cancer.

Role of bacterial strain diversity of Helicobacter pylori in gastric carcinogenesis induced by N-methyl-N-nitrosourea in Mongolian gerbils

AIM

Helicobacter pylori is known to enhance gastric carcinogenesis induced by chemical carcinogens. We previously demonstrated that infection with H. pylori strain SS1 did not enhance such carcinogenesis in C57BL/6 mice. Whether this result was due to the bacterial strain SS1 or to the experimental host, C57BL/6 mice, should be addressed. Therefore, we examined whether H. pylori strains introduced to the same host (Mongolian gerbils) differed in carcinogenicity.

MATERIALS AND METHODS

H. pylori TN2GF4 strain (CagA(+), VacA(+)) and SS1 strain (CagA functionally(-), VacA(-)) were infected to Mongolian gerbils (n = 126). In the first experiment (induction of gastritis), histologic change in gastric mucosa of gerbils infected by H. pylori (TN2GF4, SS1, vehicle) without N-methyl-N-nitrosourea (MNU) at 1 month or 6 months was assessed. In the second experiment (experimental carcinogenesis), H. pylori (TN2GF4, SS1, vehicle) was inoculated to the gerbils after administration of MNU for 10 weeks, and the number of cancers and histopathologic changes at week 54 were assessed.

RESULTS

In the first experiment, activity and inflammation in the TN2GF4 group were significantly greater than in the SS1 group at 1 month, while no significant difference was noted at 6 months. On the other hand, intestinal metaplasia and atrophy were significantly greater with TN2GF4 than with SS1 at 6 months but not at 1 month. In studies on experimental carcinogenesis, microscopically, 47.8% (11/23), 26% (7/26), and 0% (0/26), of animals had gastric adenocarcinoma in the MNU + TN2GF4 group, MNU + SS1 group, and MNU alone group, respectively.

CONCLUSION

Both H. pylori strains, TN2GF4 and SS1, promoted carcinogenesis in Mongolian gerbils. The severity of gastritis and destruction and restoration of gastric mucosa may be related to gastric carcinogenesis. That the SS1 strain significantly accelerated carcinogenesis only in Mongolian gerbils and not in C57BL/6 mice suggests the crucial role of host factors in carcinogenesis by H. pylori infection.

Helicobacter pylori alters the distribution of ZO-1 and p120ctn in primary human gastric epithelial cells

Helicobacter pylori infection is related to the development of diverse gastric pathologies, possibly by affecting epithelial junctional complexes that define cell polarity and play an essential role in transepithelial transport and cell-cell adhesion. Using primary gastric epithelial cell cultures, effects of H. pylori on the expression and localization of tight/adherence junction proteins and the resulting morphological changes and migratory capabilities were studied under in vivo-like conditions. Gastric epithelial cells were isolated from biopsies or gastrectomies and maintained in Quantum286 on collagen I-coated culture dishes or cover-slips. Cell cultures were characterized and further analyzed by western blot and immunofluorescent staining for ZO-1, p120ctn, and H. pylori CagA. Morphological changes and migratory response were monitored by time-lapse digital image microscopy. ZO-1 and p120ctn protein expression levels remain unaffected by H. pylori infection. Immunocytochemistry on H. pylori-infected primary cell monolayers focally showed disruption of intercellular ZO-1 staining and accumulation of ZO-1 in small vesicles. H. pylori infection recruited non-phosphorylated p120ctn to perinuclear vesicles. The fraction of phosphorylated p120ctn increased and could be detected in the nucleus, at the cell membrane, and at the leading edge of migrating cells. These alterations, triggered by H. pylori infection, are associated with an elongation phenotype and increased migration.

Up-regulation of Mac-2 binding protein by hTERT in gastric cancer

Mac-2 binding protein (Mac-2BP) is a secreted tumor antigen that is elevated in many cancers and implicated in tumor metastasis, as well as cell adhesion and immune functions. We focused on the human telomerase reverse transcriptase (hTERT) induced Mac-2BP expression and the relationship between Mac-2BP expression and the progression of gastric cancer. A cDNA expression array analysis was performed on the telomerase-negative cell line, SW13, which was engineered to overexpress hTERT when compared with the parental SW13 cell. hTERT-induced Mac-2BP expression was confirmed via RT-PCR and Northern blotting. ELISA and flow cytometric analyses revealed that Mac-2BP protein was increased by 2- to 4-fold in hTERT-overexpressing cells compared with the mock control. Mac-2BP expression was significantly reduced when the overexpressed hTERT was neutralized by the introduction of hTERT-specific siRNA. These results suggest that Mac-2BP expression is modulated by hTERT. Mac-2BP levels in both gastric cancer cells and tumor tissues were determined via Northern blot analysis and immunohistochemistry. Mac-2BP protein was highly expressed in most gastric cancer cell lines, and gastric tumor tissues were stained more densely than normal tissues. The intracellular and secreted Mac-2BP levels were also evaluated via ELISA, indicating that Mac-2BP was expressed and secreted more abundantly in gastric cancer patients than in healthy donors. The elevated serum Mac-2BP level in gastric tumor patients was also significantly associated with distant metastasis (p = 0.05) and higher tumor stage (p = 0.04). Our findings suggest that Mac-2BP is induced by hTERT, and that it may prove to be a useful prognostic marker for the detection of malignant progression of metastatic stomach cancers.

Relationship of IL-8 production and the CagA status in AGS cells infected with Helicobacter pylori exposed to low pH and activating transcription factor 3 (ATF3)

We examined the kinetics of IL-8 production and CagA status in AGS infected with Helicobacter pylori, 26695 (Western CagA-type), HPK5 (Eastern CagA-type) and isogenic cagA-disrupted mutants, exposed to different pH (pH 6 and pH 3). IL-8 was produced in the early and late phases after infection in CagA-dependent and -independent manners, respectively, irrespective of CagA-type. The wild-type exposed to low pH tremendously reduced IL-8 level at early phase, but restored with urea, suggesting that low pH exerted the kinetics of H. pylori-induced IL-8 production in CagA-dependent manner and urea was necessary for effective induction. CagA and phosphorylated CagA increased time-dependently after infection. Phosphorylated CagA from 26695, but not HPK5, rapidly peaked, consistent with the kinetics of IL-8 induction and appearance of hummingbird phenotype. ATF3 transcripts peaked late phase by wild-type, however, induced in two peaks early and late phases by cagA-disrupted mutants, indicating that different CagA-type proteins altered ATF3 induction in the infected cells.

Association of interleukin-1 gene polymorphisms with gastric cancer: a meta-analysis

Previous studies on the association between interleukin-1 (IL-1) genetic polymorphisms and the risk of gastric cancer have produced conflicting results. The purpose of this study was to examine the association between IL-1 genotype and gastric cancer by systematically reviewing the risk of the original studies. Thirty-nine studies, which included 6,863 gastric cancer cases and 8,434 controls, met the inclusion criteria and were included in the meta-analysis. By pooling all the studies identified, the summary odds ratio (OR) of gastric cancer risk associated with IL-1B-511T, -31C, +3954T and IL-1RN*2 was 1.26 (95% confidence interval (CI): 1.03-1.55), 1.00 (95% CI: 0.82-1.22), 1.37 (95% CI: 0.94-2.00) and 1.20 (95% CI: 1.01-1.41), respectively. A stratified analysis showed that IL-1B-511T was associated with an increased risk of gastric cancer (intestinal type) (OR = 1.76, 95% CI: 1.12-2.57). Moreover, IL-1RN*2 was also associated with an increased risk of gastric cancer among Caucasians (OR = 1.30, 95% CI: 1.09-1.54). In conclusion, IL-1B-511 and IL-1RN genetic polymorphisms are associated with an increased risk of developing gastric cancer.

5-LOX inhibitor modulates the inflammatory responses provoked by Helicobacter pylori infection

BACKGROUND

Arachidonic acid metabolites have been considered as pivotal mediators in Helicobacter pylori-induced inflammatory response, which are mainly metabolized by two distinct enzymes: cyclooxygenase (COX) and lipoxygenase (LOX). While COX has become well known to play a key role in either carcinogenesis or inflammation related to H. pylori infection, little is known regarding the implication of LOX in H. pylori infection. In this study, we evaluated the roles of 5-LOX and its metabolites in H. pylori-induced host responses and further a potential beneficial action of specific LOX inhibitors against H. pylori infection.

MATERIALS AND METHODS

Expressions of cytosolic phospholipase A(2) (cPLA(2)), COX-2, and 5-LOX after H. pylori infection were evaluated by immunofluorescence staining and Western blotting. Synthesis of LOX metabolites was measured with reversed-phase high-performance liquid chromatography. For analyzing the influence of 5-LOX inhibitors, nordihydroguaiaretic acid (NDGA) and geraniin, on H. pylori-induced inflammatory responses, RNase protection assay and RT-PCR were performed.

RESULTS

H. pylori stimulated the translocation of cPLA(2) from cytoplasm to nucleus and increased the biosynthesis of hydroxyeicosatetraenoic acids (HETEs) as a predominant form of 5S-HETE in gastric epithelium. NDGA exerted a strong suppression activity of H. pylori-induced 5-LOX signaling. The administration of LOX inhibitors was related with down-expression of proinflammatory mediators such as interleukin-8 and tumor necrosis factor-alpha in both H. pylori-infected gastric epithelial cells and macrophage cells.

CONCLUSION

LOX modulation with its specific inhibitors could impose significant anti-inflammatory responses after H. pylori infection, based on the fact that H. pylori infection provoked gastric inflammation through metabolizing arachidonic acid by the 5-LOX pathway.