Gastric cancer and H. pylori: Host genetics open the way

Initiation and Maintenance of Gastric Cancer: A Focus on CD44 Variant Isoforms and Cancer Stem Cells

Gastric cancer is the third most common cause of cancer-related death. Although the incidence of gastric cancer in the United States is relatively low, it remains significantly higher in some countries, including Japan and Korea. Interactions between cancer stem cells and the tumor microenvironment can have a substantial impact on tumor characteristics and contribute to heterogeneity. The mechanisms responsible for maintaining malignant cancer stem cells within the tumor microenvironment in human gastric cancer are largely unknown. Tumor cell and genetic heterogeneity contribute to either de novo intrinsic or the therapy-induced emergence of drug-resistant clones and eventual tumor recurrence. Although chemotherapy often is capable of inducing cell death in tumors, many cancer patients experience recurrence because of failure to effectively target the cancer stem cells, which are believed to be key tumor-initiating cells. Among the population of stem cells within the stomach that may be targeted during chronic Helicobacter pylori infection and altered into tumor-initiating cells are those cells marked by the cluster-of-differentiation (CD)44 cell surface receptor. CD44 variable isoforms (CD44v) have been implicated as key players in malignant transformation whereby their expression is highly restricted and specific, unlike the canonical CD44 standard isoform. Overall, CD44v, in particular CD44v9, are believed to mark the gastric cancer cells that contribute to increased resistance for chemotherapy- or radiation-induced cell death. This review focuses on the following: the alteration of the gastric stem cell during bacterial infection, and the role of CD44v in the initiation, maintenance, and growth of tumors associated with gastric cancer.

Multiplex H. pylori Serology and Risk of Gastric Cardia and Noncardia Adenocarcinomas

The reported associations with gastric adenocarcinoma and seropositivity to different Helicobacter pylori antigens using multiplex serology have not been consistent across studies. We aimed to investigate the association between 15 different multiplex serology antigens and the risk of gastric cardia (GCA) and gastric noncardia (GNCA) adenocarcinomas in northeastern Iran, a population with high rates of gastric adenocarcinoma. We included 272 cases of gastric adenocarcinoma (142 GCA, 103 GNCA, and 27 unspecified) and 524 controls who were individually matched to cases for age, sex, and place of residence in a population-based case-control study. Seropositivity to H. pylori was assessed using both multiplex serology and H. pylori IgG ELISA. Ninety-five percent of controls were seropositive to H. pylori. Of the 15 antibodies in the multiplex assay, 11 showed no significant association with gastric adenocarcinomas. CagA and VacA were associated with a significantly increased risk of all gastric adenocarcinoma and GNCA in multivariate models. Surprisingly, GroEL and NapA were significantly associated with a reduced risk of these tumors. Only CagA antigen was associated with significantly elevated risk of GCA. We found no associations between H. pylori seropositivity overall either by whole-cell ELISA test or multiplex serology, likely due to the high prevalence of seropositivity. Individual antigen testing showed that CagA positivity was associated with increased risk of both noncardia and cardia adenocarcinoma, which is similar to some other Asian populations, whereas two antigens were associated with lower risk of gastric cancer. This latter result was unexpected and should be retested in other populations.

Micronutrient-gene interactions related to inflammatory/immune response and antioxidant activity in ageing and inflammation. A systematic review

Recent longitudinal studies in dietary daily intake in human centenarians have shown that a satisfactory content of some micronutrients within the cells maintain several immune functions, a low grade of inflammation and preserve antioxidant activity. Micronutrients (zinc, copper, selenium) play a pivotal role in maintaining and reinforcing the performances of the immune and antioxidant systems as well as in affecting the complex network of the genes (nutrigenomic) with anti- and pro-inflammatory tasks. Genes of pro- and anti-inflammatory cytokines and some key regulators of trace elements homeostasis, such as Metallothioneins (MT), are involved in the susceptibility to major geriatric disease/disorders. Moreover, the genetic inter-individual variability may affect the nutrients' absorption (nutrigenetic) with altered effects on inflammatory/immune response and antioxidant activity. The interaction between genetic factors and micronutrients (nutrigenomic and nutrigenetic approaches) may influence ageing and longevity because the micronutrients may become also toxic. This review reports the micronutrient-gene interactions in ageing and their impact on the healthy state with a focus on the method of protein-metal speciation analysis. The association between micronutrient-gene interactions and the protein-metal speciation analysis can give a complete picture for a personalized nutrient supplementation or chelation in order to reach healthy ageing and longevity.

Quantitative assessment of the influence of prostate stem cell antigen polymorphisms on gastric cancer risk

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored 123-amino acid protein related to the cell proliferation inhibition and/or cell death induction activity which has attracted considerable attention as a candidate gene for gastric cancer (GC) since it was first identified through genome-wide association approach. Since then, the relationship between PSCA polymorphisms (rs2294008, rs2976392) and GC has been reported in various ethnic groups; however, these studies have yielded inconsistent results. To investigate this inconsistency, we performed a meta-analysis of 16 studies involving a total of 18,820 cases and 35,756 controls for the two widely studied polymorphisms of PSCA on genetic susceptibility for GC. Overall, the summary odds ratio for GC was 1.46 (95% CI 1.30-1.69, P < 10(-5)) and 1.49 (95% CI 1.22-1.82, P < 10(-4)) for PSCA rs2294008 and rs2976392 polymorphisms, respectively. Meanwhile, haplotype analyses of the two polymorphisms revealed a significant association between the combination of these alleles and GC risk. When stratifying for ethnicity, significantly increased risks were found for rs2294008 and rs2976392 polymorphism among East Asians in all genetic models, while no significant associations were observed for the rs2294008 polymorphism in Caucasians. In the stratified analyses according to histological type, and source of controls, evidence of gene-disease association was still obtained. In addition, our data indicate that rs2294008 of PSCA is involved in GC susceptibility and confer its effect primarily in noncardia tumors (OR = 1.30, 95% CI 1.12-1.53, P < 10(-4)). Our findings demonstrated that rs2294008 and rs2976392 polymorphism of PSCA is a risk-conferring factor associated with increased GC susceptibility, especially in East Asians.

Card15 mutations and gastric cancer in a Portuguese population

BACKGROUND. CARD15 is involved in the innate immune response and mutations of this gene have been linked with increased risk of Crohn's disease and colorectal cancer. The relation between CARD15 mutations and gastric cancer (GC) remains controversial. AIMS. To assess whether CARD15 mutations are risk factors for GC in Portugal and whether there are genotype-phenotype correlations in these patients. METHODS. The 3 main CARD15 mutations (3020insC, R702W and G908R) were searched in 150 patients with GC and in 202 healthy controls. RESULTS. Overall, CARD15 mutations were found in 28 patients (18.7%) and in 27 controls (13.4%) (p = 0.176). Individually, the incidence of 3020insC was significantly higher in patients than in controls (6.0% vs. 1.0%, p = 0.021). This polymorphism was linked with an increased risk for the intestinal-type of GC (p = 0.002), while no association was found with the diffuse and/or mixed types. Genotype frequencies for R702W (10.0% vs. 7.9%) and G908R (4.0% vs. 4.0%) were not statistically different between the two groups. Similarly, no significant associations were detected between these two polymorphisms and the different histological GC types. No correlations were observed between CARD15 mutations and family history, mean age at diagnosis or GC stage. CONCLUSIONS. The CARD15 3020insC variant is a risk factor for intestinal GC in Portugal. CARD15 variants are not correlated with age of diagnosis or family aggregation of the disease neither with the GC stage.

Quantitative assessment of the influence of tumor necrosis factor alpha polymorphism with gastritis and gastric cancer risk

Tumor necrosis factor alpha (TNFA) is an important molecule in inflammatory, infectious, and tumoral processes. Inflammation is one of the early phases in the development of gastric cancer (GC). Therefore, several studies have examined the association of polymorphism in TNFA with gastritis and GC risk. A functional polymorphism, -308G>A (rs1800629), which is located in the promoter of TNFA gene, has been suggested to alter the production of TNF-α and influence cancer risk. To date, a number of studies have been carried out to investigate the relationship between the polymorphism and gastritis or GC susceptibility, but the results were conflicting. To investigate this inconsistency, we performed a meta-analysis of 36 studies for TNFA -308G>A polymorphism to evaluate the effect of TNFA on genetic susceptibility for gastritis and GC. An overall random-effects per-allele odds ratio of 1.16 (95 % confidence interval 1.04-1.29, P = 0.008) was found for the polymorphism. Significant results were also observed using dominant or recessive genetic models. In the subgroup analyses by ethnicity, significant results were found in Caucasians, whereas no significant associations were found among East Asians and other ethnic populations. No associations between the polymorphism and gastritis were observed. In addition, our data indicate that TNFA is involved in GC susceptibility and confers its effect primarily in diffuse type of tumors. Besides, -308G>A polymorphism was found to be significantly associated with both cardiac and noncardiac tumors. This meta-analysis demonstrated that the TNFA -308G>A polymorphism is a risk factor for developing GC, but the associations vary in different ethnic populations.

Associations between the four toll-like receptor polymorphisms and the risk of gastric cancer: a meta-analysis

PURPOSE

The association between Toll-like receptor 2 (TLR2) -196 to -174del polymorphism and Toll-like receptor 4 (TLR4) polymorphisms (Asp299Gly, Thr399Ile, and 3725G>C) and gastric cancer risk are still conflicting. For better understanding of the effects of these four polymorphisms on gastric cancer risk, a meta-analysis was performed.

METHODS

An extensive search was performed to identify all case-control studies investigating such associations. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the relationship.

RESULTS

A total of 21 studies (3,436 cases and 4,239 controls) were found to be eligible for meta-analysis. In the overall analysis, a significantly increased risk was observed in TLR4 Asp299Gly polymorphism (G allele vs. A allele: OR=1.84, 95%CI: 1.41, 2.39; GA vs. AA: OR=1.89, 95%CI: 1.43, 2.48; Recessive model: OR=1.90, 95%CI: 1.44, 2.49) and TLR4 Thr399Ile polymorphism (T allele vs. C allele: OR=1.97, 95%CI: 1.22, 3.18; TC vs. CC: OR=1.94, 95%CI: 1.19, 3.15; Recessive model: OR=1.98, 95%CI: 1.21, 3.21), whereas no associations were found in any genetic models of TLR2 -196 to -174del and TLR4 3725G>C polymorphisms. Similar results were found in the subgroup analyses by ethnicity. However, we detected that A allele carriers of the TLR4 Asp299Gly polymorphism might have an increase risk of gastric cancer in the Helicobacter pylori-positive population (G allele vs. A allele: OR=2.01, 95%CI: 1.22, 3.31).

CONCLUSION

The results of this meta-analysis indicate that the TLR4 Asp299Gly and Thr399Ile polymorphisms are risk factors for gastric cancer development.

Quantitative assessment of the influence of glutathione S-transferase T1 null variant on gastric cancer risk

Glutathione S-transferase T1 (GSTT1) catalyzes reactions between glutathione and lipophilic compounds with electrophilic centers, leading to neutralization of toxic compounds, xenobiotics, and products of oxidative stress. In the past decade, a number of case-control studies have been carried out to investigate the relationship between the GSTT1 null polymorphism and gastric cancer (GC), but the results have been inconclusive. To investigate this inconsistency, we performed a meta-analysis of 46 studies involving a total of 9012 GC cases and 14,215 controls for null variant of the GSTT1 gene to evaluate the effect of GSTT1 on genetic susceptibility for GC. Potential sources of heterogeneity including ethnicity, source of control, and sample size were also assessed. Overall, significantly increased GC risk was associated with GSTT1 null polymorphism with OR of 1.20 (95% CI, 1.10-1.32; P < 0.05). In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians and Indians, while no significant associations were found among Caucasian, and Middle Eastern and African populations. By pooling data from 19 studies that considered combinations of GSTT1 and GSTM1 genotypes, a statistically significant increased risk for GC (OR = 2.04, 95% CI, 1.49-2.64; P < 0.05) was detected for individuals with dual deletion in both genes compared with positive genotypes. In addition, we found that cigarette smoking and alcohol drinking may modified the association of GSTT1 null genotypes with the risk of GC. In conclusion, this meta-analysis suggests that GSTT1 null polymorphism is associated with elevated GC risk, but these associations vary in different ethnic populations.

The prognostic significance of whole blood global and specific DNA methylation levels in gastric adenocarcinoma

Background

Epigenetics, particularly DNA methylation, has recently been elucidated as important in gastric cancer (GC) initiation and progression. We investigated the clinical and prognostic importance of whole blood global and site-specific DNA methylation in GC.

Methods

Genomic DNA was extracted from the peripheral blood of 105 Omani GC patients at diagnosis. DNA methylation was quantified by pyrosequencing of global DNA and specific gene promoter regions at 5 CpG sites for CDH1, 7 CpG sites for p16, 4 CpG sites for p53, and 3 CpG sites for RUNX3. DNA methylation levels in patients were categorized into low, medium, and high tertiles. Associations between methylation level category and clinicopathological features were evaluated using χ² tests. Survival analyses were carried out using the Kaplan-Meier method and log rank test. A backward conditional Cox proportional hazards regression model was used to identify independent predictors of survival.

Results

Older GC patients had increased methylation levels at specific CpG sites within the CDH1, p53, and RUNX-3 promoters. Male gender was significantly associated with reduced global and increased site-specific DNA methylation levels in CDH1, p16, and p53 promoters. Global DNA low methylation level was associated with better survival on univariate analysis. Patients with high and medium methylation vs. low methylation levels across p16 promoter CpG sites, site 2 in particular, had better survival. Multivariate analysis showed that global DNA hypermethylation was a significant independent predictor of worse survival (hazard ratio (HR) = 2.0, 95% CI: 1.1–3.8; p = 0.02) and high methylation mean values across p16 promoter sites 1–7 were associated with better survival with HR of 0.3 (95% CI, 0.1–0.8; p = 0.02) respectively.

Conclusions

Analysis of global and site-specific DNA methylation in peripheral blood by pyrosequencing provides quantitative DNA methylation values that may serve as important prognostic indicators.

Soybean product intake modifies the association between interleukin-10 genetic polymorphisms and gastric cancer risk

In this study, our aim was to investigate the association of inflammation-related genetic polymorphisms and gastric cancer risk and to examine whether the combined effect of soybean product intake modified cancer risk. Eighty-four incident gastric cancer cases and 336 matched controls were selected from the Korean Multi-Center Cancer Cohort. We selected 14 single nucleotide polymorphisms (SNP) from 5 genes [interleukin (IL)-1beta, IL-2, IL-4, IL-8, and IL-10] and used unconditional logistic regression model to calculate the odds ratios (OR) and 95% CI adjusting for H. pylori seropositivity, smoking, age, sex, enrollment year, and residential area. The risk for gastric cancer in relation to genetic polymorphisms and haplotypes were assessed according to soybean product intake levels. Although no single SNP effect was found, the combined effect between IL-10 gene variants of -592 GG/GA, -819 TC/CC, or -1082 AG/GG and low intake of soybean products had an increased risk for gastric cancer compared with the group with no risk gene variants and a high intake of soybean products (OR [95% CI] = 2.82 [1.04-7.62], 2.75 [1.02-7.44], and 4.34 [1.51-12.5], respectively). Among the low-soybean product intake group, IL-10 CCG haplotype had an increased risk of gastric cancer (OR = 3.38 [1.40-8.13]) relative to the ATA haplotype. Our results suggest that the association between IL-10 genetic polymorphisms and gastric cancer risk was modified by soybean product intake.

Combined polymorphism analysis of glutathione S-transferase M1/G1 and interleukin-1B (IL-1B)/interleukin 1-receptor antagonist (IL-1RN) and gastric cancer risk in an Omani Arab Population

BACKGROUND

Host genetics have been implicated in gastric cancer carcinogenesis. Polymorphisms of glutathione S-transferase (GST) M1 and G1 and of interleukin-1B (IL-1B) and interleukin-1 receptor antagonist (IL-1RN) were shown to increase gastric cancer predisposition in several studies. To our knowledge, this is the first report on the combined analysis of polymorphisms GSTM1/G1 and IL-1B/IL-1RN genes in gastric adenocarcinoma.

METHODS

Genomic DNA was extracted from peripheral blood of 107 control subjects and 107 gastric cancer patients. Analysis for the GSTM1 and GSTT1 gene polymorphisms was performed by multiplex polymerase chain reaction. The DNA samples were analyzed using the TaqMan allelic discrimination test for the polymorphism of IL-1B at positions-31. The variable number of tandem repeats of IL-1RN was genotyped using polymerase chain reaction followed by agarose gel electrophoresis.

RESULTS

There were no statistically significant associations between the GSTM1/G1 or IL-1B-31 genes and gastric cancer risk. There was a statistical association between the presence of the IL-1RN*2 allele and gastric cancer (odds ratio 2.2, 95% confidence interval=1.2-3.7, P=0.01). Combined analysis showed that a combination of the null GSTM1 genotype and carriers of IL-1RN*2 was associated with a statistically significant correlation with gastric cancer (odds ratio=3.6, 95% confidence interval=1.4-9.4, P=0.008).

CONCLUSIONS

The current study suggests that the individual variation in both the cellular inflammatory modulator IL-1RN and the antioxidative property of GSTM1 may predispose individuals to an increased risk of gastric cancer.

IL-1 gene polymorphisms and genetic susceptibility of gallbladder cancer in a north Indian population

Long-standing gallstones are generally present in 65-80% patients of gallbladder cancer (GBC). It has also been suggested that inflammation caused by gallstones may be involved in the development of GBC. Interleukin-1 receptor antagonist (IL-1RN) and interleukin-1 beta (IL-1B) are proinflammatory cytokine genes at the interleukin-1 locus, and polymorphisms of these genes have been associated with various inflammatory diseases. The aim of this study was to investigate whether polymorphism in the IL-1RN and IL-1B genes are associated with GBC patients with and without gallstones. Polymorphisms within the IL-1RN 86-base pair VNTR (variable number tandem repeat) and IL-1B (-511C --> T) were genotyped using polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism in 166 healthy subjects and 124 GBC patients. The frequency of the IL-1RN, VNTR 2/2 genotype was significantly higher in GBC patients [P = 0.017; odds ratio (OR) = 3.25; 95% confidence interval (CI) = 1.23-8.58]. CC genotype and 'C' allele of the -511IL-1B C --> T polymorphism also showed high risk for GBC (P = 0.033; OR = 3.36; 95%CI = 1.52-7.43, P = 0.047, OR = 1.41; 95%CI = 1.00-1.98, respectively). The higher cancer risk due to the IL-1RN, 2/2 genotype was observed in GBC patients with or without stones (P = 0.038; OR = 3.58; 95%CI = 1.08-11.65, P = 0.035; OR = 3.33; 95%CI = 1.08-10.61). Risk due to the CC genotype of IL-1B, however, was confined to GBC patients harboring gallstones (P = 0.0003; OR = 6.92; 95%CI = 2.65-18.03). The haplotype 1/C of IL-1RN and IL-1B was found to confer a significantly enhanced risk of GBC in cancer patients with gallstones (P = 0.022; OR = 2.19; 95%CI = 1.12-4.27), while higher risk resulting from 2/C haplotype was of borderline significance (P = 0.061; OR = 3.04; 95%CI = 0.95-9.70). Individuals with 1/C and 2/C haplotypes of IL-1RN VNTR and -511IL-1B C --> T polymorphisms were more susceptible to develop GBC with gallstones compared to healthy controls in north India.

Frequency of Helicobacter pylori and CagA antibody in patients with gastric neoplasms and controls: the Indian enigma

BACKGROUND

Despite association between H. pylori and gastric neoplasm (GN) from the developed world, studies from India, where infection is more common and acquired early, are scant and contradictory.

METHODS

Two hundred and seventy-nine patients with GN from two northern and one eastern Indian centers during the period 1997-2005, 101 non-ulcer dyspepsia (NUD), and 355 healthy volunteers (HV) were evaluated for H. pylori [rapid urease test (RUT), histology and anti-H. pylori, and CagA IgG serology].

RESULTS

Patients with GN [263 gastric carcinoma and 16 (6%) primary gastric lymphoma, 208 male] were older than HV (n = 355, 188 male) and NUD (n = 101, 54 male) patients (53 +/- 12 versus 44 +/- 17 and 43 +/- 13 years, respectively; P < 0.001). Eastern Indian patients with GN (n = 145) were younger than those from northern India (n = 134; 52 +/- 12 versus 55 +/- 12 years; P < 0.007, t-test). In GN and NUD patients H. pylori positivity by RUT [86/225 (38%) versus 46/101 (46%)], anti-H. pylori IgG [154/198 (78%) versus 85/101 (84%)], and histology [136/213 (64%) versus 55/101 (55%)] were comparable (chi(2)-test). Serum IgG anti-H. pylori antibody was more common among HV than among GN patients [300/355 (85%) versus 154/198 (78%); P = 0.04, chi(2)-test]. Intestinal metaplasia was more common in GN than in NUD patients [101/252 (40%) versus 2/98 (2%), P < 0.000, chi(2)-test]. CagAIgG was more common in GN than in NUD patients [124/163 (76%) versus 64/101 (63%)] but comparable to that in HV patients [87/98 (89%), P = NS].

CONCLUSION

Frequency of H. pylori as detected using endoscopy and serology-based tests is not higher among patients with GN as compared with controls in India.

Analysis of Pro12Ala PPAR gamma polymorphism and Helicobacter pylori infection in gastric adenocarcinoma and peptic ulcer disease

BACKGROUND

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-dependent transcription factor involved in various disease processes including inflammation and carcinogenesis. We investigated the association of Pro12Ala PPARgamma polymorphism and Helicobacter pylori infection with gastric cancer and peptic ulcer disease (PUD).

PATIENTS AND METHODS

In total, 348 adult patients [62 gastric adenocarcinoma, 45 PUD and 241 nonulcer dyspepsia (NUD)] who underwent an upper gastrointestinal endoscopy were enrolled. PPARgamma polymorphism was analyzed by PCR-based restriction fragment length polymorphism. H. pylori infection was diagnosed by rapid urease test, culture, histopathology and PCR.

RESULTS

PPARgamma G carrier had significant association with gastric adenocarcinoma [P = 0.023, odds ratio (OR) = 2.136, 95% CI = 1.112-4.104] and PUD (P = 0.028, OR = 2.165, 95% CI = 1.008-4.306) when compared with NUD. Combination of G carrier and H. pylori infection further increased the risk of gastric adenocarcinoma (OR = 3.054, 95% CI = 1.195-7.807) and PUD (OR = 11.161, 95% CI = 3.495-35.644). PPARgamma polymorphism did not increase the risk of gastric adenocarcinoma and PUD in H. pylori-negative subjects.

CONCLUSIONS

The study suggests that Pro12Ala PPARgamma polymorphism is associated with gastric adenocarcinoma and PUD, and is a potential marker for genetic susceptibility to these two diseases in the presence of H. pylori infection.

Transactivation of the EGFR by AP-1 is induced by Helicobacter pylori in gastric cancer

BACKGROUND

Helicobacter pylori infection of the gastric mucosa is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. However, the mechanisms by which H. pylori causes cancer are currently unknown. Binding of epidermal growth factor (EGF) to its receptor (EGFR) may be important in the development of gastric cancer. This interaction accelerates cell proliferation and migration, and triggers epithelial cell signaling. In this study, we investigated the effects of H. pylori on EGFR- and AP-1-mediated signal transduction pathways in the AGS gastric epithelial cell line and gastric tissue from humans.

METHODS

Cells were treated with H. pylori and cell death was examined at a variety of time points using cell viability and trypan blue exclusion dye assay. To investigate the effects on EGFR regulation, AGS cells were transfected with a full-length and truncated EGFR luciferase (luc) reporter. Tissue microarray containing 44 samples of gastric biopsies from H. pylori-positive patients was analyzed for protein expression level of EGFR by immunohistochemistry.

RESULTS

EGFR promoter activity was increased (twofold) 3 h after treatment with H. pylori commenced. Using a series of EGFR promoter deletion mutants, we identified a region that was crucial for transactivation of the EGFR by H. pylori. To determine whether AP-1 binding was altered, we transfected AGS cells with an AP-1 luciferase construct and then treated them with H. pylori for up to 6 h. We found that AP-1 activity was induced by H. pylori in gastric cells, while electrophoretic mobility shift assays confirmed that binding of AP-1 to the EGFR promoter site was increased following H. pylori treatment. Binding of c-Jun and c-Fos to the EGFR promoter region -1,062/-900 was induced eight- and six fold, respectively, using ChIP assay. Active EGFR staining was markedly increased in gastric mucosa from infected persons, compared to uninfected controls.

CONCLUSIONS

We conclude that exposure of gastric cells to H. pylori induces increased production of EGFR through various signal transduction pathways, including those mediated by the EGFR and AP-1. Distinct effects on EGFR activation may specify the subset of AP-1 target genes that are selected, including those involved in proliferation and apoptosis. This is consistent with EGFR activation that was found in the gastric mucosa of humans infected with H. pylori. Hence, the balance between apoptosis and proliferation in these cells may be altered in response to injury caused by H. pylori infection, leading to an increased risk of cancer.

Helicobacter pylori infection and the risk of gastric malignancy

OBJECTIVE

This prospective cohort study investigated the impact of Helicobacter pylori infection on the development of various gastric malignancies.

METHODS

We prospectively followed up 1,225 dyspeptic Taiwanese who had nonulcer dyspepsia, gastric ulcers, or duodenal ulcers at enrollment. Among them, 618 (50.4%) had H. pylori infection and 607 (49.6%) did not. Patients underwent endoscopy at enrollment and at 1- to 3-yr intervals thereafter.

RESULTS

During a mean follow-up of 6.3 yr, gastric adenocarcinoma developed in 7 of the 618 H. pylori-infected patients, but in none of the 607 uninfected patients (1.1%vs 0.0%, P= 0.015). The incidence of gastric lymphoma was 0.2% (1/618) and 0% in H. pylori-infected and uninfected patients. Taken together, the development rate of gastric malignancy in H. pylori-infected patients was significantly higher than that in uninfected patients (1.3%vs 0%, P= 0.007). Among H. pylori-infected subjects, the incidence of gastric malignancy was similar between those receiving and not receiving eradication therapy (1.4%vs 1.2%). Multivariate analysis showed that intestinal metaplasia was the only independent factor predicting subsequent development of gastric malignancy in H. pylori-infected subjects with an odds ratio of 4.5 (95% CI 1.1-19.1).

CONCLUSIONS

In this prospective cohort study, all gastric malignancies, including adenocarcinoma and lymphoma, developed in H. pylori-infected patients. The finding implies that H. pylori is a necessary cause of most gastric malignancies. Follow-up for H. pylori-infected patients who have intestinal metaplasia is indicated.

Treatment and dosing of Helicobacter pylori infection: when pharmacology meets clinic

Helicobacter pylori infection is a major cause of diseases located in the upper gastrointestinal tract. Successful eradication of the bacteria may improve H. pylori-related symptomatic complaints in functional dyspepsia, cure peptic ulcer disease and prevent gastric cancer. As vaccines are not available, the search for the optimal drug regimen has dominated the last decade. Today, most countries prefer a 7- to 10-day regimen containing a proton pump inhibitor, clarithromycin and amoxicillin as first-line treatment. An alternative (or second-line) treatment contains a proton pump inhibitor, bismuth, tetracycline and metronidazole. This review also highlights the impact of new drugs, new drug combinations, and their optimal dosing required to maximise clinical outcome.

Interleukin-1beta gene (IL-1B) and interleukin 1 receptor antagonist gene (IL-1RN) polymorphisms and gastric cancer risk in an Omani Arab population

BACKGROUND

Gastric cancer (GC) is the most common malignancy in Oman. Interleukin-1beta gene (IL-1B) and interleukin-1 receptor antagonist gene (IL-1RN) polymorphisms have been associated with increased GC risk. No previous studies have examined their role in an Arab population. We tested the associations between polymorphisms of IL1B at positions -31, -511, and +3954 and the IL-1RN polymorphism [variable number of tandem repeats (VNTR) and TC polymorphism at the -2018 position] and GC in Omani Arab patients.

METHODS

Genomic DNA was extracted from peripheral blood of 245 control subjects and 118 gastric cancer patients. The DNA samples were analyzed using the TaqMan allelic discrimination test for IL-1B -31, -511, and +3954 polymorphisms and IL-1RN -2018 polymorphism. The VNTR of IL-1RN was genotyped using the polymerase chain reaction followed by agarose gel electrophoresis.

RESULTS

There was an association between the presence of IL-1RN*2 allele and gastric cancer [odds ratio (OR) = 2.2, 95% confidence interval (CI) = 1.0-3.3, P = 0.04). The GC risk further increased to OR = 3.5 (95% CI = 1.0-11.9) in Helicobacter pylori-positive patients. No association was found between any of the other polymorphisms studied and GC.

CONCLUSION

IL-1RN polymorphism increased the risk of GC in an Omani Arab population, consistent with previous reports. In contrast, the IL-1B -31 polymorphism was not associated with an increased GC risk. These findings underscore the role of cytokine gene polymorphisms in the development of GC and further support the ethnic differences in the effect of IL-1B polymorphism on GC carcinogenesis.

Significant association between PTPN11 polymorphism and gastric atrophy among Japanese Brazilians

BACKGROUND

Helicobacter pylori, especially the cytotoxin-associated antigen A (cagA)-positive strains, plays a crucial role in the development of gastric atrophy and gastric cancer. CagA delivered into gastric epithelial cells combines with src homology 2 domain-containing protein tyrosine phosphatase-2 (SHP-2), possibly leading to atrophy/cancer. Our previous study found that a single-nucleotide polymorphism (SNP; IMS-JST057927) of the PTPN11 gene encoding SHP-2, was associated with gastric atrophy among H. pylori-seropositive subjects. This study aimed to examine the reproducibility of the association among Japanese residing in a different circumstance.

METHODS

The subjects were 918 healthy adult Japanese Brazilians from four different areas in Brazil. Blood was sampled from March to May 2001. The target SNP in intron 3 of PTPN11 was genotyped by polymerase chain reaction with confronting two-pair primers (PCR-CTPP). Gastric atrophy was evaluated with serum pepsinogens (PGs); PG I, less than 70 ng/dl and PG I/II ratio, less than 3.

RESULTS

The genotype frequency of PTPN11 was in Hardy-Weinberg equilibrium: 65.5% for G/G, 30.4% for G/A, and 4.1% for A/A. The PTPN11 polymorphism had no significant association with H. pylori seropositivity. Among the H. pylori-seropositive subjects, the odds ratios (ORs) of gastric atrophy were 0.93 (95% confidence interval [CI], 0.59-1.47) for the G/A genotype and 0.31 (95% CI, 0.10-0.95) for the A/A genotype, compared with the G/G genotype.

CONCLUSIONS

The present study reproduced the significant association between the A/A genotype and reduced risk of gastric atrophy among Japanese outside Japan. According to the Japan Single Nucleotide Polymorphisms (JSNP) database (db)SNP data, the G allele is very frequent among Japanese and rare in Caucasians. This fact may partly explain the distribution of gastric atrophy/cancer in the world.

Polymorphisms in inflammation-related genes and risk of gastric cancer (Finland)

Helicobacter pylori infection is an important risk factor for gastric cancer, but <3% of carriers of this organism will ever develop gastric cancer. Since inflammation plays a significant role in gastric carcinogenesis, it has been suggested that polymorphisms in genes involved in inflammatory response may partly explain why only a subgroup of patients infected with H. pylori develop gastric cancer. We compared relative frequencies of 17 single nucleotide polymorphisms (SNPs) in eight inflammation-related genes between 112 gastric cancer patients and 208 controls. Cases and controls were selected from a large cohort of Finnish male smokers who were recruited into the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study. The studied SNPs were IL-1A (-889 C/T), IL-1B (-511 C/T and -31 T/C), IL-6 (-174 G/C and -597 G/A), IL-8 (-251 T/A, +396 T/G and +781 C/T), IL-8RA (Ex2 +860 G/C), IL-8RB (Exon 3 +1235 T/C, Exon 3 +811 C/T, and Exon 3 +1010 G/A), IL-10 (-819 C/T, -592 C/A, -1082 A/G), and TNF A (-308 G/A, -238 G/A). We found no statistically significant association between any of these SNPs, or the number of pro-inflammatory polymorphisms, with risk of gastric cancer. Our results do not support the hypothesis that polymorphisms in genes involved in the inflammatory response confer differences in gastric cancer risk among different individuals.

Erythrocyte Lewis (A+B-) host phenotype is a factor with familial clustering for increased risk of Helicobacter pylori-related non-cardiac gastric cancer

BACKGROUND

The purpose of the present study was to test whether host erythrocyte Lewis phenotypes correlated with the risk of gastric cancers. Because of the association of gastric cancer with familial clustering, cancer relatives were investigated as to whether they had unique distribution of Lewis phenotypes.

METHODS

The study prospectively enrolled 74 Helicobacter pylori-positive gastric cancer patients and 100 H. pylori-positive duodenal ulcer patients to serve as non-cancer controls after panendoscopy. In addition, 433 family members from the 74 index cancer and 100 non-cancer control patients were enrolled. All enrolled cases were checked for their H. pylori status and erythrocyte Lewis phenotypes, defined as Le(a-b-), Le(a-b+), Le(a+b-), and Le(a+b+) subtypes by the anti-Le(a) and anti-Le(b) monoclonal antibodies.

RESULTS

These H. pylori-infected patients with gastric cancer had a higher rate of Le(a+b-) phenotype and a lower rate of Le(a-b+) phenotype than the non-cancer duodenal ulcer controls (20.3% vs 9%; 51.4% vs 72%, P < 0.05). Among these H. pylori-infected patients, the risk of the patients with Le(a+b-) phenotype having gastric cancer was 3.15-fold higher as compared with those with the Le(a-b+) phenotype (P = 0.02, 95% confidence interval: 1.26-7.87). The offspring and cousins of the cancer patients had a higher rate of Le(a+b-) phenotype as compared to either that of the spouses of cancer index patients or to that of the family members of the non-cancer control (P < 0.05).

CONCLUSION

Le(a+b-) phenotype of the H. pylori-infected host could be a risk factor (with familial clustering) for gastric carcinogenesis.

Causal role of Helicobacter pylori infection in gastric cancer

Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori (H pylori) is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of H pylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.

Association of interleukin-1beta gene polymorphisms with precancerous gastric lesions in African Americans and Caucasians

OBJECTIVE

Interleukin-1beta plays an important role in inflammation and gastric physiology. Polymorphisms of the IL1B gene have been associated with gastric atrophy and increased cancer risk, especially in Helicobacter pylori-infected subjects. The aim of this study was to evaluate the relationship between IL1B and IL1 receptor antagonist gene polymorphisms and the risk of multifocal atrophic gastritis in African Americans and Caucasians.

METHODS

Genomic DNA was extracted from gastric biopsies of 269 adult outpatients (172 African Americans and 97 Caucasians) undergoing diagnostic upper gastrointestinal endoscopy. Histological diagnosis was evaluated according to the updated Sydney System and H. pylori status was assessed by Steiner silver stain. Polymorphisms of the IL1B gene (-511, -31, and +3954) and the IL1 receptor antagonist were investigated by PCR-RFLP. Logistic regression models were used to identify variables associated with multifocal atrophic gastritis in terms of odds ratios and 95% confidence intervals.

RESULTS

Considering subjects with normal histology and nonatrophic gastritis as controls, a significant association was found between IL1B+3954T carrier and multiatrophic gastritis (OR 2.23, 95% CI 1.28, 3.88). Analyses stratified by ethnic group demonstrated similar associations in both African Americans (OR 2.23, 95% CI 1.14, 4.37) and Caucasians (OR 2.04, 95% CI 0.74, 5.65). A positive but not significant association was found between the allele 2 of the IL1RN and the presence of multifocal atrophic gastritis. The remaining proinflammatory polymorphisms were not associated with this precancerous lesion.

CONCLUSIONS

Our results suggest that the presence of IL1B+3954T allele is a risk marker for multifocal atrophic gastritis in the population studied.

Association between serum pepsinogens and polymorphismof PTPN11 encoding SHP-2 among Helicobacter pylori seropositive Japanese

Helicobacter pylori (H. pylori) plays a crucial role in the development of gastric atrophy and cancer, and cagA-positive strains, which are universal in Japan, increase the risk of these outcomes substantially. The CagA protein is injected from attached H. pylori into gastric epithelial cells and undergoes Src-dependent tyrosine phosphorylation and activation of the eukaryotic phosphatase SHP-2. The CagA/SHP-2 interactions elicit cellular changes that increase the risk of carcinogenesis. We investigated the association of a frequent single nucleotide polymorphism (SNP; JST057927; G-to-A) in the PTPN11 gene that encodes SHP-2 with gastric atrophy and gastric cancer in Japan. Gastric atrophy was assessed by measuring serum pepsinogen I and II levels. The subjects comprised 454 healthy controls (126 males; mean age, 58.4) and 202 gastric cancer cases (134 males and 68 females; mean age, 66.7). All gastric cancer cases and 250 (55%) controls were H. pylori seropositive; 179 (89%) of the gastric cancer cases had gastric atrophy compared to 137 (55%) of the H. pylori seropositive controls (p < 0.001). Among HP seropositive controls compared to the common PTPN11 G/G genotype, the odds ratio of atrophy was nonsignificantly reduced with the G/A genotype (0.70; 95% CI = 0.39-1.25) and significantly reduced with the A/A genotype (0.09; 95% CI = 0.01-0.72). Lower risk for gastric atrophy had a gene-dose association with the A allele (p = 0.01, trend test). There was a clear deficiency of the A/A genotype in those with atrophy compared to those without (1 subject in the gastric atrophy group vs. 8 in the group without). Cancer cases differed from controls in frequencies of PTPN11 G/A genotype only because of a higher prevalence of atrophy among the cancer cases. The G/A SNP in the PTPN11 gene appears to be a risk factor for gastric atrophy in subjects infected with cagA-positive H. pylori. This may explain why only a proportion of CagA-positive individuals develop gastric atrophy and gastric cancer, even though infection with cagA strains is universal in Asian countries such as Japan. The functional consequences of the G/A polymorphism remain to be elucidated.

A candidate gene approach of immune mediators effecting the susceptibility to and severity of upper gastrointestinal tract diseases in relation to Helicobacter pylori and Epstein-Barr virus infections

This review focuses on immunogenetic aspects of diseases of the upper gastrointestinal tract in which infectious agents may play a role in the aetiopathogenesis, such as Helicobacter pylori, Epstein-Barr virus (EBV) and HIV. Gastric adenocarcinoma is a common cancer all around the world, with declining incidences in Europe and high incidences in Asia and central and south America. Together with gastric atrophy and peptic ulcer disease, gastric adenocarcinoma belongs to the commonest upper gastrointestinal tract diseases. These diseases are multifactorial and factors such as smoking and dietary habits contribute to the pathogenesis. More recently, scientists have turned their eyes on the host. Functional polymorphisms in the genes regulating the host immune system may contribute to the susceptibility to and progression of disease. In multifactorial and polygenetic diseases, candidate gene studies of single nucleotide polymorphisms (SNPs) detect small to moderate relative risks. Unfortunately, only a few functional SNPs have been identified. The candidate gene approach can be seen as a useful first step in exploring causal pathways between genetic determinants and complex diseases such as those mentioned above. To date, little is known about the immunogenetics of upper gastrointestinal tract diseases. We review the literature on H. pylori, EBV and gene polymorphisms that affect key immune mediators influencing the pathogenesis of the inflammatory response, such as the genes that code for the IL-1 family, TNF-alpha, lymphotoxin alpha, and IL-10. IL-1, IL-10, lymphotoxin alpha and TNF-alpha polymorphisms increase the risk of upper gastrointestinal pathogenesis in H. pylori-infected patients, whereas IL-1 and TNF-alpha polymorphisms confer risk in EBV-infected patients.

Multidisciplinary approach to understand the pathogenesis of gastric cancer

Gastric carcinoma remains a common disease worldwide with a dismal prognosis. Therefore, it represents a very important health problem. It occurs with a high incidence in Asia and is one of the leading causes of cancer death in the world. Although the incidence and mortality of gastric carcinoma are decreasing in many countries, gastric cancer still represents the second most frequent malignancies in the world and the fourth in Europe. The 5-year survival rate of gastric carcinoma is low. The etiology and pathogenesis are not yet fully known. The study of gastric cancer is important in clinical medicine as well as in public health. Over the past 15 years, integrated research in molecular pathology has clarified the details of genetic and epigenetic abnormalities of cancer-related genes in the course of the development and progression of gastric cancer. Gastric cancer, as all cancers, is the end result of the interplay of many risk factors as well as protective factors. Although epidemiological evidence indicates that environmental factors play a major role in gastric carcinogenesis, the role of immunological, genetic, and immunogenetic factors are thought to contribute to the pathogenesis of gastric carcinoma. Among the environmental factors, diet and Helicobacter pylori are more amenable to intervention aimed at the prevention of gastric cancer. The aim of the present paper is to review and include the most recent published evidence to demonstrate that only a multidisciplinary approach will lead to the advancement of the pathogenesis and prevention of gastric cancer. On the immunogenetic research it is clear that evidence is accumulating to suggest that a genetic profile favoring the proinflammatory response increases the risk of gastric carcinoma.

Gastric cancer: new genetic developments

Gastric cancer's (GC) incidence shows large geographic differences worldwide with the lowest rates occurring in most Western industrialized countries including the United States and the United Kingdom; in contrast, relatively high rates of GC occur in Japan, Korea, China, and South America, particularly Chile. The Laurén classification system classifies GC under two major histopathological variants: 1) an intestinal type and 2) a diffuse type. The intestinal type is more common in the general population, more likely to be sporadic and related to environmental factors such as diet, particularly salted fish and meat as well as smoked foods, cigarette smoking, and alcohol use. It exhibits components of glandular, solid, or intestinal architecture, as well as tubular structures. On the other hand, the diffuse type is more likely to have a primary genetic etiology, a subset of which, known as hereditary diffuse gastric cancer (HDGC), is due to the E-cadherin (CDH1) germline mutation. The diffuse type pathology is characterized by poorly cohesive clusters of cells which infiltrate the gastric wall, leading to its widespread thickening and rigidity of the gastric wall, known as linitis plastica. Helicobacter pylori infection is associated with risk for both the intestinal and diffuse varieties of gastric cancer. Germline truncating mutations of the CDH1 gene, which codes for the E-cadherin protein, were initially identified in three Maori families from New Zealand that were predisposed to diffuse GC. Since then, similar mutations have been described in more than 40 additional HDGC families of diverse ethnic backgrounds. It is noteworthy that two-thirds of HDGC families reported to date have proved negative for the CDH1 germline mutation. A number of candidate genes have been identified through analysis of the molecular biology of E-cadherin. Patients with evidence of the CDH1 germline mutation in the context of a family history of HDGC must be considered as candidates for prophylactic gastrectomy, given the extreme difficulty in its early diagnosis and its exceedingly poor prognosis when there is regional or distant spread. Specifically, the E-cadherin cytoplasmic tail interacts with catenins, assembling the cell-adhesion complex involved with E-cadherin mediated cell:cell adhesion. Beta-catenin and gamma-catenin compete for the same binding site on the E-cadherin cytoplasmic tail, directly linking the adhesion complex to the cytoskeleton through alpha-catenin. Beta-catenin gene (CTNNB1) mutations have been described predominantly in intestinal-type gastric cancers and CTNNB1 gene amplification and overexpression have recently been described in a mixed-type gastric cancer. This paper reviews the genetics of both intestinal and diffuse types of gastric carcinoma, their differential diagnosis, molecular genetics, pathology, and, when known, their mode of genetic transmission within families.

Association of the myeloperoxidase-468G→A polymorphism with gastric inflammation and duodenal ulcer risk

AIM: To elucidate the relations between the myeloperoxidase^-468G→A polymorphism and the development of duodenal ulcer (DU), and to investigate the impacts of this host genetic polymorphism on the histopathological features of Helicobacter pylori (H pylori)-related gastritis.

METHODS: In a case-control study of 115 consecutive DU patients and 182 controls, the myeloperoxidase^-468G→A polymorphism was genotyped. Additionally, gastric mucosal changes were examined according to the updated Sydney System.

RESULTS: The two study groups differed in the distributions of myeloperoxidase genotypes (P = 0.008). All six individuals carrying myeloperoxidase A/A genotypes were in the DU group. The carriage of myeloperoxidase allele A and H pylori infection were associated with an increased risk of DU with odds ratios (OR) of 2.3 and 5.8, respectively. The combined risk of the carriage of myeloperoxidase allele A and H pylori infection for DU was 8.7 (95% CI, 3.5-21.8). In the H pylori-infected individuals, allele A carriers displayed higher bacterial density scores (P = 0.04) in the antrum than did non-carriers.

CONCLUSION: This work verifies for the first time the association of myeloperoxidase^-468G→A polymorphism with antral H pylori density and DU disease. The mechanisms underlying this genetic polymorphism in developing DU disease merit further investigations.

Allele 2 of the interleukin-1 receptor antagonist gene is associated with early gastric cancer

PURPOSE

In advanced gastric cancer (tumor stages T2-T4), associations with polymorphisms of the interleukin-1 (IL-1) gene cluster have been made. In early-stage gastric cancer, which we defined as adenocarcinoma confined to the mucosa or submucosa (stage T1), the role of host genetic susceptibility remains to be determined.

PATIENTS AND METHODS

Eighty-eight patients with early-stage gastric cancer (stage T1, 77 positive for Helicobacter pylori) and 145 controls were genotyped for polymorphisms in the IL-1 gene cluster and the tumor necrosis factor alpha (TNF-A) gene. Statistical analysis was performed using the chi2 test and the Fisher's exact test, respectively.

RESULTS

The homozygous genotype IL-1RN*2/2 of the IL-RN gene was strongly associated with early-stage gastric cancer (P < .0001), whereas further associations with the IL-1 gene cluster were not observed. A weak association of the TNF-A-308A allele with the diffuse type of early-stage gastric cancer, and an association with a composite of two or three proinflammatory polymorphisms, which predispose to increased production of the proinflammatory cytokines IL-1beta and TNF-alpha, could also be demonstrated.

CONCLUSION

The genotype IL-1RN*2/2 seems to be associated with early-stage gastric cancer. As opposed to advanced-stage gastric cancer, further proinflammatory cytokine polymorphisms were not associated independently, but might act in combination and mirror early steps of gastric carcinogenesis in hosts colonized by Helicobacter pylori. However, these findings await confirmation in future trials and should be underscored by gene expression studies.

The interleukin-1 RN polymorphism and Helicobacter pylori infection in the development of duodenal ulcer

BACKGROUND

The host genetic factors that determine the clinical outcomes for Helicobacter pylori-infected individuals remain unclear.

AIMS

To elucidate the relations among interleukin-1 locus polymorphisms, and H. pylori infection in the development of duodenal ulcers.

MATERIALS AND METHODS

In a case-control study involving 168 control subjects and 147 patients with duodenal ulcer, biallelic polymorphisms of two interleukin-1 loci, IL-1B(-511) and IL-1B(+3954), as well as the penta-allelic variable number of tandem repeats of interleukin-1 receptor antagonist IL-1RN, were genotyped, and the H. pylori states of controls and patients were examined.

RESULTS

Helicobacter pylori infection, male gender and the carriage of IL-1RN*2 independently increased the risk of duodenal ulcer with odds ratios of 6.4 (95% confidence interval, 3.7-11.0), 1.9 (95% confidence interval, 1.1-3.4) and 2.7 (95% confidence interval, 1.1-6.8), respectively. Statistical analysis revealed an interaction between IL-1RN*2 and H. pylori infection with the duodenal ulcer risk conferred by the H. pylori infection substantially increased (odds ratios, 22.6; 95% confidence interval, 5.9-86.5) by the carriage of IL-1RN*2. In addition, a synergistic interaction between IL-1RN*2 and blood group O existed. The combined risk of H. pylori infection, the carriage of IL-1RN*2 and blood group O for duodenal ulcer was 27.5 (95% confidence interval, 3.1-243.6).

CONCLUSIONS

This work is the first to verify IL-1RN*2 as an independent factor that governs the development of duodenal ulcers. Our data indicate that H. pylori infection and IL-1RN*2 synergistically determine susceptibility to duodenal ulcer. The blood group phenotype is possibly a crucial determinant for the outcome of the impact of an interleukin-1 locus polymorphism on H. pylori-infected individuals.

Relationship between bcl-2 gene expression and cell proliferation and apoptosis in human gastric carcinomas

AIM: To investigate the relationship between bcl -2 gene expression levels in human gastric carcinoma and the frequency of tumor cell proliferation activity and apoptosis.

METHODS: In situ hybridization and immunohistochemistry methods were used to study the frequencies of expressions of bcl -2 gene and nuclear antigen of proliferating cells (PCNA) in 53 gastric carcinomas. Meanwhile, an in situ apoptotic cell detection (TUNEL method) was adopted to compare the number of apoptotic cells and PCNA with the Bcl -2 protein expression in each case.

RESULTS: Of the 53 gastric carcinomas, 41 and 43 expressed bcl -2 mRNA and Bcl -2 protein, which were count for 77.4% and 81.1% respectively. There was no significant difference between the positive rates obtained by these two methods. The apoptotic index of gastric carcinomas negatively related to PCNA index (r = -0.993, P < 0.01). With the increase of Bcl-2 protein expression , the cell proliferating activity increased but the apoptosis decreased in the tumor cells. Significant difference of cell proliferation and apoptosis existed between +++ group and ++ group of Bcl -2 protein expression (t = 2.552, 2.699, P < 0.05) as well as between the former two groups and the -, + group (t = 4.487, 3.975, 2.807, 3.094, 4.885, 5.816, 3.404, 3.895, P < 0.01) respectively.

CONCLUSION: The overexpression of bcl -2 gene inhibits cell apoptosis and excessive cell proliferation in the development and progress of gastric carcinomas.

A novel genetic polymorphism of inducible nitric oxide synthase is associated with an increased risk of gastric cancer

AIM

Inducible nitric oxide synthase (iNOS) plays a central role in the pathway of reactive oxygen and nitrogen species metabolism when Helicobacter pylori (H pylori) infection occurs in humans. iNOS Ser(608)Leu allele, a novel genetic polymorphism (C/T) occurring within exon 16 of the iNOS reductase domain, may have a dramatic effect on the enzymatic activity. The aim of this study was to determine whether iNOS C/T polymorphism was associated with increased susceptibility to gastric cancer.

METHODS

We conducted a population based case-control study in a high gastric cancer incidence area, Yangzhong, China. Questionnaires from 93 patients with intestinal type gastric cancer (IGC), 50 with gastric cardia cancer (GCC) and 246 healthy controls were obtained between 1997 and 1998, and iNOS genotyping was carried out. Odds ratios (ORs), interaction index (gamma), and 95% confidence intervals for the combined effects of iNOS genotype and H pylori infection, cigarette smoking or alcohol drinking were estimated.

RESULTS

The frequency of (CT+TT) genotypes was higher in cases than in control group (24.48% vs 23.17%), but the difference was not statistically significant. After adjusting for age and gender, past cigarette smokers with (CT+TT) genotypes had a significantly increased risk of IGC (OR = 3.62, 95% CI: 1.23-10.64), while past alcohol drinkers with (CT+TT) genotypes had a significantly increased risk of GCC (OR = 3.33, 95% CI: 1.14-9.67). H pylori CagA negative subjects with (CT+TT) genotypes had a significantly increased risk of both IGC and GCC (OR = 2.19 and 3.52, respectively).

CONCLUSION

iNOS Ser(608)Leu allele may be a potential determinant of susceptibility to cigarette -alcohol induced gastric cancer, but larger studies are needed to confirm the observations.

Interleukin-1B gene promoter variants are associated with an increased risk of gastric cancer in a Chinese population

Studies suggest that IL-1beta (encoded by IL-1B gene) is a pro-inflammatory cytokine and potent inhibitor of gastric acid secretion, which is proposed as a key determinant in gastric carcinogenesis. Two potentially functional polymorphisms (C-31T and T-511C) in the IL-1B promoter were suggested to be correlated with alteration of Helicobacter pylori infection and IL-1beta expression and therefore may be associated with risk of gastric cancer. To test the hypothesis that these two polymorphisms are associated with gastric cancer risk, we performed a case-control study of 280 histologically confirmed gastric cancer patients and 258 age, sex frequency-matched cancer-free controls in a Chinese population. Multivariate logistic regression analyses revealed that the risks (adjusted odds ratio [OR] and 95% confidence interval [CI]) associated with the IL-1B variant genotypes were 1.64 (95% CI, 1.01-2.66) for -31TT and 1.52 (95% CI, 0.91-2.54) for -511CC, respectively, compared with their wild-type homozygotes. The risks were significantly more evident in individuals with H. pylori infection (adjusted OR, 2.14; 95% CI, 1.13-4.06 for -31TT; adjusted OR, 2.00; 95% CI, 1.02-3.89 for -511CC), which was consistent with the biological effects of IL-1beta. When we used the haplotype analyses and assumed the IL-1B -31T and -511C as risk alleles, no synergistic effect was found between these two loci. These findings indicate that these two IL-1B promoter variants may contribute to the risk of developing gastric cancer in the Chinese population, especially in individuals with H. pylori infection.

Risks of interleukin-1 genetic polymorphisms and Helicobacter pylori infection in the development of gastric cancer

BACKGROUND

The host genetic factors that determine the clinical outcomes of Helicobacter pylori-infected individuals remain unclear.

AIM

To elucidate the risks of host interleukin-1 (IL-1) genetic polymorphisms and H. pylori infection in the development of gastric cancer.

METHODS

In a case-control study of 164 controls and 142 patients with gastric cancer, the IL-1B-511 biallelic polymorphisms and the IL-1RN penta-allelic variable number of tandem repeats were genotyped.

RESULTS

The carriage of IL-1RN*2, male gender, old age and H. pylori infection independently increased the risk of gastric cancer, with odds ratios of 3.3 [95% confidence interval (CI), 1.4-7.7], 2.1 (95% CI, 1.2-3.8), 5.3 (95% CI, 3.1-9.0) and 2.2 (95% CI, 1.3-3.8), respectively. H. pylori-infected individuals who were carriers of IL-1RN*2 showed increased risks of both intestinal and diffuse types of gastric cancer, with odds ratios of 11.0 and 8.7, respectively. In addition, these individuals also had a higher score of intestinal metaplasia in the corpus than did uninfected non-carriers.

CONCLUSIONS

This study is the first to verify IL-1RN*2 as an independent factor governing the development of gastric cancer in Asian individuals. A combination of H. pylori testing and host genotyping may target the eradication of H. pylori to high-risk individuals.

Effect of Helicobacter pylori infection on bax protein expression in patients with gastric precancerous lesions

AIM: To evaluate the effect of Helicobacter pylori (H. pylori) infection on bax protein expression, and explore the role of H. pylori in the development of gastric carcinoma.

METHODS: H. pylori was examined by rapid urease test and Warthin-Starry method, and bax protein was examined by immunohistochemical staining in 72 patients with pre-malignant lesions.

RESULTS: Bax protein was expressed with different degree in intestinal metaplasia and gastric dysplasia, its positive rate being 63.9%. The positive rate of Bax protein expression in H. pylori-positive gastric precancerous lesions (72.3%) was significantly higher than that in H. pylori-negative gastric precancerous lesions (48.0%, x² = 4.191, P < 0.05). H. pylori infection was correlated well with the expression of Bax protein in gastric precancerous lesions(r = 0.978, P < 0.01). After eradication of H. pylori, the positive rate of bax protein expression was significantly decreased in H. pylori-positive gastric precancerous lesions(x² = 5.506, P < 0.05). In the persistent H. pylori infected patients, the positive rate of Bax protein expression was not changed.

CONCLUSION: H. pylori is involved in the expression of Bax gene. H. pylori infection increases the expression of Bax protein, this may be one of the mechanisms of H. pylori infection in the induction of gastric epithelial cell apoptosis. H. pylori might act as a tumor promoter in the genesis of gastric carcinoma. Eradication of H. pylori could inhibit the formation and development of gastric carcinoma.

Genetic polymorphisms of XRCC1 and risk of gastric cancer

Coding polymorphisms of the DNA repair gene XRCC1 have been shown to affect the DNA repair capacity and to be associated with genetic susceptibility to carcinogenesis. In our association study between three amino acid substitution polymorphisms of XRCC1 (Arg194Trp, Arg280His, and Arg399Gln) and the risk of gastric cancer in the Korean population, none of the polymorphisms were associated with increased risk of gastric cancer. We then extended our study by building haplotypes of the entire XRCC1 gene with six single neuclotide polymorphisms (SNPs), including two novel polymorphisms at the 5'-flanking sequence. When haplotype frequencies in cases and controls and haplotype-specific odds ratios (ORs) were estimated, haplotype A (194Trp, 280Arg, and 399Arg) was associated with significant reduction in gastric cancer risk (adjusted OR=0.65, 95% CI=0.43-0.99) whereas haplotype D (194Arg, 280Arg, and 399Arg alleles) was a risk type for gastric cancer (adjusted OR=1.57, 95% CI=0.93-2.65). The association with the haplotype D was more pronounced in the cancers of antrum (adjusted OR=2.06, 95% CI=1.03-2.00). Our results suggest that the haplotype estimation is advantageous for association studies of such a complex disease as gastric cancer.

Genetic susceptibility and gastric cancer risk

The aim of the present paper is to review and evaluate, in a comprehensive manner, the most recent published evidence on the contribution of genetic susceptibility to gastric cancer risk in humans. We have identified all studies available in MEDLINE published up to October 2001. Only studies carried out in humans and comparing gastric cancer cases with at least 1 standard control group were included in the analysis. We were able to find 31 articles based on 25 case-control studies carried out in Caucasian, Asian and African populations. Most of the studies assess the effect of genes involved in detoxifying pathways (n = 12) and inflammatory responses (n = 7). The most widely studied is the GSTM1 null polymorphism. Only a very few studies have evaluated the risk of gastric cancer associated with genes acting on mucosa protection, oxidative damage and DNA repair. The most consistent results are the increased gastric cancer risk associated with IL1B and NAT1 variants, which may account for up to 48% of attributable risk of gastric cancer. Only polymorphisms at HLA-DQ, TNF and CYP2E genes may confer some protective effect against gastric cancer. The most important limitations that preclude definitive conclusions are (i) the lack of appropriate control of potential sources of bias (only 5 population-based studies have been published so far); (ii) the low number of cases analyzed (14 studies included fewer than 99 cases); and (iii) the low number of studies (n = 3) offering concomitant analysis of genetic susceptibility and exposure to relevant cofactors (Helicobacter pylori infection, diet and smoking). We conclude that the scientific data on the role of genetic factors in gastric cancer risk are promising. The lack of association reported so far should be considered with caution due to significant limitations in study design. Cohort studies taking into account simultaneously the different genetic and environmental factors potentially involved in gastric tumorigenesis are needed to ascertain not only the relative contribution of these factors to tumor development but also the contribution of their putative interactions.

Interleukin 1beta polymorphisms increase risk of hypochlorhydria and atrophic gastritis and reduce risk of duodenal ulcer recurrence in Japan

BACKGROUND & AIMS

Interleukin-1 beta (IL-1beta) polymorphisms are associated with increased risk of gastric cancer in whites. This study aimed to examine effects of these polymorphisms on gastric acid secretion, atrophic gastritis, and risk of peptic ulcer in Japan.

METHODS

We determined IL-1B-511/-31 and IL-1RN genotypes and measured gastric juice pH, serum pepsinogen (PG) I and II levels, and gastritis and atrophy scores in Helicobacter pylori-positive patients with gastritis only, gastric ulcers, or duodenal ulcers (DUs), and H. pylori-negative controls.

RESULTS

In the H. pylori-positive group, subjects with the proinflammatory IL-1B-511 T/T genotype had the highest atrophy and gastritis scores, the highest median gastric juice pH, and the lowest median serum PG I/PG II ratios. Although gastric juice pH significantly increased and serum PG I and PG I/PG II ratios significantly decreased in the IL-1B-511 T/T genotype group with age, no such age-dependent changes were observed in the C/C genotype group. Changes in the C/T genotype group were intermediate. In the H. pylori-negative group, the IL-1 loci had no effect on any of the physiologic or morphologic parameters. Carriage of IL-1RN allele 2 significantly protected against DU disease while the IL-1B-511 T/T genotype significantly protected against DU recurrence in patients older than 60 years.

CONCLUSIONS

Proinflammatory IL-1beta polymorphisms are associated with hypochlorhydria and atrophic gastritis in Japan. The effects are dependent on H. pylori infection and become more significant with advancing age. This may explain the high incidence of gastric cancer in Japan and also the age-dependent decrease in DU recurrence in infected subjects.