Association of interleukin-1B and interleukin-1RN polymorphisms with gastric cancer in a high-risk population of Costa Rica

The pertinence of gastric cancer and interleukin 10-819 single nucleotide polymorphisms: a meta-analysis and systematic review

PURPOSE

Cytokines regulate the interaction between the immune system and malignant tumors. Among them, interleukin-10 (IL-10) is a multifunctional anti-inflammatory cytokine mainly produced by immune cells. The correlation between gastric cancer and T/C single nucleotide polymorphism (SNP) of interleukin-10 (IL-10) promoter-819(rs1800871)was opaque and remained to be determined. We aim to explore the pertinence of gastric cancer and SNP of interleukin 10-819 by meta-analysis via five statistical models.

METHODS

Databases including PubMed, Cochrane Library, Embase, the Scopus, and Google Scholars were comprehensively retrieved for the eligible studies on the related topic from inception to March 2022. Odds ratios (ORs) were generated for dichotomous variants by meta-analysis in each model via STATA 17.0 MP. The statistical models comprised recessive model, over-dominant model, allele model, co-dominant model and dominant model. Subgroup analysis was performed to investigate the difference across races as well as the source of heterogeneity if necessary.

RESULTS

Eventually a total of 15 articles reporting 7779 patients were enrolled in our study. There were 2383 patients and 5396 controls, collectively. There was no correlation between gastric cancer and IL-10 819 in recessive model, co-dominant model or dominant model, and subgroup analysis showed that Asian, Latin American and Caucasian had no correlation with the risk of gastric cancer. In the allelic model, there was significant correlation between gastric cancer and IL-10 819 (OR = 3.96%, 95%CI: 3.28 to 3.78). In the over-dominant model, there is no correlation between gastric cancer and IL-10 819, but subgroup analysis uncovered significant vulnerability of Asian people with regard to gastric cancer.

CONCLUSIONS

In our study, both Asians, Latin Americans, and Europeans showed an increased risk of gastric cancer in the allelic model, whereas only Asians showed significant susceptibility in the super dominant model. Of course, more large cohort studies are needed to confirm our results.

Role of IL-1β rs1143634 (+3954C>T) polymorphism in cancer risk: an updated meta-analysis and trial sequential analysis

OBJECTIVE

Oxidative stress caused by the pro-inflammatory cytokine interleukin (IL)-1β has been widely investigated for cancer risk. In this study, we focused on the role of IL-1β rs1143634 polymorphism to reveal its impact on cancer development.

METHODS

Related studies with fixed inclusion criteria were selected from electronic databases to May 2021. This meta-analysis was performed with odds ratios and 95% confidence intervals. Heterogeneity, publication bias and sensitivity analyses were also conducted. Trial sequential analysis (TSA) and in-silico gene expression analysis were performed.

RESULTS

Forty-four case-control studies involving 18,645 patients with cancer and 22,882 controls were included. We observed a significant association of this single nucleotide polymorphism with overall cancer risk in the codominant model 3 (1.13-fold), recessive model (1.14-fold) and allelic model (1.08-fold). Subgroup analysis revealed that rs1143634 elevated the risk of gastric cancer, breast cancer and multiple myeloma. In addition, Asian and mixed populations and hospital-based controls had a significantly higher risk of cancer development. TSA confirmed our findings.

CONCLUSION

Our meta-analysis revealed that the presence of IL-1β rs1143634 polymorphism increases the risk of cancer development. Among polymorphism carriers, the Asian population has a higher risk than other ethnic populations.This meta-analysis was registered retrospectively at INPLASY (https://inplasy.com/, INPLASY2021100044).

Association of Interleukin-10 Polymorphisms with Susceptibility to Colorectal Cancer and Gastric Cancer: an Updated Meta-analysis Based on 106 Studies

BACKGROUND

The purpose of this study was to explore the association of IL-10 polymorphisms with susceptibility to colorectal cancer (CRC) and gastric cancer (GC).

METHODS

PubMed, Scopus, Embase, SciELO, medRxiv, China Biology Medicine Disc, DeepDyve, CNKI, and Web of Science were used to identify all relevant articles published up to 20th June 2021, without any restrictions on ethnicity. Summary odds ratios (ORs) with 95% confidence intervals (CIs) were used to determine the strength of the associations.

RESULTS

A total of 106 case-control studies were included. For CRC, 15 studies with 2772 cases and 3719 controls on -1082A/G, 11 studies with 3259 cases and 4992 controls on -592C/A, and 3 studies with 477 cases and 544 controls on -819 T/C were selected. For GC, 31 studies with 6229 cases and 8666 controls on -1082A/G, 27 studies with 5457 cases and 8381 controls on -592C/A, and 19 studies with 3556 cases and 6218 controls on -819 T/C were included. Pooled data showed a significant association between IL-10-819 T/C polymorphism and CRC susceptibility in overall population, but not for IL-10-1082A/G and -592C/A polymorphisms. However, IL-10-592C/A polymorphism was associated with CRC risk in Asians. A significant association of IL-10-1082A/G polymorphism with the GC risk was found. In the ethnicity subgroup analysis, a significant association was found between IL-10-1082A/G polymorphism and GC risk among Asians. The IL-10-819 T/C was not associated with GC risk in overall population and by ethnicity.

CONCLUSIONS

Our pooled data show a significant association of IL-10-819 T/C and IL-10-1082A/G polymorphisms with CRC and GC in overall population, respectively. However, other factors may influence these associations, and large-scale studies with adequate methodological quality are necessary to confirm the impact on CRC and GC risk.

The TNF-A-857*T Polymorphism is Associated with Gastric Adenocarcinoma Risk in a Costa Rican Population

BACKGROUND

Costa Rica is ranked as one of the countries with highest incidence of gastric cancer worldwide. Previous studies in Costa Rican populations have revealed associations between gastric cancer risk and several cytokine polymorphisms that seem to play a role in the regulation of the expression of these proteins. In this study, we assessed associations of the polymorphisms IL-6-174 G/C, IFNGR1-56 C/T, IL-8-251 T/A and TNF-A (-857 C/T, -308 A/G) with gastric pathologies in a high-risk population of Latin America.

METHODS

DNA samples of 47 patients with gastric adenocarcinoma, 53 with chronic gastritis, 56 with duodenal ulcer and 94 healthy controls, were genotyped for the five mentioned SNPs. All participants were ≥50-years-old. Genotyping was performed by PCR-RFLP and 5'-nuclease PCR assay. H. pylori infection, CagA status, pepsinogen (PG) I and II blood levels were determined by ELISA. Logistic regression analysis was used to determine possible associations of the polymorphisms with cancer, gastritis and duodenal ulcer, and linear regression analysis to determine associations with blood PG levels.

RESULTS

A total of 86.6% of the population was positive for H. pylori; of them, 51.6% was CagA+. Patients with the TNF-A-857*T allele had an increased risk for gastritis (OR: 3.67, p = 0.015) and gastric adenocarcinoma (OR:6.15, p = 0.001). Associations between other polymorphisms and gastric diseases, or PG levels, were not found.

CONCLUSIONS

Our results indicate that the TNF-A-857*T SNP is among the risk factors associated with the risk of gastric cancer in Costa Rica.

Gastric Cancer in the Era of Immune Checkpoint Blockade

Gastric cancer (GC) is one of the most important malignancies worldwide because of its high incidence and mortality. The very low survival rates are mainly related to late diagnosis and limited treatment options. GC is the final clinical outcome of a stepwise process that starts with a chronic and sustained inflammatory reaction mounted in response to Helicobacter pylori infection. The bacterium modulates innate and adaptive immunity presumably as part of the strategies to survive, which favors the creation of an immunosuppressive microenvironment that ultimately facilitates GC progression. T-cell exhaustion, which is characterized by elevated expression of immune checkpoint (IC) proteins, is one of the most salient manifestations of immunosuppressive microenvironments. It has been consistently demonstrated that the tumor-immune microenvironment(TIME)‐exhausted phenotype can be reverted by blocking ICs with monoclonal antibodies. Although these therapies are associated with long-lasting response rates, only a subset of patients derive clinical benefit, which varies according to tumor site. The search for biomarkers to predict the response to IC inhibition is a matter of intense investigation as this may contribute to maximize disease control, reduce side effects, and minimize cost. The approval of pembrolizumab for its use in GC has rocketed immuno-oncology research in this cancer type. In this review, we summarize the current knowledge centered around the immune contexture and recent findings in connection with IC inhibition in GC.

Virulence factor genotyping of Helicobacter pylori isolated from Costa Rican dyspeptic patients

BACKGROUND AND AIMS

Costa Rica is one of the countries with the highest incidence and mortality rates for gastric cancer. Helicobacter pylori infection rates are high in the whole country. We have previously shown that H. pylori CagA+ is significantly associated with atrophic gastritis (AG) of the antrum in a dyspeptic population. The aim of this work is to determine if other H. pylori virulence factors (vacA, dupA, oipA, iceA and babA2) are associated with atrophic gastritis (AG) or duodenal ulcer (DU).

METHODS

The presence of virulence genes in Costa Rican H. pylori isolates was analyzed by PCR in 151 cultured strains from patients with dyspeptic symptoms. Endoscopic and histopathological diagnoses were available. Odds-ratio and 95% confidence intervals for AG patients vs. non-atrophic gastritis (NAG) or DU patients vs. no duodenal ulcer (NDU) patients were calculated.

RESULTS

Amongst the studied isolates, 82% had the cagA⁺, 76.2% had the vacA s1m1, 97.0% had the oipA⁺, 21.0% had the icea1, 79.0% had the iceA2, 44.0% had the babA2⁺ and 76.0% the dupA⁺ genotypes. Infection with H pylori cagA⁺, dupA⁺, oipA⁺, iceA, babA2⁺, and vacA s1m1 genotypes was not associated with AG risk. The frequency of the dupA gene was 78.7 and 60.9% in isolates from patients with NDU and DU, respectively, and its presence was significantly associated with decreased risk of duodenal ulcer [odds-ratio: 0.33, p = 0.024, confidence interval 95% (0.11-0.85)].

CONCLUSION

H. pylori dupA genotype is inversely associated with DU risk in this population.

ASSOCIATION OF INTERLEUKIN-10 -592A>C AND -819T>C POLYMORPHISMS WITH GASTRIC CANCER RISK: A SYSTEMATIC REVIEW AND META-ANALYSIS OF 44 CASE-CONTROL STUDIES

INTRODUCTION

A series of studies have evaluated the association between -592A>C and -819T>C polymorphisms in the promoter regions of Interleukin-10 (IL-10) and gastric cancer (GC) risk. However, the results remain inconclusive.

OBJECTIVE

To better understand the association of the polymorphisms with GC risk, we performed a comprehensive meta-analysis.

METHOD

An electronic search was performed of several databases to identify relevant studies up to April 2018.

RESULTS

A total of 44 case-control studies, including 26 studies on IL-10 -592A>C (5,332 cases and 8,272 controls) and 18 studies on IL-10 -819T>C (3,431 cases and 6,109 controls) were selected. Overall, -592A>C polymorphism was associated with the risk of GC under the heterozygote model (OR=1.153, 95% CI=1.020-1.305, p=0.023), but not -819T>C polymorphism. When stratified by ethnicity, significant association was only observed in the Asians under the allele model (OR=1.153, 95% CI=1.007-1.320, p=0.040) and the heterozygote model (OR=1.218, 95% CI=1.076-1.379, p=0.002) for -592A>C.

CONCLUSION

The current meta-analysis results inconsistent with previous meta-analyses; showed that the IL-10 -592A>C polymorphism, but not -819T>C polymorphism, may be contributed to the susceptibility of GC in overall and Asian populations.

Priming the seed: Helicobacter pylori alters epithelial cell invasiveness in early gastric carcinogenesis

Helicobacter pylori (H. pylori) infection is a well-established risk factor for the development of gastric cancer (GC), one of the most common and deadliest neoplasms worldwide. H. pylori infection induces chronic inflammation in the gastric mucosa that, in the absence of treatment, may progress through a series of steps to GC. GC is only one of several clinical outcomes associated with this bacterial infection, which may be at least partially attributed to the high genetic variability of H. pylori. The biological mechanisms underlying how and under what circumstances H. pylori alters normal physiological processes remain enigmatic. A key aspect of carcinogenesis is the acquisition of traits that equip preneoplastic cells with the ability to invade. Accumulating evidence implicates H. pylori in the manipulation of cellular and molecular programs that are crucial for conferring cells with invasive capabilities. We present here an overview of the main findings about the involvement of H. pylori in the acquisition of cell invasive behavior, specifically focusing on the epithelial-to-mesenchymal transition, changes in cell polarity, and deregulation of molecules that control extracellular matrix remodeling.

Association between interleukin-10 -592 A/C polymorphism and gastrointestinal tract cancer risk: A meta-analysis

BACKGROUND

Recent evidence suggests that -592 A/C polymorphism in the interleukin-10 (IL-10) gene may influence risk of gastrointestinal tract cancer; however, individual studies have provided conflicting and inconclusive results. Therefore, this meta-analysis was conducted to assess the association between IL-10 -592 A/C polymorphism and gastrointestinal tract cancer susceptibility.

METHODS

EMBASE, PubMed, Web of Science, and China National Knowledge Infrastructure databases were searched for case-control studies published before 1 May 2017. A total of 36 studies involving 8069 cases and 13,089 controls were included in the present meta-analysis according to the inclusion criteria. The random- or fixed-effect model was utilized to calculate pooled odds ratio (OR) with 95% confidence interval (CI), and to survey the association.

RESULTS

By and large IL-10 -592 A/C (rs1800872) polymorphism was not associated with gastrointestinal cancer risk in five genetic models (A vs. C: OR 1.00; 95% CI 0.93, 1.08; P_OR = 0.960; AA vs. CC: OR 0.98; 95% CI 0.85, 1.14; P_OR = 0.835; CA vs. CC: OR 1.01; 95% CI 0.94, 1.08; P_OR = 0.776; AA+CA vs. CC: OR 1.03; 95% CI 0.94, 1.12; P_OR = 0.592; AA vs. CA+CC: OR 0.98; 95% CI 0.87, 1.10; P_OR = 0.666). Similar results were also achieved after stratification by the Hardy-Weinberg equilibrium, ethnicity, source of controls, and cancer type.

CONCLUSION

The results of this meta-analysis indicated that there is no association between the IL-10 -592 A/C promoter polymorphism and gastrointestinal tract cancer susceptibility.

ASSOCIATION OF INTERLEUKIN-10 -1082 A/G (RS1800896) POLYMORPHISM WITH SUSCEPTIBILITY TO GASTRIC CANCER: META-ANALYSIS OF 6,101 CASES AND 8,557 CONTROLS

BACKGROUND

The promoter -1082 A/G (rs1800896) polymorphism of Interleukin-10 (IL-10) gene have been widely reported and considered to have a significant role on gastric cancer risk, but the results are inconsistent.

OBJECTIVE

To clarify the association, we conducted a meta-analysis to investigate the associations IL-10 -1082 A/G polymorphism with gastric cancer.

METHODS

Eligible articles were identified by searching databases including PubMed, Web of Science, and Google Scholar up to August 03, 2017. Odds ratios (OR) with corresponding 95% confidence intervals (CIs) were used to assess the association.

RESULTS

A total of 30 case-control studies with 6,101 cases and 8,557 controls were included in this meta-analysis. Overall, a significant association between IL-10 -1082 A/G polymorphism and gastric cancer risk was observed under the allele model (G vs A: OR=1.305, 95% CI=1.076-1.584; P=0.007), heterozygote model and (GA vs AA: OR=1.252, 95% CI=1.252-1.054; P=0.011) and dominant model (GG+GA vs AA: OR=1.264, 95% CI=1.053-1.516; P=0.012). In the subgroup analysis by ethnicity, increased gastric cancer risk were found in Asians under the allele model (G vs A: OR=1.520, 95% CI=1.172-1.973; P=0.002), homozygote model (GG+GA vs AA: OR=1.571, 95% CI=1.023-2.414; P= 0.039), heterozygote model (GA vs AA: OR=1.465, 95% CI=1.192-1.801; P≤0.001) and dominant model (GG+GA vs AA: OR=1.448, 95% CI=1.152-1.821; P=0.002), but not among Caucasian and Latinos populations.

CONCLUSION

These results suggested that the IL-10 -1082 A/G (rs1800896) polymorphism might contribute to the gastric cancer susceptibility, especially among Asians.

Association of the IL-1RN variable number of tandem repeat polymorphism and Helicobacter pylori infection: A meta-analysis

The aim of this study was to clarify the association of IL-1RN variable number of tandem repeat (VNTR) polymorphism and H. pylori infection. We performed a meta-analysis of studies retrieved by systematic searches of Pubmed, Embase and the Cochrane Library. Data were analyzed with STATA 13.1 using pooled odds ratios (ORs) with 95% confidence intervals (CIs). A total of 18 studies were included in our meta-analysis, and IL-1RN VNTR was found to be significantly associated with H. pylori infection in the comparisons of 22+2L vs. LL (OR = 1.17, 95% CI = 1.02-1.33) and 2 allele vs. L allele (OR = 1.18, 95% CI = 1.00-1.40). Stratified analyses on study designs and ethnicities were also conducted. IL-1RN VNTR was positively correlated with H. pylori infection in Asian subgroup and Hospital-Based subgroup (i.e., study samples obtained from hospital inpatients). In conclusion, our study demonstrated that IL-1RN VNTR polymorphism might increase the risk of H. pylori infection, especially in Asians.

Relationship Between Interleukin-10 Gene C-819T Polymorphism and Gastric Cancer Risk: Insights From a Meta-Analysis

BACKGROUND As a pleiotropic cytokine, interleukin-10 (IL-10) plays a regulatory role in carcinogenesis and tumor growth. The aim of this meta-analysis was to assess the susceptibility of the IL-10 gene C-819T polymorphism to gastric cancer. MATERIAL AND METHODS Study identification and data extraction were independently completed by 2 authors. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated and summarized. RESULTS In total, 11 articles including 1960 gastric cancer patients and 3705 controls were qualified. Overall analyses revealed a 13% reduced risk of gastric cancer conferred by the -819T allele relative to the -819C allele (OR=0.87; 95% CI: 0.77-0.97; P=0.016), without heterogeneity (I2=35.1%). In subgroup analyses, a significant difference was identified in East Asian populations (OR=0.85; 95% CI: 0.73-0.98; P=0.029, I2=43.6%), for gastric adenocarcinoma (OR=0.80; 95% CI: 0.66-0.96; P=0.017, I2=0.0%), and in population-based studies (OR=0.81; 95% CI: 0.70-0.93; P=0.003, I2=0.0%). The visual funnel plots and Egger's tests suggested no evidence of publication bias. CONCLUSIONS Extending previous findings, we demonstrate a protective role of the IL-10 gene -819T allele in susceptibility to gastric cancer, and this role was more evident for gastric adenocarcinoma.

A Causal Role of Genetically Elevated Circulating Interleukin-10 in the Development of Digestive Cancers: Evidence from Mendelian Randomization Analysis Based on 29,307 Subjects

Recent studies have observed a high level of circulating interleukin-10 (IL-10) in patients with digestive cancers, yet whether elevated IL-10 is causally associated with digestive cancers so far remained unresolved. We therefore meta-analyzed available observational studies with Mendelian randomization method to explore this causal association by employing IL-10 gene 3 variants (-592C>A, -819C>T, and -1082A>G) as instruments. Data were available from 52 articles encompassing 29,307 subjects. Subgroup analysis by cancer type indicated that -1082A>G was associated with increased risk of gastric cancer (odds ratio [OR] = 1.19; 95% confidence interval [CI]: 1.05-1.35; P = 0.006), and the association was reinforced for intestinal type gastric cancer (OR = 1.26; 95%CI: 1.09-1.44; P = 0.001). By ethnicity, risk estimate for -1082G allele carriers was increased by 21% for digestive cancers in East Asians (95%CI: 1.05-1.40; P = 0.009). As for the genotype-phenotype association, carriers of -1082G allele had an overall 20.21 pg/mL higher IL-10 level than those with -1082AA genotype (P = 0.023). In further Mendelian randomization analysis, the predicted OR for 10 pg/mL increment in IL-10 was 1.14 (95%CI: 1.01-16.99) in gastric cancer. Our findings provided evidence for a causal role of genetically elevated IL-10 in the development of gastric cancer, especially in East Asians and for intestinal type gastric cancer.

Interleukin-1B 31 C>T polymorphism combined with Helicobacter pylori-modified gastric cancer susceptibility: evidence from 37 studies

Gastric cancer is one of the most common malignancies worldwide. Interleukin‐1‐beta (IL‐1β) is a pro‐inflammatory cytokine and potent inhibitor of gastric acid secretion. Some studies provided evidence of the association between IL‐1B 31 polymorphism and gastric cancer risk while other studies did not. Therefore, we conducted a comprehensive meta‐analysis to reassess the association. A systematic literature search of the PubMed and EMBASE databases identified 37 studies with 6108 cases and 8980 controls for this meta‐analysis. The crude odd ratios (ORs) and the 95% confidence intervals (CIs) were calculated to evaluate the strength of the association. Meta‐regression was used to determine the major source of heterogeneity across the studies. The pooled analysis did not suggest the significant association of IL‐1B 31 C>T polymorphism with gastric cancer risk. Stratified analysis was performed by ethnicity, source of control, genotype method, and indicated a significantly increased gastric cancer risk associated with IL‐1B 31T variant in the population‐based subgroup (heterozygous model: OR = 1.22, 95% CI = 1.03–1.45). Moreover, stratified analysis by Helicobacter pylori infection status indicated that IL‐1B 31 polymorphism increased gastric cancer risk in infection‐positive subgroup (homozygous model: OR = 1.35, 95% CI = 1.02–1.78; heterozygous model: OR = 1.31, 95% CI = 1.04–1.66; recessive model: OR = 1.29, 95% CI = 1.04–1.61). The study suggested that IL‐1B 31 polymorphism might confer susceptibility to gastric cancer in the presence of H. pylori infection, indicating a gene–environment interaction in gastric carcinogenesis.

Polymorphisms of the IL-6, IL-8 and IL-10 genes and the risk of gastric pathology in patients infected with Helicobacter pylori

BACKGROUND/PURPOSE

Helicobacter pylori-induced gastric mucosal inflammation is mediated by proinflammatory and anti-inflammatory cytokines. Polymorphisms in genes that code cytokines influence cytokine secretion levels and appear to contribute to the risk of gastric diseases. In this sense, we performed this study to identify the polymorphisms in the IL-6, IL-8, and IL-10 genes and their associations with H. pylori infection and gastric pathologies.

METHODS

Gastric biopsy samples of 151 patients infected with H. pylori and 76 uninfected individuals were used. Helicobacter pylori infection was diagnosed by histological examination and the detection of the ureA and glmM genes. The polymorphisms in the IL-6 (at position -174), IL-8 (at position -251), and IL-10 (at position -819) were detected by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Among the genetic polymorphisms studied, we observed that only the presence of the A allele at position -251 of the IL-8 gene was significantly associated with H. pylori infection. In addition, patient carriers of the A/A genotype at position -251 of the IL-8 gene and carriers of the T allele at position -819 of the IL-10 gene had an increased risk of peptic ulcer disease in the presence of H. pylori infection. We did not find a correlation between polymorphisms in the IL-6, IL-8, and IL-10 genes and a higher risk of gastric carcinoma.

CONCLUSION

We demonstrated that polymorphisms in the IL-8 gene was significantly associated with H. pylori infection. Furthermore, polymorphisms in the IL-8 and IL-10 genes were associated with an enhanced risk of peptic ulcer disease in H. pylori-positive patients.

Effects of the interleukin-1β-511 C/T gene polymorphism on the risk of gastric cancer in the context of the relationship between race and H. pylori infection: a meta-analysis of 20,000 subjects

The interleukin (IL)-1β-511 C/T polymorphism has been shown to be functional and to contribute to the risk of gastric cancer. However, the relationship between the IL-1β-511 C/T polymorphism and gastric carcinogenesis remains inconclusive. A systematical electronic search was conducted of the MEDLINE, EMBASE, and CENTRAL databases. A random and a fixed effects model were exploited to estimate summary odds ratios and 95 % confidence intervals. Subgroup and sensitivity analyses were carried out with respect to ethnicity, quality assessment scores, control sources, genotyping methods, cancer histopathology and location, and Helicobacter pylori (H. pylori) infection. A total of 45 studies containing 9,066 cases of gastric cancer and 11,192 control subjects satisfied the inclusion criteria. The IL-1β-511 C/T polymorphism was found to enhance the risk of stomach cancer for overall and HWE-satisfying studies. Asians showed a positive relationship in both the overall and HWE-satisfying groups, whereas Caucasians did not. Based on subgroup analysis, H. pylori infection and genotype analysis using PCR-RFLP methods increase the association between IL-1β-511 T allele carrier and risk of stomach cancer. A positive relationship was found between the IL-1β-511 C/T SNP and stomach carcinoma susceptibility, and the results suggest that Asian ethnicity, H. pylori infection and methodologically, PCR-RFLP genotyping strengthen this relationship. Reflecting on prevalence of H. pylori in Asian countries, additional studies on the IL-1β-511 C/T SNP in the context of ethnicity and H. pylori infection may provide key insights into the mechanism underlying gastric cancer carcinogenesis. It was found PCR-RFLP is the most reliable genotyping method, and thus, it is recommendable to adopt it to determine the presence of the IL-1β-511 C/T SNP.

The -1082A>G polymorphism in promoter region of interleukin-10 and risk of digestive cancer: a meta-analysis

The -1082A>G polymorphism is located in promoter region of interleukin-10 (IL-10) and it could affect the production of IL-10. Numerous studies have investigated the association between IL-10 -1082A>G and risk of digestive cancer. However, the conclusion is still inconsistent. Here, we have performed a meta-analysis and systematic review to determine the association between the IL-10 -1082A>G and susceptibility to digestive cancer. In this meta-analysis, we identified 40 eligible studies, involving 7195 patients of digestive cancer and 11755 controls. By pooling all eligible studies, we found the variant -1082G allele significantly increased risk of digestive cancer (G vs. A: OR = 1.181, 95% CI: 1.057-1.319). Further stratified analysis was performed to evaluate the influence of cancer types, ethnicities, study design, sample size and Hardy-Weinberg equilibrium. Stratified analysis suggested that, the -1082A>G polymorphism was only associated with increased risk for gastric cancer (G vs. A: OR = 1.281, 95% CI: 1.102-1.488) and in Asian population (G vs. A: OR = 1.399, 95% CI: 1.188-1.646). No significant publication bias was detected. Based on 40 studies and 18950 participants, we found the variant IL-10 -1082G allele significantly increased susceptibility to digestive cancer, especially for gastric cancer and in Asian population.

The geographic origin of Helicobacter pylori isolated from Costa Rican patients

Helicobacter pylori infects a significant proportion of the world population and it is associated with pathologies which include chronic atrophic gastritis, peptic ulcer, and gastric neoplasias such as gastric adenocarcinoma and MALT lymphoma. Costa Rica has a high prevalence of the infection and an elevated incidence of gastric cancer and its associated mortality. The global population structure for H. pylori has been established using a MLST scheme. The population structure of the strains of H. pylori circulating in Costa Rica is currently unknown. We characterized the geographical origin of 24 H. pylori isolates from Costa Rican patients. We identified 142 new alleles for the genes included in the scheme and in eight of the 24 isolates from Costa Rican patients, all seven alleles sequenced were described for the first time. Twenty-one isolates from Costa Rican patients group with hpEurope strains and the remaining three isolates grouped with hspWAfrica isolates (Bayesian posterior probability values above 0.70, P = 0.05, after 2 000 000 generations). The obtained result in the MLST analysis was not unexpected and reflects the genetic composition of the Costa Rican population.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.

The interleukin 10 -819C/T polymorphism and cancer risk: a HuGE review and meta-analysis of 73 studies including 15,942 cases and 22,336 controls

The aim of the present work was to perform a meta-analysis to evaluate the association between the interleukin 10 (IL-10) -819C/T (rs1800871) polymorphism and cancer risk. A total of 73 studies, including 15,942 cancer cases and 22,336 controls, were identified in this meta-analysis. The odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Overall, no significant association was identified between the IL-10 -819C/T polymorphism and cancer risk. In the subgroup analyses, the T allele and TT genotype were associated with a moderately reduced cancer risk in the Asian population (T allele vs. C allele: OR=0.93, 95%CI: 0.87, 0.99; TT vs. CC: OR=0.86, 95%CI: 0.76, 0.98; TT vs. CT/CC: OR=0.90, 95%CI: 0.82, 0.98). Individuals who were homozygous for the T allele (TT) were found to be associated with significantly reduced gastric cancer risk in the Asian population. The heterozygous variant (CT) and the dominant model (TT/CT vs. CC) were associated with an increased risk for cervical and ovarian cancer. However, the IL-10 -819C/T polymorphism was not significantly associated with breast cancer, colorectal cancer, lung cancer, hepatocellular carcinoma, prostate cancer, lymphoma, or melanoma. The depressed cancer risk of the TT genotype occurred in the studies of hospital-based case-control studies and the studies recruited less than 500 subjects, but no statistically significant results were found in the stratified analyses using genotyping method. The results suggest that the IL-10 -819TT genotype may be a protective factor for cancer in Asians, especially gastric cancer. In contrast, the CT genotype and the dominant model could be risk factors for cervical and ovarian cancer. The importance of stratifying by ethnicity, cancer type, study design, and sample size needs to be standardized in future studies, together with considering the association between the IL-10 -819C/T polymorphism and cancer risk. Furthermore, the linkage of -819C/T with other polymorphisms of the IL-10 gene may help explain the variability in findings.

Polymorphisms in genes coding for HSP-70 are associated with gastric cancer and duodenal ulcer in a population at high risk of gastric cancer in Costa Rica

BACKGROUND AND AIMS

Costa Rica has among the highest incidence and mortality rates for gastric cancer worldwide. The reasons for this are largely unknown. Polymorphisms of inflammatory response genes including genes encoding heat shock proteins (HSP) have been shown to be associated with the risk of gastric cancer in some populations. This study addresses the possible association between the HSP70-2 +1267 and HSP70-Hom +2437 polymorphisms and the risk of developing gastric cancer in a high-risk population in Costa Rica.

METHODS

DNA from 39 individuals diagnosed with gastric cancer, 79 healthy controls, 55 individuals with chronic gastritis and 52 individuals with duodenal ulcer was genotyped for the polymorphisms HSP70-2 +1267 and HSP70-Hom +2437 by RFLP. Logistic regression analysis was used to determine possible associations with the diagnoses and lineal regression analysis to determine associations with blood pepsinogen (PGs) levels as measured by serology.

RESULTS

The GA genotype of HSP70-2 was associated with increased risk of gastric cancer (OR = 3.42; 95% CI = 1.27-9.21; p = 0.015) and duodenal ulcer (OR = 2.57; 95% CI = 1.03-6.36; p = 0.042) as compared to the GG genotype. Persons with C carrier genotypes of HSP70-Hom were significantly less susceptible to gastric cancer than those with the TT genotype (OR = 0.29; 95% CI = 0.09-0.87; p = 0.027). The C carrier genotype was associated with lower PGI concentrations but none of the polymorphisms were associated with PGI/PGII.

CONCLUSIONS

Polymorphisms of HSP70 genes are associated with the development of gastric cancer and duodenal ulcers in a population at high risk for gastric cancer in Costa Rica.

Systematic review and meta-analysis on the association between IL-1B polymorphisms and cancer risk

BACKGROUND

Interleukin-1 beta (IL-1β), a pro-inflammatory cytokine, is emerging as a key mediator of carcinogenesis that characterizes host-environment interactions. Epidemiological studies investigating the association between two polymorphisms of IL-1B (-511C/T and +3954C/T) and cancer susceptibility have shown conflicting results. The aim of this study is to derive a more precise estimation of the relationship.

METHODS

Related studies were identified through a systematic literature search of PubMed and Web of Science from their inception to September 15, 2012. Summary odds ratios (ORs) and 95% confidence intervals (CIs) for the IL-1B -511C/T and +3954C/T polymorphisms and cancer risk were calculated. Heterogeneity among studies and publication bias were also tested.

RESULTS

The meta-analysis included 91 case-control studies in 85 publications, 81 studies for the -511C/T (19547 cases and 23935 controls) and 26 studies for the +3954C/T polymorphisms (8083 cases and 9183). The pooled results indicated that IL-1B +3954C/T (dominant model: OR = 1.15, 95% CI: 1.01-1.30) was significantly associated with increased overall cancer risk, especially among hospital-based case-control studies (dominant model: OR = 1.30, 95% CI: 1.02-1.66). As for -511C/T, we observed an inverse relationship in cervical cancer (dominant model: OR = 1.74, 95% CI: 1.35-2.23) and hepatocellular carcinoma (dominant model: OR = 0.68, 95% CI: 0.47-0.99). Moreover, -511C/T was associated with risk of specific subtypes of gastric carcinoma.

CONCLUSION

This meta-analysis suggested that both the IL-1B -511C/T and +3954C/T polymorphisms might modulate cancer susceptibility. Further well-designed studies based on larger sample sizes should be performed to confirm the findings.

The interleukin-10 promoter polymorphism rs1800872 (-592C>A), contributes to cancer susceptibility: meta-analysis of 16,785 cases and 19,713 controls

Interleukin-10 (IL-10) is a multifunctional cytokine which participates in the development and progression of various malignant tumors. To date, a number of case–control studies were conducted to detect the association between IL-10-592C>A polymorphism and cancer risk in humans. However, the results of these studies on the association remain conflicting. In an effort to solve this controversy, we performed a meta-analysis based on 70 case–control studies from 65 articles, including 16 785 cancer cases and 19 713 controls. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall results suggested that the variant homozygote genotype AA of the IL-10-592C>A polymorphism was associated with a moderately decreased risk of all cancer types (OR = 0.90, 95% CI = 0.83–0.98 for homozygote comparison, OR = 0.92, 95% CI = 0.86–0.98 for recessive model). In the stratified analyses, the risk remained for studies of smoking-related cancer, Asian populations and hospital-based studies. These results suggested that the IL-10-592C>A polymorphism might contribute to the cancer susceptibility, especially in smoking-related cancer, Asians and hospital-based studies. Further studies are needed to confirm the relationship.

Risk factors for gastric cancer in Latin America: a meta-analysis

BACKGROUND

Latin America has among the highest gastric cancer incidence rates in the world, for reasons that are still unknown. In order to identify region-specific risk factors for gastric cancer, we conducted a meta-analysis summarizing published literature.

METHODS

Searches of PubMed and regional databases for relevant studies published up to December 2011 yielded a total of 29 independent case-control studies. We calculated summary odds ratios (OR) for risk factors reported in at least five studies, including socioeconomic status (education), lifestyle habits (smoking and alcohol use), dietary factors (consumption of fruits, total vegetables, green vegetables, chili pepper, total meat, processed meat, red meat, fish, and salt), and host genetic variants (IL1B-511T, IL1B-31C, IL1RN*2, TNFA-308A, TP53 codon 72 Arg, and GSTM1 null). Study-specific ORs were extracted and summarized using random-effects models.

RESULTS

Chili pepper was the only region-specific factor reported in at least five studies. Consistent with multifactorial pathogenesis, smoking, alcohol use, high consumption of red meat or processed meat, excessive salt intake, and carriage of IL1RN*2 were each associated with a moderate increase in gastric cancer risk. Conversely, higher levels of education, fruit consumption, and total vegetable consumption were each associated with a moderately decreased risk. The other exposures were not significantly associated. No prospective study data were identified.

CONCLUSION

Risk factor associations for gastric cancer in Latin America are based on case-control comparisons that have uncertain reliability, particularly with regard to diet; the specific factors identified and their magnitudes of association are largely similar to those globally recognized. Future studies should emphasize prospective data collection and focus on region-specific exposures that may explain high gastric cancer risk.

A meta-analysis of interleukin-10 -592 promoter polymorphism associated with gastric cancer risk

We aimed to explore the role of IL-10 -592 A/C SNP in the susceptibility to gastric cancer through a systematic review and meta-analysis. Each initially included article was scored for quality appraisal. 17 studies were eligible for the meta-analysis. We adopted the most probably appropriate genetic model (recessive model). Potential sources of heterogeneity were sought out via subgroup and sensitivity analyses, and publication biases were estimated. IL-10-592 AA genotype is associated with the reduced risk of developing gastric cancer among Asians and even apparently observed among Asians high quality subgroup, suggesting IL-10-592 AA genotype may seem to be more protective from overall gastric cancer in Asian populations. IL-10-592 AA genotype is also associated with the overall reduced gastric cancer susceptibility in persons with H. pylori infection compared with controls without H. pylori infection, suggesting IL-10-592 AA genotype may seem to be more protective from overall gastric cancer susceptibility in persons infected with H. pylori. IL-10-592 AA genotype is not associated with either pathologic subtypes (intestinal or diffuse) or anatomic subtypes (non-cardia or cardia) of gastric cancer susceptibility. Genotyping methods like direct sequencing should be highly advocated to be conducted in future well-designed high quality studies among different ethnicities or populations.

Multifactorial etiology of gastric cancer

The prevalence of gastric cancer is associated with several factors including geographical location, diet, and genetic background of the host. However, it is evident that infection with Helicobacter pylori (H. pylori) is crucial for the development of the disease. Virulence of the bacteria is also important in modulating the risk of the disease. After infection, H. pylori gains access to the gastric mucosa and triggers the production of cytokines that promote recruitment of inflammatory cells, probably involved in tissue damage. Once the infection is established, a cascade of inflammatory steps associated with changes in the gastric epithelia that may lead to cancer is triggered. H. pylori-induced gastritis and H. pylori-associated gastric cancer have been the focus of extensive research aiming to discover the underlying mechanisms of gastric tissue damage. This research has led to the association of host genetic components with the risk of the disease. Among these is the presence of single nucleotide polymorphisms (SNPs) in several genes, including cytokine genes, which are able to differentially modulate the production of inflammatory cytokines and then modulate the risk of gastric cancer. Interestingly, the frequency of some of these SNPs is different among populations and may serve as a predictive factor for gastric cancer risk within that specific population. However, the role played by other genetic modifications should not be minimized. Methylation of gene promoters has been recognized as a major mechanism of gene expression regulation without changing the primary structure of the DNA. Most DNA methylation occurs in cytosine residues in CpG dinucleotide, but it can also be found in other DNA bases. DNA methyltransferases add methyl groups to the CpG dinucleotide, and when this methylation level is too high, the gene expression is turned off. In H. pylori infection as well as in gastric cancer, hypermethylation of promoters of genes involved in cell cycle control, metabolism of essential nutrients, and production of inflammatory mediators, among others, has been described. Interestingly, DNA changes like SNPs or mutations can create CpG sites in sequences where transcription factors normally sit, affecting transcription.In this chapter, we review the literature about the role of SNPs and methylation on H. pylori infection and gastric cancer, with big emphasis to the H. pylori role in the development of the disease due to the strong association between both.

Interleukin-10-819 promoter polymorphism in association with gastric cancer risk

Background

Potential functional allele T/C single nucleotide polymorphism (SNP) of Interleukin 10 (IL-10) promoter -819 (rs1800871) has been implicated in gastric cancer risk. We aimed to explore the role of T/C SNP of IL-10 -819 in the susceptibility to gastric cancer through a systematic review and meta-analysis.

Methods

Each initially included article was scored for quality appraisal. Desirable data were extracted and registered into databases. 11 studies were ultimately eligible for the meta-analysis of IL-10 -819 T/C SNP. We adopted the most probably appropriate genetic model (recessive model). Potential sources of heterogeneity were sought out via subgroup and sensitivity analyses, and publication biases were estimated.

Results

IL-10 -819 TT genotype is associated with the overall reduced gastric cancer risk among Asians and even apparently observed among high quality subgroup Asians. IL-10-819 TT genotype is not statistically associated with the overall reduced gastric cancer susceptibility in persons with H. pylori infection compared with controls without H. pylori infection. IL-10 -819 TT genotype is reversely associated with diffuse-subtype risk but not in intestinal-subtype risk. IL-10 -819 TT genotype is not reversely associated with non-cardia or cardia subtype gastric cancer susceptibility.

Conclusions

IL-10 -819 TT genotype seems to be more protective from gastric cancer in Asians. Whether IL-10 -819 TT genotype may be protective from gastric cancer susceptibility in persons infected with H. pylori or in diffuse-subtype cancer needs further exploring in the future well-designed high quality studies among different ethnicity populations. Direct sequencing should be more used in the future.

Association of IL-10-1082 promoter polymorphism with susceptibility to gastric cancer: evidence from 22 case-control studies

Evidence suggested that interleukin-10 (IL-10) may be involved in the etiology of gastric cancer (GC). However, epidemiological studies on the association between IL-10-1082 promoter polymorphism and GC risk are still ambiguous. To quantitatively summarize the evidence for such a relationship, we performed a meta-analysis. Systemic searches of the PubMed and Medline databases were performed, with the last report up to July 2011. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. 22 independent studies including 4,289 cases and 5,965 controls were involved in this meta-analysis. Obvious association was found when all studies were pooled into the meta-analysis (A vs. G: OR = 0.489, 95% CI = 0.335-0.713, P < 0.001). In the subgroup analysis by ethnicity, we observed significant associations in Asians (A vs. G: OR = 0.651, 95% CI = 0.506-0.838, P = 0.001; AA vs. GG: OR = 0.482, 95% CI = 0.328-0.709, P < 0.001; AA/AG vs. GG: OR = 0.711, 95% CI = 0.527-0.959, P = 0.025; AA vs.

AG/GG

OR = 0.701, 95% CI = 0.520-0.944, P = 0.019) and Caucasians (A vs. G: OR = 0.365, 95% CI = 0.140-0.949, P = 0.039), but not in Latino population. When stratified analysis by control sources, our results indicated that A allele decreased approximately 48% risk among population-based studies (A vs. G: OR = 0.524, 95% CI = 0.374-0.733, P < 0.001). Taken together, this meta-analysis suggests that IL-10-1082 polymorphism is associated with GC risk.

Multifactorial etiology of gastric cancer

The prevalence of gastric cancer is associated with several factors including geographical location, diet, and genetic background of the host. However, it is evident that infection with Helicobacter pylori (H. pylori) is crucial for the development of the disease. Virulence of the bacteria is also important in modulating the risk of the disease. After infection, H. pylori gains access to the gastric mucosa and triggers the production of cytokines that promote recruitment of inflammatory cells, probably involved in tissue damage. Once the infection is established, a cascade of inflammatory steps associated with changes in the gastric epithelia that may lead to cancer is triggered. H. pylori-induced gastritis and H. pylori-associated gastric cancer have been the focus of extensive research aiming to discover the underlying mechanisms of gastric tissue damage. This research has led to the association of host genetic components with the risk of the disease. Among these is the presence of single nucleotide polymorphisms (SNPs) in several genes, including cytokine genes, which are able to differentially modulate the production of inflammatory cytokines and then modulate the risk of gastric cancer. Interestingly, the frequency of some of these SNPs is different among populations and may serve as a predictive factor for gastric cancer risk within that specific population. However, the role played by other genetic modifications should not be minimized. Methylation of gene promoters has been recognized as a major mechanism of gene expression regulation without changing the primary structure of the DNA. Most DNA methylation occurs in cytosine residues in CpG dinucleotide, but it can also be found in other DNA bases. DNA methyltransferases add methyl groups to the CpG dinucleotide, and when this methylation level is too high, the gene expression is turned off. In H. pylori infection as well as in gastric cancer, hypermethylation of promoters of genes involved in cell cycle control, metabolism of essential nutrients, and production of inflammatory mediators, among others, has been described. Interestingly, DNA changes like SNPs or mutations can create CpG sites in sequences where transcription factors normally sit, affecting transcription.In this chapter, we review the literature about the role of SNPs and methylation on H. pylori infection and gastric cancer, with big emphasis to the H. pylori role in the development of the disease due to the strong association between both.

The interleukin-10-1082 promoter polymorphism and cancer risk: a meta-analysis

Interleukin-10 (IL-10) is a multifunctional cytokine with both immunosuppressive and anti-angiogenic properties and play an important role in the pathogenesis of cancer. IL-10-1082A>G polymorphism is the most extensively studied polymorphism in the IL-10 gene in cancer susceptibility. To date, a number of case-control studies were conducted to investigate the association between IL-10-1082A>G polymorphism and cancer risk in humans. However, the association between the IL-10-1082A>G polymorphism and cancer risk is still ambiguous. In an effort to solve this controversy, we performed a meta-analysis based on 61 case-control studies, including 14,499 cancer cases and 16,967 controls. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. In the stratified analyses by specific cancer type, increased risk was found in lung cancer (OR = 3.16, 95% CI = 1.16-8.63 for GA versus AA; OR = 2.07, 95% CI = 1.16-3.70 for GG versus AA; OR = 3.17, 95% CI = 1.31-7.68 for GA/GG versus AA) and non-Hodgkin's lymphoma (OR = 1.18, 95% CI = 1.02-1.36 for GA versus AA; OR = 1.17, 95% CI = 1.02-1.35 for GA/GG versus AA). The meta-analysis also indicated that the variant genotypes were associated with a moderately increased risk in Asians in all genetic models (OR = 1.80, 95% CI = 1.17-2.76 for GA versus AA; OR = 3.32, 95% CI = 1.62-6.82 for GG versus AA; OR = 1.67, 95% CI = 1.07-2.60 for GA/GG versus AA; OR= 2.93, 95% CI = 1.43-6.03 for GG versus AA/GA). The meta-analysis suggested that the IL-10-1082A>G polymorphism was associated with increased risk of cancer in Asians and lung cancer and non-Hodgkin's lymphoma. To draw comprehensive and true conclusions, more researches with larger numbers of worldwide participants are needed to examine associations between IL-10-1082A>G polymorphism and cancer risk.

Infection with specific Helicobacter pylori-cag pathogenicity island strains is associated with interleukin-1B gene polymorphisms in Venezuelan chronic gastritis patients

BACKGROUND

The cag pathogenicity island (cag-PAI) is one of the major virulence factors of Helicobacter pylori, showing considerable geographic variation.

AIM

We investigated the prevalence of cagA, cagE, and cagT genes of cag-PAI and their association with proinflammatory IL-1B-511/-31/+3954 polymorphisms in Venezuelan chronic gastritis patients from a high-risk gastric cancer region.

METHODS

Presence of cag-PAI genes and IL-1B polymorphisms in 121 biopsy specimens was evaluated by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP), respectively.

RESULTS

cagA (+) and triple-positive (cagAET (+)) strains were detected in 79.3% and 70.2% of patients, respectively. We found that infection with cagA (+) and cagAET (+) strains was associated (P < 0.05) with hosts harboring both IL-1B +3954C allele and IL-1B-511T/-31C/+3954C haplotype (TCC (+)). The frequency of gastric atrophy was significantly higher (P < 0.020) among cagAET (+)/IL-1B-TCC (+) combined genotype carriers.

CONCLUSION

Carriage of IL-1B +3954C allele and IL-1B-TCC (+) haplotype could favor colonization of bacterial cagAET (+) strains, and the combination of these bacterial and host haplotypes could play a synergistic role in development of premalignant gastric lesions. This work contributes to understanding of the complex interaction between H. pylori virulence factors and cytokine genotypes involved in gastrointestinal diseases.

Association of haplotypes of inflammation-related genes with gastric preneoplastic lesions in African Americans and Caucasians

Identification of biomarkers is needed for development of screening programs to prevent gastric cancer. Because racial differences exist in cancer rates, we aimed to evaluate the association between polymorphisms in inflammation-related genes and gastric preneoplastic lesions in African Americans and Caucasians from Louisiana, USA. Gastric biopsies from 569 adults (361 African Americans and 208 Caucasians) undergoing diagnostic endoscopy were used for histological diagnosis and genomic DNA extraction. Polymorphisms within eight genes (IL1B, IL8, IL6, TNF, PTGS2, ARG1, IL10 and TGFB1) were investigated by TaqMan. The cagA status of Helicobacter pylori infection was assessed by PCR. Haplotype logistic regression models were used to identify variables associated with intestinal metaplasia or dysplasia. African Americans carrying the haplotype IL1B-511T/-31C/+3954T, which includes the three risk-associated alleles at the IL1B locus, were more likely to being diagnosed with intestinal metaplasia or dysplasia than those carrying the most common haplotype T-C-C (adjusted OR: 2.51, 95% CI: 1.1-5.5). None of the polymorphisms were associated with intestinal metaplasia and dysplasia in Caucasians. Age and cagA-positive status were independent factors associated with these lesions. Haplotypes at the IL1B locus may participate in mediating the susceptibility to gastric carcinogenesis and might be useful as markers of advanced premalignant lesions in African Americans. Interestingly, carriage of IL1B+3954T allele seems to be the key factor, even though the role played by other polymorphisms cannot be excluded.

Polymorphisms in inflammatory response genes and their association with gastric cancer: A HuGE systematic review and meta-analyses

To evaluate the association between gastric cancer susceptibility and inflammation-related gene polymorphisms, the authors conducted a series of meta-analyses using a predefined protocol. Genes investigated were those coding for the interleukin (IL) proteins (IL1B, IL1RN, IL8, and IL10) and for tumor necrosis factor-alpha. Gastric cancers were stratified by histologic subtype and anatomic subsite, by Helicobacter pylori infection status, by geographic location (Asian or non-Asian study population), and by a quantitative index of study quality. All published literature and meeting abstracts from the period 1990-2006 were considered. Results consistently supported increased cancer risk for IL1RN2 carriers; the increased risk was specific to non-Asian populations and was seen for intestinal and diffuse cancers, distal cancers, and, to a lesser extent, cardia cancers. Analyses restricted to high-quality studies or H. pylori-positive cases and controls also showed significant associations with both carrier status and homozygosity status. In Asian populations, reduced risk was observed in association with IL1B-31C carrier status. This effect was also observed in analyses restricted to high-quality studies. These results indicate the importance of stratification by anatomic site, histologic type, H. pylori infection, and country of origin. Study quality considerations, both laboratory and epidemiologic, can also affect results and may explain, in part, the variability in results published to date.

Interleukin-10 -1082 promoter polymorphism and gastric cancer risk in a Chinese Han population

Studies investigating the association between interleukin-10 (IL-10) -1082 promoter polymorphism and gastric cancer risk report conflicting results. Our recent meta-analysis suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer among Asians. The objective of this study was to investigate the association between IL-10 -1082 promoter polymorphism and gastric cancer risk in Chinese Han patients. We extracted the peripheral blood samples in 150 patients with gastric cancer and 150 controls. PCR-RFLP analysis was performed to detect IL-10 -1082 promoter polymorphism in these patients. Patients with gastric cancer had a significantly lower frequency of AA (OR = 0.45, 95% CI = 0.27, 0.76; P = 0.003) than controls. Patients with cardia gastric cancer had a significantly higher frequency of GG (OR = 2.17, 95% CI = 1.08, 4.38; P = 0.03) than those with noncardia gastric cancer. Patients with advanced gastric cancer had a significantly higher frequency of AA (OR = 5.21, 95% CI = 1.71, 15.87; P = 0.004) than those with early gastric cancer. When stratified by the Lauren's classification, histological differentiation of gastric cancer, no statistically significant results were observed. This study suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer in Chinese Han patients, and that difference in genotype distribution may be associated with the location and stage of gastric cancer.

Interleukin-1B and interleukin-1 RN polymorphisms and gastric carcinoma risk: a meta-analysis

BACKGROUND AND AIM

We aimed to explore the role of interleukin (IL)-1B cluster gene polymorphisms at positions -511, -31, and +3954 and the receptor IL-1RN variable number tandem repeat polymorphisms in the susceptibility to gastric carcinoma through a systematic review and meta-analysis.

METHODS

Each initially included article was scored for quality appraisal. The desirable data were extracted and registered into databases. Studies that deviated from Hardy-Weinberg equilibrium were excluded. Eighteen studies were ultimately eligible for the meta-analysis of IL1B-511, 21 studies for IL1B-31, 10 studies for IL1B+3954, and 20 studies for IL1RN variable number tandem repeat genetic polymorphisms, respectively. Original groups were collapsed and re-grouping was adopted in line with the most probably appropriate genetic models. Potential sources of heterogeneity were sought out via stratification and sensitivity analyses, and biases across studies were estimated.

RESULTS

The pooled odds ratios (95% confidence intervals, P-value) associated with IL-1B -511 T carriers versus CC genotypes and with RN *2 carriers versus L/L were 1.23 (1.04-1.45, P = 0.015) and 1.26 (1.06-1.51, P = 0.010), respectively, for overall gastric carcinoma; 1.31 (1.04-1.64, P = 0.020) and 1.47 (1.21-1.79, P = 0.000), respectively, for non-cardia gastric cancer; 1.55 (1.05-2.28, P = 0.026) and 1.66 (1.23-2.25, P = 0.001), respectively, for intestinal type gastric carcinoma; and 1.33 (1.04-1.71, P = 0.023) and 1.31 (1.07-1.61, P = 0.010), respectively, in Caucasians for overall gastric carcinoma. The pooled odds ratio (95% confidence interval, P-value) regarding IL-1B-31 CC plus TT versus CT was 0.73 (0.60-0.89, P = 0.002) for intestinal type gastric carcinoma. Genotyping methods and publication time could constitute the sources of heterogeneity across studies. Publication biases were not found.

CONCLUSION

IL-1B -511 T allele and IL-1 RN *2 VNTR are significantly associated with an increased risk of developing gastric carcinoma and even more significantly with non-cardia gastric carcinoma or with intestinal-type gastric carcinoma. Both are significantly associated with an increased risk of developing gastric carcinoma among Caucasians, but not among Asians or Hispanics.

Interleukin10 -592 promoter polymorphism associated with gastric cancer among Asians: a meta-analysis of epidemiologic studies

PURPOSE

Studies investigating the association between interleukin10 (IL10) -592 promoter polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarize the evidence for such a relationship.

METHODS

Two investigators independently searched the MEDLINE and Embase databases. This meta-analysis included ten case-control studies, which included 1,715 gastric cancer cases and 2,783 controls.

RESULTS

The combined results based on all studies showed that there was no significant difference in genotype distribution (AA odds ratio [OR] = 0.88, 95% confidence interval [CI] = 0.66, 1.18; AC OR = 1.09, 95% CI = 0.95, 1.24; CC OR = 1.03, 95% CI = 0.89, 1.18) between gastric cancer and noncancer patients. When stratifying for race, the results were similar, except that patients with gastric cancer had a significantly lower frequency of AA (OR = 0.67, 95% CI = 0.52, 0.87) and a higher frequency of AC (OR = 1.34, 95% CI = 1.07, 1.68) than noncancer patients among Asians. When stratifying by the location of gastric cancer, we found that patients with cardia gastric cancer had a significantly lower frequency of AA (OR = 0.41, 95% CI = 0.20, 0.84) than those with noncardia gastric cancer among Caucasians. When stratifying by Lauren's classification of gastric cancer, we found that patients with diffuse gastric cancer had a significantly higher frequency of AA (OR = 1.91, 95% CI = 1.07, 3.41) than those with intestinal gastric cancer among Caucasians.

CONCLUSIONS

This meta-analysis suggests that the IL10 -592 promoter polymorphism may be associated with gastric cancer among Asians, and that differences in genotype distribution may be associated with the location and Lauren's classification of gastric cancer.

Combination of Helicobacter pylori-iceA2 and proinflammatory interleukin-1 polymorphisms is associated with the severity of histological changes in Venezuelan chronic gastritis patients

Helicobacter pylori is a major cause of chronic gastritis (CG) and a firmly established carcinogen for gastric adenocarcinoma. However, the underlying pathogenic mechanisms are not fully understood. In this work we studied the association of the allelic variation of H. pylori-iceA virulence factor and human proinflammatory interleukin (IL)-1 polymorphisms (IL-1B-31, IL-1B-511, IL-1B+3954 and IL-1RN) with histopathological changes in the gastric mucosa of patients with CG in Venezuela, a country with a high incidence of and mortality from gastric cancer. Although in this work the iceA1 allele was found more frequently (69.7%), iceA2 allele prevalence was higher in samples with atrophic gastritis (AG) and more severe grades of granulocytic (G2/G3) [P=0.02; odds ratio (OR) 3.3] and lymphocytic infiltration (L2/L3). The carriage of iceA2 strains combined with proinflammatory IL-1 polymorphisms IL-1-31C or IL-1-511T allele carrier genotypes increased even more the risk of presenting G2/G3 with ORs of 5.1 and 5.4, respectively. Moreover, the iceA2/IL-1B-511T and iceA2/IL-1B-31C/-511T/IL-1RN(*)2 bacteria/host genotype combinations showed a significant association with AG and L2/L3, respectively. Despite not being well established, the bacterial risk factor iceA2 seems an important predictor of severe histological changes in CG, separately or in combination with host genetic factors in the Venezuelan population.

Interleukin-10-819 Promoter Polymorphism Associated with Gastric Cancer among Asians

Studies investigating the association between interleukin-10-819 promoter polymorphism and gastric cancer risk report conflicting results. This study aimed to summarize quantitatively the evidence for such a relationship. Two investigators independently searched the Medline (January 1966 – January 2009) and Embase (January 1980 – January 2009) databases for eligible studies to be included in a meta-analysis. Six case-control studies, which included 681 gastric cancer cases and 1621 control subjects were selected. Combined results for all studies showed that there was no significant difference in genotype distribution (TT, TC or CC) between gastric cancer patients and control subjects. When stratifying for race, results were similar except that Asian patients with gastric cancer had a significantly lower frequency of TT and a higher frequency of TC than Asian control subjects. When stratifying by location and Lauren's classification of gastric cancer, there was no significant difference in genotype distribution between patients with gastric cancer and control subjects. This meta-analysis suggests that the interleukin-10-819 promoter polymorphism may be associated with gastric cancer in Asians.

The association between interleukin-10-592 polymorphism and gastric cancer risk: a meta-analysis

Relationship of gastric cancer with the presence of IL-10-592 polymorphism was reported with inconsistent results. The objective of this study was to quantitatively evaluate the association between IL-10-592 allele polymorphism and gastric cancer susceptibility. We performed an extensive search of relevant studies and made a meta-analysis, including 12 studies with 2,285 gastric cancer cases and 4,236 controls. The combined results based on all studies showed that there were no significant differences in genotype distribution between gastric cancer cases and controls, CC versus CA/AA (OR = 1.05, 95% CI: 0.92-1.18), CC/CA versus AA (OR = 1.16, 95% CI: 0.92-1.46), CC versus CA (OR = 1.03, 95% CI: 0.90-1.17), CC versus AA (OR = 1.10, 95% CI: 0.90-1.34), and CA versus AA (OR = 1.16, 95% CI: 0.92-1.45). When stratifying for the race, it was found that gastric cancer cases had a significantly higher frequency of CC/CA versus AA (OR = 1.31, 95% CI: (1.08-1.59) and a significantly upper frequency of CA versus AA (OR = 1.33, 95% CI: 1.09-1.63) than control in Asians. When stratifying for the location and the Lauren's classification of gastric cancer, there were no statistically significant differences in genotype distribution between gastric cancer cases and controls. This meta-analysis suggested that IL-10-592 allele polymorphism might be a risk factor for gastric cancer among Asians.

Urokinase plasminogen activator receptor is expressed in invasive cells in gastric carcinomas from high- and low-risk countries

Gastric cancer is the second cancer causing death worldwide. Both incidence and mortality rates vary according to geographical regions. The receptor for urokinase plasminogen activator (uPAR) is involved in extracellular matrix degradation by mediating cell surface associated plasminogen activation, and its presence on gastric cancer cells is linked to micro-metastasis and poor prognosis. Immunohistochemical analyses of a set of 44 gastric cancer lesions from Costa Rica showed expression of uPAR in cancer cells in both intestinal subtype (14 of 27) and diffuse subtype (10 of 17). We compared the expression pattern of uPAR in gastric cancers from a high-risk country (Costa Rica) with a low-risk country (Norway). We found uPAR on gastric cancer cells in 24 of 44 cases (54%) from Costa Rica and in 13 of 23 cases (56%) from Norway. uPAR was seen in macrophages and neutrophils in all cases. We also examined the nonneoplastic mucosa and found that uPAR was more frequently seen in epithelial cells located at the luminal edge of the crypts in cases with Helicobacter pylori infection than in similar epithelial cells in noninfected mucosa (p = 0.033; chi(2) = 4.54). In conclusion, the expression of uPAR in cancer cells in more than half of the gastric cancer cases suggests that their uPAR-positivity do not contribute to explain the different mortality rates between the 2 countries, however, the actual prevalence of uPAR-positive cancer cells in the gastric cancers may still provide prognostic information.

Synergistic effect of HLA class II loci and cytokine gene polymorphisms on the risk of gastric cancer in Japanese patients with Helicobacter pylori infection

It has been reported that polymorphisms of human leukocyte antigen (HLA) genes and several cytokine genes are associated with an increased risk of developing gastric cancer (GC). However, the results of studies from different geographic regions, ethnic groups and study groups are inconsistent. The aim of this study was to evaluate the influence of H. pylori infection and host genetic factors on GC susceptibility in Japanese patients with GC. We analyzed genotypes for HLA class I and II, tumor necrosis factor alpha, interleukin (IL)-1beta, IL-1 receptor, IL-4, IL-4Ralpha and IL-10 in 330 H. pylori-infected noncardia patients with GC and 190 H. pylori-infected nonulcer dyspeptic controls. Haplotype analyses indicated that the frequencies of the HLA DRB1*0405 and DQB1*0401 alleles were increased in the patients with intestinal-type GC when compared with controls (both DRB1*0405 and DQB1*0401: p = 0.015, OR = 1.57, 95% CI = 1.09-2.26), but the changes were not statistically significant after correction for multiple comparisons. None of the cytokine gene polymorphisms were associated with GC susceptibility, whether patients with GC were analyzed as a group according to the histological subtype. Of interest was the comparison of controls and patients with intestinal-type GC. The frequency of an IL-10-592AA homozygote showing concomitant carriage of the HLA DRB1*0405-DQB1*0401 haplotype was significantly higher in patients with intestinal-type GC (chi(2) = 6.369, p = 0.0116, p(c) = 0.0464, OR = 2.43, 95% CI = 1.21-4.48). Our results suggest that the HLA class II and IL-10-592A/C polymorphisms synergistically affect the susceptibility to GC development of H. pylori-infected individuals in the Japanese population.

Cytokine genetic polymorphisms and prostate cancer aggressiveness

Prostate cancer (PCa) is one of the most common cancers in the world. Inflammation has been described as a risk factor for PCa and depends on the production of cytokines in response to tissue damage or the presence of stimuli that induces cellular stress. Interindividual variation in cytokine production is partially controlled by single-nucleotide polymorphisms (SNPs) that have been associated with differential production of cytokines. We have recently showed that SNP-SNP interactions of cytokine genes are associated with PCa risk. However, little is known about the association of cytokine SNPs and PCa aggressiveness. In this study, we evaluated the association of 15 SNPs in five cytokine genes and aggressiveness of PCa in African- and Caucasian-American individuals. Caucasian Americans with the genotypes IL10-1082GG or IL1B+3954TT had 2.31-fold [95% confidence interval (CI) = 1.13-4.72] and 3.11 (95% CI = 1.20-8.06)-fold risk, respectively, of developing aggressive PCa, as compared with individuals without those genotypes. We did not find any associations in the African-American group. Using Multivariate Adaptive Regression Splines modeling for exploratory SNP-SNP interactions, our results showed that more aggressive PCa in Caucasians Americans is associated with the CT genotype at IL8-47 [odds ratios (OR) = 3.50; 95% CI = 1.13-10.88] or combined genotypes of IL1B-511CC and IL10-1082GG (OR = 3.38; 95% CI = 1.70-6.71). Unfortunately, the same analysis could not be performed in the African-Americans due to limited number of individuals. With limited sample size, the results from this study suggest that SNPs in cytokine genes may be associated with PCa aggressiveness. More extensive studies are warranted to validate our findings.

Interleukin 1-beta gene polymorphisms and risk of gastric cancer in Sweden

OBJECTIVE

Helicobacter pylori (H. pylori) infection stimulates the production of interleukin (IL)-1 beta, a pro-inflammatory cytokine and suppressor of gastric acid secretion. As both inflammation and hypochlorhydria, which might facilitate proximal colonization of H. pylori and other bacterial species alike, have been implicated in gastric carcinogenesis, much attention has been directed to functional genetic polymorphisms that affect the production of IL-1 beta. The purpose of this study was to clarify the role of these polymorphisms.

MATERIAL AND METHODS

We analysed a population-based, case-control study in 5 Swedish counties and a hospital-based, case-control study conducted in 8 Swedish hospitals, with a total of 351 gastric cancer cases and 539 controls. The IL1B-31, IL1B-511 and IL1B+3954 biallelic polymorphisms were genotyped using pyrosequencing. The variable number of tandem repeats (VNTR) polymorphism of IL1-RN was analysed using polymerase chain reaction (PCR) followed by gel electrophoresis. Relative risks were estimated by odds ratios with 95% confidence intervals, derived from unconditional logistic regression.

RESULTS

The risk of gastric cancer was unrelated to genotype in all of the studied polymorphic loci, and the absence of any association was confirmed in both the population-based and hospital-based case-control studies. Analyses confined to histological subtypes (intestinal or diffuse) and site-specific tumours (cardia or distal stomach), as well as analyses stratified by H. pylori infection status and family history of gastric cancer, did not reveal any significant increases or decreases in risk.

CONCLUSION

Our results do not lend support to the hypothesis that human genetic polymorphisms related to the production of IL-1 beta are associated with the risk of gastric cancer.

Role of bacterial and genetic factors in gastric cancer in Costa Rica

AIM: To evaluate several risk factors for gastric cancer (GC) in Costa Rican regions with contrasting GC incidence rate (GCIR).

METHODS: According to GCIR, 191 Helicobacter pylori (H pylori)-positive patients were classified into groups A (high GCIR, n = 101) and B (low GCIR, n = 90). Human DNA obtained from biopsy specimens was used in the determination of polymorphisms of the genes coding for interleukin (IL)-1&bgr; and IL-10 by PCR-RFLP, and IL-1RN by PCR. H pylori DNA extractions obtained from clinical isolates of 83 patients were used for PCR-based genotyping of H pylori cagA, vacA and babA2. Human DNA from gastric biopsies of 52 GC patients was utilized for comparative purposes.

RESULTS: Cytokine polymorphisms showed no association with GCIR variability. However, gastric atrophy, intestinal metaplasia and strains with different vacA genotypes in the same stomach (mixed strain infection) were more frequently found in group A than in group B, and cagA and vacA s1b were significantly associated with high GCIR (P = 0.026 and 0.041, respectively). IL-1&bgr;+3954_T/C (OR 2.1, 1.0-4.3), IL-1RN*2/L (OR 3.5, 1.7-7.3) and IL-10-592_C/A (OR 3.2, 1.5-6.8) were individually associated with GC, and a combination of these cytokine polymorphisms with H pylori vacA s1b and m1 further increased the risk (OR 7.2, 1.4-36.4).

CONCLUSION: Although a proinflammatory cytokine genetic profile showed an increased risk for developing GC, the characteristics of H pylori infection, in particular the status of cagA and vacA genotype distribution seemed to play a major role in GCIR variability in Costa Rica.

Relation of atrophic gastritis with Helicobacter pylori-CagA+ and interleukin-1 gene polymorphisms

AIM: To determine the association of Helicobacter pylori (H pylori) CagA⁺ infection and pro-inflammatory polymorphisms of the genes interleukin (IL)-1RN and IL-1B with the risk of gastric atrophy and peptic ulcers in a dyspeptic population in Costa Rica, a country with high incidence and mortality of gastric cancer.

METHODS: Seven biopsy specimens, a fasting blood sample and a questionnaire concerning nutritional and sociodemographic factors were obtained from 501 consecutive patients who had undergone endoscopy for dyspeptic symptoms. A histopathological diagnosis was made. Pepsinogen concentrations were analyzed by enzyme linked immunosorbent assay (ELISA). Infection with H pylori CagA⁺ was determined by serology and polymerase chain reaction (PCR). IL-1B and IL-1RN polymorphisms genotyping was performed by PCR-restriction fragment length polymorphism (PCR-RFLP) and PCR respectively.

RESULTS: In this dyspeptic population, 86% were H pylori positive and of these, 67.8% were positive for CagA. Atrophic antral gastritis (AAG) was associated with CagA⁺ status [odd ratio (OR) = 4.1; P < 0.000] and fruit consumption (OR = 0.3; P < 0.00). Atrophic body gastritis (ABG) was associated with pepsinogen PGI/PGII < 3.4 (OR = 4.9; P < 0.04) and alcohol consumption (OR = 7.3; P < 0.02). Duodenal ulcer was associated with CagA⁺ (OR = 2.9; P < 0.04) and smoking (OR = 2.4; P < 0.04). PGI < 60 μg/L as well as PGI/PGII < 3.4 were associated with CagA⁺.

CONCLUSION: In a dyspeptic population in Costa Rica, H pylori CagA⁺ is not associated with ABG, but it is a risk factor for AAG. The pro-inflammatory cytokine polymorphisms IL-1B + 3945 and IL-1RN are not associated with the atrophic lesions of this dyspeptic population.

Concurrent genotyping of Helicobacter pylori virulence genes and human cytokine SNP sites using whole genome amplified DNA derived from minute amounts of gastric biopsy specimen DNA

Background

Bacterial and cellular genotyping is becoming increasingly important in the diagnosis of infectious diseases. However, difficulties in obtaining sufficient amount of bacterial and cellular DNA extracted from the same human biopsy specimens is often a limiting factor. In this study, total DNA (host and bacterial DNA) was isolated from minute amounts of gastric biopsy specimens and amplified by means of whole genome amplification using the multiple displacement amplification (MDA) technique. Subsequently, MDA-DNA was used for concurrent Helicobacter pylori and human host cellular DNA genotyping analysis using PCR-based methods.

Results

Total DNA was isolated from gastric biopsy specimens of 12 subjects with gastritis and 16 control subjects having a normal mucosa. The DNA was amplified using a multiple displacement amplification (MDA) kit. Next, concurrent genotyping was performed using H. pylori-specific virulence gene PCR amplification assays, pyrosequencing of bacterial 16S rDNA and PCR characterisation of various host genes. This includes Interleukin 1-beta (IL1B) and Interferon-gamma receptor (IFNGR1) SNP analysis, and Interleukin-1 receptor antagonist (IL1RN) variable tandem repeats (VNTR) in intron 2. Finally, regions of the vacA-gene were PCR amplified using M13-sequence tagged primers which allowed for direct DNA sequencing, omitting cloning of PCR amplicons. H. pylori specific multiplex PCR assays revealed the presence of H. pylori cagA and vacA genotypic variations in 11 of 12 gastritis biopsy specimens. Using pyrosequencing, 16S rDNA variable V3 region signatures of H. pylori were found in 11 of 12 individuals with gastritis, but in none of the control subjects. Similarly, IL1B and IFNGR1-SNP and IL1RN-VNTR patterns could be established in all individuals. Furthermore, sequencing of M13-sequence tagged vacA-PCR amplicons revealed the presence of highly diverse H. pylori vacA-s/i/m regions.

Conclusion

The PCR-based molecular typing methods applied, using MDA-amplified DNA derived from small amounts of gastric biopsy specimens, enabled a rapid and concurrent molecular analysis of bacterial and host genes in the same biopsy specimen. The principles and technologies used in this study could also be applied to any situation in which human host and microbial genes of interest in microbial-host interactions would need to be sequenced.

Interleukin-10 -1082 promoter polymorphism associated with gastric cancer among Asians

Studies investigating the association between interleukin-10 (IL-10) -1082 promoter polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarise the evidence for such a relationship. Two investigators independently searched the Medline and Embase databases. This meta-analysis included 13 case-control studies, which included 2227 gastric cancer cases and 3538 controls. The combined results based on all studies showed that there was no significant difference in genotype distribution [AA odds ratio (OR)=0.92, 95% confidence interval (CI)=0.73, 1.14; AG (OR=1.09, 95% CI=0.87, 1.36); GG (OR=1.03, 95% CI=0.85, 1.25)] between gastric cancer and noncancer patients. When stratifying for race, results were similar except that patients with gastric cancer had a significantly lower frequency of AA (OR=0.71, 95% CI=0.52, 0.97) and higher frequency AG (OR=1.53, 95% CI=1.15, 2.03) than noncancer patients among Asians. When stratifying by the location of gastric cancer, we found that patients with cardia gastric cancer had a significantly lower frequency of AA (OR=0.53, 95% CI=0.34, 0.83) and higher frequency AG (OR=1.50, 95% CI=1.06, 2.11) than those with noncardia gastric cancer among Caucasians. When stratifying by the Lauren's classification of gastric cancer, we observed no statistically significant differences in genotype distribution. This meta-analysis suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer among Asians, and that differences in genotype distribution may be associated with the location of gastric cancer.

Interleukin-1B (IL1B) and interleukin-6 (IL6) gene polymorphisms are associated with risk of chronic lymphocytic leukaemia

Common polymorphisms in genes encoding for cytokines implicated in the inflammatory response and Th1/Th2 balance might play a role in the development and prognosis of chronic lymphocytic leukaemia (CLL). To test the hypothesis, we investigated 13 single nucleotide polymorphisms (SNPs) in nine of such genes in a population-based case-control study, conducted in the Italian region of Sardinia in 1999-2003. Forty incident CLL cases and 113 population controls were available for study. The following SNPs were selected: IL1A-889C > T, IL1RN 9589A > T, IL1B-31C > T, IL1B-511C > T, IL2-384T > G, IL6-174G > C, IL6-597G > A, IL10-1082A > G, IL10-3575T > A, TNF-308G > A, LTA- 91A > C, LTA 252A > G and CARD15 nt1007. After adjusting by age and gender, individuals homozygous for the IL1B-511T allele run a lower risk of CLL (OR = 0.1, 95% CI 0.0, 0.8, p = 0.032), while risk showed a 4.5-fold increase associated with the genotype homozygous for the IL6-174C allele (OR = 4.5; 95% CI 1.1, 19.3, p = 0.041). Individuals homozygous for the IL6-174C allele and carrying the homozygous IL1B-511C allele showed an 11-fold increase in CLL risk (OR = 11.4, 95% CI 1.9, 69.4, p = 0.008). None of the other interleukin SNPs evaluated showed any association with CLL risk. Large multicentre pooled studies are warranted, achieving the statistical power required to confirm whether IL6 and IL1B gene polymorphisms might play a role in CLL development and prognosis, as well as the null associations herein reported.

Ethnic differences in cytokine gene polymorphisms: potential implications for cancer development

Differences in incidence and outcome of cancer among ethnic groups may be explained by biological and/or socio-economic factors. Genetic variations that affect chronic inflammation, a potentially important risk factor for carcinogenesis, may differ across ethnic groups. Such differences may help explain cancer disparities among these groups. Single nucleotide polymorphisms (SNPs) within cytokine genes can affect cytokine levels and the degree of inflammation. Associations between cancer and some cytokine SNPs have been suggested. However, these have not been consistently replicated among populations, suggesting that SNP function may differ according to ethnicity, or that SNPs alone do not completely account for regulation of inflammation. We examined seven polymorphisms in African-American (n = 294) and Caucasian (n = 299) newborns in Louisiana: IL1B-511C > T, IL1B-31T > C, IL1B + 3954C > T, IL1RN*2, IL10-1082G > A, IL10-592C > A, and TNF-308G > A. African-American newborns had significantly higher frequencies of IL1B-511T, IL1B-31C, IL10-1082A and IL10-592A alleles and complete linkage equilibrium between IL1B + 3954 and IL1B-31. In contrast, IL1B + 3954T, IL1RN*2, and TNF-308A were more frequent in Caucasian newborns and exhibited strong linkage disequilibrium between IL1B + 3954 and IL1B-31. All allelic frequencies were significantly different between groups. We hypothesize that these dissimilarities may contribute to differences in the inflammatory response and cancer incidence and mortality between African-Americans and Caucasians in Louisiana.