Role of cytokine polymorphisms in the risk of distal gastric cancer development

Blood index panel for gastric cancer detection

BACKGROUND

Gastric cancer is a common malignant tumor. Early detection and diagnosis are crucial for the prevention and treatment of gastric cancer.

AIM

To develop a blood index panel that may improve the diagnostic value for discriminating gastric cancer and gastric polyps.

METHODS

Thirteen tumor-related detection indices, 38 clinical biochemical indices and 10 cytokine indices were examined in 139 gastric cancer patients and 40 gastric polyp patients to build the model. An additional 68 gastric cancer patients and 22 gastric polyp patients were enrolled for validation. After area under the curve evaluation and univariate and multivariate analyses.

RESULTS

Five tumor-related detection indices, 12 clinical biochemical indices and 1 cytokine index showed significant differences between the gastric cancer and gastric polyp groups. Carbohydrate antigen (CA) 724, phosphorus (P) and ischemia-modified albumin (IMA) were included in the blood index panel, and the area under the curve (AUC) of the index panel was 0.829 (0.754, 0.905). After validation, the AUC was 0.811 (0.700, 0.923). Compared to the conventional index CA724, the blood index panel showed significantly increased diagnostic value.

CONCLUSION

We developed an index model that included CA724, P and IMA to discriminate the gastric cancer and gastric polyp groups, which may be a potential diagnostic method for clinical practice.

The application of transgenic and gene knockout mice in the study of gastric precancerous lesions

Gastric intestinal metaplasia is a precursor for gastric dysplasia, which is in turn, a risk factor for gastric adenocarcinoma. Gastric metaplasia and dysplasia are known as gastric precancerous lesions (GPLs), which are essential stages in the progression from normal gastric mucosa to gastric cancer (GC) or gastric adenocarcinoma. Genetically-engineered mice have become essential tools in various aspects of GC research, including mechanistic studies and drug discovery. Studies in mouse models have contributed significantly to our understanding of the pathogenesis and molecular mechanisms underlying GPLs and GC. With the development and improvement of gene transfer technology, investigators have created a variety of transgenic and gene knockout mouse models for GPLs, such as H/K-ATPase transgenic and knockout mutant mice and gastrin gene knockout mice. Combined with Helicobacter infection, and treatment with chemical carcinogens, these mice develop GPLs or GC and thus provide models for studying the molecular biology of GC, which may lead to the discovery and development of novel drugs. In this review, we discuss recent progress in the use of genetically-engineered mouse models for GPL research, with particular emphasis on the importance of examining the gastric mucosa at the histological level to investigate morphological changes of GPL and GC and associated protein and gene expression.

The Role of GSK3β in the Regulation of IL-10 and IL-12 Production Induced by Lipopolysaccharide in PK-15 Cells

Glycogen synthase kinase-3β (GSK3β) plays a fundamental role in the inflammatory response by controlling the balance between pro- and anti-inflammatory cytokine production induced by lipopolysaccharide (LPS). However, the inflammatory roles of different porcine GSK3β isoforms in response to LPS remain unknown. In this study, the activity of porcine GSK3β was inhibited in response to LPS stimulation through increased serine 9 phosphorylation of GSK3β, which increased the production of interleukin (IL)-10 and IL-12 in PK-15 cells. However, treatment with an inhibitor of GSK3β, lithium chloride, significantly increased the production of IL-10 and IL-12 compared with the untreated control and significantly decreased the production of IL-10 and IL-12 compared with LPS stimulation. Moreover, all four glycogen synthase kinase-3 transcripts had positive roles in the production of IL-10 and IL-12 to varying degrees, suggesting their importance in the LPS-induced inflammatory response in pigs.

Progress in understanding the association between interleukin-1B gene polymorphisms and susceptibility to gastric cancer

Gastric cancer is one of severe diseases threatening human health and has a close association with Helicobacter pylori infection. Interleukin-1B (IL-1B) gene polymorphisms have been suggested to be associated with susceptibility to gastric cancer; however, there is still controversy over this point of view. In this paper we will summarize recent progress in understanding the association between IL-1B gene polymorphisms and susceptibility to gastric cancer in population in different areas or of different races

Socioeconomic and nutritional factors account for the association of gastric cancer with Amerindian ancestry in a Latin American admixed population

Gastric cancer is one of the most lethal types of cancer and its incidence varies worldwide, with the Andean region of South America showing high incidence rates. We evaluated the genetic structure of the population from Lima (Peru) and performed a case-control genetic association study to test the contribution of African, European, or Native American ancestry to risk for gastric cancer, controlling for the effect of non-genetic factors. A wide set of socioeconomic, dietary, and clinic information was collected for each participant in the study and ancestry was estimated based on 103 ancestry informative markers. Although the urban population from Lima is usually considered as mestizo (i.e., admixed from Africans, Europeans, and Native Americans), we observed a high fraction of Native American ancestry (78.4% for the cases and 74.6% for the controls) and a very low African ancestry (<5%). We determined that higher Native American individual ancestry is associated with gastric cancer, but socioeconomic factors associated both with gastric cancer and Native American ethnicity account for this association. Therefore, the high incidence of gastric cancer in Peru does not seem to be related to susceptibility alleles common in this population. Instead, our result suggests a predominant role for ethnic-associated socioeconomic factors and disparities in access to health services. Since Native Americans are a neglected group in genomic studies, we suggest that the population from Lima and other large cities from Western South America with high Native American ancestry background may be convenient targets for epidemiological studies focused on this ethnic group.

IL-1ra anti-inflammatory cytokine polymorphism is associated with risk of gastric cancer and chronic gastritis in a Brazilian population, but the TNF-β pro-inflammatory cytokine is not

Genetic polymorphisms in genes that codify inflammatory cytokines have been associated with gastric carcinogenesis. This study evaluated polymorphisms IL-1RN VNTR and TNFB+252A/G in a population from Southeast Brazil with regard to the risk of chronic gastritis and gastric cancer and the presence of an association of gastric lesions with risk factors such as gender, age, smoking, drinking and Helicobacter pylori infection. In this case-control study, polymorphism at IL-1RN VNTR was investigated using the allele-specific polymerase chain reaction method, while the polymerase chain reaction-restriction fragment length polymorphism technique was used to identify the TNFB+252A/G genotype in 675 Brazilian individuals [229 with chronic gastritis (CG), 200 with gastric cancer (GC) and 246 healthy individuals as controls (C)]. Multiple logistic regression analysis (log-additive, dominant, and recessive models) have not showed association of the genotype frequencies for the SNP TNFB + 252A/G with risk of CG or GC. However, as for IL-1RN VNTR it was observed significant differences in all three analysis models, with higher values of OR in recessive model, both in the GC group (OR = 3.04, 95% CI = 1.41-6.56, p < 0.01) and CG (OR = 2.32, 95% CI = 1.10-4.90, p = 0.02) compared to the C group. In addition, the multiple logistic regression showed also an association with risk factors such as male gender, older age and alcohol intake regarded GC group. So, our results indicated that the IL-1RN*2 allele may increase the risk of gastric cancer and precancerous lesions in the Southeast Brazilian population, reinforcing the importance of host genetic factors in the susceptibility to gastric cancer and the participation of cytokines in both the inflammation and the carcinogenic process.

Gene expression in response to ionizing radiation and family history of gastric cancer

Genes and molecular pathways involved in familial clustering of gastric cancer have not yet been identified. The purpose of the present study was to investigate gene expression changes in response to a cellular stress, and its link with a positive family history for this neoplasia. To this aim leukocytes of healthy first-degree relatives of gastric cancer patients and controls were challenged in vitro with ionizing radiation and gene expression evaluated 4 h later on microarrays with 1,800 cancer-related genes. Eight genes, mainly involved in signal transduction and cell cycle regulation, were differentially expressed in healthy relatives of gastric cancer cases. Functional class scoring by Gene Ontology classification highlighted two G-protein related pathways, implicated in the proliferation of neoplastic tissue, which were differentially expressed in healthy subjects with positive family history of gastric cancer. The relative expression of 84 genes related to these pathways was examined using the SYBR green-based quantitative real-time PCR. The results confirmed the indication of an involvement of G-protein coupled receptor pathways in GC familiarity provided by microarray analysis. This study indicates a possible association between familiarity for gastric cancer and altered transcriptional response to ionizing radiation.

Association of IL1B -511C/-31T haplotype and Helicobacter pylori vacA genotypes with gastric ulcer and chronic gastritis

Background

The association between proinflammatory cytokine gene polymorphisms and gastric diseases related to Helicobacter pylori varies by population and geographic area.

Our objective was to determine if the IL-1B -511 T>C and -31 C>T polymorphisms and H. pylori vacA genotypes are associated with risk of chronic gastritis and gastric ulcer in a Mexican population.

Methods

We conducted endoscopic studies in 128 patients with symptoms of dyspepsia. We took two biopsies from the body, antrum, or ulcer edge from each patient, and classified our histopathological findings according to the Sydney System. H. pylori infection and vacA genotyping were accomplished via PCR from total DNA of the gastric biopsies. We confirmed the presence of anti-H. pylori serum IgG and IgM in 102 control subjects. In both case subjects and control subjects, the IL-1B -511 T>C polymorphism was genotyped by PCR-RFLPs and the IL-1B -31 C>T polymorphism was genotyped by pyrosequencing.

Results

Sixty-two point seven (62.7%) of the 102 control subjects were H. pylori-seropositive. Among the case subjects, 100 were diagnosed with chronic gastritis and 28 with gastric ulcer. We found that 77% of the patients with chronic gastritis and 85.7% of the patients with gastric ulcer were H. pylori-positive. The predominant H. pylori genotype was vacA s1m1 (58.4%) and the most frequent subtype was vacA s1. The -511 TC, (rs16944 -511 T>C) genotype and the -511C allele were associated with chronic gastritis (OR = 3.1, 95% CI = 1.4-6.8 and OR = 3.0, 95% CI = 1.4-6.0, respectively). The subjects carrying -31T (rs1143627 -31 C>T) were found to be at a higher risk of having chronic gastritis (OR = 2.8, 95% CI = 1.3-5.8). The IL-1B -511C/-31T haplotype was associated with chronic gastritis (OR = 2.1, 95% CI = 1.2-3.8) but not with gastric ulcer.

Conclusions

The H. pylori vacA genotypes identified herein were similar to those reported for other regions of Mexico. The vacA s1m1 genotype was not associated with gastric ulcer. In the southern Mexican population, the IL-1B -511C and -31T alleles and the -511C/-31T and -511T/-31T haplotypes are associated with increased risk of chronic gastritis and gastric ulcer.

Helicobacter pylori infection generates genetic instability in gastric cells

The discovery that Helicobacter pylori is associated with gastric cancer has led to numerous studies that investigate the mechanisms by which H. pylori induces carcinogenesis. Gastric cancer shows genetic instability both in nuclear and mitochondrial DNA, besides impairment of important DNA repair pathways. As such, this review highlights the consequences of H. pylori infection on the integrity of DNA in the host cells. By down-regulating major DNA repair pathways, H. pylori infection has the potential to generate mutations. In addition, H. pylori infection can induce direct changes on the DNA of the host, such as oxidative damage, methylation, chromosomal instability, microsatellite instability, and mutations. Interestingly, H. pylori infection generates genetic instability in nuclear and mitochondrial DNA. Based on the reviewed literature we conclude that H. pylori infection promotes gastric carcinogenesis by at least three different mechanisms: (1) a combination of increased endogenous DNA damage and decreased repair activities, (2) induction of mutations in the mitochondrial DNA, and (3) generation of a transient mutator phenotype that induces mutations in the nuclear genome.

Interleukin-1 beta single-nucleotide polymorphism's C allele is associated with elevated risk of gastric cancer in Helicobacter pylori-infected Peruvians

Particular alleles of the interleukin-1B (IL-1B) gene have been correlated with increased risk of atrophic gastritis and gastric cancer in the populations of East Asia and Europe. No such data exist from Peru, a developing country with a population genotypically different from others studied and with a high prevalence of Helicobacter pylori infection and gastric cancer. We conducted a case-control study comparing 334 hospitalized patients with atrophic gastritis or gastric cancer with 158 nonatrophic gastritis patients (controls). Conditional logistic regression analysis revealed that an increased risk of atrophic gastritis (odds ratio, 5.60) and gastric cancer (odds ratio, 2.36) was associated with the IL-1B-511 C allele. Our study is the first to establish this allele as a risk for these conditions. Given the high prevalence of H. pylori and recurrence rate after treatment, IL-1B-511 single-nucleotide polymorphism analysis may identify those individuals who would benefit most from robust H. pylori eradication efforts in Peru.

Evaluation of radiation-induced chromosome instability in subjects with a family history of gastric cancer

Gastric cancer (GC) shows a familiar predisposition which is largely unexplained. In this study the hypothesis that radiation sensitivity is implicated in the familiar predisposition to GC was investigated by means of the cytokinesis-block micronucleus assay. Data indicate that a family history of GC is not associated with any of the biomarkers investigated and does not interact with the demographic variables considered. When study subjects were dichotomized around the median age, a significant prevalence of micronuclei was observed in older subjects. Age and both spontaneous and radiation-induced micronuclei were linearly correlated. The effect of age was not modified by gender or smoking habits.

Interleukin-1 and TNF-alpha polymorphisms and Helicobacter pylori in a Brazilian Amazon population

AIM

To study the association between Interleukin-1 (IL-1) and tumor necrosis factor (TNF)-alpha polymorphisms, infection by Helicobacter pylori (H pylori) and the development of gastrointestinal diseases.

METHODS

Genomic DNA was extracted from the peripheral blood of 177 patients with various gastrointestinal diseases and from 100 healthy volunteers. The polymorphisms in IL-1beta and TNF-alpha genes were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) and those from IL-1RN with PCR. The presence of infection due to H pylori and the presence of the CagA toxin were detected by serology. The histopathological parameters in the gastric biopsies of the patients were according to the Sydney classification.

RESULTS

A comparison of the frequencies of the different polymorphisms studied among the patients and the control group demonstrated that the allele IL-1RN*2 was more frequent among patients with gastric ulcers and adenocarcinoma. Carriers of the allele IL-RN*2 and those with reactive serology for anti-CagA IgG had a greater risk of developing peptic ulcer and gastric adenocarcinoma, as well as a higher degree of inflammation and neutrophilic activity in the gastric mucosa.

CONCLUSION

Our results indicate a positive association between IL-1RN gene polymorphism and infection by positive H pylori CagA strains and the development of gastric ulcers and adenocarcinoma.

A role for glycogen synthase kinase-3 in antagonizing mycobacterial immune evasion by negatively regulating IL-10 induction

Mtb dysregulates monocyte/macrophage functions to produce a large amount of the immunosuppressive cytokine IL-10. An important function of IL-10 in promoting Mtb survival is the suppression of antigen presentation of monocytes/macrophages to T cells. This dampens the host immune responses and provides an opportunity for immune evasion. GSK3 has been shown to control the balance between pro- and anti-inflammatory cytokine productions. Here, we investigated whether GSK3 regulates IL-10 expression and mediates a protective role upon live mycobacterial challenge using BCG as a model. Our results showed that BCG increased Akt phosphorylation and inhibited GSK3 activity, resulting in increased IL-10 production. We confirmed further that suppression of GSK3 activities by a specific chemical inhibitor strongly enhanced BCG-induced IL-10 production. We also showed that IL-10 secreted by BCG-infected human PBMo was a major suppressor of subsequent IFN-gamma production by PBMC and HLA-DR expression on PBMo in response to BCG. Neutralization of PBMo-secreted IL-10 by anti-IL-10 antibodies restored the IFN-gamma production and HLA-DR surface expression. Taken together, GSK3 negatively regulates mycobacteria-induced IL-10 production in human PBMo. The kinase may play a role in restoring IFN-gamma secretions and subsequent antigen presentation in response to mycobacterial infection. In conclusion, our results suggest a significant role for GSK3 in guarding against mycobacterial evasion of immunity via IL-10 induction in the host.

Interleukin-1 and TNF-α polymorphisms and Helicobacter pylori in a Brazilian Amazon population

AIM: To study the association between Interleukin-1 (IL-1) and tumor necrosis factor (TNF)-α polymorphisms, infection by Helicobacter pylori (H pylori) and the development of gastrointestinal diseases.

METHODS: Genomic DNA was extracted from the peripheral blood of 177 patients with various gastrointestinal diseases and from 100 healthy volunteers. The polymorphisms in IL-1β and TNF-α genes were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) and those from IL-1RN with PCR. The presence of infection due to H pylori and the presence of the CagA toxin were detected by serology. The histopathological parameters in the gastric biopsies of the patients were according to the Sydney classification.

RESULTS: A comparison of the frequencies of the different polymorphisms studied among the patients and the control group demonstrated that the allele IL-1RN*2 was more frequent among patients with gastric ulcers and adenocarcinoma. Carriers of the allele IL-RN*2 and those with reactive serology for anti-CagA IgG had a greater risk of developing peptic ulcer and gastric adenocarcinoma, as well as a higher degree of inflammation and neutrophilic activity in the gastric mucosa.

CONCLUSION: Our results indicate a positive association between IL-1RN gene polymorphism and infection by positive H pylori CagA strains and the development of gastric ulcers and adenocarcinoma.

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.

What lurks beneath: IL-11, via Stat3, promotes inflammation-associated gastric tumorigenesis

Chronic inflammation in the stomach induces cellular transformation and gastric cancer primarily in the distal stomach or antrum. In this issue of the JCI, a study in mice by Ernst et al. provides new insight into the role of IL-11 and its glycoprotein 130 (gp130) receptor in inflammation-associated gastric epithelial cell oncogenic transformation, which they show is mediated by and dependent on increased activation of Stat3 and, to a lesser extent, Stat1 (see the related article beginning on page 1727). Prior studies from this group have shown that Stat3 hyperactivity stimulates the TGF-beta inhibitor Smad7. Collectively, the studies suggest that an important pathway of oncogenic transformation in the stomach is through suppression of growth inhibitory signals, such as members of the TGF-beta family, that originate from the stroma.

IL-4 -588C>T polymorphism and IL-4 receptor alpha [Ex5+14A>G; Ex11+828A>G] haplotype concur in selecting H. pylori cagA subtype infections

BACKGROUND

The Th2 cytokine IL-4 might limit H. pylori associated gastric inflammation and favour H. pylori clearance. The aim of the study was to verify whether IL-4 -588C>T SNP, or two SNPs of the gene coding the alpha chain of IL-4 receptor (IL-4RA Ex5+14A>G, IL-4RA Ex11+828A>G) considered singly or as haplotypes, are correlated with H. pylori virulence genes or H. pylori associated diseases.

METHODS

We studied 144 patients with non-cardia gastric cancer (NCGC)(41/50 with present or past H. pylori infection), 75 with duodenal ulcer (DU)(66 H. pylori infected) and 171 with gastritis (CG)(107 H. pylori infected). cagA gene was present in 24/28 NCGC, 45/59 DU and 56/107 CG.

RESULTS

All SNPs were in Hardy-Weinberg equilibrium. IL-4RA haplotypes frequencies were estimated using Arlequin software. Neither the SNPs nor the IL-4RA haplotype correlated with disease diagnosis, H. pylori infection, degree of mucosal inflammation or intestinal metaplasia. IL-4 -588T allele (OR=3.69, 95% CI:1.34-10.16) and IL-4RA GA haplotype (p<0.05) enhanced the risk for cagA positive infections. IL-4RA GA haplotype correlated with IL-4 protein levels in H. pylori infected gastric mucosa.

CONCLUSIONS

IL-4 and IL-4RA gene polymorphisms concur in selecting the H. pylori infecting strain, probably influencing the IL-4 signalling pathway.

Interaction of polymorphisms in the interleukin 1B-31 and general transcription factor 2A1 genes on the susceptibility to gastric cancer

Proinflammatory genotypes of the IL-1 (interleukin-1) gene have been associated with an increased gastric cancer risk in Caucasians, whereas some studies in Asian populations did not find such association. Furthermore, the risk genotypes differed somewhat between Caucasian and Asian populations. These findings might reflect more complex genetic mechanisms in Asian compared with Caucasian populations. Therefore, we examined a polymorphism (rs1864169) in the general transcription factor 2A1 (GTF2A1) gene as a test of the hypothesis that this transcription factor and IL-IB gene polymorphisms interact in the effects on the gastric cancer risk due to the possible biological relationship between the two genes. Genotyping of the 515 control and 342 case samples was performed by primer extension assay and SNaPshot assays. We found an association between carriage of the IL1B-31C allele and gastric cancer among Koreans, which was observed only in subjects with GTF2A1 GG genotype. The GTF2A1GG/IL1B-31C carrier genotype combination showed stronger association with diffuse type gastric cancer cases. These findings indicate that the effect of the two genetic polymorphisms on risk of gastric cancer is synergistic. Our results also suggest that an additional host genetic factor acting epistatically may differentially contribute to the histogenesis of the diffuse and intestinal subtypes.

Assessment of the toll-like receptor 4 Asp299Gly, Thr399Ile and interleukin-8 -251 polymorphisms in the risk for the development of distal gastric cancer

Background

The intensity of the inflammation induced by Helicobacter pylori colonization is associated with the development of distal gastric cancer (GC). The host response to H. pylori has been related to genetic polymorphisms that influence both innate and adaptive immune responses.

Our aim was to investigate whether the presence of the TLR4 Asp299Gly, TLR4 Thr399Ile and IL-8-251 A/T polymorphisms had any influence in the development of distal GC in a Mexican population.

Methods

We studied 337 patients that were divided in two groups: 78 patients with histologically confirmed distal GC and 259 non-cancer controls. The presence of H. pylori in the control population was defined by positive results of at least two of four diagnostic tests: serology, histology, rapid urease test and culture. Human DNA was purified and genotyped for TLR4 Asp299Gly polymorphism by pyrosequencing, for TLR4 Thr399Ile by PCR-RFLP and for IL8-251 by the amplification refractory mutation system (ARMS)-PCR.

Results

The non-cancer control group was found to be in Hardy-Weinberg equilibrium at the polymorphic loci studied (chi-square _H-W = 0.58 for IL8-251, 0.42 for TLR4 Asp299Gly and 0.17 for TLR4 Thr399Ile). The frequencies of mutated alleles (homozygous plus heterozygous) were compared between cases and controls. We found no significant difference for TLR4- Asp299Gly [the 7.7% of distal GC patients and 7.7 % non-cancer controls (p = 0.82)] and for TLR4 Thr399Ile [the 1.3% of GC patients and the 5% of the control population (p = 0.2)]. In contrast, for IL-8-251 A/T, 80.77% of the GC patients and 66.4% in the control group age and gender matched had at least one copy of mutated allele (OR = 2.12, 95% CI = 1.1–4.2) (p = 0.023).

Conclusion

This study showed that the IL8-251*A allele could be related to the development of distal gastric cancer in this Mexican population.

Inflammation, atrophy, and gastric cancer

The association between chronic inflammation and cancer is now well established. This association has recently received renewed interest with the recognition that microbial pathogens can be responsible for the chronic inflammation observed in many cancers, particularly those originating in the gastrointestinal system. A prime example is Helicobacter pylori, which infects 50% of the world's population and is now known to be responsible for inducing chronic gastric inflammation that progresses to atrophy, metaplasia, dysplasia, and gastric cancer. This Review provides an overview of recent progress in elucidating the bacterial properties responsible for colonization of the stomach, persistence in the stomach, and triggering of inflammation, as well as the host factors that have a role in determining whether gastritis progresses to gastric cancer. We also discuss how the increased understanding of the relationship between inflammation and gastric cancer still leaves many questions unanswered regarding recommendations for prevention and treatment.