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

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

Polymorphisms of TNF-alpha (− 308), IL-1beta (+ 3954) and IL1-Ra (VNTR) are associated to severe stage of endometriosis in Mexican women: a case control study

Background

Endometriosis is an estrogen-dependent and chronic inflammatory disease affecting up to 10% of women. It is the result of a combined interaction of genetic, epigenetic, environmental, lifestyle, reproductive and local inflammatory factors. In this study, we investigated whether single nucleotide polymorphisms (SNPs) mapping to TNF-alpha (TNF, rs1800629) and IL-1beta (IL1B, rs1143634) and variable number tandem repeat polymorphism mapping to IL1-Ra (IL1RN intron 2, rs2234663) genetic loci are associated with risk for endometriosis in a Mexican mestizo population.

Methods

This study included 183 women with confirmed endometriosis (ENDO) diagnosed after surgical laparoscopy and 186 women with satisfied parity and without endometriosis as controls (CTR). PCR/RFLP technique was used for genotyping SNPs (rs1800629 and rs1143634); PCR for genotyping rs2234663.

Results

We found no statistical differences in age between groups nor among stages of endometriosis and the CTR group. We observed no difference in genotype and allele frequencies, nor carriage rate between groups in none of the three studied polymorphisms. The prevalence of TNF*2-allele heterozygotes (p = 0.025; OR 3.8), TNF*2-allele (p = 0.029; OR 3.4), IL1B*2-allele heterozygotes (p = 0.044; OR 2.69) and its carriage rate (p = 0.041; OR 2.64) in endometriosis stage IV was higher than the CTR group. Surprisingly, the carriage rate of IL1RN*2-allele (ENDO: p = 0.0004; OR 0.4; stage I: p = 0.002, OR 0.38; stage II: p = 0.002, OR 0.35; stage III: p = 0.003, OR 0.33), as well as the IL1RN*2-allele frequencies (ENDO: p = 0.0008, OR 0.55; I: p = 0.037, OR 0.60; II: p = 0.002, OR 0.41; III: p = 0.003, OR 0.38) were lower than the CTR group. Women with endometriosis stage IV (severe) had frequencies more alike to the CTR group in the IL1RN*2 allele frequency (31.2% vs. 27.2%) and carriage rate (37.5% vs. 41.9%).

Conclusion

Although these polymorphisms are not associated with the risk of endometriosis, Mexican mestizo women with severe stage of endometriosis have higher frequencies of TNF*2-, IL1B*2- and IL1RN*2-alleles, which may explain a possible correlation with disease severity rather than predisposition or risk.

Helicobacter pylori-induced inflammation masks the underlying presence of low-grade dysplasia on gastric lesions

BACKGROUND

Helicobacter pylori (H. pylori) infection has been associated with a long-term risk of precancerous gastric conditions (PGC) even after H. pylori eradication.

AIM

To investigate the efficacy of High-Resolution White-Light Endoscopy with Narrow-Band Imaging in detecting PGC, before/after H. pylori eradication.

METHODS

We studied 85 consecutive patients with H. pylori-related gastritis with/without PGC before and 6 mo after proven H. pylori eradication. Kimura-Takemoto modified and endoscopic grading of gastric intestinal metaplasia classifications, were applied to assess the endoscopic extension of atrophy and intestinal metaplasia. The histological result was considered to be the gold standard. The Sydney System, the Operative-Link on Gastritis-Assessment, and the Operative-Link on Gastric-Intestinal Metaplasia were used for defining histological gastritis, atrophy and intestinal metaplasia, whereas dysplasia was graded according to World Health Organization classification. Serum anti-parietal cell antibody and anti-intrinsic factor were measured when autoimmune atrophic gastritis was suspected.

RESULTS

After H. pylori eradication histological signs of mononuclear/polymorphonuclear cell infiltration and Mucosal Associated Lymphoid Tissue-hyperplasia, disappeared or decreased in 100% and 96.5% of patients respectively, whereas the Operative-Link on Gastritis-Assessment and Operative-Link on Gastric-Intestinal Metaplasia stages did not change. Low-Grade Dysplasia prevalence was similar on random biopsies before and after H. pylori eradication (17.6% vs 10.6%, P = 0.19), but increased in patients with visible lesions (0% vs 22.4%, P < 0.0001). At a multivariate analysis, the probability for detecting dysplasia after resolution of H. pylori-related active inflammation was higher in patients with regression or reduction of Mucosal Associated Lymphoid Tissue hyperplasia, greater alcohol consumption, and anti-parietal cell antibody and/or anti-intrinsic factor positivity [odds ratio (OR) = 3.88, 95% confidence interval (CI): 1.31-11.49, P = 0.01; OR = 3.10, 95%CI: 1.05-9.12, P = 0.04 and OR = 5.47, 95%CI: 1.33-22.39, P < 0.04, respectively].

CONCLUSION

High-Resolution White-Light Endoscopy with Narrow-Band Imaging allows an accurate diagnosis of Low-Grade Dysplasia on visible lesions after regression of H. pylori-induced chronic gastritis. Patients with an overlap between autoimmune/H. pylori-induced gastritis may require more extensive gastric mapping.

The NLRP3 inflammasome: a therapeutic target for inflammation-associated cancers

Introduction: Inflammasomes are large multimeric intracellular complexes that are capable of maturation and secretion of pro-inflammatory cytokines, IL-1β and IL-18, in response to danger signal molecules. As a member of the inflammasome family, the NLRP3 inflammasome has recently been under intense investigation revealing its possible role in several human diseases especially cancers.Areas covered: In this review, we will discuss the biology and mechanism of NLRP3 inflammasome activation, its role in specific types of tumors and the novel therapeutic modalities targeting this complex.Expert opinion: The NLRP3 inflammasome and its components including the adapter apoptosis-associated speck-like (ASC) protein and caspase-1 impose different and sometimes contrasting effects in tumorigenesis depending on various contexts. Considering the novel role of this complex in the initiation and progression of neoplasia, the NLRP3 inflammasome and its pathways provide desirable therapeutic targets for prevention, treatment, and prognosis of certain types of cancer. To date, several agents have been introduced for this purpose, some of which have shown promising results in the clinic.

DNA variants in Helicobacter pylori infected patients with chronic gastritis, dysplasia and gastric cancer

PURPOSE

The main scope of this study was to evaluate the importance of selected DNA variants for developing inflammation of gastric mucosa and carcinogenesis in gastrointestinal diseases in patients infected with Helicobacter pylori.

PATIENTS AND METHODS

Patients subjected to analysis constituted a group of 131 consecutive cases, with control groups consisting of 100 healthy volunteers and 13 dyspeptic patients. Molecular analysis included the following genes: TP53 (c.743 G > A, c.746 G > A, c.749C > T), MSH2 (c.942 + 3A > T), MLH1 (c.2041 G > A), NOD2/CARD15 (c.3016_3017insC, c.802C > T), IL1A (c.-949C > T) and IL1B (c.315C > T). DNA variants were detected using PCR-RFLP, pyrosequencing and sequencing.

RESULTS

Mutations of the analyzed genes were observed more frequently in patients with a higher degree of mucosal lesions (50.9%) than in patients with milder mucosal changes (27.6%). Single mutations and polymorphisms did not affect the course of the disease. Our analysis confirms the influence of the NOD2/CARD15 c.802C > T polymorphism on the development of mucosal changes. A correlation of the frequency of the CT genotype of the NOD2/CARD15 c.802C > T polymorphism with the NOD2/CARD15 c.3016_3017insC mutation was observed. The TT genotype frequency in the c.315C > T IL1B gene polymorphism was statistically significantly higher in patients with mucosa changes.

CONCLUSIONS

Accumulation of molecular abnormalities may increase the susceptibility to inflammatory response of the gastric mucosa in H. pylori-infected patients and play an important role in the development of chronic active gastritis, atrophy, intestinal metaplasia, dysplasia and the intestinal type of gastric cancer. The severity of gastric mucosal damage correlates with the presence of mutations in the gastric mucosa and the age of patients.

Role of polymorphisms in genes that encode cytokines and Helicobacter pylori virulence factors in gastric carcinogenesis

The Helicobacter pylori (H. pylori) infection is a determinant factor in gastric cancer (GC) development. However, the infection outcomes are variable and depend on both host and bacterial characteristics. Some host cytokines such as interleukin (IL)-1β, IL-1Ra, IL-8, IL-10 and tumor necrosis factor-α play important roles in the host immune system response to the pathogen, in the development of gastric mucosal lesions and in cell malignant transformation. Therefore, these host factors are crucial in neoplastic processes. Certain polymorphisms in genes that encode these cytokines have been associated with an increased risk of GC. On the other hand, various virulence factors found in distinct H. pylori bacterial strains, including cytotoxin-associated antigen A, vacuolating cytotoxin, duodenal ulcer promoting gene A protein, outer inflammatory protein and blood group antigen binding adhesin, have been associated with the pathogenesis of different gastric diseases. The virulent factors mentioned above allow the successful infection by the bacterium and play crucial roles in gastric mucosa lesions, including malignant transformation. Moreover, the role of host polymorphisms and bacterial virulence factors in gastric carcinogenesis seems to vary among different countries and populations. The identification of host and bacterium factors that are associated with an increased risk of GC development may be useful in determining the prognosis of infection in patients, what could help in clinical decision-making and in providing of an optimized clinical approach.

Helicobacter pylori associated factors in the development of gastric cancer with special reference to the early-onset subtype

Nowadays, gastric cancer is one of the most common neoplasms and the fourth cause of cancer-related death on the world. Regarding the age at the diagnosis it is divided into early-onset gastric carcinoma (45 years or younger) and conventional gastric cancer (older than 45). Gastric carcinomas are rarely observed in young population and rely mostly on genetic factors, therefore provide the unique model to study genetic and environmental alternations. The latest research on early-onset gastric cancer are trying to explain molecular and genetic basis, because young patients are less exposed to environmental factors predisposing to cancer. In the general population, Helicobacter pylori, has been particularly associated with intestinal subtype of gastric cancers. The significant association of Helicobacter pylori infection in young patients with gastric cancers suggests that the bacterium has an etiologic role in both diffuse and intestinal subtypes of early-onset gastric cancers. In this paper we would like to ascertain the possible role of Helicobacter pylori infection in the development of gastric carcinoma in young patients. The review summarizes recent literature on early-onset gastric cancers with special reference to Helicobacter pylori infection.

Interleukin-1β and interleukin-1receptor antagonist polymorphisms in Egyptian children with febrile seizures: A case-control study

Febrile seizure is the most common seizure disorder of childhood. Of the pro-inflammatory cytokines, interleukin-1 is defined as the first endogenous pyrogen.We designed this study to investigate single-nucleotide polymorphisms (SNPs) situated at positions -31 (C/T), and -511 (C/T) of interleukin-1beta (IL-1β) gene promoter and interleukin-1receptor antagonist (IL-1RA) gene variable number of tandem repeats in intron 2 (VNTR); to determine whether these polymorphisms could be a marker of susceptibility to febrile seizures in Egyptian children and we also measured the serum level of IL-1β to assess its relation to such polymorphisms.This was a case-control study included 155 patients with febrile seizure, and matched with age, sex, ethnicity 155 healthy control subjects. IL-1β promoter at positions -31 (C/T), -511 (C/T), and IL-1RA gene VNTR polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum IL-1β levels were measured by enzyme-linked immunosorbent assay (ELISA) method.The frequency of the IL-1β-511 TT genotype and T allele at the same position were observed to be increased in patients with febrile seizures (FS) compared with the control group (odds ratio [OR]: 3.96; 95% confidence interval [CI]: 1.68-9.5; P = 0.001 for the TT genotype and OR: 1.65; 95% CI: 1.18-2.3; P = 0.003 for the T allele, respectively). The IL-1 RA II/II homozygous variant and IL-1 RA allele II were overrepresented in patients with FS than control group (OR: 4.02; 95% CI: 1.78-9.15; P = 0.001and OR: 1.73; 95% CI: 1.24-2.4; P = 0.001, respectively). We found a significant positive association between the IL-1 RA II/II genotype and susceptibility to FS in sporadic cases as did allele II at the same position (OR: 5.04; 95% CI: 2.1-12.5 for the IL-1 RA II/II genotype; P = 0.001) and (OR: 1.94; 95% CI: 1.3-2.8 for the allele II; P = 0.001, respectively). Carriers of the IL-1RA II/II homozygous variant and allele II had significantly higher serum levels of IL-1β compared with those with other genotypes and alleles.We demonstrate for the first time that the presence of a T allele or TT genotype at -511 of IL-1β promoter and IL-1RA II/II genotype constitute risk factors for developing FS in Egyptian children.

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

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

Effect of IL-1β and IL-1RN polymorphisms in carcinogenesis of the gastric mucosa in patients infected with Helicobacter pylori in Algeria

Background

Infection with Helicobacter pylori is considered a potential risk of developing gastric cancer in association with contributing host genetic factor. IL-1β and IL-1RN polymorphisms appear to maintain and promote Helicobacter pylori infection and to stimulate neoplastic growth of the gastric mucosa.

Objective and methods

In order to elucidate the effect of these polymorphisms in combination with gastric cancer in a population from northwestern Algeria, a case-control study was carried out on 79 patients infected with H. pylori with chronic atrophic gastritis and/or gastric carcinoma, and 32 subjects were recruited as case-control. IL-1β-31 bi-allelic and IL-1β-511 bi-allelic polymorphisms and IL-1RN penta-allelic were genotyped.

Results

IL-1β-31C was associated with an increased risk of developing gastric carcinoma (OR=4.614 [1.43−14.81], p=0.01). However, IL-1RN2 heterozygous allele type was significantly associated with chronic atrophic gastritis (OR=4.2 [1.23−3.61], p=0.022). IL-1β-511T was associated with an increased risk of development of chronic atrophic gastritis (OR=4.286 [1.54−11.89], p=0.005).

Conclusion

IL-1β and IL-1RN polymorphisms associated with H. pylori infection contribute to the development of chronic atrophic gastritis and gastric carcinomas in an Algerian population. The alleles IL-1β-31C and IL-1RN were associated with an increased risk of developing gastric carcinoma, and IL-1β-511T with an increased risk of developing chronic atrophic gastritis with no significant association of developing gastric carcinoma.

Familial Clustering of Gastric Cancer: A Retrospective Study Based on the Number of First-Degree Relatives

This comprehensive cross-sectional study aimed to identify factors contributing to familial aggregation of gastric cancer (GC). A total of 1058 GC patients and 1268 controls were analyzed separately according to the presence or absence of a first-degree relative of GC (GC-relative). Logistic regression analysis adjusted for age, gender, residence during childhood, smoking, alcohol intake, monthly income, spicy food ingestion, Helicobacter pylori status and host cytokine polymorphisms was performed. Cytotoxin-associated gene A (cagA) positivity was a distinctive risk factor for GC in the family history (FH)-positive group (odds ratio [OR], 2.39; 95% confidence interval [CI], 1.42-4.00), while current/ex-smoker, moderate to strong spicy food ingestion, and non-B blood types were more closely associated with GC in the FH-negative group. Among the FH-positive group, alcohol consumption showed a synergistic carcinogenic effect in the at least 2 GC-relatives group compared to the 1 GC-relative group (1.71 vs. 9.58, P for interaction = 0.026), and this was dose-dependent. In the subjects with ≥2 GC-relatives, TGFB1-509T/T was a risk factor for GC (OR 23.74; 95% CI 1.37-410.91), as were rural residency in childhood, alcohol consumption, spicy food ingestion, and cagA positivity. These results suggest that subjects with FH may be a heterogeneous group in terms of gastric cancer susceptibility. Especially, subjects with ≥2 GC-relatives should undergo risk stratification including TGFB1-509T/T and alcohol consumption.

Helicobacter pylori infection and gastric carcinoma: Not all the strains and patients are alike

Gastric carcinoma (GC) develops in only 1%-3% of Helicobacter pylori (H. pylori) infected people. The role in GC formation of the bacterial genotypes, gene polymorphisms and host's factors may therefore be important. The risk of GC is enhanced when individuals are infected by strains expressing the oncoprotein CagA, in particular if CagA has a high number of repeats containing the EPIYA sequence in its C'-terminal variable region or particular amino acid sequences flank the EPIYA motifs. H. pylori infection triggers an inflammatory response characterised by an increased secretion of some chemokines by immunocytes and colonised gastric epithelial cells; these molecules are especially constituted by proteins composing the interleukin-1beta (IL-1β) group and tumour necrosis factor-alpha (TNF-α). Polymorphisms in the promoter regions of genes encoding these molecules, could account for high concentrations of IL-1β and TNF-α in the gastric mucosa, which may cause hypochlorhydria and eventually GC. Inconsistent results have been attained with other haplotypes of inflammatory and anti-inflammatory cytokines. Genomic mechanisms of GC development are mainly based on chromosomal or microsatellite instability (MSI) and deregulation of signalling transduction pathways. H. pylori infection may induce DNA instability and breaks of double-strand DNA in gastric mucocytes. Different H. pylori strains seem to differently increase the risk of cancer development run by the host. Certain H. pylori genotypes (such as the cagA positive) induce high degrees of chronic inflammation and determine an increase of mutagenesis rate, oxidative-stress, mismatch repair mechanisms, down-regulation of base excision and genetic instability, as well as generation of reactive oxygen species that modulate apoptosis; these phenomena may end to trigger or concur to GC development.

Helicobacter pylori Infection Synergistic with IL-1β Gene Polymorphisms Potentially Contributes to the Carcinogenesis of Gastric Cancer

Helicobacter pylori (H. pylori) infection is the most common chronic bacterial infection in the world and the etiological agent for most gastric cancer (GC). Interleukin-1β (IL-1β) is a potent proinflammatory cytokine, and its deregulation is closely associated with the tumorigenesis of several cancers. Recent studies have revealed that the IL-1β-31 and -511T alleles are closely associated with gastric carcinogenesis due to their roles in the induction of gastric precancerous lesions and hypochlorhydria. Furthermore, H. pylori infection has a synergistic effect on the development of GC with IL-1β gene polymorphisms, and the highest prevalence of severe gastric abnormalities are found in patients with both host and bacterial high-risk genotypes (cagA(+)/vacAs1(+)/IL-1β-511T). Therefore, these recent advances demonstrate that H. pylori synergistic with IL-1β gene polymorphisms contribute to the gastric carcinogenesis by their involvement in precancerous gastric lesions and low gastric acid secretion.

Evaluation of selected interleukins in patients with different gastric neoplasms: a preliminary report

Abnormal interactions between cytokines may be an overlooked mechanism linking the development of different types of gastric neoplasms. In this study a comprehensive analysis of the systemic levels of interleukins (IL-1,IL-6, IL-8,IL-10 and IL-12) was performed in 75 patients with different gastric neoplasms (cancer, gastrointestinal stromal tumors, neuroendocrine neoplasms, lymphomas) and 40 healthy volunteers. Patients with gastric cancer (GC) have significantly higher IL-6 levels, and lower IL-8 and IL-10 concentrations, in comparison to controls and patients with other gastric neoplasms. Analogous results were observed in terms of IL-6/IL-8 and IL-6/IL-10 ratios, whose values were also higher in GC patients. In GC patients no associations were detected between the systemic levels/values of interleukins (ratios) and TNM staging. IL-6, IL-10, IL-6/IL-8 and IL-6/IL-10 ratios appeared to hold diagnostic potential in confirming/excluding the presence of GC. Their sensitivity/specificity in GC detection/exclusion was approximately 54–72%. In conclusion, disturbed systemic biochemical balance in multiple interleukins exists at the earliest stages of and appears to be specific to GC. The interleukin ratios proposed here seem to be more promising indicators of GC in humans than direct systemic levels of interleukins, and probably possess the potential to be applied as a supporting factor for techniques routinely used.

Genetic Variations and Gastric Cancer

<b><i>Background:</i></b> Gastric cancer (GC) has an apparent hereditary component. However, in a large fraction of gastric cases, no known genetic syndrome or family history can be identified, suggesting the presence of ‘missing heritability' in GC etiology. Genome-wide association studies (GWAS) and traditional candidate gene studies have both led to the identification of multiple replicable common genetic variants associated with GC risk. <b><i>Summary:</i></b> We summarize the genetic variants associated with GC risk identified up to date. Achievements derived from translational cancer research including the following aspects: (a) contribution to the our understanding of gastric tumorigenesis, (b) guidance to individualized treatment and (c) prediction of patient prognosis. We also prospect future research direction such as post-GWAS analyses and rare variants studies. <b><i>Key Message:</i></b> Many genetic variants were found through GWAS or candidate gene studies, and interpreting their underlying mechanisms will help us translate risk profiles generated from these variations into use in the clinical setting for targeted screening and treatment. <b><i>Practical Implications:</i></b> Investigation of the potential use of genetic variations as prognostic and predictive markers is a developing field. Many people could benefit from a better understanding of genetic polymorphisms to potentially identify a priori individuals who might have the best chance of survival and therefore derive most clinical benefit from treatment. Outcomes of particular scientific interest for molecular epidemiologic studies should include overall survival, recurrence- and progression-free survival, response to treatment, and early and late toxicities stemming from chemotherapy and radiation.

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.

Review article: the epidemiology and prevention of gastric cancer

BACKGROUND

Gastric cancer can be divided into cardia and noncardia gastric adenocarcinoma (NCGA). Non cardia gastric cancer is a disease that has declined in global incidence but has remained as an extremely lethal cancer.

AIM

To review recent advances in epidemiology and strategies in prevention of non cardia gastric cancer.

METHODS

A rapid literature search strategy was developed for all English language literature published before March 2013. The search was conducted using the electronic databases PubMed and EMBASE. The search strategy included the keywords 'stomach neoplasms', 'gastric cancer', 'epidemiology', 'risk factor', 'early detection of cancer', 'mass screening', 'cancer burden', 'prevention' and 'cost-effectiveness'. The search strategy was adjusted according to different requirements for each database. The specific search was also performed in cancer-related websites for country-specific information. The search was limited to past 10 years.

RESULTS

Gastric cancer is the fifth most common cancer but the third leading cause of cancer death. The case fatality rate is 75%. Screening by radiological or endoscopic methods has limited success in prevention of gastric cancer. Helicobacter pylori has been identified as a carcinogen, accounting for 60-70% of gastric cancer globally and eradication is a potential preventive measure. A meta-analysis in 2009 demonstrated that individuals treated with H. pylori eradication therapy can reduce gastric cancer risk. The extended Shandong Intervention trial that lasted 14.3 years showed that H. pylori eradication therapy significantly reduced gastric cancer incidence by 39%. Consensus groups from Asia, Europe and Japan have recommended H. pylori eradication as primary prevention in high-risk areas. Following eradication therapy, endoscopic surveillance of pre-malignant lesions using enhanced imaging appears to be another promising preventive strategy.

CONCLUSIONS

Gastric cancer remains a major diagnostic and therapeutic challenge. There is emerging evidence that H. pylori eradication in high gastric cancer regions can lead to a decline in the incidence of this highly lethal disease.

At the bedside: Helicobacter pylori, dysregulated host responses, DNA damage, and gastric cancer

Clinical trials performed in populations at high GC risk have demonstrated that eradication of Helicobacter pylori from the stomach with a course of combination antimicrobials helps prevent gastric carcinogenesis when they are administered before precancerous lesions have yet developed. In this review, we consider the insights into H. pylori-associated gastric carcinogenesis that have been gained from these and many other clinical studies in the field to highlight priority areas for basic research and clinical investigation. Among these are defining the magnitude of the risk reduction that may be achieved in clinical practice and at a population level by H. pylori eradication and investigating when, during the slow multistep progression to GC, intervention will be of the most benefit. Additional strategies to prevent GC induced by H. pylori, including chemoprevention, dietary modification, and close endoscopic surveillance, may also have value in augmenting the risk reduction. Why only a small subpopulation of those infected by H. pylori go on to develop GC may be partially explained by genetic susceptibility related to SNPs in several genes regulating the intensity of the gastric inflammatory response to H. pylori. Investigation of the basic mechanisms underlying the promotion of GC by H. pylori and the associated inflammatory response will likely continue to improve clinical strategies for the prevention of one of the most common causes of cancer death globally. See related review, At the Bench: H. pylori, dysregulated host responses, DNA damage, and gastric cancer.

Association between MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population: a systematic review and meta-analysis

The association between the C3435T polymorphism in the MDR1 gene and refractory epilepsy remains controversial. The association appears to be influenced by ethnicity and region. We have performed a systematic review and meta-analysis to assess the link between the MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population. We searched the Cochrane Library, MIDLINE, EMBASE, CBM disc, CNKI, VIP, and WANFANG databases for literature published through August 2013 for case-control studies that evaluated the association between the MDR1 C3435T polymorphism and refractory epilepsy. Twenty-one case-control studies involving 4269 patients (1863 cases in the group with drug-resistant epilepsy and 2406 in the group with drug-responsive epilepsy) were included in the systematic review and meta-analysis. The analysis showed that there were significantly more cases with the MDR1 3435 CC genotype in the group with drug-resistant epilepsy than in the group with drug-responsive epilepsy [odds ratio (OR)=1.50, 95% confidence interval (CI)=1.09-2.06, P=0.01]. In a subanalysis of patients from the southern regions of China, the correlation was not significant [odds ratio (OR)=1.2, 95% confidence interval (CI)=0.89-1.64, P=0.24]. The relationship established in a subset of the Chinese population between the MDR1 C3435T polymorphism and refractory epilepsy will guide epilepsy treatment and development of new AEDs.

Genetic polymorphisms of interleukin-1 beta and osteosarcoma risk

PURPOSE

Osteosarcoma is the most common childhood bone cancer. Interleukin-1 beta (IL-1B) is crucially involved in osteosarcoma carcinogenesis. Whether genetic polymorphisms of IL-1B also influence osteosarcoma risk is unknown. The aim of this study was to investigate the association between IL-1B gene polymorphisms and osteosarcoma risk in Chinese Han patients.

METHODS

A hospital-based case-control study involving 120 osteosarcoma patients and 120 controls was conducted. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to detect three IL-1B gene polymorphisms (-31 T/C, -511 C/T and +3954 C/T) in these patients.

RESULTS

Patients with osteosarcoma had a significantly lower frequency of -31 CC genotype [odds ratio (OR) = 0.40, 95% confidence interval (CI) = 0.17-0.92; P = 0.03] and -31 C allele (OR = 0.67, 95% CI = 0.46-0.99; P = 0.04) than controls. Patients with osteosarcoma had a significantly lower frequency of -511 TT genotype (OR = 0.40, 95% CI = 0.17-0.95; P = 0.04) than controls. The +3954 C/T gene polymorphisms were not associated with a risk of osteosarcoma. When stratified by Enneking stage, tumour location, histological type, tumour metastasis of osteosarcoma and family history of cancer, no statistically significant results were found.

CONCLUSIONS

This is the first study to provide evidence for an association of IL-1B gene polymorphisms with osteosarcoma risk.

Helicobacter pylori and gastric cancer

Infection with Helicobacter pylori is established as the major risk factor for gastric cancer development. Damage of the mucosal barrier due to H. pylori-induced inflammation enhances the carcinogenic effect of other risk factors such as salt intake or tobacco smoking. The genetic disposition of both the bacterial strain and the host can increase the potential towards gastric cancer formation. Genetic variance of the bacterial proteins CagA and VacA is associated with a higher gastric cancer risk, as are polymorphisms and epigenetic changes in host gene coding for interleukins (IL1β, IL8), transcription factors (CDX2, RUNX3) and DNA repair enzymes. Application of high-throughput assays for genome-wide assessment of either genetic structural variance or gene expression patterns may lead to a better understanding of the pathobiological background of these processes, including the underlying signaling pathways. Understanding of the stepwise alterations that take place in the transition from chronic atrophic gastritis, via metaplastic changes, to invasive neoplasia is vital to define the 'point of no return' before which eradication of H. pylori has the potential to prevent gastric cancer. Currently, eradication as preventive strategy is only recommended for high-incidence regions in Asia; large population studies with an adequate follow-up are required to demonstrate the effectiveness of such an approach in Western populations.

Inflammasomes in cancer: a double-edged sword

Chronic inflammatory responses have long been observed to be associated with various types of cancer and play decisive roles at different stages of cancer development. Inflammasomes, which are potent inducers of interleukin (IL)-1β and IL-18 during inflammation, are large protein complexes typically consisting of a Nod-like receptor (NLR), the adapter protein ASC, and Caspase-1. During malignant transformation or cancer therapy, the inflammasomes are postulated to become activated in response to danger signals arising from the tumors or from therapy-induced damage to the tumor or healthy tissue. The activation of inflammasomes plays diverse and sometimes contrasting roles in cancer promotion and therapy depending on the specific context. Here we summarize the role of different inflammasome complexes in cancer progression and therapy. Inflammasome components and pathways may provide novel targets to treat certain types of cancer; however, using such agents should be cautiously evaluated due to the complex roles that inflammasomes and pro-inflammatory cytokines play in immunity.

The role of inflammation in gastric cancer

Gastric cancer, despite its declining incidence rate, is still the second cause of cancer-related death worldwide, killing 750,000 people each year and remaining the second common type of cancer. The best examples of inflammation-associated cancer in human beings may be gastric cancer. Understanding the molecular mechanism of the inflammation in gastric carcinogenesis is important for developing new strategies against gastric cancer.

Interleukin-1 gene polymorphisms in chronic gastritis patients infected with Helicobacter pylori as risk factors of gastric cancer development

Epidemiological investigations indicated association of the Helicobacter pylori infections with the occurrence of inflammatory conditions of the gastric mucosa and development of chronic gastritis and intestinal type of gastric cancer. IL1A and IL1B genes have been proposed as key factors in determining risk of gastritis and malignant transformation. The aim of this paper was to evaluate association of interleukin-1 gene polymorphisms with chronic gastritis, atrophy, intestinal metaplasia, dysplasia and intestinal type of gastric cancer in H. pylori-infected patients. Patients subjected to analysis represent group of 144 consecutive cases that suffered from dyspepsia with coexisting infection of H. pylori and chronic gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia or gastric cancer. Molecular studies involved analysis of –889C>T polymorphism of IL1A gene and +3954C>T polymorphism of IL1B gene. Statistical analysis of association of polymorphism –889C>T of gene IL1A with changes in gastric mucosa showed lack of significance, whereas +3954C>T polymorphism of IL1B gene showed significant association. Frequency of allele T of +3954C>T polymorphism of IL1B gene was higher in group of patients with chronic gastritis, atrophy, intestinal metaplasia, dysplasia or intestinal type of gastric cancer (32.1 %) as compared with population group (23 %), χ² = 4.61 and p = 0.03. This corresponds to odds ratio: 1.58, 95 % CI: 1.04–2.4. Our results indicate that +3954C>T polymorphism of IL1B gene increase susceptibility to inflammatory response of gastric mucosa H. pylori-infected patients and plays a significant role in the development of chronic gastritis, atrophy, intestinal metaplasia, dysplasia and the initiation of carcinogenesis.

Genotyping of IL-8-251 T > A yields prognostic information in patients with gastric carcinoma

This study was designed to investigate the association of the IL-8-251 T > A gene polymorphism with clinicopathological features and the prognostic role of the gene polymorphism in patients with gastric adenocarcinoma. The gene polymorphism was detected by the polymerase chain reaction-restriction fragment length polymorphism method, followed by univariate and multivariate analyses to elicit its prognostic role. The frequency of IL-8-251 A/A, A/T and T/T genotypes were 11.0% (23/210), 43.8% (92/210) and 45.2% (95/210), respectively. The IL-8-251 gene polymorphism was closely correlated with depth of invasion (p = 0.007), grade of differentiation (p = 0.002) and TNM stage (p = 0.009). A/A genotype carriers showed more frequency of serosa involvement, low grade of differentiation and advanced stage of gastric carcinoma. IL-8-251 T > A gene polymorphism have no significant correlation with other clinicopathological features. The 5-year overall survival of IL-8-251 A/A genotype and T allele carriers were 30.8% and 59.2%, respectively. There is a significant discrepancy among the different genotype carriers. Multivariate analysis with the Cox regression model revealed that the IL-8-251 A/A genotype is an independent prognostic indicator (HR = 2.285, 95% Confidence Interval = 1.06-4.93, p = 0.035). We conclude that the IL-8-251 A/A genotype may indicate a poor prognosis for gastric adenocarcinoma patients.

Helicobacter pylori induces increased expression of Toll-like receptors and decreased Toll-interacting protein in gastric mucosa that persists throughout gastric carcinogenesis

BACKGROUND

Toll-like receptors (TLR) are essential for Helicobacter pylori (HP) recognition. Their role in the progression of gastric lesions leading to cancer is not established.

AIM

To evaluate for the first time in humans the expression of TLR2, TLR4, and TLR5, as well as the expression of other related molecules in the entire sequence of gastric lesions.

METHODS

Biopsy samples (n = 80, 48% HP+) from normal mucosa, HP gastritis, metaplasia, dysplasia or adenocarcinoma were obtained from 44 patients. mRNA quantification of TLR2, TLR4, TLR5, Toll-interacting protein (TOLLIP), PPAR-γ, NF-κB, TNF-α, COX-1, COX-2, and CDX-2 was performed by real-time RT-PCR. TLR2, TLR4, and TLR5 protein expression was quantified by immunohistochemistry.

RESULTS

When compared to normal mucosa (1.0 arbitrary unit (AU)), HP gastritis presented higher expression of TLR2 (2.23 ± 0.36 AU), TLR4 (1.92 ± 0.40 AU) and TNF-α (2.14 ± 0.50 AU) and lower TOLLIP and PPARγ expression (0.72 ± 0.12 AU, p < .05 all genes). Metaplasia and dysplasia/carcinoma presented higher expression of TLR2 (1.66 ± 0.46 and 1.48 ± 0.20 AU, respectively, p < .05), lower expression of TOLLIP (0.66 ± 0.09 and 0.52 ± 0.04 AU, p < .05) and PPARγ (0.73 ± 0.12 and 0.63 ± 0.10 AU, p < .05). The significant trend for decrease in TOLLIP and PPARγ was associated with increasing levels of CDX-2 from normal mucosa to carcinoma (p < .05), translating that in diffuse and higher TLRs protein expression (p < .05).

CONCLUSION

Gastric carcinogenesis is associated with decreasing levels of TLRs inhibitors and elevated TLRs levels throughout all the spectrum of lesions. Future studies should investigate if modulation of these receptors activity may influence gastric carcinogenesis and tumor progression.

Associations between interleukin-1 polymorphisms and gastric cancers among three ethnicities

AIM

To investigate the associations between interleukin (IL)-1B and IL-1RN polymorphisms and gastric cancers among the Tibet, Hui and Han ethnicities.

METHODS

Genomic DNA was extracted from peripheral blood of 210, 205, and 202 healthy volunteers and from 155, 158, and 197 gastric cancer patients from the Tibet, Hui, and Han populations, respectively. Polymorphisms in IL-1B and IL-1RN were analyzed by denaturing high-performance liquid chromatography.

RESULTS

Carriers of the IL-1B-31 CC genotype had an increased risk of intestinal type gastric cancer [odds ratio (OR) = 2.17, P = 0.037] in the Tibet ethnicity. Carriers of the IL-1B 2/L genotype had an increased risk of both intestinal and diffuse types of gastric cancer (OR = 2.08, 2.31, P = 0.007, 0.016, respectively) in the Hui ethnicity. In the Han population, carriers of the IL-1B-31 CC, IL-1B-511CT, TT genotypes had increased risk of intestinal type gastric cancer (OR = 2.51, 2.74, 5.66, P = 0.005, 0.002, 0.000, respectively).

CONCLUSION

IL-1B and IL-RN genotypes may differentially contribute to gastric cancer among the Tibet, Hui, and Han ethnicities in the Qinghai area of China.

IL1 receptor antagonist gene IL1-RN variable number of tandem repeats polymorphism and cancer risk: a literature review and meta-analysis

IL1 receptor antagonist (IL1RA) and IL1beta (IL1β), members of the pro-inflammatory cytokine interleukin-1 (IL1) family, play a potential role against infection and in the pathogenesis of cancers. The variable number of tandem repeats (VNTR) polymorphism in the second intron of the IL1 receptor antagonist gene (IL1-RN) and a polymorphism in exon 5 of IL1B (IL1B+3954C>T, rs1143634) have been suggested in predisposition to cancer risk. However, studies have shown inconsistent results. To validate any association, a meta-analysis was performed with 14,854 cases and 19,337 controls from 71 published case–control studies for IL1-RN VNTR and 33 eligible studies contained 7,847 cases and 8917 controls for IL1B +3954. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated from comparisons to assess the strength of the association. There was significant association between the IL1-RN VNTR polymorphism and the risk of cancer for any overall comparison. Furthermore, cancer type stratification analysis revealed that there were significantly increased risks of gastric cancer, bladder cancer and other cancer groups. Infection status analysis indicated that the H. pylori or HBV/HCV infection and IL1-RN VNTR genotypes were independent factors for developing gastric or hepatocellular cancers. In addition, a borderline significant association was observed between IL1B+3954 polymorphism and the increased cancer risk. Although some modest bias could not be eliminated, this meta-analysis suggested that the IL1-RN VNTR polymorphisms may contribute to genetic susceptibility to gastric cancer. More studies are needed to further evaluate the role of the IL1B+3954 polymorphism in the etiology of cancer.

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.

Capsaicin consumption, Helicobacter pylori CagA status and IL1B-31C>T genotypes: a host and environment interaction in gastric cancer

Gastric cancer (GC) has been associated with a complex combination of genetic and environmental factors. In contrast to most countries, available information on GC mortality trends showed a gradual increase in Mexico. Our aim was to explore potential interactions among dietary (chili pepper consumption), infectious (Helicobacter pylori) and genetic factors (IL1B-31 genotypes) on GC risk. The study was performed in three areas of Mexico, with different GC mortality rates. We included 158 GC patients and 317 clinical controls. Consumption of capsaicin (Cap), the pungent active substance of chili peppers, was estimated by food frequency questionnaire. H. pylori CagA status was assessed by ELISA, and IL1B-31 genotypes were determined by TaqMan assays and Pyrosequencing in DNA samples. Multivariate unconditional logistic regression was used to estimate potential interactions. Moderate to high Cap consumption synergistically increased GC risk in genetically susceptible individuals (IL1B-31C allele carriers) infected with the more virulent H. pylori (CagA+) strains. The combined presence of these factors might explain the absence of a decreasing trend for GC in Mexico. However, further research on gene-environment interactions is required to fully understand the factors determining GC patterns in susceptible populations, with the aim of recommending preventive measures for high risk individuals.

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.

Genetics of inflammation in the gastrointestinal tract and how it can cause cancer

Genetic epidemiology is an important discipline that is helping to unravel the aetiology and pathogenesis of complex human diseases. In the context of gastrointestinal malignancy, the paradigm model of host genetic influence on disease outcome is H. pylori-associated gastric adenocarcinoma. This cancer represents a classic example of an inflammation-induced malignancy and highlights the importance of host genetics in disease development. This chapter gives an insight into how genetic epidemiology can play an important role in the development of gastric cancer. Increasing our understanding of host genetics in cancer development may allow particularly susceptible individuals to be targeted for screening or treatment to reduce risk of future malignant transformation.

Carcinogenesis, prevention and early detection of gastric cancer: where we are and where we should go

Helicobacter pylori is the most common cause of gastric cancer (GC), though smoking, alcohol, diet, genetics and epigenetic factors may also have a role in the occurrence of the disease. Why H. pylori cause GC in only a minority of those infected remains unknown. Although mechanisms of H. pylori-induced carcinogenesis are not yet well understood, several genotypes of H. pylori have been associated with strain virulence and disease risk. Primary prevention of GC should be addressed by avoiding exposure to factors that increase the risk and to promote factors associated with decrease risk. Vaccines against H. pylori are an ongoing promise and not yet available. Chemoprevention through vitamin supplementation has shown no benefit. Screening and eradication of H. pylori in the general population is not advised. Given that GC is a multiple-steps process, the identification of patients with preneoplastic lesions with high risk of progression, and periodic endoscopic surveillance of them represents the most effective way for early diagnosis of GC. However, clinical guidelines for surveillance are lacking and there are no clear criteria to classify patients into high or low risk of progressing to GC. No study has shown the potential usefulness of combining the information on the type of preneoplastic lesions, genetic and epigenetic, lifestyle and virulence bacterial factors in order to identify high risk patients who need more intensive surveillance. The integration of all this information, in a prediction model requires further research and could be the most important contribution for reducing the burden of GC.

The role of interleukin DNA polymorphisms in gastric cancer

Gastric carcinoma is one of the most widespread malignancies worldwide. Interleukins are the key group of cytokines which may have tumor-promoting or tumor-suppressing effect, and receptors for them, of course, have the same importance in this context. However, mechanisms of their impact on tumor are not fully understood up to date. Numerous studies provide conflicting data, that makes picture more confusing and complicated. It is known that single nucleotide polymorphisms in interleukin genes may dramatically affect on protein expression level, or alter its functions, which may lead to gastritis or ulcer, and eventually promote cancer occurrence. Furthermore, some of these genetic polymorphisms may serve as predictive factors for cancer prognosis and prevention. In order to understand the impact of each genetic polymorphism, the review of IL-1B, IL-4, IL-6, IL-8, IL-10, IL17A, IL-17F DNA polymorphisms on gastric carcinoma was done, and risk alleles were recommended for further research.

Gastric carcinogenesis

INTRODUCTION

In most patients, gastric cancer is diagnosed in advanced stage. Curative treatment options are limited and the mortality is high. The process of gastric carcinogenesis is triggered by Helicobacter pylori-driven gastritis and is further characterized by its complexity of interaction with other risk factors. Health care systems are challenged for the improvement of prevention, early diagnosis, and effective treatments.

METHODS

An extensive literature research has been performed to elucidate the interplay between etiological factors involved in gastric carcinogenesis.

RESULTS

H. pylori is the most important carcinogen for gastric adenocarcinoma. Evidence is provided by experiments including animal studies as well as clinical observational and interventional studies in humans. Eradication has the potential to prevent gastric cancer and offers the greatest benefit if performed before premalignant changes of the gastric mucosa have occurred. Bacterial virulence factors are essential players in modulating the immune response involved in the initiation of the carcinogenesis in the stomach. Host genetic factors contribute to the regulation of the inflammatory response and in the aggravation of mucosal damage. The harmful role of environmental factors is restricted to salt intake and smoking of tobacco. The ingestion of fruit and vegetables has some protective effect.

CONCLUSION

Infection with H. pylori is the major risk factor for gastric cancer development, and thus, eradication of the Helicobacter offers a promising best option for prevention of the disease. Bacterial virulence, host genetic factors, and environmental influences are interacting in the multifactorial process of gastric carcinogenesis.

Polymorphisms in interleukin-1B (IL-1B) and interleukin 1 receptor antagonist (IL-1RN) genes associate with gastric cancer risk in the Chinese population

BACKGROUND

Gastric cancer is one of the most common malignancies afflicting the Chinese population. Polymorphisms in interleukin-1B (IL-1B) and interleukin-1 receptor antagonist (IL-1RN) genes have been associated with increased gastric cancer risk.

AIMS

A case-control study enrolled 392 gastric cancer patients and 508 healthy were carried out to investigate the association between polymorphisms in IL-1B and IL-1RN and gastric cancer risk.

METHODS

Polymerase chain reaction (PCR)-restriction fragment length polymorphism was used for detection of two potentially functional polymorphisms (IL-1B-31 and IL-1B-511) in the IL-1B gene promoter and PCR was used for detection of the variable tandem repeat in the second intron of IL-1RN.

RESULTS

The data showed that the IL-1B-31CC genotype increased gastric cancer risk to an adjusted odd of 2.27 (95% CI, 1.49-3.46), IL-1B-31CT to 1.48 (95% CI, 1.01-2.16) and IL-1B-31CT/CC to 1.68 (95% CI, 1.17-2.40), while IL-1B-51TT genotype associated with increased gastric cancer risk to an adjusted odd of 2.53 (95% CI, 1.67-3.84), IL-1B-511TC to 1.45 (95% CI, 1.02-2.06), and IL-1B-511TC TT/TC to 1.72 (95% CI, 1.23, 2.39). Furthermore, IL-1RN heterogeneity genotype (IL-1RN2L) was associated with gastric cancer risk to an adjusted odd of 1.70 (95% CI, 1.05-2.74) compared to the wild-type homozygote (IL-1RNLL). In addition, H. pylori infection enhanced gastric cancer risk through these SNPs.

CONCLUSIONS

The data from the current study demonstrated that the genotype CC or CT of IL-1B-31, TT or CT of IL-1B-511, and 2L of IL-1RN increased risk of gastric cancer in this Chinese population and the risk was further enhanced by H. pylori.

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.

Role of bacteria in oncogenesis

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

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.

Role of interleukin polymorphisms in gastric cancer: "Pros and cons"

Helicobacter pylori (H. pylori) infection is the leading cause of gastric cancer worldwide. Infection with this bacterium causes a chronic active immune response that persists for the life of the host. The combination of bacterial factors, environmental insults, and the host immune response drives the initiation and progression of mucosal atrophy, metaplasia, and dysplasia toward GC. Among the host factors, IL-1 gene cluster polymorphisms (IL-1B encoding IL-1β and IL-1RN encoding IL-1ra, its naturally occurring receptor antagonist) play a decisive role in modulating the risk of developing hypochlorhydria, gastric atrophy and GC in the presence of H. pylori infection. In particular, one single nucleotide polymorphism in the IL-1B promoter (IL-1B-511C⁄T), and the short allele of a 86-bp variable number of tandem repeats polymorphism in the IL-1RN second intron (IL-1RN*2) are associated with an increased risk for GC. However this hypothesis is still to be fully confirmed. This review focuses on the divergent results obtained by several epidemiological and functional in vitro and in vivo studies and show that IL-1 genotyping has still no role in the clinical management of patients with H. pylori infection.

Association between cytokine gene polymorphisms and gastric precancerous lesions: systematic review and meta-analysis

Polymorphisms within interleukin-1 (IL1) and tumor necrosis factor alpha (TNFA) gene clusters are associated with an increased risk of gastric cancer. However, their role in gastric precancerous lesions remains poorly understood. Our objective was to perform a meta-analysis of studies addressing the association between IL1B-511, IL1RN variable number of tandem repeat, and TNFA-308 gene polymorphisms and gastric precancerous lesions, including original data from Portugal and Mozambique. Published studies on the association between these cytokine gene polymorphisms and gastric precancerous lesions were identified by systematic review, and estimates of the association were combined using random-effects meta-analysis taking into account new data obtained from Portuguese volunteer shipyard workers (n = 215) and Mozambican dyspeptic patients (n = 96) who underwent endoscopic and pathologic evaluation following the same protocol. Odds ratio (OR) estimates for intestinal metaplasia were 2.83 [95% confidence interval (95% CI), 1.15-6.96] for the IL1RN*22 genotype, 1.86 (95% CI, 1.03-3.36) for IL1B-511 T carriers, and 0.59 (95% CI, 0.12-3.04) for the TNFA-308*AA genotype in the Portuguese sample. All Mozambican subjects with intestinal metaplasia were T carriers for IL1B-511 and none had the 2 allele for IL1RN. In meta-analysis, IL1RN*22 genotype was associated with an increased risk of gastric precancerous lesions (22 versus LL: OR, 2.27; 95% CI, 1.40-3.70; I(2) = 26.4%; 12 studies). No such association was found for the IL1B-511 (TT versus CC: OR, 1.34; 95% CI, 0.87-2.07; I(2) = 65.7%; 13 studies) or TNFA-308 genotypes (AA versus GG: OR, 0.93; 95% CI, 0.35-2.43; I(2) = 0.0%; 7 studies). The IL1RN*22 genotype seems to consistently increase the risk of gastric precancerous lesions, supporting a role for this polymorphism in the early stages of gastric carcinogenesis.

IL-1B-511 polymorphism is associated with increased risk of certain subtypes of gastric cancer in Chinese: a case-control study

OBJECTIVES

The association of interleukin-1B (IL-1B)-511 polymorphism with gastric cancer is still controversial, and the association of IL-1B-511 polymorphism with subtypes of gastric cancer is still largely unknown. We investigated whether the association between IL-1B-511 polymorphism and gastric cancer risk varies by clinically important tumor characteristics and the prognostic value of this polymorphism in a large population-based case-control study among Chinese.

METHODS

A population-based case-control study was conducted between 1999 and 2006 in Guangdong Province, China. A total of 1,010 gastric cancer patients and 1,500 healthy controls were enrolled in this study. Polymorphism in IL-1B-511 was analyzed by PCR-restriction fragment length polymorphism on 501 gastric cancers and 500 healthy controls.

RESULTS

Compared with the CC genotype, carriers of IL-1B-511 TT genotype had an increased gastric cancer risk (odds ratio (OR)=1.97, 95% confidence interval (CI)=1.29-3.01, P=0.0016). TT genotype was significantly associated with intestinal type of gastric cancer (OR=3.16, 95% CI=1.74-5.71, P=0.0001) but not with diffuse or mixed-type gastric cancer. The test for OR heterogeneity between the intestinal-type and non-intestinal-type gastric cancers was statistically significant (P=0.02). In subgroup analyses, TT genotype was found to be associated with poorly differentiated gastric cancer (OR=3.31, 95% CI=1.43-3.60, P<0.0001), but not with moderately or well-differentiated gastric cancer. IL-1B-511 genotypes were not associated with the prognosis of gastric cancer patients.

CONCLUSIONS

IL-1B polymorphism influences certain subtypes of gastric cancer according to the clinical and pathological features. Understanding the etiologic heterogeneity of gastric cancer may result in improvements in controlling this disorder.

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.

Family history and the risk of gastric cancer

Both environmental and genetic factors have a role in the aetiology of gastric cancer. The nature of the genetic factors has not been well-studied and, outside of a few rare cancer syndromes, the genes involved have not been identified. Having a first-degree relative with gastric cancer is a consistent risk factor for gastric cancer, although the magnitude of the odds ratio (OR) associated with a positive family history varies with the ethnic group and with the geographic region. In published case–control studies, the odds ratio varies from approximately 2 to 10, depending on the country. Unlike other common adult cancers, the risk of gastric cancer in migrants is similar to that of the population of origin and does not approach that of the host population in the first generation post-migration. It is hoped that molecular studies, including genomewide association studies (GWAS), will illuminate the genetic factors underlying this important association.

Genetic aspects of inflammation

Chronic inflammation underlies many human diseases including cancer. The magnitude and direction of the inflammatory response is often directed by host genetic factors interacting with environmental exposures. Quite often, the environmental trigger is a microbial agent and the host's genetically determined response is crucial in setting the right tone for handling this threat. An inadequate response runs the risk of allowing the infection to become permanently established causing chronic damage, while too vigorous a response might cause collateral damage to the host's essential physiological pathways. Helicobacter pylori-induced gastric cancer is a paradigm for microbially induced and chronic inflammation-driven malignancy. In this review, we summarise current knowledge about the role of host genetic factors in the pathogenesis of this malignancy. The review illustrates the basic principles of genetic epidemiology and host-bacterial interactions and offers an example of how basic knowledge of the pathophysiology of a disease directed the search for the relevant host genetic factors. This contrasts with current approaches, driven by advanced technology, where genetic risk factors are being identified first with the hope that these will shed light on the pathogenesis of disease. Both approaches are necessary to make advances in reducing disease burden in society.

Molecular aspects in the diagnosis of gastric cancer

BACKGROUND

Gastric cancer (GC) represents the second most common cause of cancer-related death worldwide. The prognosis remains poor, with limited treatment options. A better understanding of the initiation and progression of GC would enable the development of general screening strategies and individualized treatment modalities.

OBJECTIVE

The assessment of tools and molecular markers for the early detection and diagnosis of GC.

METHODS

Human clinical studies published within the past 5 years are reviewed. Also, significant previous data on markers in clinical use or on relevant animal or cell culture experiments are considered.

RESULTS/CONCLUSION

Serum-based screening strategies are not ready for routine application but represent an opportunity for the identification of individuals at high risk with the need for primary gastroscopy and further surveillance, which would ultimately improve survival and prognosis of GC. Infection with Helicobacter pylori represents the principal risk factor for gastric carcinogenesis. Bacterial virulence and host genetic factors contribute to individual susceptibility. Key molecular alterations in gastric carcinogenesis are related to intra- and extracellular cascades that regulate cell proliferation, tumor invasion and metastastic spread. For the development of effective prevention and treatment modalities, it is essential to unravel the basic mechanisms of gastric carcinogenesis.