Genetic polymorphisms of interleukin (IL)-1B, IL-1RN, IL-8, IL-10 and tumor necrosis factor {alpha} and risk of gastric cancer in a Chinese population

Influence of interleukin polymorphisms on development of gastric cancer and peptic ulcer

Pro-inflammatory cytokines are produced in the gastric mucosa by inflammatory cells activated by chronic Helicobacter pylori (H. pylori) infection. Polymorphisms of these cytokine genes are associated with individual differences in gastric mucosal cytokine mRNA level, which result in differences in gastric mucosal inflammation, acid inhibition and gastroduodenal disease risk in response to H. pylori infection. Although polymorphisms of interleukin (IL)-1B, IL-1RN and TNF-A have been reported to relate well with gastric cancer and peptic ulcer risk, those of IL-2, IL-4, IL-6 and IL-8 genes are unclear. In combined analyses using data from previous studies, we found that the risk of gastric non-cardia cancer development was significantly associated with IL-4-168 C allele (OR: 0.81, 95% CI: 0.69-1.00) and IL-4-590 T allele carrier status (0.61, 0.53-0.73), and IL-6-174 G/G genotype (2.02, 1.31-3.10). In peptic ulcer development, IL-2-330 G and IL-4-590 T allele carriers had a significantly decreased risk (0.37, 0.27-0.50 and 0.58, 0.34-0.99, respectively). Moreover, IL-2, IL-4, IL-6 and IL-8 gene genotypes prevalence differs among populations. The inflammatory cytokine gene polymorphisms (e.g. IL-4-590 and IL-6-572 for gastric cancer, and IL-4-590, IL-6-572 and IL-8-251 for peptic ulcer) have a more potent influence on development of gastroduodenal diseases in Western than East Asian populations. These cytokine gene polymorphisms, as well as those of IL-1B, IL-1RN and TNF-A, may be used to identify groups at higher risk of gastric cancer and peptic ulcer, and those suitable for their prevention by H. pylori eradication therapy in Western populations.

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.

CyclinD1 and interleukin-1 receptor antagonist polymorphisms are associated with prognosis in neoadjuvant-treated gastric carcinoma

PURPOSE

We evaluated DNA polymorphisms in genes related to DNA repair, cell-cycle control and tumour microenvironment to determine possible associations with response and survival in neoadjuvant-treated gastric cancer patients.

PATIENTS AND METHODS

One hundred and seventy eight patients who received platinum/5FU-based chemotherapy were genotyped for 10 polymorphisms in nine genes (ERCC1: Asn118Asn, C > T; ERCC1: 8092C > A; TP53: Arg72Pro, G < C; cyclinD1: Pro241Pro, G > A; STK15: Phe31Ile, A > T; VEGF: 936C > T; TNF-alpha: -308G > A; interleukin-1b (IL-1B): -511C >T; IL-1 receptor antagonist (IL-1RN): variable tandem repeat; IL-8: -251T>A). Genotypes were correlated with histopathological and clinical response and overall (OS) and progression-free survival (PFS).

RESULTS

Only the cyclinD1 genotypes were associated with clinical response (P(x)(2)=0.044). Significantly worse survival rates were noted in patients homozygous for the G-allele as compared to patients with the AG or AA genotypes of the cyclinD1 polymorphism (OS: P(log-rank) = 0.024; PFS: P(log-rank)=0.007) and in patients homozygous for the short allele compared to all other genotypes at the IL-1RN polymorphic locus (OS: P(log-rank) = 0.026; PFS: P(log-rank) = 0.013). The combination of both unfavourable genotypes demonstrated strong prognostic relevance (OS: P(log-rank) = 0.006; PFS: P(log-rank) = 0.001). Multivariate analysis for OS in the group of completely resected patients (n = 139) revealed statistical significance for ypM (P < 0.001), histopathological response (P < 0.001) and the combined cyclinD1/IL-1RN genotypes (P = 0.043).

CONCLUSION

The cyclinD1 and IL-1RN polymorphisms were associated with survival. The combination of specific cyclinD1 and IL-1RN genotypes showed a particular prognostic relevance and should be considered an independent prognostic marker for neoadjuvant-treated gastric cancer patients.

Helicobacter pylori infection, host genetics and gastric cancer

Helicobacter pylori infects half the world's population and is responsible for a considerable global health burden, including peptic ulcer disease and gastric cancer. The infection causes a chronic gastritis, the severity and distribution of which determine the clinical outcome. Bacterial, environmental and host genetic factors combine to define the degree of gastric damage. Most patients have a limited mild pan-gastritis with no significant clinical consequences. Antral-predominant gastritis is associated with high gastric acid output and an increased risk of duodenal ulcers. Corpus-predominant gastritis is associated with a reduction in gastric acid, multifocal gastric atrophy and an increased risk of gastric cancer. Host genetic factors are particularly important in defining the severity and extent of Helicobacter-induced gastritis. The most relevant and consistent genetic factors uncovered thus far are in the interleukin-1 and tumor necrosis factor-A gene clusters. These cytokines appear to play a key role in the pathophysiology of gastric cancer and their roles have been confirmed in animal models that mimic human gastric neoplasia. More genetic factors have also been uncovered and, with advancing technology, there is every prospect of defining a full genetic risk profile in the next decade. This will aid in targeting the testing and treatment of Helicobacter pylori, which offers a true opportunity to prevent and defeat this global killer.

The role of TNF genetic variants and the interaction with cigarette smoking for gastric cancer risk: a nested case-control study

BACKGROUND

The aim of this study was to investigate the role of TNF genetic variants and the combined effect between TNF gene and cigarette smoking in the development of gastric cancer in the Korean population.

METHODS

We selected 84 incident gastric cancer cases and 336 matched controls nested within the Korean Multi-Center Cancer Cohort. Six SNPs on the TNF gene, TNF-alpha-238 G/A, -308 G/A, -857 C/T, -863 C/A, -1031 T/C, and TNF-beta 252 A/G were genotyped. The ORs (95% CIs) were calculated using unconditional logistic regression model to detect each SNP and haplotype-pair effects for gastric cancer. The combined effects between the TNF gene and smoking on gastric cancer risk were also evaluated. Multi dimensionality reduction (MDR) analyses were performed to explore the potential TNF gene-gene interactions.

RESULTS

TNF-alpha-857 C/T containing the T allele was significantly associated with an increased risk of gastric cancer and a linear trend effect was observed in the additive model (OR = 1.6, 95% CI 1.0-2.5 for CT genotype; OR = 2.6, 95% CI 1.0-6.4 for TT genotype). All haplotype-pairs that contained TCT or CCC of TNF-alpha-1031 T/C, TNF-alpha-863 C/A, and TNF-alpha-857 C/T were associated with a significantly higher risk for gastric cancer only among smokers. In the MDR analysis, regardless of smoking status, TNF-alpha-857 C/T was included in the first list of SNPs with a significant main effect.

CONCLUSION

TNF-alpha-857 C/T polymorphism may play an independent role in gastric carcinogenesis and the risk for gastric cancer by TNF genetic effect is pronounced by cigarette smoking.

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.

Effect of Helicobacter pylori eradication on incidence of gastric cancer in human and animal models: underlying biochemical and molecular events

BACKGROUND

Gastric cancer remains one of the most common cancers worldwide. A strong association exists between Helicobacter pylori infection and the risk of developing noncardia gastric cancer. H. pylori eradication by antibiotic treatment is regarded as a primary chemoprevention strategy to reduce gastric cancer incidence.

AIM

To analyze the efficacy of H. pylori eradication in preventing gastric cancer in human and animal models, and to discuss whether biochemical, genetic, and epigenetic changes associated with H. pylori infection are reversible after curing the infection.

RESULTS

Several intervention trials have indicated that in some patients, H. pylori eradication leads to regression and prevents the progression of precancerous lesions. The eradication therapy reduces gastric cancer incidence in patients without any precancerous lesions at the baseline and is most effective before the development of atrophic gastritis. A few recent intervention studies in Japan have demonstrated significant prophylactic effects of eradication therapy on the development of gastric cancer, suggesting the use of eradication therapy in high-risk populations as a gastric cancer reduction strategy. However, gastric cancer may still develop despite successful eradication therapy. Studies in animal models have confirmed the use of eradication therapy at an early point of infection to prevent gastric cancer development.

CONCLUSION

H. pylori eradication may not completely abolish the risk of gastric cancer. However, eradication therapy may be used in high-risk populations to reduce gastric cancer incidence. It can reverse many biochemical, genetic, and epigenetic changes that H. pylori infection induces in the stomach.

The effects of genetic polymorphisms of IL-6, IL-8, and IL-10 on Helicobacter pylori-induced gastroduodenal diseases in Korea

BACKGROUND

The genes that encode proinflammatory and anti-inflammatory cytokines are good candidate markers of host susceptibility to gastroduodenal disease. The present study was performed to evaluate whether or not the genetic polymorphisms of IL-6, IL-8, and IL-10 are associated with gastroduodenal disease in the Korean population.

METHODS

This study enrolled 1187 patients, including controls, those with gastric cancer (GC), benign gastric ulcer (BGU), and duodenal ulcer patients. Six polymorphisms were genotyped, 3 of IL-10 (at -592, -819, and -1082), 1 of IL-8 (at -251), and 2 of IL-6 (at -174 and -572), by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

The frequency of IL-10-1082 G carriers was higher in cases of a diffuse type GC [odds ratio (OR) 1.8, 95% confidence interval (CI): 1.0-3.1, P=0.041] or BGU (OR 1.6, 95% CI: 1.0-2.5, P=0.040), than in the control group regardless of Helicobacter pylori infection. The IL-8-251 A/A genotype was more common in H. pylori-positive patients with GC (OR 2.0, 95% CI: 1.2-3.6, P=0.013) or BGU (OR 2.7, 95% CI: 1.5-4.8, P=0.001) than in H. pylori-positive controls. In addition, the frequencies of IL-6-572 G/G (OR 0.3, 95% CI: 0.1-0.9, P=0.027) and of G carriers (OR 0.5, 95% CI: 0.4-0.8, P=0.003) were lower in H. pylori-positive duodenal ulcer patients than in H. pylori-positive controls. IL-10-592 C/C (OR 0.4, 95% CI: 0.2-0.9, P=0.028) was an independent factor associated with a decreased risk of the intestinal type of GC by multivariate analysis. Furthermore, a synergistic effect was observed between IL-10-592 A/A and IL-8-251 A/A with respect to the development of GC or BGU.

CONCLUSIONS

These results suggest that the genetic polymorphisms of these 3 inflammation-related cytokines, IL-10, IL-8, and IL-6, are associated with the development of H. pylori-associated gastroduodenal disease.

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

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

The interleukin-8-251 A allele is associated with increased risk of noncardia gastric adenocarcinoma in Helicobacter pylori-infected Koreans

BACKGROUND AND GOALS

Chronic inflammation associated with Helicobacter pylori infection is a risk factor of gastric adenocarcinoma. Interleukin-8 (IL-8) plays an important role in gastric mucosal inflammation induced by H. pylori infection. Recently, studies on the association of genetic polymorphisms of various proinflammatory cytokines with gastric carcinogenesis showed varying results on the basis of the ethnicity. We conducted this study to investigate the association of IL-8-251 A/T polymorphism with gastric carcinogenesis in H. pylori-infected Koreans.

STUDY

The IL-8-251 A/T polymorphism was identified by polymerase chain reaction-restriction fragment length polymorphism using DNA from a total of 605 H. pylori-infected subjects; 206 controls, 149 chronic atrophic gastritis and/or intestinal metaplasia, 97 gastric dysplasia, and 153 gastric adenocarcinoma. Degrees of gastric mucosal inflammation and mucosal IL-8 level were also assessed.

RESULTS

The IL-8-251 A carriers showed a higher risk of gastric adenocarcinoma (adjusted odds ratio 2.06, 95% confidence interval 1.16-3.68) than IL-8-251 T/T genotypes. The IL-8-251 A allele was also significantly associated with the degree of neutrophil infiltration, atrophy, and intestinal metaplasia in a younger age group. Among the chronic atrophic gastritis and/or intestinal metaplasia group, mucosal IL-8 level was significantly higher in subjects with IL-8-251 A allele than those with IL-8-251 T/T genotypes (P=0.011).

CONCLUSIONS

The IL-8-251 A allele is associated with higher IL-8 production, more severe inflammation, mucosal atrophy, and intestinal metaplasia than IL-8-251 T/T genotype in H. pylori-infected hosts. The IL-8-251 A allele may also increase the risk of gastric adenocarcinoma through an enhanced inflammatory process in H. pylori-infected Koreans.

Genetic polymorphisms of IL-1A, IL-1B, IL-1RN, NFKB1, FAS, and FASL, and risk of silicosis in a Chinese occupational population

OBJECTIVE

To test whether polymorphisms in IL-1, NF-KB, FAS, and FASL genes are associated with risk of silicosis.

METHODS

A case-control study was conducted with 183 silicosis patients and 111 silica-exposed miners who were frequency-matched by age, dust exposure duration, work location, and type of work. Genotype analysis was performed on genomic DNA, using a PCR-RFLP assay.

RESULTS

Individuals carrying the NFKB1 ins/del genotype had a decreased risk of silicosis (adjusted OR = 0.57, 95% CI = 0.32-0.998, P = 0.049) compared with subjects carrying the ins/ins genotype and individuals with the FAS-1377AA homozygote had a decreased risk of silicosis compared with those with the -1377GG genotype (adjusted OR = 0.42, 95% CI = 0.19-0.93, P = 0.03). The analysis of haplotypes of polymorphisms in FAS showed that there was a 2.71-fold (OR = 2.71, 95% CI = 1.22-6.03, P = 0.011) increased risk of silicosis for subjects with alleles of FAS-1377G and FAS-670G, compared with those carrying alleles of FAS-1377G and FAS-670A.

CONCLUSION

Although the polymorphisms at NFKB1, FAS-1377, and extended haplotype FAS-1377G/-670G may play a role in the development of silicosis in the Chinese population, our findings should be verified by larger studies with >1 case/control ratio.

Genetic polymorphism of MCP-1-2518, IL-8-251 and susceptibility to acute pancreatitis: a pilot study in population of Suzhou, China

AIM

To study the relationship between MCP-1-2518A/G, IL-8-251A/T polymorphism and acute pancreatitis (AP) in the Han population of Suzhou, China.

METHODS

A case-control study was conducted to compare the distribution of genotype and genetic frequency of MCP-1-2518A/G, IL-8-251A/T gene polymorphism among AP (n = 101), including mild AP (n = 78) and severe AP (n = 23) and control healthy individuals (n = 120) with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing, and analyze the relationship between the MCP-1-2518A/G, IL-8-251A/T gene polymorphism and the susceptibility to AP.

RESULTS

Significant differences were found in the distribution of genotype of MCP-1-2518A/G between the healthy control group and mild AP group (chi2 = 32.015, P < 0.001), the same was evident between the healthy control group and severe AP group (chi2 = 12.932, P < 0.05) in Suzhou. However, no difference of genotypic distribution was noted between MAP and SAP (chi2 = 0.006, P = 0.997). The genetic frequencies of G allele in mild AP were 72.4% (113/156) and 76.1% (35/46) in severe AP, both were higher than the controls, 47.1% (113/240) (chi2 = 24.804; P < 0.001, and chi2 = 13.005; P < 0.001), but no difference was found between severe AP and mild AP (chi2 = 0.242; P = 0.623). No difference was found in the distribution of genotype of IL-8-251A/T between the healthy control group and AP group neither in the frequency of A and T allele.

CONCLUSION

The MCP-1-2518 AA genotype of the population in Suzhou may be a protective genotype of AP, while one with higher frequency of G allele is more likely to suffer from pancreatitis. But the genotype of AA and the frequency of G allele could not predict the risk of severe AP. No correlation is found between the IL-8-251 polymorphism and the liability of AP.

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

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

Helicobacter pylori: host genetics and disease outcomes

Helicobacter pylori infection is the most common chronic bacterial infection worldwide and is associated with divergent clinical outcomes that range from simple asymptomatic gastritis to more serious conditions, such as peptic ulcer disease and gastric cancer. The key determinants of these outcomes are the severity and distribution of H. pylori-induced gastritis. Host genetic factors play an important role in influencing disease risk, but identifying candidate genes is a major challenge that has to stem from a profound understanding of the pathophysiology of the disease. In the case of H. pylori, the most promising candidate genes are ones that attenuate gastric acid secretion and lead to a destructive chronic inflammatory response against the infection. In particular, certain cytokine and innate immune response gene polymorphisms appear to influence risk of gastric cancer and its precursor conditions. There are currently no convincing genetic risk markers for acquisition of H. pylori infection or risk of developing peptic ulcer disease. Future research agendas should focus on identifying the full genetic risk profile for H. pylori-induced gastric neoplasia. This will help to target the population most at risk by directing eradication therapy and closer follow-up to the affected individuals.

Prevalence and risk factors of atrophic gastritis and intestinal metaplasia in a Korean population without significant gastroduodenal disease

BACKGROUND AND AIM

The prevalence of gastric cancer and Helicobacter pylori infection is unacceptably high in Korea. This study was performed to evaluate the prevalence of atrophic gastritis (AG) and intestinal metaplasia (IM) and to identify their risk factors with respect to H. pylori virulence factors, and environmental and host factors, in Korean population without significant gastroduodenal disease.

METHODS

The study cohort consisted of 389 subjects (> or = 16 years). AG and IM were scored histologically using the Sydney classification in the antrum and body, respectively. Prevalences and bacterial factors (i.e. cagA, vacA m1, and oipA), environmental factors (i.e. smoking and alcohol), and host factors (i.e. genetic polymorphisms of IL-1B-511, IL-1RN, TNF-A-308, IL-10-592, IL-10-819, IL-10-1082, IL-8-251, IL-6-572, GSTP1, p53 codon 72, and ALDH2) were evaluated.

RESULTS

Prevalences of AG in the antrum and body were 42.5% and 20.1%, and those of IM were 28.6% and 21.2%, respectively. The presences of AG and IM were significantly higher in H. pylori-positive than in the H. pylori-negative subjects. Multivariate analysis showed that the risk factors for AG were H. pylori infection, age > or = 61 years, and cagA and vacA m1 positivity. For IM the risk factors were H. pylori infection, age > or = 61 years, a smoking history (rather than current smoking), strong spicy food, occupation (unemployed or nonprofessional vs. professional), and the presence of IL10-592 C/A as opposed to A/A. In addition, IL6-572 G carrier was found to have a protective effect against IM development as compared with C/C.

CONCLUSION

H. pylori infection was most important risk factor of AG and IM. Bacterial factors were found to be important risk factor for AG but environmental and host factors were more important for IM.

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

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

Transgenic cyclooxygenase-2 expression and high salt enhanced susceptibility to chemical-induced gastric cancer development in mice

Cyclooxoygenase (COX)-2 overexpression is involved in gastric carcinogenesis. While high-salt intake is a known risk factor for gastric cancer development, we determined the effects of high salt on gastric chemical carcinogenesis in COX-2 transgenic (TG) mice. COX-2 TG mice were developed in C57/BL6 strain using the full-length human cox-2 complementary DNA construct. Six-week-old COX-2 TG and wild-type (WT) littermates were randomly allocated to receive alternate week of N-methyl-N-nitrosourea (MNU, 240 p.p.m.) in drinking water or control for 10 weeks. Two groups of mice were further treated with 10% NaCl during the initial 10 weeks. All mice were killed at the end of week 50. Both forced COX-2 overexpression and high-salt intake significantly increased the frequency of gastric cancer development in mice as compared with WT littermates treated with MNU alone. However, no additive effect was observed on the combination of high salt and COX-2 expression. We further showed that MNU and high-salt treatment increased chronic inflammatory infiltrates and induced prostaglandin E(2) (PGE(2)) production in the non-cancerous stomach. Whereas high-salt treatment markedly increased the expression of inflammatory cytokines (tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-1 beta and IL-6) in the gastric mucosa, COX-2 overexpression significantly altered the cell kinetics in the MNU-induced gastric cancer model. In conclusion, both high salt and COX-2 overexpression promote chemical-induced gastric carcinogenesis, possibly related to chronic inflammation, induction of PGE(2), disruption of cell kinetics and induction of inflammatory cytokines.

Helicobacter pylori infection and the pathogenesis of gastric cancer: a paradigm for host-bacterial interactions

Helicobacter pylori infection is the most important acquired risk factor for gastric cancer. The infection initiates a chronic inflammatory process that eventually alters the physiology of the gastric environment and leads to achlorohydria. Gastric atrophy may be part of this process but cancer can arise without this precursor. The net effect of decades of inflammation is the establishment of a milieu awash with pro-inflammatory cytokines and characterized by the activation of signalling pathways that cross-talk between inflammation and carcinogenesis. Many of the factors involved in chronic inflammation play a dual role in the process-promoting neoplastic progression but also facilitating cancer prevention. H. pylori bacterial virulence factors as well as host genetic factors play a major role in orchestrating the increased risk of cancer. The study of such host-bacterial interaction is key to uncovering the molecular and cellular pathways involved and will ultimately lead to developing preventive and therapeutic strategies against this global killer.

Polymorphisms of tumor necrosis factor-alpha are associated with increased susceptibility to gastric cancer: a meta-analysis

We conducted a meta-analysis to assess the association between tumor necrosis factor-alpha (TNF-alpha) gene TNFA-308 (G > A) and TNFA-857 (C > T) polymorphisms and gastric cancer (GC) susceptibility. We also performed subgroup analyses based on ethnicity (Caucasian, east Asian, and other populations) and tumor location [noncardia gastric cancer (NCGC)]. There were 3,335 GC patients and 5,286 controls for TNFA-308, and 1,118 GC patients and 1,591 controls for TNFA-857 in our analysis. Overall, allele contrast (A vs. G) of TNFA-308 polymorphism produced significant results in worldwide populations [Pheterogeneity = 0.05, random-effects (RE) odds ratio (OR) 1.19; 95% confidence interval (CI) 1.03-1.37, P = 0.02] and Caucasian populations (Pheterogeneity = 0.15, fixed-effects (FE), OR 1.27; 95% CI 1.11-1.45, P = 0.0005). Similar results were also obtained in recessive models and homozygote contrasts. No significant association was observed in NCGC and east Asian subgroup analysis. T variant of TNFA-857 produced significant results only in allele contrast (Pheterogeneity = 0.38, FE OR 1.17; 95% CI 1.01-1.35, P = 0.04). In conclusion, TNFA-308 locus of TNF-alpha would be a risk factor for GC, especially in Caucasian populations. Besides, TNFA-857 locus may be related to GC risk, which demonstrated changeability of results in different contrasts.

Relationship between precancerous gastric lesions and cell proliferation and apoptosis in a high-risk population

AIM: To evaluate the relationship between gastric lesions and cell proliferation and apoptosis activity.

METHODS: A total of 1523 subjects received an endoscopic examination and five biopsies were obtained from standard sites of the stomach. Expression of Ki-67 was assessed by immunohistochemistry, and apoptotic cells were detected with the terminal deoxynucleotide transferase mediated dUTP nick end-labeling (TUNEL) method.

RESULTS: Among the subjects screened by endoscopic examination, 93.8% had chronic atrophic gastritis, intestinal metaplasia or dysplasia. The prevalence rates of gastric lesions varied in different sites of the stomach. In the greater curvature of the body, the proportion of normal mucosa or superficial gastritis was 84.56%, but dysplasia was only 0.07%. In the angulus, the proportion of normal mucosa or superficial gastritis was reduced to 19.19%, while the proportion of dysplasia reached 5.26%. Furthermore, gastric lesions were positively associated with cell proliferation activity, showing a tendency to increase Ki-67 labeling index according to the severity of gastric lesions. However, no significant association was seen between gastric lesion and cell apoptosis (P = 0.159).

CONCLUSION: Advanced gastric lesions, such as intestinal metaplasia and dysplasia, tend to occur along the lesser curvature of stomach, where gastric cancer occurs. Imbalance in cell proliferation and apoptosis can be observed in advanced gastric lesions.

Genetic aspects of inflammation and cancer

Chronic inflammation is involved in the pathogenesis of most common cancers. The aetiology of the inflammation is varied and includes microbial, chemical and physical agents. The chronically inflamed milieu is awash with pro-inflammatory cytokines and is characterized by the activation of signalling pathways that cross-talk between inflammation and carcinogenesis. Many of the factors involved in chronic inflammation play a dual role in the process, promoting neoplastic progression but also facilitating cancer prevention. A comprehensive understanding of the molecular and cellular inflammatory mechanisms involved is vital for developing preventive and therapeutic strategies against cancer. The purpose of the present review is to evaluate the mechanistic pathways that underlie chronic inflammation and cancer with particular emphasis on the role of host genetic factors that increase the risk of carcinogenesis.

Tumour-necrosis factor-A polymorphisms and gastric cancer risk: a meta-analysis

Inflammation is one of the early phases in the development of gastric cancer. Therefore, several studies have examined the association of polymorphisms in tumour-necrosis factor-A gene (TNF-A) with gastric cancer risk. This meta-analysis reviews and summarises published evidence for these associations. Searching several databases yielded 24 independent studies that reported on the associations between TNF-A polymorphisms and gastric cancer risk. We analysed available data for the most commonly investigated polymorphisms: TNF-A –308G>A (23 studies), TNF-A –238G>A (9 studies), and TNF-A –857C>T (5 studies). Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated in the random-effects model using the DerSimonian–Laird method. Q-statistic and I²-statistic were calculated to examine heterogeneity, and funnel plots were plotted to examine small study effects. The overall ORs (95% CIs) for AG and AA genotypes vs GG genotype for TNF-A –308 were 1.09 (0.94–1.27) and 1.49 (1.11–1.99), respectively. For TNF-A –238, the corresponding ORs (95% CIs) were 1.05 (0.84–1.33) and 1.25 (0.30–5.26), respectively. The overall ORs (95% CIs) for CT and TT genotypes (vs CC) for TNF-A –857 were 1.06 (0.89–1.27) and 1.57 (0.91–2.70), respectively. The statistically significant association between TNF-A –308GG and gastric cancer was limited to western populations. This association showed little heterogeneity (I²=0) and remained consistently strong when analyses were limited to anatomic and histologic subtypes of gastric cancer, or limited to studies in which genotype frequencies were in Hardy–Weinberg equilibrium, or limited to larger studies. These same subgroup analyses did not change results associated with other polymorphisms. In conclusion, TNF-A –308AA genotype was associated with a statistically significant increased risk of gastric cancer, whereas other studied polymorphisms were not. The association between TNF-A –857TT genotype and gastric cancer was near significant, and may become significant if more studies are published.

The interleukin-8-251*T/*A polymorphism is not associated with risk for gastric carcinoma development in a Portuguese population

It has been demonstrated that polymorphisms within inflammation-related genes are associated with risk of gastric carcinoma in Helicobacter pylori-infected individuals. Recently, several studies have reported conflicting results regarding the association between the interleukin (IL)8-251*T/*A polymorphism and risk of gastric carcinoma. In this study, we performed a case-control analysis, including 693 controls, 187 chronic gastritis cases and 333 gastric carcinoma cases, to determine the association between the IL8-251 polymorphism and risk of chronic gastritis and gastric carcinoma in the northern Portugal population. We found no significant association between the IL8-251 polymorphism and increased risk of chronic gastritis or gastric carcinoma, in agreement with that reported in other populations of white origin. The retrospective analysis of published data shows that the association between the IL8-251 polymorphism and risk of gastric carcinoma tends to be reproducible in populations of Asian origin. The estimated effect of the polymorphism under analysis was not significantly different in subgroups of gastric carcinoma cases defined by histologic type and anatomic site of the tumours, and by sex and age of the participants. In conclusion our results indicate that although the IL8-251 polymorphism might be a relevant host susceptibility factor for gastric carcinoma development, this association is likely to be ethnic-specific.

Host-bacterial interactions in Helicobacter pylori infection

Helicobacter pylori are spiral-shaped gram-negative bacteria with polar flagella that live near the surface of the human gastric mucosa. They have evolved intricate mechanisms to avoid the bactericidal acid in the gastric lumen and to survive near, to attach to, and to communicate with the human gastric epithelium and host immune system. This interaction sometimes results in severe gastric pathology. H pylori infection is the strongest known risk factor for the development of gastroduodenal ulcers, with infection being present in 60%-80% of gastric and 95% of duodenal ulcers.(1)H pylori is also the first bacterium to be classified as a definite carcinogen by the World Health Organization's International Agency for Research on Cancer because of its epidemiologic relationship to gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue lymphoma.(2) In the last 25 years, since H pylori was first described and cultured, a complete paradigm shift has occurred in our clinical approach to these gastric diseases, and more than 20,000 scientific publications have appeared on the subject. From the medical point of view, H pylori is a formidable pathogen responsible for much morbidity and mortality worldwide. However, H pylori infection occurs in approximately half of the world population, with disease being an exception rather than the rule. Understanding how this organism interacts with its host is essential for formulating an intelligent strategy for dealing with its most important clinical consequences. This review offers an insight into H pylori host-bacterial interactions.

Interleukin 1 beta gene polymorphism and risk of cervical cancer

OBJECTIVE

To determine whether a polymorphism at position +3953 in exon 5 of the lL-1beta gene (IL-1beta +3953), a condition associated with an increased risk for a number of inflammatory diseases, is also involved in the development of cervical cancer.

METHOD

We isolated DNA from peripheral blood in 150 women with cervical cancer and 200 healthy controls, and IL-1beta +3953 allele polymorphism was determined by polymerase chain reaction.

RESULTS

Genotypes A1/A2 and A2/A2+A1/A2 were associated with increased risk of cervical cancer (odds ratio [OR], 2.88; 95% confidence interval [CI], 1.78-4.67; P<0.001 and OR, 2.85; 95% CI, 1.77-4.6; P<0.001, respectively). The risk in a passive smoker with A2/A2 or A1/A2 genotype was increased more than 5-fold (OR, 5.69; 95% CI, 2.61-12.50; P<0.001) compared with a nonsmoker with the A1/A1 genotype.

CONCLUSION

This study provides evidence of an association between lL-1beta +3953 polymorphism and risk of cervical cancer.

Prevalence of Helicobacter pylori infection in advanced gastric carcinoma

BACKGROUND

[corrected] There is substantial evidence that infection with Helicobacter pylori plays a role in the development of gastric cancer and that it is rarely found in gastric biopsy of atrophic gastritis and gastric cancer. On advanced gastric tumors, the bacteria can be lost from the stomach.

AIMS

To analyze the hypothesis that the prevalence of H.pylori in operated advanced gastric carcinomas and adjacent non-tumor tissues is high, comparing intestinal and diffuse tumors according to Lauren's classification

METHODS

A prospective controlled study enrolled 56 patients from "Hospital Universitário", Federal University of Rio Grande do Norte, Natal, RN, Brazil, with advanced gastric cancer, treated from February 2000 to March 2003. Immediately after partial gastrectomy, the resected stomach was opened and several mucosal biopsy samples were taken from the gastric tumor and from the adjacent mucosa within 4 cm distance from the tumor margin. Tissue sections were stained with hematoxylin and eosin. Lauren's classification for gastric cancer was used, to analyse the prevalence of H. pylori in intestinal or diffuse carcinomas assessed by the urease rapid test, IgG by ELISA and Giemsa staining. H. pylori infected patients were treated with omeprazole, clarithromycin and amoxicillin for 7 days. Follow-up endoscopy and serology were performed 6 months after treatment to determine successful eradication of H. pylori in non-tumor tissue. Thereafter, follow-up endoscopies were scheduled annually. Chi-square and MacNemar tests with 0.05 significance were used.

RESULTS

Thirty-four tumors (60.7%) were intestinal-type and 22 (39.3%) diffuse type carcinomas. In adjacent non-tumor gastric mucosa, chronic gastritis were found in 53 cases (94.6%) and atrophic mucosa in 36 patients (64.3%). All the patients with atrophic mucosa were H. pylori positive. When examined by Giemsa and urease test, H. pylori positive rate in tumor tissue of intestinal type carcinomas was higher than that in diffuse carcinomas. In tumor tissues, 34 (60.7%) H. pylori-positive in gastric carcinomas were detected by Giemsa method. H. pylori was observed in 30 of 56 cases (53.5%) in tissues 4 cm adjacent to tumors. This difference was not significant. Eradication of H. pylori in non-tumor tissue of gastric remnant led to a complete negativity on the 12th postoperative month

CONCLUSIONS

The data confirmed the hypothesis of a high prevalence of H. pylori in tumor tissue of gastric advanced carcinomas and in adjacent non-tumor mucosa of operated stomachs. The presence of H. pylori was predominant in the intestinal-type carcinoma.

The chemokine network. II. On how polymorphisms and alternative splicing increase the number of molecular species and configure intricate patterns of disease susceptibility

In this second review on chemokines, we focus on the polymorphisms and alternative splicings and on their consequences in disease. Because chemokines are key mediators in the pathogenesis of inflammatory, autoimmune, vascular and neoplastic disorders, a large number of studies attempting to relate particular polymorphisms of chemokines to given diseases have already been conducted, sometimes with contradictory results. Reviewing the published data, it becomes evident that some chemokine genes that are polymorphic have alleles that are found repeatedly, associated with disease of different aetiologies but sharing some aspects of pathogenesis. Among CXC chemokines, single nucleotide polymorphisms (SNPs) in the CXCL8 and CXCL12 genes stand out, as they have alleles associated with many diseases such as asthma and human immunodeficiency virus (HIV), respectively. Of CC chemokines, the stronger associations occur among alleles from SNPs in CCL2 and CCL5 genes and a number of inflammatory conditions. To understand how chemokines contribute to disease it is also necessary to take into account all the isoforms resulting from differential splicing. The first part of this review deals with polymorphisms and the second with the diversity of molecular species derived from each chemokine gene due to alternative splicing phenomena. The number of molecular species and the level of expression of each of them for every chemokine and for each functionally related group of chemokines reaches a complexity that requires new modelling algorithms akin to those proposed in systems biology approaches.

After Helicobacter pylori, genetic susceptibility to gastric carcinoma revisited

Genetically, it is possible to distinguish two main forms of gastric carcinoma (GC): a hereditary form in which the initiating genetic alteration is inherited and the remaining mutations are acquired somatically; and a sporadic form in which every mutation is of somatic origin and where the environment is thought to play a major role. Although rare, the identification of germline mutations is proving invaluable in the clinical management of GC families. In the setting of sporadic-type GC it has been shown that individuals infected with Helicobacter pylori have an increased risk of developing GC. Recently, abundant evidence has been collected showing that the risk for sporadic GC development also depends on host genetic factors. Despite providing important insights into the understanding of the disease pathogenesis, the genetic markers we have at present are not sensitive/specific enough to form the basis of a screening strategy.

Role of CD14 promoter polymorphisms in Helicobacter pylori infection--related gastric carcinoma

PURPOSE

Genetic variation in CD14 may affect CD14 expression and susceptibility to Helicobacter pylori infection-related cancers. This study examined functional single nucleotide polymorphisms (SNP) in the CD14 promoter and their associations with risk of developing gastric carcinoma in relation to H. pylori infection.

EXPERIMENTAL DESIGN

Thirty individual DNAs were sequenced to identify variants, and the function of the variants was examined by reporter gene assays. Genotypes and haplotypes were analyzed in 470 patients and 470 controls, and odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression. Serologic H. pylori antibody and soluble CD14 (sCD14) levels were measured by ELISA.

RESULTS

Two SNPs (-651C>T and -260C>T) were identified, of which the -260CT and -260TT genotypes were associated with elevated risk of gastric carcinoma (OR, 1.77; 95% CI, 1.09-2.85 and OR, 1.95; 95% CI, 1.20-3.16, respectively). Haplotype analysis suggested a synergistic effect of the two SNPs (OR for the T(-651)-T(-260) haplotype, 3.39 versus OR for the C(-651)-T(-260) haplotype, 1.45; P = 0.02), which is consistent with reporter gene assays. A multiplicative joint effect between H. pylori infection and -260C>T polymorphism was observed (OR for the presence of both -260TT genotype and H. pylori infection, 4.03; 95% CI, 1.80-9.04). Patients had significantly higher sCD14 than controls (1,866 +/- 2,535 ng/mL versus 1,343 +/- 2,119 ng/mL; P < 0.001), and this difference was associated with the CD14 -260 polymorphism and H. pylori infection.

CONCLUSIONS

Functional polymorphism in CD14 is associated with greater risk of H. pylori-related gastric carcinoma, which might be mediated by elevated sCD14.

Effects of interleukin-10 gene polymorphism on the development of gastric cancer and peptic ulcer in Japanese subjects

BACKGROUND

Anti-inflammatory cytokines play an important role in downregulation of inflammation and the prevention of neoplastic disorders. Genetic variations of anti-inflammatory cytokines are assumed to influence such responses. The aim of the present study was to clarify the association between the IL-10 polymorphism, one of the representative anti-inflammatory cytokines, and susceptibility to gastric cancer and peptic ulcer in Japan.

METHODS

The IL-10-1082 (A/G)/-819 (T/C)/-592 (A/C) polymorphisms were assessed in Helicobacter pylori-positive patients with gastritis only (n = 162), gastric ulcers (n = 110), duodenal ulcers (n = 94), or gastric cancers (n = 105), and H. pylori-negative controls (n = 168) by allele specific primer-polymerase chain reaction methods.

RESULTS

The carriage of IL-10-592 C (age and sex-adjusted odds ratio [OR]: 1.851, 95% confidence interval [CI]: 1.018-3.380) and IL-10-819 C (adjusted OR: 1.868, 95%CI: 1.023-3.411) allele were associated with an increased risk for gastric cancer development, not gastric ulcer and duodenal ulcer. The IL-10-1082 polymorphism had no association with development of gastric cancer and peptic ulcers. The presence of the ATA/GCC haplotype of IL-10-1082/-819/-592 polymorphism significantly increased the risk of gastric cancer development (adjusted OR: 2.805, 95%CI: 1.258-6.254) compared with presence of the ATA/ATA haplotype.

CONCLUSIONS

The IL-10-1082/-819/-592 genotype status and haplotype were associated with an increased risk for gastric cancer development, not peptic ulcer, in Japan. The genotyping test of this anti-inflammatory cytokine would be useful for the detection of individuals with higher risk of gastric cancer development.

Single nucleotide polymorphism and haplotype association of the interleukin-8 gene with nasopharyngeal carcinoma

The cytokine interleukin-8 (IL-8) may play a role in the pathogenesis of nasopharyngeal carcinoma (NPC) through the modulation of tumor immune response or enhanced angiogenesis. Polymorphism of IL-8 gene, which may affect the production level of cytokine, has been inversely associated with a number of cancers. To test this hypothesis, we investigated the relationship of IL-8 gene polymorphisms and NPC in a Chinese population. We analyzed single nucleotide polymorphisms (SNPs) of IL-8 gene -845 T/C, -738 T/A, -353 A/T, -251 A/T and +678 T/C in 280 patients with NPC and 290 age and sex matched controls, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction-sequence specific primers method (PCR-SSP). There were significant differences in the genotype and allele distribution of -251 A/T polymorphism of the IL-8 gene among cases and controls. The -251 AA and AT genotypes were associated with a significantly increased risk of NPC as compared with the -251 TT genotypes (OR=1.820, 95% CI, 1.120-2.959, P=0.015 and OR=1.590, 95% CI, 1.104-2.290, P=0.013, respectively). Haplotype analysis revealed that the homozygosity of the AAT haplotype (defined by SNPs at positions -353, -251 and +678) of IL-8 gene conveys the highest risk for NPC compared with the homozygosity for the TTC haplotype (OR=1.396; 95% CI, 1.064-1.831; P=0.016). The -251 A/T polymorphism of IL-8 and its haplotype are associated with NPC in a Chinese population. Our data suggests that IL-8 gene may play a role in the development of NPC.

Analysis of phenotype-genotype connection: the story of dissecting disease pathogenesis in genomic era in China, and beyond

DNA is the ultimate depository of biological complexity. Thus, in order to understand life and gain insights into disease pathogenesis, genetic information embedded in the sequence of DNA base pairs comprising chromosomes should be deciphered. The stories of investigating the association between phenotype and genotype in China and other countries further demonstrate that genomics can serve as a probe for disease biology. We now know that in Mendelian disorders, one gene is not only a dictator of one phenotype but also a dictator of two or more distinct disorders. Dissecting genetic abnormalities of complex diseases, including diabetes, hypertension, mental diseases, coronary heart disease and cancer, may unravel the complicated networks and crosstalks, and help to simplify the complexity of the disease. The transcriptome and proteomic analysis for medicine not only deepen our understanding of disease pathogenesis, but also provide novel diagnostic and therapeutic strategies. Taken together, genomic research offers a new opportunity for determining how diseases occur, by taking advantage of experiments of nature and a growing array of sophisticated research tools to identify the molecular abnormalities underlying disease processes. We should be ready for the advent of genomic medicine, and put the genome into the doctors' bag, so that we can help patients to conquer diseases.

How do we improve outcomes for gastric cancer?

Although the incidence of gastric cancer is decreasing globally, it remains the second leading cause of cancer death, accounting for 600,000 deaths annually worldwide. It is particularly common in Asia and especially in China, Japan and Korea. In Singapore, it is the fourth commonest cancer in men, who have a 1:50 lifetime risk of developing gastric cancer. Gastric cancer traditionally carries a poor prognosis because of late presentation at an advanced stage of disease. If diagnosed at an early stage, it is a curable disease. Four strategies will systematically help to improve outcomes for gastric cancer: (i) early detection by screening of high-risk groups; (ii) clarification of the hypothesis that Helicobacter pylori eradication in endemic areas with a high incidence of gastric cancer is an effective primary prevention strategy; (iii) improvement of treatment by well-designed clinical trials, coupled with molecular characterization of tumors; and (iv) improving our biological understanding of gastric carcinogenesis.

Interleukin-1B polymorphisms and gastric cancer risk--a meta-analysis

Some studies have reported that proinflammatory polymorphisms in interleukin-1B (IL-1B) and IL-1 receptor antagonist (IL-1RN) genes are associated with increased gastric cancer risk. However, other studies have shown null or inverse associations. This meta-analysis reviews and summarizes published evidence for these associations. Searching the PubMed Database yielded 35 studies that reported on the association between IL-1B -511 C>T, IL-1B -31 T>C, or IL-1RN variable number tandem repeat polymorphisms and gastric cancer risk. Q-statistics and I(2) statistics were calculated to examine heterogeneity. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were calculated in the random-effects model using the DerSimonian-Laird method. For all gastric cancers, the overall ORs (95% CIs) for IL-1B -511 CT versus CC and TT versus CC genotypes were 1.07 (0.91-1.25) and 1.16 (0.95-1.42), respectively. ORs (95% CIs) for the association between IL-1B -31 CT versus TT and CC versus TT genotypes were 0.99 (0.83-1.19) and 0.98 (0.78-1.21), respectively. For the associations between IL-1RN and gastric cancer, ORs (95% CIs) for *2/L versus LL and *2/*2 versus L/L were 1.15 (0.96-1.38) and 1.23 (0.79-1.92). For each of the examined associations, there was significant heterogeneity among studies; P(heterogeneity) < or = 0.001 and I(2) ranged from 0.54 to 0.71. Noncardia cancers showed stronger associations with IL-1B -511 CT or TT and IL1-RN *2/*2 genotypes, but limiting the analysis to intestinal-type cancers, studies conducted in Western countries, or studies in which polymorphisms were in Hardy-Weinberg equilibrium, made no material difference in the results. The overall associations between IL-1B or IL-1RN proinflammatory polymorphisms and gastric cancer were null but several studies showed an association. The sources of this variation are unclear.

Helicobacter pylori infection and gastric cancer

Gastric cancer remains a major health burden on many societies claiming hundreds of thousands of lives every year. The discovery of Helicobacter pylori has no doubt revolutionised our understanding of this malignancy, which is now regarded as a paradigm for infection-induced chronic inflammation-mediated cancer. In this paper, we discuss the evidence for the association between H. pylori and gastric adenocarcinoma and MALT lymphoma. We also discuss the pathogenesis of these two forms of cancer and the factors that determine their outcome. There is no doubt that the knowledge accumulated over the past two decades will be translated into eventual victory over this killer cancer, largely because we now appreciate that the best way to prevent the cancer is by preventing acquisition of the infection in the first place, or by eradicating the infection in infected subjects. Defining the optimal timing of intervention is going to be the challenge facing us over the next two decades.

Genetic polymorphisms in anti-inflammatory cytokine signaling and the prevalence of gastric precancerous lesions in Venezuela

OBJECTIVES

The aim of the study was to assess the effects of genetic polymorphisms in anti-inflammatory mediators, i.e., IL10, IL4 and IL4R on the prevalence of gastric precancerous lesions and their interactions with other environmental factors.

METHODS

The study population consisted of 2,033 Venezuelan subjects known to have extremely high Helicobacter Pylori (HP) infection rates. The odds ratios (OR) and 95% confidence intervals (CI) associated with these polymorphisms were estimated by multinominal logistic regression models for gastric precursor lesions.

RESULTS

We found a 60% increase in risk of intestinal metaplasia (IM) and dysplasia combined (OR 1.62, 95% CI: 1.10-2.38) among the carriers of the IL10-1082 low activity allele. This increased risk was more pronounced for dysplasia than for IM. On the other hand, homozygotes with the low activity allele of the A398G polymorphism in the IL4R gene had a modest increase in risk of atrophic gastritis (OR = 1.52, 95% CI: 1.05-2.21), compared with homozygotes of the high activity allele. There were no statistically significant synergetic interactions between these polymorphisms and environmental risk factors (low fruit intake, high starchy vegetable intake and cigarette smoking) for these lesions.

CONCLUSION

While the results of the present study suggest roles of genetic variability in these anti-inflammatory mediators in different stages of gastric carcinogenesis, there is high likelihood that they were chance findings due to multiple comparisons.

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

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

Association between interleukin-1 gene polymorphisms and Helicobacter pylori infection in gastric carcinogenesis in a Chinese population

BACKGROUND AND AIM

Helicobacter pylori is a major cause of chronic gastritis and peptic ulcer disease and a definite carcinogen for gastric adenocarcinoma. However, the underlying pathogenic mechanisms are not fully understood. Interleukin-1 (IL-1) is a key cytokine involved in H. pylori-induced gastric inflammation. The present study aimed to determine polymorphisms of IL-1B and IL-1 receptor antagonist (IL-1RN) genes and their association with H. pylori infection and gastroduodenal diseases in Chinese patients.

METHODS

Three hundred and ninety-nine patients with gastroduodenal diseases (129 chronic gastritis, 127 duodenal ulcer and 143 non-cardiac gastric cancer) and 264 healthy controls were genotyped for IL-1B-511 and IL-1RN gene polymorphisms by the PCR-RFLP method. H. pylori infection status was determined by a validated serological test.

RESULTS

The frequency of IL-1B-511 T allele was significantly higher in H. pylori positive patients with non-cardiac gastric cancer than in both H. pylori negative patients with non-cardiac gastric cancer (60%vs 46%, P = 0.0342, OR = 1.666, 95% confidence interval [CI]: 1.045-2.656) and in healthy controls (60%vs 48%, P = 0.0071, OR = 1.665, 95%CI: 1.149-2.412). However, the polymorphism was not associated with chronic gastritis and duodenal ulcer. Multivariate logistic regression analyses identified that IL-1B-511 T/T carrier status was an independent risk factor for non-cardiac gastric cancer in the presence of H. pylori infection (adjusted OR = 3.01, 95%CI: 1.27-7.11, P = 0.01), and the frequency of IL-1B-511 T allele was an increased risk factor for developing gastric cancer (P = 0.03, adjusted OR = 2.29, 95%CI: 1.08-4.86). There was no association between IL-1RN gene polymorphisms and H. pylori infection and other gastroduodenal diseases.

CONCLUSION

IL-1B-511 T allele is associated with H. pylori infection in non-cardiac gastric cancer in a Chinese population. The IL-1B-511 gene polymorphism appears to play an important role in gastric carcinogenesis in Chinese patients with H. pylori infection.

Th1 and Th2 cytokine gene polymorphisms in two indigenous ethnic groups in Iran

Cytokines are important immunomodulatory molecules in immune responses against microorganisms and also have an important role in the setting of disorders affecting immune system. Cytokine single nucleotide polymorphisms have been extensively studied in different normal populations as well as in relation to diseases. Some of these polymorphisms (SNP) affect cytokine gene transcription and expression. The polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility and clinical outcome or as a tool for anthropological studies. In this study, samples have been collected from 261 healthy individuals located in two different regions of Iran (Tehran and Yazd). The allele and genotype frequencies of Th1 and Th2 cytokines SNP including interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma have been investigated, using the polymerase chain reaction-sequence-specific primer method. The allele and genotype frequencies in Tehran and Yazd populations were similar except for the IL-2, IL-4, IL-6 and IL-10. The IL-4 C allele, C/C -33 and T/T -1098 genotype were significantly more frequent in Tehran than in Yazd population (P = 0.04, P = 0.004 and P = 0.001, respectively). The G/A genotype of the IL-6 (nt565) and IL-10 (-1082) was significantly less frequent in Tehran than in Yazd population (P = 0.01 and P = 0.003, respectively). The GT haplotype of the IL-2 (-330, +166) was significantly less frequent in Tehran than in Yazd population (P = 0.0002). We have also compared our whole samples with the reported data from other countries showing that Iranian population have cytokine gene polymorphism profile similar to that of Caucasians, especially Italian population.

Interleukin-1beta and interleukin-1 receptor antagonist gene polymorphisms and gastric cancer: a meta-analysis

BACKGROUND

Polymorphisms of interleukin-1B (IL1B) and its receptor antagonist (IL1RN) genes have been inconsistently associated with gastric cancer risk. We examined these associations by performing meta-analyses.

MATERIALS AND METHODS

Twenty-five studies testing the association between IL1B and/or IL1RN gene polymorphisms and gastric cancer were examined: 14 studies of IL1B-511, 14 studies of IL1B-31, 8 studies of IL1B+3954, and 23 studies of IL1RN. Overall and ethnicity-specific summary odds ratios and corresponding 95% confidence intervals for gastric cancer associated with these polymorphisms were estimated using fixed- and random-effects models. Heterogeneity and publication bias were evaluated.

RESULTS

IL1B-511T and IL1RN*2 were associated with gastric cancer risk in Caucasians, but not in Asians. For IL1B-511T, the association in Caucasians was stronger when intestinal-subtype and noncardia gastric cancer cases were examined. A nonsignificant trend was observed between IL1B-31C and gastric cancer in Caucasians. No significant association of IL1B+3954T and gastric cancer risk was detected. Studies with better methodologic characteristics reported stronger effects. There was no evidence of publication bias.

CONCLUSION

IL1B-511T is associated with gastric cancer susceptibility in Caucasians. The meta-analyses suggest that the conflicting results among studies may be explained by variation in allele frequencies among the ethnic groups and variation in tumor types, as well as by the methodologic quality of the studies.

Helicobacter pylori and gastric cancer

PURPOSE OF REVIEW

Although chronic Helicobacter pylori infection is the strongest known risk factor for development of gastric adenocarcinoma, only a small proportion of infected individuals will ever develop tumours. This article discusses various bacterial, host and environmental factors which may influence an individual's susceptibility.

RECENT FINDINGS

Recent research on bacterial virulence factors has focussed upon the cag pathogenicity island, particularly its roles in regulating epithelial growth and adhesion. Studies of host genetic factors have included several analyses of polymorphisms in inflammatory cytokines in human cohorts. Animal studies have recently clarified the roles of dysregulated epithelial apoptosis, proliferation and differentiation pathways during gastric carcinogenesis, and novel experiments involving H. felis infection of bone marrow transplanted irradiated mice have suggested that gastric cancer may originate from bone marrow-derived stem cells. Important roles for signalling between epithelial and mesenchymal cells, particularly myofibroblasts, are also emerging. Recent research on the importance of environmental factors has demonstrated how helminth coinfection may protect against atrophic gastritis and T helper type 1 responses.

SUMMARY

Complex interactions between several bacterial, host genetic and environmental factors determine whether H. pylori infected individuals develop gastric carcinoma. The importance of bone marrow stem cell engraftment during human gastric neoplasia is an area requiring urgent investigation.

Mechanisms of Disease: Helicobacter pylori-related gastric carcinogenesis—implications for chemoprevention

Gastric adenocarcinoma is the second most common cause of cancer-related mortality worldwide. Infection with Helicobacter pylori is the single most common cause of adenocarcinoma of the distal stomach. Cancer risk is believed to be related to differences among H. pylori strains and inflammatory responses governed by host genetics. In particular, specific interactions between host factors that modulate the response to the infection, and bacterial virulence factors that can directly cause tissue damage seem to have a major pathogenic role in the development of gastric cancer. In addition, environmental factors can modify key growth signaling pathways within the gastric mucosa, which leads to the alteration of epithelial cell growth. Preventive strategies represent the most promising means of decreasing cancer risk, and must be aimed at the control of H. pylori infection, improvement of environmental conditions, and the identification of subjects who are genetically predisposed to the development of cancer in response to H. pylori infection. Understanding the intracellular signaling pathways that are specifically affected by H. pylori and that promote phenotypic and genotypic changes that might ultimately progress to malignant transformation could enable physicians to focus eradication therapy appropriately and design interventions targeted at the molecular level to prevent the development of gastric cancer.

Genetic factors involved in the development of Helicobacter pylori-related gastric cancer

Developmental process to gastric cancer by Helicobacter pylori infection consists of three steps: (1) H. pylori infection; (2) gastric atrophy development; and (3) carcinogenesis. In each step, genetic traits may influence the process, interacting with lifestyle. In the step of H. pylori infection, two lines of genetic polymorphisms were assumed: one influencing gastric acid inhibition interacting with smoking, and the other concerning innate immune response attenuation. The former includes functional polymorphisms of IL-1B (C-31T or tightly linked T-511C), and TNF-A (T-1031C and C-857T), and the latter possibly includes NQO1 C609T. In the step to gastric atrophy, polymorphisms pertaining to the signal transduction from cytotoxin-associated gene A (PTPN11 A/G at intron 3) and to T-cell responses (IL-2 T-330G and IL-13 C-1111T) were hypothesized. There are a limited number of epidemiological genotype studies on the final step of literal carcinogenesis, potentially interacting with smoking, a low vegetable and fruit intake, and salty foods, the well-documented risk factors. In past case-control studies on the associations between genotype and gastric cancer risk, the cases consisted of H. pylori-related and unrelated gastric cancer patients and the controls consisted of individuals including the uninfected (H. pylori unexposed and exposed) and the infected with and without gastric atrophy. Accordingly, it was not clear whether the observed risk was for H. pylori-related or -unrelated gastric cancer, nor which step was involved in the observed associations even when nearly all cases were H. pylori-related. In order to elucidate the genetic traits of H. pylori-related gastric cancer, stepwise evaluation will be required.

Host-bacterial interaction in the development of gastric precancerous lesions in a high risk population for gastric cancer in Venezuela

Helicobacter pylori (HP) infection affects over 50% of the world's population. The prevalence is over 90% in populations at high risk for gastric cancer, but clinical outcomes of the infection are highly variable and thus host genetic factors have been suggested to play a role in its outcomes in addition to bacterial factors. In this study, we examined the effects of common functional genetic polymorphisms of several proinflammatory cytokines known to be overexpressed in HP-infected gastric mucosa on the risk of various stages of gastric premalignant lesions. The odds ratios (ORs) and 95% confidence intervals (CI) for atrophic gastritis, intestinal metaplasia and dysplasia were estimated by multinominal logistic regression analysis among 2,033 Venezuelan subjects. There was a significant effect of IL8 -251A allele on the prevalence of dysplasia (p = 0.021). The OR associated with the A-allele was 1.34 (95% CI: 0.82-2.18) for heterozygotes and 2.00 (95% CI: 1.13-3.56) for homozygotes, compared with the TT genotype. Furthermore, there was a statistically significant interaction between the number of A-alleles and HP cag A genotype (p = 0.009), suggesting that the A-allele increased the risk of dysplasia only when cag A was present. The OR for the AA compared with TT genotype was 3.22 (95% CI: 1.60-6.52) in this group. There were no associations with other proinflammatory cytokines studied, i.e., IL1 beta, IL6, monocyte chemoattractant protein 1 (MCP1) and TNF alpha, or with other stages of premalignant lesions. The present study provides important evidence suggesting host-bacterial interactions in the development of gastric precancerous lesions.