Increased risk of noncardia gastric cancer associated with proinflammatory cytokine gene polymorphisms

Arsenic sulfide induces miR-4665-3p to inhibit gastric cancer cell invasion and migration

Purpose

Gastric carcinogenesis is a multistep process and is the second-highest cause of cancer death worldwide with a high incidence of invasion and metastasis. MicroRNAs (miRNAs) engage in complex interactions with the machinery that controls the transcriptome and concurrently target multiple mRNAs. Recent evidence has shown that miRNAs are involved in the cancer progression, including promoting cell-cycle, conferring resistance to apoptosis, and enhancing invasiveness and metastasis. Here, we aim to elucidate the roles of miRNAs, especially microRNA-4665-3p (miR-4665-3p), in the inhibitory effect of arsenic sulfide in gastric cancer (GC).

Methods

The arsenic sulfide-induced miRNA expression alterations in AGS cells was determined by miRNA microarray. RT-PCR was used to further verify the arsenic sulfide-regulated miRNAs in GC tissues. The inhibition of miR-4665-3p on the migration and invasion of GC cells were determined by wound healing assay and transwell assay. Western blot analysis was used to detect the expression of EMT related proteins and the putative target of miR-4665-3p.

Results

The miR-4665-3p was up-regulated by arsenic sulfide and showed inhibition upon the migration and invasion of GC cells. MiRBase and Western blotting indicated that miR-4665-3p directly down-regulated the oncoprotein GSE1. Morphological observation also indicated that the up-regulation of miR-4665-3p inhibits the EMT in GC cells.

Conclusion

Our data demonstrates that the increased expression of miR-4665-3p induced by arsenic sulfide suppresses the cell invasion, metastasis and EMT of GC cells, and has the potential to be a novel therapeutic target in GC.

TNF-α -308 A allele is associated with an increased risk of distant metastasis in rectal cancer patients from Southwestern China

Tumor necrosis factor-α (TNF-α), an important factor in systematic inflammation, is reportedly involved in several cancer types. The TNF-α -308 G>A (rs1800629) polymorphism in the promoter region influences TNF-α production. The association between TNF-α -308 G>A polymorphism and colorectal cancer (CRC) is not fully understood, especially the connections between TNF-α -308 G>A polymorphism and clinical features of CRC. In this study, TNF-α -308 G>A polymorphism was genotyped in 1140 individuals with or without CRC from Southwestern China. In case-control studies, we found no association between TNF-α -308 G>A polymorphism and CRC risk. Analysis of the correlations between TNF-α -308 G>A polymorphism and clinical features of CRC revealed that TNF-α -308 A allele was associated with higher body mass index (BMI) larger tumor size, and distant tumor metastasis in all CRC patients. Notably, rectal cancer (a subtype of CRC) patients with TNF-α -308 A allele had a very high risk of distant tumor metastasis [odds ratio (OR) = 4.481; 95% confidence interval (CI): 2.072–9.693; P = 0.00025]. The association between TNF-α -308 A allele and distant tumor metastasis remained even significant after adjusting all clinical characteristics (OR = 7.099; 95% CI: 2.482–20.301; P = 0.000256) in rectal cancer patients. Our results suggested that TNF-α -308 A allele was significantly associated with distant tumor metastasis in rectal cancer patients.

Interleukin-1β induced by Helicobacter pylori infection enhances mouse gastric carcinogenesis

Interleukin-1β (Il1b) is considered to be involved in Helicobacter pylori (HP)-induced human gastric carcinogenesis, while the role of its polymorphisms in gastric cancer susceptibility remains controversial. Here, we aimed to clarify the role of HP infection-induced IL1B in gastric inflammation and carcinogenesis using Il1b(-/-) (Il1b-null) mice. In gastric mucosa of the Il1b(+/+) (WT) mice, HP infection induced Il1b expression and severe inflammation. In contrast, in Il1b-null mice, recruitment of neutrophils and macrophages by HP infection was markedly suppressed. In a carcinogenicity test, the multiplicity of gastric tumors was significantly suppressed in theIl1b-null mice (58% of WT; P<0.005). Mechanistically, HP infection induced NF-κB activation both in the inflammatory and epithelial cells in gastric mucosae, and the activation was attenuated in the Il1b-null mice. Accordingly, increased proliferation and decreased apoptosis of gastric epithelial cells induced by HP infection in the WT mice were attenuated in the Il1b-null mice. These results demonstrated that the IL1B physiologically induced by HP infection enhanced gastric carcinogenesis by affecting both inflammatory and epithelial cells.

MicroRNA-219-2-3p functions as a tumor suppressor in gastric cancer and is regulated by DNA methylation

Background & Aims

Gastric cancer is the most frequent gastrointestinal tumor in adults and is the most lethal form of human cancer. Despite of the improvements in treatments, the underlying mechanism of gastric carcinogenesis is not well known. To define novel modulators that regulate susceptibility to tumorgenesis, we focused on miR-219-2-3p.

Methods

Quantitative RT-PCR was employed to investigate the level of miR-219-2-3p in gastric cancer (GC) tissues (n = 113) and their matched adjacent normal tissues (n = 113). In vitro cell proliferation, apoptosis assays, cell migration, and invasion assays were performed to elucidate biological effects of miR-219-2-3p. Since silencing of miRNA by promoter CpG island methylation may be an important mechanism in tumorgenesis, GC cells were treated with 5-aza-2′-deoxycytidine and trichostatin A, and expression changes of miR-219-2-3p were subsequently examined by quantitative RT-PCR. Finally, the methylation status of CpG island upstream of miR-219-2-3p was analyzed by methylation-specific PCR in GC tissues (n = 22).

Results

miR-219-2-3p was down-regulated in GC and cell lines. In addition, the experiments documented the lower expression of miR-219-2-3p in GC specimens with higher grade and later stage tumors. Meanwhile, miR-219-2-3p exerted antiproliferative, proapoptotic, and antimetastatic roles and reduced levels of p-ERK1/2 in GC cells. Furthermore, 5-aza-2′-deoxycytidine and trichostatin A increased the expression (∼2 fold) of miR-219-2-3p in GC cells. By methylation-specific PCR, DNA methylation in the upstream region of miR-219-2-3p was detected in both adjacent normal tissues and cancer tissues. As expected, the methylation level was considerably higher in the miR-219-2-3p down-regulated group than up-regulated group.

Conclusions

miR-219-2-3p is potentially involved in gastric cancer progression and metastasis by regulating ERK1/2-related signal pathways, which may provide a novel therapeutic strategy for treatment of gastric cancer. Methylation mechanism may be involved in modulating the expression level of miR-219-2-3p in gastric cancer.

MicroRNAs in pathogenesis, diagnosis, and treatment of gastroesophageal cancers

The incidence of gastroesophageal cancers is increasing each year, but despite much research, their molecular mechanisms are incompletely understood. microRNAs (miRNAs) are noncoding RNAs that have been associated with gastroesophageal carcinogenesis. We review the involvement of miRNAs in gastric and esophageal cancers and their mechanisms of regulation, effects on gene expression, and biological functions. Many miRNAs are dysregulated in gastroesophageal cancer cells via alterations in transcription, epigenetic features, or copy number of the genes that encode them. Each type of gastroesophageal tumor has a unique gene expression profile. miRNAs contribute to gastroesophageal carcinogenesis by altering expression of oncogenes and tumor suppressors to affect cell proliferation, apoptosis, and motility and invasion. A number of miRNAs, including circulating miRNAs, have been associated with tumor type or stage, or patient survival, and might be developed as diagnostic or prognostic markers. Greater understanding of the roles of miRNAs in gastroesophageal carcinogenesis could provide insights into the mechanisms of tumor development and identify therapeutic targets.

[Low penetrance gene polymorphisms involved in Helicobacter pylori-immune response. Relevance on gastric cancer risk]

Gastric cancer is a complex pathology which represents a worldwide health burden due to its high prevalence and poor prognosis. Therefore, prevention and early detection are considered the best options for controlling the disease. Current research is based on the study of genetic variants that confer a higher risk and their interactions with environmental exposure. A deeper knowledge of factors involved on gastric cancer development may allow identification of those individuals at elevated risk and will provide useful predictive information for subgroups of patients who need surveillance or early treatment strategies. In the present paper we review in a comprehensive manner, the most recent published studies on the contribution of gene polymorphisms and Helicobacter pylori infection to gastric cancer risk.

MicroRNA dysregulation in gastric cancer: a new player enters the game

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Recent discoveries have shed new light on the involvement of a class of noncoding RNA known as microRNA (miRNA) in gastric cancer. A substantial number of miRNAs show differential expression in gastric cancer tissues. Genes coding for these miRNAs have been characterized as novel proto-oncogenes and tumor-suppressor genes based on findings that these miRNAs control malignant phenotypes of gastric cancer cells. In this connection, miRNA dysregulation promotes cell-cycle progression, confers resistance to apoptosis, and enhances invasiveness and metastasis. Moreover, certain polymorphisms in miRNA genes are associated with increased risks for atrophic gastritis and gastric cancer, whereas circulating levels of miRNAs may serve as biomarkers for early diagnosis. Several miRNAs have also been shown to correlate with gastric cancer progression, and thus may be used as prognostic markers. Elucidating the biological aspects of miRNA dysregulation may help us better understand the pathogenesis of gastric cancer and promote the development of miRNA-directed therapeutics against this deadly disease.

Dysregulation of cellular signaling in gastric cancer

The pathogenesis of gastric cancer is complex and related to multiple factors. Dysregulation of intracellular signaling pathways represents a common pathogenic mechanism and may be amenable to drug targeting. Multiple well-established oncogenic pathways, such as those mediated by cell cycle regulators, nuclear factor-kappaB, cyclooxygenase-2 and epidermal growth factor receptor are implicated in gastric carcinogenesis. Emerging evidence also underscores the importance of signaling pathways involved in the developmental process, including transforming growth factor-beta/bone morphogenetic protein signaling, Wnt/beta-catenin signaling, Hedgehog signaling and Notch signaling. Understanding their biological significance will provide a rational basis for drug development. Their relative importance and cross-talk in gastric carcinogenesis, however, are still not completely understood and warrant further investigation.

Helicobacter pylori, inflammation, oxidative damage and gastric cancer: a morphological, biological and molecular pathway

Gastric carcinogenesis is a complex, multistep and multifactorial event, characterized by progressive cyto-histological dedifferentiation, in which the role of Helicobacter pylori infection has been established. Among the pathways relevant to gastric carcinogenesis and correlated with H. pylori infection, it has been demonstrated that the production of reactive oxygen species, with damage to the DNA, may be quite important. Oxidative damage, alone and/or in combination with exogenous and endogenous factors, induces several molecular changes. The assumption is that, in precancerous lesions, these molecular changes belong to the same biological spectrum as their invasive counterpart. The molecular profile of these preneoplastic lesions is heterogeneous, however, and there are still no molecular markers enabling the distinction between atypical hyperplastic lesions and low-grade noninvasive neoplasia (NiN) or between high-grade NiN and early invasive neoplasia. Indeed, within the spectrum of morphological changes characterizing this multistep evolution, dysplasia (NiN) is the lesion coming closest to the development of invasive adenocarcinoma. Several of the genetic and epigenetic alterations reported in gastric precancerous lesions affect DNA repair system genes, tumor suppressor genes, oncogenes, cell cycle regulators, growth factors, and adhesion molecules. Although we await reliable molecular markers, it is best to monitor patients harboring NiN closely with endoscopy and extensive bioptic sampling, and to eradicate any H. pylori to prevent the accumulation of oxidative DNA damage and its consequent progression. The growing body of evidence of the regression of precancerous changes and the high prevalence of superficial gastric carcinoma demonstrated in long-term follow-up studies on NiN make this approach mandatory.

Oxidative DNA damage in gastric cancer: CagA status and OGG1 gene polymorphism

Oxidative DNA damage is thought to play an important part in the pathogenesis of H. pylori-induced mucosal damage. 8-OHdG is a sensitive marker of DNA oxidation and is repaired by a polymorphic glycosylase (OGG1) more effectively than by OGG1-Cys(326). The aims of this study were to ascertain the respective roles of H. pylori, cagA status and OGG1 polymorphism in determining 8-OHdG levels in benign and premalignant stomach diseases and in gastric cancer (GC). The study involved 50 GC patients (for whom both neoplastic tissue and surrounding mucosa were available), 35 with intestinal metaplasia and atrophy (IMA) and 43 controls. H. pylori and cagA status were determined by histology and polymerase chain reaction for urease and cagA. 8-OHdG was assayed using HPLC with an electrochemical detector (HPLC-ED). The OGG1 1245C-->G transversion was identified using RFLP analyses. 8-OHdG levels were significantly higher in GC, with no differences in relation to H. pylori or cagA status. OGG1 polymorphism was documented in 34% of GC (15 Ser/Cys, 2 Cys/Cys). OGG1 1245C-->G polymorphism was detected in 54% of IMA patients, but only 16% of controls (p = 0.0004) and coincided with significantly higher 8-OHdG levels. In the multivariate analysis, 8-OHdG levels were predicted by histotype and OGG1 status. OGG1 1245C-->G polymorphism was common in both GC and IMA, but very rare in controls, and correlated more closely with 8-OHdG levels than do H. pylori infection or cagA status.

Is interleukin-1 genotyping useful for the clinical management of patients with atrophic body gastritis?

BACKGROUND

Atrophic body gastritis patients are at increased risk for gastric cancer. IL-1B/IL-1RN polymorphisms have been associated with gastric cancer susceptibility. The relationship between these polymorphisms and the long-term outcome of atrophic body gastritis patients is not known.

AIM

To investigate whether the genotyping of IL-1B-511/IL-1RN polymorphisms is useful to characterize atrophic body gastritis patients at increased risk for gastric neoplasms.

METHODS

IL-1B-511/IL-1RN polymorphisms were compared between 110 atrophic body gastritis patients and 110 age- and gender-matched controls, and patients were followed up (median 4.1 years) according to a cohort study design.

RESULTS

Genotype frequencies of IL-1B-511/IL-1RN were similar between patients and controls. Atrophic body gastritis patients harbouring the wild type of IL-1B-511/IL-1RN polymorphisms were not different from those harbouring the proinflammatory pattern as far as regards gender, age, gastric cancer family history and metaplastic atrophy. Sixteen atrophic body gastritis patients developed a gastric neoplastic lesion at follow-up: eight were IL-1B-511-T carriers and eight were IL-1RN-allele-2 carriers. Harbouring the proinflammatory genotypes was not significantly associated with developing gastric neoplastic lesions.

CONCLUSIONS

In atrophic body gastritis patients, IL-1B-511 and IL-1RN polymorphisms do not appear to be associated either with specific clinical, biochemical or histological features or with the development of gastric neoplastic lesions at long-term follow-up.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clarithromycin resistance, tumor necrosis factor alpha gene polymorphism and mucosal inflammation affect H. pylori eradication success

Several bacterial and host-related factors concur in causing Helicobacter pylori eradication failure. We ascertained the role of bacterial virulence genes (cagA, vacA), clarithromycin resistance [Cla(R), 23S ribosomal RNA (rRNA) mutations], host polymorphism of CYP2C19 (polyphosphoinositide, PPI, metabolism) and of the cytokines IL-1B-31C>T, IL-1RN VNTR, IFN-gamma+874A>T, TNF-alpha-1031T>C, TNF-alpha-857C>T, TNF-alpha-376G>A, TNF-alpha-308G>A, TNF-alpha-238G>A, IL-10-1082A>G, IL-10-819C>T, IL-10-592C>A, IL-12A+6686G>A, IL-12B+15485A>C. Two groups of H. pylori-infected and H. pylori-treated patients were retrospectively identified: 45 not eradicated and 57 eradicated. Treatment failure was significantly correlated with Cla(R) (all resistant strains in non-eradicated patients); with TNF-alpha-238, IL10-819, IL10-592, IL-12B+15485 single nucleotide polymorphism (SNP); with IL10 ATA/ATA haplotype; and with antral inflammatory grade. On considering Cla(S)-infected patients only, logistic regression analysis (eradication = dependent; TNF-alpha-238, IL12B + 15485 genotypes, IL10 ATA/ATA as present or absent, antral gastritis grade = covariates) confirmed as significantly correlated with eradication antral gastritis grade only (Exp(B) = 6.48; 95% CI, 1.2-35.01). In conclusion, the bacterial determinant causing triple therapy failure is clarithromycin resistant, being virulence genes not involved. The host related factors that favor eradication are those linked to inflammation: a higher inflammatory infiltrate in the mucosa, possibly favored by genotypes able to down regulate the anti-inflammatory cytokine response, enhance the chance of eradication success.

Gastric cancer susceptibility is not linked to pro-and anti-inflammatory cytokine gene polymorphisms in whites: a Nationwide Multicenter Study in Spain

BACKGROUND AND AIMS

Recent studies have reported an association between cytokine gene polymorphisms and GC risk. However, results are inconsistent among studies from different geographic regions and ethnic groups. Our goal was to evaluate the influence of Helicobacter pylori (H. pylori) infection and host genetic factors on GC susceptibility in a population of Spanish white GC patients.

METHODS

DNA from 404 unrelated patients with GC and 404 sex- and age-matched healthy controls was typed for several functional polymorphisms in pro- (IL-1B, TNFA, LTA, IL-12p40) and anti-inflammatory (IL-4, IL-1RN, IL-10, TGFB1) genes by PCR, RFLP, and TaqMan assays. H. pylori infection and CagA/VacA antibody status were also determined by western blot serology.

RESULTS

Logistic regression analysis identified H. pylori infection with cagA strains (OR 2.54, 95% CI 1.77-3.66), smoking habit (OR 1.91, 95% CI 1.25-2.93), and positive family history of GC (OR 3.67, 95% CI 2.01-6.71) as independent risk factors for GC. None of the cytokine gene polymorphisms analyzed in this study were associated with susceptibility to GC development, whether GC patients were analyzed as a group or categorized according to anatomic location or histological subtype. Some simultaneous combinations of proinflammatory genotypes reportedly associated with greater GC risk yielded no significant differences between patients and controls.

CONCLUSIONS

Our results show that, at least in some white populations, the contribution of the cytokine gene polymorphisms evaluated in this study (IL-1B, IL-1RN, IL-12p40, LTA, IL-10, IL-4, and TGF-B1) to GC susceptibility may be less relevant than previously reported.

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.

TGFB1 gene polymorphisms: their relevance in the susceptibility to Helicobacter pylori-related diseases

Recent studies have revealed elevated expression of transforming growth factor beta1 (TGF-beta1) in gastric mucosa of patients with gastric cancer (GC) and those undergoing ulcer repair. As production of TGF-beta1 is genetically regulated, we aimed to assess whether functional polymorphisms of the TGFB1 gene are involved in susceptibility to and clinical characteristics of Helicobacter pylori-related diseases. DNA from 142 unrelated Spanish patients with GC, 200 with peptic ulcer and 342 healthy controls was typed for the MspA1I T+869C, and the Sau96I G+915C polymorphisms of the TGFB1 gene using polymerase chain reaction and RFLP analysis. H. pylori infection and CagA/VacA antibody status were determined by Western blot in patients and controls. H. pylori infection (odds ratio (OR): 11.44; 95% confidence interval (CI): 4.45-29.42; P<0.001) and non-steroidal anti-inflammatory drugs (OR: 5.07; 95% CI: 2.53-10.16; P<0.001) were identified as independent risks factors for duodenal ulcer (DU), whereas the TGFB1+869(*)C/C genotype was associated with reduced risk of developing the disease (OR: 0.32; 95% CI=0.15-0.68; P=0.003). Our results show that the TGFB1 T+869C gene polymorphism is involved in the susceptibility to DU and provide further evidence that host genetic factors play a key role in the pathogenesis of H. pylori-related diseases.

Effect of NaCl and Helicobacter pylori vacuolating cytotoxin on cytokine expression and viability

AIM: To determine whether Helicobacter pylori (H pylori) vacuolating cytotoxin (VacA) regulates release of pro-inflammatory cytokines (IL-1β, IL-8, TNF-α, and IL-6) or alters gastric epithelial cell viability and to determine whether NaCl affects these VacA-induced changes.

METHODS: Vacuolating activity was determined by measuring the uptake of neutral red into vacuoles of VacA-treated human gastric epithelial (AGS) cells. AGS cell viability was assessed by direct cell counting. Specific enzyme-linked immunosorbent assays (ELISA) and reverse transcriptase-polymerase chain reaction(RT-PCR) were performed to examine the effects of H pylori VacA and NaCl on cell pro-inflammatory cytokine production in AGS cells. Immunohistochemical staining of gastric tissue from Mongolian gerbils was used to confirm VacA-induced pro-inflammatory cytokine production and the effects of NaCl on this VacA-induced response.

RESULTS: Addition of VacA alone reduced AGS cell viability (P < 0.05), and this reduction was enhanced by high doses of NaCl (P < 0.05). VacA alone induced expression of TNF-α, IL-8 and IL-1β, while NaCl alone induced expression of TNF-α and IL-1β. Changes in mRNA levels in the presence of both VacA and NaCl were more complicated. For the case of TNF-α, expression was dose-dependent on NaCl. IL-6 mRNA was not detected. However, low levels of IL-6 were detected by ELISA. Positive immunohistochemical staining of IL-1, IL-6, and TNF-α was found in gastric tissue of H pylori-infected gerbils fed with either a normal diet or a high salt diet. However, the staining of these three cytokines was stronger in H pylori-infected animals fed with a 5g/kg NaCl diet.

CONCLUSION: VacA decreases the viability of AGS cells, and this effect can be enhanced by NaCl. NaCl also affects the production of pro-inflammatory cytokines induced by VacA, suggesting that NaCl plays an important role in H pylori-induced gastric epithelial cell cytotoxicity.

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

We review the current information concerning the role of cytokine polymorphisms and the risk of develop distal gastric cancer in different populations. We have included populations colonized with Helicobacter pylori as well as populations without colonization. We found that the study of polymorphisms alone seems insufficient to assess gastric cancer risk and it is necessary to examine environmental factors in different ethnic groups and geographic areas along with the study of H. pylori strains to define better the risk factors associated with distal gastric cancer.

Interleukin-1 gene polymorphisms and gastric cancer risk in a high-risk Italian population

OBJECTIVES

Host genetic factors, including the IL1 gene cluster, play a key role in determining the long-term outcome of Helicobacter pylori infection. The aim of the study was to investigate the relationship between selected IL1 loci polymorphisms and gastric cancer risk in an Italian population.

METHODS

In a case-control study we compared the IL1B-31 and IL1B+3954 biallelic and IL1RN pentaallelic variable number of tandem repeats (VNTR) polymorphisms in 185 gastric cancer patients and 546 controls randomly sampled from the general population of an area at high gastric cancer risk (Tuscany, Central Italy).

RESULTS

Genotype frequencies of the IL1B-31 T/C, IL1B+3954 C/T, and IL1RN polymorphisms among our population controls were in Hardy-Weinberg equilibrium. In multivariate analyses, no increase in gastric cancer risk was observed for the IL1B-31*C- and IL1B+3954*T- carriers; a significant 50% increase emerged for IL1RN*2 allele carriers (OR = 1.49; 95% CI: 1.01-2.21). Analyses based on combined genotypes showed also that the association with IL1RN*2 allele was limited to two-variant allele carriers who were also homozygous for the IL1B-31*T allele (OR = 2.23; 95% CI: 1.18-4.23) with a statistically significant interaction between these two genotypes (p= 0.043). Haplotype analysis showed an increased risk for the haplotype IL1RN*2/IL1B-31*T.

CONCLUSIONS

Our results suggest that host genetic factors (such as the IL1RN and the IL1B-31 polymorphisms) interact in the complex process of gastric carcinogenesis in this high-risk Italian population. Overall, this effect appears more modest than previously reported in other populations, supporting the hypothesis that other still-to-be-defined factors are important in gastric carcinogenesis. These findings might be due to a haplotype effect.

H. pylori infection: bacterial virulence factors and cytokine gene polymorphisms as determinants of infection outcome

The gram negative bacterium H. pylori infects the human stomach worldwide, invariably causing mucosal inflammation. In the majority of cases, H. pylori-associated gastritis remains the only clinical manifestation of the infection, which might cause, otherwise, peptic ulcer, gastric adenocarcinoma. or MALToma. The balance between the bacterial virulence machinery and the host response to the infection determines the different clinical outcomes. The main bacterial virulence factors comprise adhesins (BabA, SabA), the vacuolating cytotoxin VacA, and the products of cag pathogenicity island. The pattern of cytokine production in response to the infection is one of the main host determinants involved in limiting the infection outcome to gastritis or in favoring peptic ulcer or cancer onset. The polymorphisms of some cytokine genes (IL-1beta IL-1RN, TNF-alpha, IFN-gamma) have been correlated with H. pylori-associated gastric adenocarcinoma or peptic ulcer, possibly because they influence the amount of cytokine production in response to H. pylori infection. This review focuses on the role of H. pylori virulence genes and on host cytokines' genes polymorphisms in determining clinical outcome to H. pylori infection.

Genetic susceptibility to tobacco-related cancer

Although cigarette smoking is the dominant risk factor for several epithelial cancers, only a small fraction of individuals with tobacco exposure develop cancer. The underlying hypothesis is that genetic factors may render certain smokers more susceptible to cancer than others. Genetic alterations in critical regulatory pathways may predispose cells to carcinogenesis. These pathways include regulation of xenobiotic metabolism; control of genomic stability, including DNA repair mechanisms, cell-cycle checkpoints, apoptosis and telomere length; and control of microenvironmental factors, such as matrix metalloproteinases, inflammation and growth factors. In addition, epigenetic events, such as promoter hypermethylation and loss of imprinting, are also involved in carcinogenesis. In this review, we will summarize recent advances in genetic susceptibility to tobacco-related cancer. Emphasizing on risk assessment, we will describe how genetic variations in the above-mentioned genetic pathways modify the tobacco-related cancer risk. In addition, we will discuss how genetic variations may assist in predicting clinical outcome, such as the natural history of cancer and treatment response. The measurements of genetic susceptibility by both genotypic and phenotypic assays are covered in the text. Finally, we present a number of current concerns that need to be addressed as the exciting field of molecular cancer epidemiology advances rapidly.