Oncogenic CagA promotes gastric cancer risk via activating ERK signaling pathways: a nested case-control study.
ABSTRACT: BACKGROUND: CagA cellular interaction via activation of the ERK signaling pathway may be a starting point in the development of gastric cancer. This study aimed to evaluate whether genes involved in ERK downstream signaling pathways activated by CagA are susceptible genetic markers for gastric cancer. METHODS: In the discovery phase, a total of 580 SNPs within +/-5 kbp of 30 candidate genes were genotyped to examine an association with gastric cancer risk in the Korean Multi-center Cancer Cohort (100 incident gastric cancer case-control sets). The most significant SNPs (raw or permutated p value<0.02) identified in the discovery analysis were re-evaluated in the extension phase using unconditional logistic regression model (400 gastric cancer case-control sets). Combined analyses including pooled- and meta-analysis were conducted to summarize all the results. RESULTS: 24 SNPs in eight genes (ERK, Dock180, C3G, Rap1, Src, CrkL, Mek and Crk) were significantly associated with gastric cancer risk in the individual SNP analyses in the discovery phase (p<0.05). In the extension analyses, ERK rs5999749, Dock180 rs4635002 and C3G rs7853122 showed marginally significant gene-dose effects for gastric cancer. Consistently, final combined analysis presented the SNPs as significantly associated with gastric cancer risk (OR?=?1.56, [95% CI: 1.19-2.06], OR?=?0.61, [95% CI: 0.43-0.87], OR?=?0.59, [95% CI: 0.54-0.76], respectively). CONCLUSIONS: Our findings suggest that ERK rs5999749, Dock180 rs4635002 and C3G rs7853122 are genetic determinants in gastric carcinogenesis.
Project description:OBJECTIVES: To evaluate whether genes that encode CagA-interacting molecules (SRC, PTPN11, CRK, CRKL, CSK, c-MET and GRB2) are associated with gastric cancer risk and whether an interaction between these genes and phytoestrogens modify gastric cancer risk. METHODS: In the discovery phase, 137 candidate SNPs in seven genes were analyzed in 76 incident gastric cancer cases and 322 matched controls from the Korean Multi-Center Cancer Cohort. Five significant SNPs in three genes (SRC, c-MET and CRK) were re-evaluated in 386 cases and 348 controls in the extension phase. Odds ratios (ORs) for gastric cancer risk were estimated adjusted for age, smoking, H. pylori seropositivity and CagA strain positivity. Summarized ORs in the total study population (462 cases and 670 controls) were presented using pooled- and meta-analysis. Plasma concentrations of phytoestrogens (genistein, daidzein, equol and enterolactone) were measured using the time-resolved fluoroimmunoassay. RESULTS: SRC rs6122566, rs6124914, c-MET rs41739, and CRK rs7208768 showed significant genetic effects for gastric cancer in both the pooled and meta-analysis without heterogeneity (pooled OR = 3.96 [95% CI 2.05-7.65], 1.24 [95% CI = 1.01-1.53], 1.19 [95% CI = 1.01-1.41], and 1.37 [95% CI = 1.15-1.62], respectively; meta OR = 4.59 [95% CI 2.74-7.70], 1.36 [95% CI = 1.09-1.70], 1.20 [95% CI = 1.00-1.44], and 1.32 [95% CI = 1.10-1.57], respectively). Risk allele of CRK rs7208768 had a significantly increased risk for gastric cancer at low phytoestrogen levels (p interaction<0.05). CONCLUSIONS: Our findings suggest that SRC, c-MET and CRK play a key role in gastric carcinogenesis by modulating CagA signal transductions and interaction between CRK gene and phytoestrogens modify gastric cancer risk.
Project description:The objective of the study was to investigate the role of genes (HSD3B1, CYP17A1, CYP19A1, HSD17B2, HSD17B1) involved in the steroid hormone biosynthesis pathway and progesterone receptor (PGR) in the etiology of gastric cancer in a population-based two-phase genetic association study.In the discovery phase, 108 candidate SNPs in the steroid hormone biosynthesis pathway related genes and PGR were analyzed in 76 gastric cancer cases and 322 controls in the Korean Multi-Center Cancer Cohort. Statistically significant SNPs identified in the discovery phase were re-evaluated in an extended set of 386 cases and 348 controls. Pooled- and meta-analyses were conducted to summarize the results.Of the 108 SNPs in steroid hormone biosynthesis pathway related genes and PGR analyzed in the discovery phase, 23 SNPs in PGR in the recessive model and 10 SNPs in CYP19A1 in the recessive or additive models were significantly associated with increased gastric cancer risk (p<0.05). The minor allele frequencies of the SNPs in both the discovery and extension phases were not statistically different. Pooled- and meta-analyses showed CYP19A1 rs1004982, rs16964228, and rs1902580 had an increased risk for gastric cancer (pooled OR [95% CI]?=?1.22 [1.01-1.48], 1.31 [1.03-1.66], 3.03 [1.12-8.18], respectively). In contrast, all PGR SNPs were not statistically significantly associated with gastric cancer risk.Our findings suggest CYP19A1 that codes aromatase may play an important role in the association of gastric cancer risk and be a genetic marker for gastric cancer susceptibility.
Project description:<h4>Objective</h4>Genetic variants regulating the host immune system may contribute to the susceptibility for the development of gastric cancer. Little is known about the role of the innate immunity- and non-Hodgkin's lymphoma (NHL)-related genes for gastric cancer risk. This nested case-control study was conducted to identify candidate genes for gastric cancer risk for future studies.<h4>Methods</h4>In the Discovery phase, 3,072 SNPs in 203 innate immunity- and 264 NHL-related genes using the Illumine GoldenGateTM OPA Panel were analyzed in 42 matched case-control sets selected from the Korean Multi-center Cancer Cohort (KMCC). Six significant SNPs in four innate immunity (DEFA6, DEFB1, JAK3, and ACAA1) and 11 SNPs in nine NHL-related genes (INSL3, CHMP7, BCL2L11, TNFRSF8, RAD50, CASP7, CHUK, CD79B, and CLDN9) with a permutated p-value <0.01 were re-genotyped in the Replication phase among 386 cases and 348 controls. Odds ratios (ORs) for gastric cancer risk were estimated adjusting for age, smoking status, and H. pylori and CagA sero-positivity. Summarized ORs in the total study population (428 cases and 390 controls) are presented using pooled- and meta-analyses.<h4>Results</h4>Four SNPS had no heterogeneity across the phases: in the meta-analysis, DEFA6 rs13275170 and DEFB1 rs2738169 had both a 1.3-fold increased odds ratio (OR) for gastric cancer (95% CIs = 1.1-1.6; and 1.1-1.5, respectively). INSL3 rs10421916 and rs11088680 had both a 0.8-fold decreased OR for gastric cancer (95% CIs = 0.7-0.97; and 0.7-0.9, respectively).<h4>Conclusions</h4>Our findings suggest that certain variants in the innate immunity and NHL-related genes affect the gastric cancer risk, perhaps by modulating infection-inflammation-immunity mechanisms that remain to be defined.
Project description:The Helicobacter pylori protein CagA may undergo tyrosine phosphorylation following its entry into human gastric epithelial cells with downstream effects on signal transduction. Disruption of the gp130 receptor that modulates the balance of the SHP2/ERK and JAK/STAT pathways enhanced peptic ulceration and gastric cancer in gp130 knock-out mice. In this study, we evaluated the effect of translocated CagA in relation to its tyrosine phosphorylation status on the gp130-mediated signal switch between the SHP2/ERK and JAK/STAT3 pathways. We showed that in the presence of CagA, SHP2 was recruited to gp130. Phosphorylated CagA showed enhanced SHP2 binding activity and ERK1/2 phosphorylation, whereas unphosphorylated CagA showed preferential STAT3 activation. These findings indicate that the phosphorylation status of CagA affects the signal switch between the SHP2/ERK and JAK/STAT3 pathways through gp130, providing a novel mechanism to explain H. pylori signaling.
Project description:Previous studies have shown that regeneration gene 3 (reg3) is significantly expressed in gastric mucosa tissues with Helicobacter pylori (HP) cytotoxin-associated gene A (CagA)-positive (HP-CagA+). CagA-positive HP increases the risk of gastric cancer. The purpose of this study was to investigate the correlation between reg3 and HP-CagA+ and explore the effects of reg3 on the proliferation of gastric cancer cells and the development of tissues and organs. We analyzed the expression of reg3 in human tissues and organs. The results showed that reg3 expression in gastric tissues was significantly higher than that in other tissues and organs. In addition, reg3 influenced the prognosis of gastric, lung, and ovarian cancers. Immunohistochemical analysis indicated that the expression of reg3 and CagA in cancerous tissues was higher than that in adjacent tissues. HP-CagA+ infection of gastric cancer cells promotes reg3 expression, suggesting that reg3 may be a target gene of CagA in gastric cancer, which together affects the formation and development of gastric cancer. reg3 and CagA promote cell proliferation, and then affect the development of mouse tissues and organs by regulating G1/S phase transition of the cell cycle via the formation of the cell cycle-dependent complex CDK4/CyclinD1. This is the first study that shows the influence of CagA on the cell cycle and induction of cell proliferation by promoting reg3 expression.
Project description:Because to date there is no available study on STAT3 polymorphism and gastric cancer in Western populations and taking into account that Helicobacter pylori CagA EPIYA-C segment deregulates SHP-2/ERK-JAK/STAT3 pathways, we evaluated whether the two variables are independently associated with gastric cancer.We included 1048 subjects: H. pylori-positive patients with gastric carcinoma (n = 232) and with gastritis (n = 275) and 541 blood donors. Data were analyzed using logistic regression model.The rs744166 polymorphic G allele (p = 0.01; OR = 1.76; 95 % CI = 1.44-2.70), and CagA-positive (OR = 12.80; 95 % CI = 5.58-19.86) status were independently associated with gastric cancer in comparison with blood donors. The rs744166 polymorphism (p = 0.001; OR = 1.64; 95 % CI = 1.16-2.31) and infection with H. pylori CagA-positive strains possessing higher number of EPIYA-C segments (p = 0.001; OR = 2.28; 95 % CI = 1.41-3.68) were independently associated with gastric cancer in comparison with gastritis. The association was stronger when host and bacterium genotypes were combined (p < 0.001; OR = 3.01; 95 % CI = 2.29-3.98). When stimulated with LPS (lipopolysaccharide) or Pam3Cys, peripheral mononuclear cells of healthy carriers of the rs744166 GG and AG genotypes expressed higher levels of STAT3 mRNA than those carrying AA genotype (p = 0.04 for both). The nuclear expression of phosphorylated p-STAT3 protein was significantly higher in the antral gastric tissue of carriers of rs744166 GG genotype than in carriers of AG and AA genotypes.Our study provides evidence that STAT3 rs744166 G allele and infection with CagA-positive H. pylori with higher number of EPIYA-C segments are independent risk factors for gastric cancer. The odds ratio of having gastric cancer was greater when bacterium and host high risk genotypes were combined.
Project description:BACKGROUND: Most of what is known about the Helicobacter pylori (H. pylori) cytotoxin, CagA, pertains to a much-vaunted role as a determinant of gastric inflammation and cancer. Little attention has been devoted to potential roles of CagA in the majority of H. pylori infected individuals not showing oncogenic progression, particularly in relation to host tolerance. Regenerating islet-derived (REG)3? encodes a secreted C-type lectin that exerts direct bactericidal activity against Gram-positive bacteria in the intestine. Here, we extend this paradigm of lectin-mediated innate immunity, showing that REG3? expression is triggered by CagA in the H. pylori-infected stomach. METHODOLOGY/PRINCIPAL FINDINGS: In human gastric mucosal tissues, REG3? expression was significantly increased in CagA-positive, compared to CagA-negative H. pylori infected individuals. Using transfected CagA-inducible gastric MKN28 cells, we recapitulated REG3? induction in vitro, also showing that tyrosine phosphorylated, not unphosphorylated CagA triggers REG3? transcription. In concert with induced REG3?, pro-inflammatory signalling downstream of the gp130 cytokine co-receptor via the signal transducer and activator of transcription (STAT)3 and transcription of two cognate ligands, interleukin(IL)-11 and IL-6, were significantly increased. Exogenous IL-11, but not IL-6, directly stimulated STAT3 activation and REG3? transcription. STAT3 siRNA knockdown or IL-11 receptor blockade respectively abrogated or subdued CagA-dependent REG3? mRNA induction, thus demonstrating a requirement for uncompromised signalling via the IL-11/STAT3 pathway. Inhibition of the gp130-related SHP2-(Ras)-ERK pathway did not affect CagA-dependent REG3? induction, but strengthened STAT3 activation as well as augmenting transcription of mucosal innate immune regulators, IL-6, IL-8 and interferon-response factor (IRF)1. CONCLUSIONS/SIGNIFICANCE: Our results support a model of CagA-directed REG3? expression in gastric epithelial cells via activation of the IL-11/gp130/STAT3 pathway. This response might allow Gram-negative H. pylori to manipulate host immunity to favour its own survival, by reducing the fitness of co-habiting Gram-positive bacteria with which it competes for resources in the gastric mucosal niche.
Project description:A higher incidence of stomach cancer in ABO blood type A individuals than in those with blood type O has been known for a long time. We studied this association in relation to Helicobacter pylori (Hp) of different cagA status. For our study, we used baseline gastric histopathology data and DNAs from frozen gastric biopsies of 2,077 subjects enrolled in a chemoprevention trial for gastric precancerous lesions in Venezuela. We analyzed six single nucleotide polymorphisms in the ABO gene, and we assessed the presence of the Hp cagA gene. Odds ratios (ORs) for risk of advanced precancerous gastric lesions were calculated using individuals with normal gastric epithelium or non-atrophic gastritis as a reference. Among individuals carrying a cagA negative Hp infection or no Hp infection, those with blood type A had a lower risk of intestinal metaplasia (IM) and dysplasia than those with blood type O (OR=0.60; 95% CI 0.38-0.94). In carriers of cagA positive Hp strains, individuals with blood type A had a higher risk of IM or dysplasia than those with blood type O (OR=1.42, 95% CI 1.09-1.86) and a higher risk if compared to subjects carrying cagA negative strain and non-A blood group (OR=3.82, 95% CI=2.80-5.20). The interaction between Hp cagA status and blood type was statistically significant (p=0.0006). We showed that SNPs in the ABO gene, predictive of ABO blood groups, are associated with risk of advanced precancerous gastric lesions in individuals infected with Hp, but the assessment of the risk is strictly dependent on cagA status.
Project description:Helicobacter pylori (HP) is a bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa. Persistent Hp infection often induces gastritis and is associated with the development of peptic ulcer disease, atrophic gastritis, and gastric adenocarcinoma. Virulent HP isolates harbor the cag (cytotoxin-associated genes) pathogenicity island (cagPAI), a 40 kb stretch of DNA that encodes components of a type IV secretion system (T4SS). This T4SS forms a pilus for the injection of virulence factors into host target cells, such as the CagA oncoprotein. We analyzed the genetic variability in cagA and other selected genes of the HP cagPAI (cagC, cagE, cagL, cagT, cagV and cag Gamma) using DNA extracted from frozen gastric biopsies or from clinical isolates. Study subjects were 95 cagA+ patients that were histologically diagnosed with chronic gastritis or gastric cancer in Venezuela and Mexico, areas with high prevalence of Hp infection. Sequencing reactions were carried out by both Sanger and next-generation pyrosequencing (454 Roche) methods. We found a total of 381 variants with unambiguous calls observed in at least 10% of the originally tested samples and reference strains. We compared the frequencies of these genetic variants between gastric cancer and chronic gastritis cases. Twenty-six SNPs (11 non-synonymous and 14 synonymous) showed statistically significant differences (P<0.05), and two SNPs, in position 1039 and 1041 of cagE, showed a highly significant association with cancer (p-value?=?2.07×10??), and the variant codon was located in the VirB3 homology domain of Agrobacterium. The results of this study may provide preliminary information to target antibiotic treatment to high-risk individuals, if effects of these variants are confirmed in further investigations.
Project description:CRK belongs to a family of adaptor proteins that consist mostly of SH2 and SH3 domains. Far Western blotting with CRK SH3 has demonstrated that it binds to 135- to 145-, 160-, and 180-kDa proteins. The 135- to 145-kDa protein is C3G, a CRK SH3-binding guanine nucleotide exchange protein. Here, we report on the molecular cloning of the 180-kDa protein, which is designated DOCK180 (180-kDa protein downstream of CRK). The isolated cDNA contains a 5,598-bp open reading frame encoding an 1,866-amino-acid protein. The deduced amino acid sequence did not reveal any significant homology to known proteins, except that an SH3 domain was identified at its amino terminus. To examine the function of DOCK180, a Ki-Ras farnesylation signal was fused to the carboxyl terminus of DOCK180, a strategy that has been employed successfully for activation of adaptor-binding proteins in vivo. Whereas wild-type DOCK180 accumulated diffusely in the cytoplasm and did not have any effect on cell morphology, farnesylated DOCK180 was localized on the cytoplasmic membrane and changed spindle 3T3 cells to flat, polygonal cells. These results suggest that DOCK180 is a new effector molecule which transduces signals from tyrosine kinases through the CRK adaptor protein.