Abstract IA06: Understanding the molecular landscape of gastric premalignant lesions

Even though the incidence of gastric cancer has been declining over the years, it still has a very high mortality rate. The incidence and mortality of gastric cancer is, however, significantly higher in minority populations with African Americans and Hispanic individuals presenting 52% and 43%, respectively, more cases than Caucasians (data for male patients). Gastric adenocarcinoma has been strongly associated to infection with Helicobacter pylori (H. pylori). The infection triggers an inflammatory cascade, known as the Correa's cascade, that changes the normal gastric epithelium into nonatrophic gastritis (NAG), multifocal atrophic gastritis (MAG), intestinal metaplasia (IM), dysplasia, and cancer. It is known that these events involve immune infiltration and damage to the gastric mucosa; however, there is still too much to learn about the gastric premalignant stages and the evolution of them over time. Over the years we have identified single-nucleotide polymorphisms (SNPs) and differential expression of genes associated with premalignant stages and with evolution of the disease over time. We found that African Americans have increased incidence of advanced premalignant lesions and have more prevalence of infection with H. pylori than Whites. In addition, we found that SNPs and haplotypes in the interleukin 1 b gene (IL1B) are associated with advanced gastritis in African American individuals. Interestingly, the frequency of these inflammatory SNPs and haplotypes is different among African American and Caucasian individuals. In terms of gene expression, we have also found that the increased expression of the gene deleted in malignant brain tumors 1 (DMBT1) is associated with the development of advanced gastritis while the expression of CD44 is associated with progression of the disease over time. Given that CD44 is a molecule involved in the homing of inflammatory cells, its association with progression of premalignant stages over time highlights the role of the immune response in the outcome of these lesions. Interestingly, these immune responses seem to be also modulated by H. pylori itself. We have shown that H. pylori components are able to modulate acquired and innate immune responses. In addition, we have also found a microRNA pattern associated with advanced premalignant gastric lesions in both African Americans and Caucasians. Understanding the molecular landscape of the gastric lesions may help us devise strategies to intervene and limit their progression into more advanced lesions, including gastric cancer.

Citation Format: Jone Garai, Maria B. Piazuelo, Maria C. Camargo, Pelayo Correa, Keith Wilson, Jovanny Zabaleta. Understanding the molecular landscape of gastric premalignant lesions [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr IA06.

Hypusination regulates the antibacterial response of macrophages

Introduction

Hypusine is an amino acid found only in the eukaryotic translation initiation factor 5A (EIF5A). Hypusine is synthesized by the enzyme deoxyhypusine synthase (DHPS) that transfers the N-moiety of spermidine to a lysine residue in EIF5A. This post-translational modification (hypusination) is essential to binding specific mRNAs. The EIF5AHyp/mRNA complex is translocated to the cytoplasm, reaches ribosomes, and allows for translation. We analyzed the role of hypusination in the innate response of macrophages.

Results

The gastric pathogen Helicobacter pylori stimulated DHPS expression and hypusination in murine bone marrow-derived macrophages (BMmacs). We generated myeloid-specific Dhps knockout mice (DhpsΔmye) by crossing Dhpsfl/fl mice to Lyz2-cre mice. By iTRAQ proteomics, 29 of the proteins induced by H. pylori in BMmacs from Dhpsfl/fl mice were significantly less expressed in infected DhpsΔmye mice. These included antibacterial effectors (IRG1, NOS2), cytokines (TNF-α, IL-1β), and mediators of autophagy (SQSTM, IRGM1). These findings were confirmed by Western blot. DhpsΔmye mice infected with H. pylori exhibited increased colonization (p<0.01) and gastritis (p<0.05) compared to Dhpsfl/fl mice. DhpsΔmye mice were also more colonized by the intestinal pathogen Citrobacter rodentium than Dhpsfl/fl mice (p<0.05). EIF5AHyp and NOS2 were more expressed in gastric and colonic CD68+ macrophages from H. pylori- and C. rodentium-infected Dhpsfl/fl mice versus uninfected animals, respectively. The staining for EIF5AHyp and NOS2 was markedly reduced in infected DhpsΔmye mice.

Conclusions

Hypusination in myeloid cells is critical for host innate immunity to limit the infectivity of pathogenic bacteria.

Innate CD8αα+ cells promote ILC1-like intraepithelial lymphocyte homeostasis and intestinal inflammation

Innate CD8αα+ cells, also referred to as iCD8α cells, are TCR-negative intraepithelial lymphocytes (IEL) possessing cytokine and chemokine profiles and functions related to innate immune cells. iCD8α cells constitute an important source of osteopontin in the intestinal epithelium. Osteopontin is a pleiotropic cytokine with diverse roles in bone and tissue remodeling, but also has relevant functions in the homeostasis of immune cells. In this report, we present evidence for the role of iCD8α cells in the homeostasis of TCR-negative NKp46+NK1.1+ IEL (ILC1-like). We also show that the effect of iCD8α cells on ILC1-like IEL is enhanced in vitro by osteopontin. We show that in the absence of iCD8α cells, the number of NKp46+NK1.1+ IEL is significantly reduced. These ILC1-like cells are involved in intestinal pathogenesis in the anti-CD40 mouse model of intestinal inflammation. Reduced iCD8α cell numbers results in a milder form of intestinal inflammation in this disease model, whereas treatment with osteopontin increases disease severity. Collectively, our results suggest that iCD8α cells promote survival of NKp46+NK1.1+ IEL, which significantly impacts the development of intestinal inflammation.

Nod1 Imprints Inflammatory and Carcinogenic Responses toward the Gastric Pathogen Helicobacter pylori

Helicobacter pylori (H. pylori) is the strongest known risk for gastric cancer. The H. pylori cag type IV secretion system is an oncogenic locus that translocates peptidoglycan into host cells, where it is recognized by NOD1, an innate immune receptor. Beyond this, the role of NOD1 in H. pylori-induced cancer remains undefined. To address this knowledge gap, we infected two genetic models of Nod1 deficiency with the H. pylori cag ⁺ strain PMSS1: C57BL/6 mice, which rarely develop cancer, and INS-GAS FVB/N mice, which commonly develop cancer. Infected C57BL/6 ^Nod1-/- and INS-GAS ^Nod1-/- mice acutely developed more severe gastritis, and INS-GAS ^Nod1-/- mice developed gastric dysplasia more frequently compared with Nod1^+/+ mice. Because Nod1 genotype status did not alter microbial phenotypes of in vivo-adapted H. pylori, we investigated host immunologic responses. H. pylori infection of Nod1^-/- mice led to significantly increased gastric mucosal levels of Th1, Th17, and Th2 cytokines compared with Nod1 wild-type (WT) mice. To define the role of specific innate immune cells, we quantified cytokine secretion from H. pylori-infected primary gastric organoids generated from WT or Nod1^-/- mice that were cocultured with or without WT or Nod1^-/- macrophages. Infection increased cytokine production from gastric epithelial cells and macrophages and elevations were significantly increased with Nod1 deficiency. Furthermore, H. pylori infection altered the polarization status of Nod1^-/- macrophages compared with Nod1^+/+ macrophages. Collectively, these studies demonstrate that loss of Nod1 augments inflammatory and injury responses to H. pylori. Nod1 may exert its restrictive role by altering macrophage polarization, leading to immune evasion and microbial persistence. SIGNIFICANCE: These findings suggest that manipulation of NOD1 may represent a novel strategy to prevent or treat pathologic outcomes induced by H. pylori infection.

EGFR-mediated macrophage activation promotes colitis-associated tumorigenesis

Epidermal growth factor receptor (EGFR) signaling is a known mediator of colorectal carcinogenesis. Studies have focused on the role of EGFR signaling in epithelial cells, although the exact nature of the role of EGFR in colorectal carcinogenesis remains a topic of debate. Here, we present evidence that EGFR signaling in myeloid cells, specifically macrophages, is critical for colon tumorigenesis in the AOM-DSS model of colitis-associated carcinogenesis (CAC). In a human tissue microarray, colonic macrophages demonstrated robust EGFR activation in the pre-cancerous stages of colitis and dysplasia. Utilizing the AOM-DSS model, mice with a myeloid-specific deletion of Egfr had significantly decreased tumor multiplicity and burden, protection from high-grade dysplasia, and significantly reduced colitis. Intriguingly, mice with gastrointestinal epithelial cell-specific Egfr deletion demonstrated no differences in tumorigenesis in the AOM-DSS model. The alterations in tumorigenesis in myeloid-specific Egfr knockout mice were accompanied by decreased macrophage, neutrophil, and T cell infiltration. Pro-tumorigenic M2 macrophage activation was diminished in myeloid-specific Egfr-deficient mice, as marked by decreased Arg1 and Il10 mRNA expression and decreased IL-4, IL-10 and IL-13 protein levels. Surprisingly, diminished M1 macrophage activation was also detectable, as marked by significantly reduced Nos2 and Il1b mRNA levels and decreased IFN-γ, TNF-α, and IL-1β protein levels. The alterations in M1 and M2 macrophage activation were confirmed in bone marrow-derived macrophages from mice with the myeloid-specific Egfr knockout. The combined effect of restrained M1 and M2 macrophage activation resulted in decreased production of pro-angiogenic factors, CXCL1 and VEGF, and reduced CD31⁺ blood vessels, which likely contributed to protection from tumorigenesis. These data reveal that EGFR signaling in macrophages, but not in colonic epithelial cells, has a significant role in CAC. EGFR signaling in macrophages may prove to be an effective biomarker of CAC or target for chemoprevention in patients with inflammatory bowel disease.

Characterization of progressive metaplasia in the gastric corpus mucosa of Mongolian gerbils infected with Helicobacter pylori

Spasmolytic polypeptide-expressing metaplasia (SPEM) and intestinal metaplasia are considered neoplastic precursors of gastric adenocarcinoma in humans. Loss of parietal cells causes the development of SPEM in the gastric corpus and then chronic inflammation drives SPEM toward a more proliferative lineage. Mongolian gerbils infected with Helicobacter pylori develop chronic gastritis and metaplasia, mimicking aspects of human gastritis with H. pylori infection. We therefore examined metaplastic lineages in the gastric corpus mucosa of gerbils infected by H. pylori strain 7.13, which produces rapid onset of severe inflammation. Six weeks following H. pylori infection, Griffonia simplicifolia lectin II (GSII)-positive SPEM developed in the base of oxyntic glands in association with parietal cell loss and inflammation. In association with severe inflammation, SPEM glands evolved into aberrant phenotypes, including branched lesions, dilated lesions, and penetrating invasive glands. Mucin 4 (MUC4) was up-regulated in SPEM and progressive SPEM. Clusterin was expressed in the tips of branched and dilated lesions and throughout regions of invasive glands. Intriguingly, clusterin-positive regions in these lesions expressed Ki67 and matrix metalloproteinase 7 (MMP-7). These same regions were also positive for expression of phospho-IkBα, suggestive of activated NFkB signalling. These findings suggest that clusterin-positive regions in progressive phenotypes of SPEM have invasive characteristics. Thus, H. pylori infection in gerbils induces SPEM, which then can progress to further aberrant and invasive metaplastic phenotypes. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pathogenic Helicobacter pylori strains translocate DNA and activate TLR9 via the cancer-associated cag type IV secretion system

Helicobacter pylori is the strongest identified risk factor for gastric cancer, the third most common cause of cancer-related death worldwide. An H. pylori constituent that augments cancer risk is the strain-specific cag pathogenicity island, which encodes a type IV secretion system (T4SS) that translocates a pro-inflammatory and oncogenic protein, CagA, into epithelial cells. However, the majority of persons colonized with CagA⁺H. pylori strains do not develop cancer, suggesting that other microbial effectors also play a role in carcinogenesis. Toll-like receptor 9 (TLR9) is an endosome bound, innate immune receptor that detects and responds to hypo-methylated CpG DNA motifs that are most commonly found in microbial genomes. High expression tlr9 polymorphisms have been linked to the development of premalignant lesions in the stomach. We now demonstrate that levels of H. pylori-mediated TLR9 activation and expression are directly related to gastric cancer risk in human populations. Mechanistically, we show for the first time that the H. pylori cancer-associated cag T4SS is required for TLR9 activation and that H. pylori DNA is actively translocated by the cag T4SS to engage this host receptor. Activation of TLR9 occurs through a contact-dependent mechanism between pathogen and host, and involves transfer of microbial DNA that is both protected as well as exposed during transport. These results indicate that TLR9 activation via the cag island may modify the risk for malignancy within the context of H. pylori infection and provide an important framework for future studies investigating the microbial-epithelial interface in gastric carcinogenesis.

MTG16 contributes to colonic epithelial integrity in experimental colitis

OBJECTIVE

The myeloid translocation genes (MTGs) are transcriptional corepressors with both Mtg8(-/-) and Mtgr1(-/-) mice showing developmental and/or differentiation defects in the intestine. We sought to determine the role of MTG16 in intestinal integrity.

METHODS

Baseline and stress induced colonic phenotypes were examined in Mtg16(-/-) mice. To unmask phenotypes, we treated Mtg16(-/-) mice with dextran sodium sulphate (DSS) or infected them with Citrobacter rodentium and the colons were examined for ulceration and for changes in proliferation, apoptosis and inflammation.

RESULTS

Mtg16(-/-) mice have altered immune subsets, suggesting priming towards Th1 responses. Mtg16(-/-) mice developed increased weight loss, diarrhoea, mortality and histological colitis and there were increased innate (Gr1(+), F4/80(+), CD11c(+) and MHCII(+); CD11c(+)) and Th1 adaptive (CD4) immune cells in Mtg16(-/-) colons after DSS treatment. Additionally, there was increased apoptosis and a compensatory increased proliferation in Mtg16(-/-) colons. Compared with wild-type mice, Mtg16(-/-) mice exhibited increased colonic CD4;IFN-γ cells in vehicle-treated and DSS-treated mice. Adoptive transfer of wild-type marrow into Mtg16(-/-) recipients did not rescue the Mtg16(-/-) injury phenotype. Isolated colonic epithelial cells from DSS-treated Mtg16(-/-) mice exhibited increased KC (Cxcl1) mRNA expression when compared with wild-type mice. Mtg16(-/-) mice infected with C rodentium had more severe colitis and greater bacterial colonisation. Last, MTG16 mRNA levels were reduced in human ulcerative colitis versus normal colon tissues.

CONCLUSIONS

These observations indicate that MTG16 is critical for colonocyte survival and regeneration in response to intestinal injury and provide evidence that this transcriptional corepressor regulates inflammatory recruitment in response to injury.

Association of haplotypes of inflammation-related genes with gastric preneoplastic lesions in African Americans and Caucasians

Identification of biomarkers is needed for development of screening programs to prevent gastric cancer. Because racial differences exist in cancer rates, we aimed to evaluate the association between polymorphisms in inflammation-related genes and gastric preneoplastic lesions in African Americans and Caucasians from Louisiana, USA. Gastric biopsies from 569 adults (361 African Americans and 208 Caucasians) undergoing diagnostic endoscopy were used for histological diagnosis and genomic DNA extraction. Polymorphisms within eight genes (IL1B, IL8, IL6, TNF, PTGS2, ARG1, IL10 and TGFB1) were investigated by TaqMan. The cagA status of Helicobacter pylori infection was assessed by PCR. Haplotype logistic regression models were used to identify variables associated with intestinal metaplasia or dysplasia. African Americans carrying the haplotype IL1B-511T/-31C/+3954T, which includes the three risk-associated alleles at the IL1B locus, were more likely to being diagnosed with intestinal metaplasia or dysplasia than those carrying the most common haplotype T-C-C (adjusted OR: 2.51, 95% CI: 1.1-5.5). None of the polymorphisms were associated with intestinal metaplasia and dysplasia in Caucasians. Age and cagA-positive status were independent factors associated with these lesions. Haplotypes at the IL1B locus may participate in mediating the susceptibility to gastric carcinogenesis and might be useful as markers of advanced premalignant lesions in African Americans. Interestingly, carriage of IL1B+3954T allele seems to be the key factor, even though the role played by other polymorphisms cannot be excluded.

CagA C-terminal variations in Helicobacter pylori strains from Colombian patients with gastric precancerous lesions

The C-terminus of the Helicobacter pylori CagA protein is polymorphic, bearing different EPIYA sequences (EPIYA-A, B, C or D), and one or more CagA multimerization (CM) motifs. The number of EPIYA-C motifs is associated with precancerous lesions and gastric cancer (GC). The relationship between EPIYA, CM motifs and gastric lesions was examined in H. pylori-infected Colombian patients from areas of high and low risk for GC. Genomic DNA was extracted from H. pylori strains cultured from gastric biopsies from 80 adults with dyspeptic symptoms. Sixty-seven (83.8%) of 80 strains were cagA positive. The 3' region of cagA was sequenced, and EPIYA and CM motifs were identified. CagA proteins contained one (64.2%), two (34.3%) or three EPIYA-C motifs (1.5%), all with Western type CagA-specific sequences. Strains with one EPIYA-C motif were associated with less severe gastric lesions (non-atrophic and multifocal atrophic gastritis), whereas strains with multiple EPIYA-C motifs were associated with more severe lesions (intestinal metaplasia and dysplasia) (p <0.001). In 54 strains, the CM motifs were identical to those common in Western strains. Thirteen strains from the low-risk area contained two different CM motifs: one of Western type located within the EPIYA-C segment and another following the EPIYA-C segment and resembling the CM motif found in East Asian strains. These strains induced significantly shorter projections in AGS cells and an attenuated reduction in levels of CagA upon immunodepletion of SHP-2 than strains possessing Western/Western motifs. This novel finding may partially explain the difference in GC incidence in these populations.

Frequent overexpression of Aurora Kinase A in upper gastrointestinal adenocarcinomas correlates with potent antiapoptotic functions

BACKGROUND

Upper gastrointestinal adenocarcinomas are a common cause of cancer-related deaths. In this study, the authors investigated the prevalence and biological significance of Aurora Kinase A (AURKA) overexpression in upper gastrointestinal adenocarcinomas.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical staining on tumor tissue microarrays (TMA) were used to study the expression of AURKA in upper gastrointestinal adenocarcinomas. To investigate the biological and signaling impact of AURKA, the authors used multiple in vitro assays that included 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), TUNEL (terminal deoxynucleotidyl transferase-mediated nick-end labeling), cytochrome C release, flow cytometry, luciferase reporter, and Western blot analysis.

RESULTS

Frequent overexpression of AURKA transcript in upper gastrointestinal adenocarcinomas was detected compared with normal samples (47%; P= .001). The immunohistochemical analysis of 130 tumors demonstrated moderate-to-strong immunostaining of AURKA in >50% of upper gastrointestinal adenocarcinomas. By using camptothecin as a drug-induced apoptosis in vitro model, the authors demonstrated that the expression of AURKA provided protection against apoptosis to gastrointestinal cancer cells (AGS and RKO) (P= .006) and RIE-1 primary intestinal epithelial cells (P= .001). The AURKA overexpression mediated an increase in phosphorylation of AKT(Ser473) with an increase in HDM2 level. The shRNA-knockdown of AKT in AURKA-overexpressing cells reversed this effect and showed a significant increase in the p53 protein level, indicating a possible nexus of AURKA/AKT/p53. Indeed, overexpression of AURKA led to a remarkable reduction in the transcription activity of p53, with subsequent reductions in transcript and protein levels of its downstream proapoptotic transcription targets (p21, BAX, NOXA, and PUMA).

CONCLUSIONS

Study results indicated that AURKA provides potent antiapoptotic properties to gastrointestinal cells by regulating levels of p53 through the AKT/HDM2 axis.

Plasma selenium measurements in subjects from areas with contrasting gastric cancer risks in Colombia

BACKGROUND

An inverse association between selenium status and incidence of different neoplasias including gastric cancer has been reported. This pilot study aimed to determine and compare selenium status in two Colombian populations with different gastric cancer risks: a high-risk area in the volcanic region of the Andes Mountains and a low-risk area on the Pacific coast.

METHODS

Eighty nine adult males were recruited in the outpatient clinics of two public hospitals (44 and 45 from high- and low-risk areas, respectively) and provided a blood sample. Seventy one (79.8%) participants underwent upper gastrointestinal endoscopy. Plasma selenium was assayed using a fluorometric method, selenoprotein-P by ELISA, and glutathione peroxidase activity by a spectrophometric method. Histological diagnosis and Helicobacter pylori infection were evaluated in gastric biopsy samples. Unpaired samples t-test and linear regression analyses were used for statistical analyses.

RESULTS

Although none of the subjects in either of the two geographic areas was selenium deficient, the level of plasma selenium was significantly lower in men from the high-risk area compared with those from the low-risk area. Levels of selenoprotein-P and glutathione peroxidase activity were similar between groups after adjustment for confounders. Selenium measurements were not associated with histopathological diagnosis.

CONCLUSIONS

The high incidence of gastric cancer in the Andean region of Colombia is unlikely to be explained by selenium deficiency. We cannot exclude, however, that suboptimal selenium levels may exist in the gastric mucosa of subjects in the high-risk area. Therefore, the benefit of selenium supplementation in gastric cancer prevention cannot be dismissed.

Interaction of Helicobacter pylori with gastric epithelial cells is mediated by the p53 protein family

BACKGROUND & AIMS

Although the p53 tumor suppressor has been extensively studied, many critical questions remain unanswered about the biological functions of p53 homologs, p73 and p63. Accumulating evidence suggests that both p73 and p63 play important roles in regulation of apoptosis, cell differentiation, and therapeutic drug sensitivity.

METHODS

Gastric epithelial cells were cocultured with Helicobacter pylori, and the roles of p63 and p73 proteins were assessed by luciferase reporter, real-time polymerase chain reaction, immunoblotting, and cell survival assays. Short hairpin RNA and dominant-negative mutants were used to inhibit activity of p73 and p63 isoforms. Human and murine gastric tissues were analyzed by immunohistochemistry with p73 and p63 antibodies and modified Steiner's silver method.

RESULTS

Interaction of H pylori with gastric epithelial cells leads to robust up-regulation of p73 protein in vitro and in vivo in human gastritis specimens and H pylori-infected mice. The p73 increase resulted in up-regulation of pro-apoptotic genes, NOXA, PUMA, and FAS receptor in gastric epithelial cells. Down-regulation of p73 activity suppressed cell death and Fas receptor induced by H pylori. Bacterial virulence factors within the cag pathogenicity island, c-Abl tyrosine kinase, and interaction with p63 isoforms control the activity of p73.

CONCLUSION

Our findings implicate p73 in H pylori-induced apoptosis and more generally suggest that the p53 family may play a role in the epithelial cell response to H pylori infection.

DeltaNp73alpha regulates MDR1 expression by inhibiting p53 function

The p73 protein is a transcription factor and member of the p53 protein family that expresses as a complex variety of isoforms. DeltaNp73alpha is an N-terminally truncated isoform of p73. We found that DeltaNp73 protein is upregulated in human gastric carcinoma suggesting that DeltaNp73 may play an oncogenic role in these tumors. Although it has been shown that DeltaNp73alpha inhibits apoptosis and counteracts the effect of chemotherapeutic drugs, the underlying mechanism by which this p73 isoform contributes to chemotherapeutic drug response remains to be explored. We found that DeltaNp73alpha upregulates MDR1 mRNA and p-glycoprotein (p-gp), which is involved in chemotherapeutic drug transport. This p-gp upregulation was accompanied by increased p-gp functional activity in gastric cancer cells. Our data suggest that upregulation of MDR1 by DeltaNp73alpha is mediated by interaction with p53 at the MDR1 promoter.

Gastric cancer risk in a Mexican population: role of Helicobacter pylori CagA positive infection and polymorphisms in interleukin-1 and -10 genes

Several polymorphisms of the IL1B and IL10 gene promoters have been reported to be associated with gastric cancer risk in Caucasians. However, studies in other populations have shown differing results. We aimed to test for associations between polymorphisms in IL1B (-31 and +3954), IL10-592 and IL1RN variable number of tandem repeats (VNTR) and risk of gastric cancer in a Mexican population. DNA was extracted from sera of 183 gastric adenocarcinoma patients and 377 controls. The IL1B-31, IL1B+3954 and IL10-592 biallelic polymorphisms were discriminated using 5' Nuclease (TaqMan) assays and Pyrosequencing. The IL1RN penta-allelic VNTR polymorphism was genotyped using PCR followed by GeneScan analysis. A significant interaction was found between IL1B-31 and CagA status for the risk of intestinal-type gastric cancer (p = 0.023). Among CagA positive subjects, those with IL1B-31CC genotype had an increased risk of intestinal-type gastric cancer (OR 3.19, 95%CI = 1.05-9.68), compared to carriers of IL1B-31TT genotype. In contrast, among CagA negative subjects, no significant association of IL1B-31CC genotype with gastric cancer was observed. The IL10-592CC genotype was associated with more than doubling of the risk of the intestinal-type gastric cancer (OR, 2.20, 95%CI = 1.04-4.65). A nonsignificantly increased risk for intestinal-type gastric cancer was found in IL1RN*2 carriers (OR 1.49, 95%CI = 0.89-2.50). None of these polymorphisms was significantly related to the risk of diffuse-type gastric cancer. No significant association was found between risk of gastric cancer and the IL1B+3954 polymorphism. Individuals carrying 2 or more of the risk-associated alleles (IL1B-31C, IL1RN *2 and IL10-592C) were at increased risk for intestinal-type gastric cancer, compared to those with 0 or 1 risk-associated allele. The risk from multiple risk-associated alleles was especially high in subjects infected with CagA positive H. pylori. Our results support the identification of the IL1B-31 promoter polymorphism as a useful marker for risk of intestinal type gastric cancer in persons with CagA positive H. pylori infections.

Long term follow up of patients treated for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori infection induces progressive inflammatory changes in the gastric mucosa that may lead to gastric cancer. Understanding long term effects resulting from the cure of this infection is needed to design cancer prevention strategies.

METHODS

A cohort of 795 adults with preneoplastic gastric lesions was randomised to receive anti-H pylori treatment and/or antioxidants. At the end of six years of intervention, those who did not receive anti-H pylori treatment were offered it. Gastric biopsies were obtained at baseline, and at 3, 6, and 12 years. A histopathology score was utilised to document changes in gastric lesions. Non-linear mixed models were used to estimate the cumulative effect of H pylori clearance on histopathology scores adjusted for follow up time, interventions, and confounders.

RESULTS

Ninety seven per cent of subjects were H pylori positive at baseline, and 53% were positive at 12 years. Subjects accumulated 1703 person years free of infection. A multivariate model showed a significant regression in histopathology score as a function of the square of H pylori negative time. Subjects who were H pylori negative had 14.8% more regression and 13.7% less progression than patients who were positive at 12 years (p = 0.001). The rate of healing of gastric lesions occurred more rapidly as years free of infection accumulated, and was more pronounced in less advanced lesions.

CONCLUSIONS

Preneoplastic gastric lesions regress at a rate equal to the square of time in patients rendered free of H pylori infection. Our findings suggest that patients with preneoplastic gastric lesions should be treated and cured of their H pylori infection.

Arginase I production in the tumor microenvironment by mature myeloid cells inhibits T-cell receptor expression and antigen-specific T-cell responses

T cells infiltrating tumors have a decreased expression of signal transduction proteins, a diminished ability to proliferate, and a decreased production of cytokines. The mechanisms causing these changes have remained unclear. We demonstrated recently that peritoneal macrophages stimulated with interleukin 4 + interleukin 13 produce arginase I, which decreases the expression of the T-cell receptor CD3zeta chain and impairs T-cell responses. Using a 3LL murine lung carcinoma model we tested whether arginase I was produced in the tumor microenvironment and could decrease CD3zeta expression and impair T-cell function. The results show that a subpopulation of mature tumor-associated myeloid cells express high levels of arginase I, whereas tumor cells and infiltrating lymphocytes do not. Arginase I expression in the tumor was seen on day 7 after tumor injection. Tumor-associated myeloid cells also expressed high levels of cationic amino acid transporter 2B, which allowed them to rapidly incorporate L-Arginine (L-Arg) and deplete extracellular L-Arg in vitro. L-Arg depletion by tumor-associated myeloid cells blocked the re-expression of CD3zeta in stimulated T cells and inhibited antigen-specific proliferation of OT-1 and OT-2 cells. The injection of the arginase inhibitor N-hydroxy-nor-L-Arg blocked growth of s.c. 3LL lung carcinoma in mice. High levels of arginase I were also found in tumor samples of patients with non-small cell carcinoma. Therefore, arginase I production by mature myeloid cells in the tumor microenvironment may be a central mechanism for tumor evasion and may represent a target for new therapies.

Epstein-Barr virus-associated gastric carcinoma in Cali, Colombia

To estimate the incidence of Epstein-Barr virus-associated gastric carcinoma (EBV-GC) in Colombia and to clarify its clinicopathological features, we examined 178 consecutive gastric carcinoma cases, diagnosed during the period from 1996 to 1998, at Hospital Universitario del Valle in Cali, Colombia. The mean age of the cases was 60 years in males and 58 years in females. Using in situ hybridization assay of EBV-encoded small RNA-1 in paraffin-embedded tissue samples, we identified 23 cases of EBV-GC (13%). After excluding remnant carcinoma, which was found to be EBV-negative in this series, there were 19 (18%) male and 4 (6%) female EBV-GC cases, and the male predominance was statistically significant (P=0.004). The proportion of EBV-GCs decreased with age (P for trend = 0.022). Using sex- and age-specific proportions of EBV-GCs estimated by logistic models and gastric cancer incidence in Cali, which was obtained from tumor registry during the period 1987-1991, we estimated sex- and age-specific incidence of EBV-GCs. The incidence of EBV-GCs (per 100,000 person-years) was 4.1 and 1.4 among men and women, respectively, after age adjustment using the standard world population. Pathological features of EBV-GCs were also examined. EBV-GCs accounted for 33% (8/24) of carcinomas located in the stomach cardia, 14% (6/43) of carcinomas in the middle-part of the stomach, and 7% (6/81) of carcinomas in the antrum. The difference by tumor location was statistically significant (P=0.009). Histology-specific analysis using Lauren classification revealed that the proportion of EBV-GCs was not different in intestinal- and diffuse-type carcinomas (13% in both types). When the classification scheme of the Japanese Research Society for Gastric Cancer was used, EBV-GCs were identified more frequently in moderately differentiated tubular adenocarcinoma, and solid poorly differentiated adenocarcinoma when compared to other histological types. No lymphoepitelioma-like histology was found in the present series. The frequency of EBV-GC was slightly higher in advanced tumors, which involved serosa. Further analysis of clinico-pathological features of EBV-GC using a larger number of cases would give invaluable insights into its etiology.

Epstein-Barr virus-associated gastric carcinoma in Cali, Colombia

To estimate the incidence of Epstein-Barr virus-associated gastric carcinoma (EBV-GC) in Colombia and to clarify its clinicopathological features, we examined 178 consecutive gastric carcinoma cases, diagnosed during the period from 1996 to 1998, at Hospital Universitario del Valle in Cali, Colombia. The mean age of the cases was 60 years in males and 58 years in females. Using in situ hybridization assay of EBV-encoded small RNA-1 in paraffin-embedded tissue samples, we identified 23 cases of EBV-GC (13%). After excluding remnant carcinoma, which was found to be EBV-negative in this series, there were 19 (18%) male and 4 (6%) female EBV-GC cases, and the male predominance was statistically significant (P=0.004). The proportion of EBV-GCs decreased with age (P for trend = 0.022). Using sex- and age-specific proportions of EBV-GCs estimated by logistic models and gastric cancer incidence in Cali, which was obtained from tumor registry during the period 1987-1991, we estimated sex- and age-specific incidence of EBV-GCs. The incidence of EBV-GCs (per 100,000 person-years) was 4.1 and 1.4 among men and women, respectively, after age adjustment using the standard world population. Pathological features of EBV-GCs were also examined. EBV-GCs accounted for 33% (8/24) of carcinomas located in the stomach cardia, 14% (6/43) of carcinomas in the middle-part of the stomach, and 7% (6/81) of carcinomas in the antrum. The difference by tumor location was statistically significant (P=0.009). Histology-specific analysis using Lauren classification revealed that the proportion of EBV-GCs was not different in intestinal- and diffuse-type carcinomas (13% in both types). When the classification scheme of the Japanese Research Society for Gastric Cancer was used, EBV-GCs were identified more frequently in moderately differentiated tubular adenocarcinoma, and solid poorly differentiated adenocarcinoma when compared to other histological types. No lymphoepitelioma-like histology was found in the present series. The frequency of EBV-GC was slightly higher in advanced tumors, which involved serosa. Further analysis of clinico-pathological features of EBV-GC using a larger number of cases would give invaluable insights into its etiology.