Genomic Analyses of early-stage diffuse-type gastric cancer lacking Helicobacter pylori infection
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ABSTRACT: We performed the expression RNA-seq experiments for mRNA of gastric cancer tissue. Most of gastric cancers (GCs) are accompanied by Helicobacter pylori (HP) infection. However, a very limited fraction lacks any signs of HP infection and exhibits early-stage diffuse (ED) phenotype. Although previous genomic cohorts have identified multiple driver mutations for gastric cancers including diffuse-type histology, any driver event of GC without HP has not been elucidated. The present study aims to explore the molecular mechanism with comprehensive genomic and transcriptomic analyses by comparing EDGC with and without HP. EDGCs were classified as HP-negative based on the following criteria: 1) no antibiotic eradication history, 2) no atrophic appearance by endoscopy, 3) no atrophic appearance by histology, 4) negativity in two or more tests such as rapid urease, urease breath, serum antibody, stool antigen and serum pepsinogen tests. DNAs and RNAs were extracted from EDGCs with over 10 mm in diameter to secure sufficient amount of cancer tissues. Laser-capture microdissection was then used to reduce contamination of normal cells for further molecular assays. For transcriptome analyses, we conducted RNA-seq of 2 HP-positive and 4 HP-negative fresh frozen EDGCs obtained endoscopically
Project description:Genome-scale DNA methylation profiling using the Infinium DNA methylation 450K BeadChip platform and samples from gastric cancer (intestinal and diffuse), precursor lesions (multifocal chronic atrophic gastritis and inestina metaplasia), non-atrophic gastritis and normal gastric mucosa.
Project description:Interventions: Drug : 1.At the time of EMR/ESD: Rapid Urease test/anti-helicobacter IgG Ab/ histology --> If two of them are (+), diagnosis of HP infection could be made. During endoscopy, designated biopsy for the evaluation of gastric atrophy should be performed (baseline data)
2.Patients are assigned to HP (+) or HP (-) group according to the HP status. (Each 120 patients)
3.HP (+) group should undergo eradication therapy after anti-ulcer medication (8weeks, LFDT 30mg + rebamipide SR 150mg bid), and diagnosis of successful eradication should be followed with urea breath test 4weeks later of last dose.
4.HP (-) group should undergo anti-ulcer medication (8weeks, LFDT 30mg + rebamipide SR 150mg bid).
5.In this time, patients are randomly allocated to rebamipide group (60 patients from each group) or placebo group (60 patients from each group).
EGD with biopsy should be repeated to evaluate the regression of atrophy at the time of 12mo, 24mo, 36mo, 48mo, 60mo, respectively.
Primary outcome(s): The primary outcome of this study is to evaluate the difference in the effect of between rebamipide and placebo on regression of gastric atrophy and intestinal metaplasia.
Primary Purpose : Treatment, Intervention Model : Parallel, Blinding/Masking : , Blinding Target : Subject, Investigator, Caregiver, Allocation : RCT
Project description:Gastric cancer is a leading cause of death from cancer globally. Gastric cancer is classified into intestinal, diffuse and indeterminate subtypes based on histology according to the Laurén classification. The intestinal and diffuse subtypes, although different in histology, demographics and outcomes, are still treated in the same fashion. This study was designed to discover proteomic signatures of diffuse and intestinal subtypes. Mass spectrometry-based proteomics using tandem mass tags (TMT)-based multiplexed analysis was used to identify proteins in tumor tissues from patients with diffuse or intestinal gastric cancer with adjacent normal tissue control. A total of 7,804 or 5,166 proteins were identified from intestinal or diffuse subtype, respectively. This quantitative mass spectrometric analysis defined a proteomic signature of differential expression across the two subtypes, which included gremlin1 (GREM1), bcl-2-associated athanogene 2 (BAG2), olfactomedin 4 (OLFM4), thyroid hormone receptor interacting protein 6 (TRIP6) and melanoma-associated antigen 9 (MAGE-A9) proteins. Although GREM1, BAG2, OLFM4, TRIP6 and MAGE-A9 have all been previously implicated in tumor progression and metastasis, they have not been linked to intestinal or diffuse subtypes of gastric cancer. Using immunohistochemical labelling of a tissue microarray comprising of 132 cases of gastric cancer, we validated the proteomic signature obtained by mass spectrometry in the discovery cohort. Our findings should help investigate the pathogenesis of these gastric cancer subtypes and potentially lead to strategies for early diagnosis and treatment.
Project description:Helicobacter pylori colonization of the human stomach is a strong risk factor for gastric cancer. To investigate H. pylori-induced gastric molecular alterations, we used a Mongolian gerbil model of gastric carcinogenesis. Histologic evaluation revealed varying levels of atrophic gastritis (a premalignant condition characterized by parietal and chief cell loss) in H. pylori-infected animals, and transcriptional profiling revealed a loss of markers for these cell types. We then assessed the spatial distribution and relative abundance of proteins in the gastric tissues using imaging mass spectrometry and liquid chromatography with tandem mass spectrometry (LC-MS/MS). We detected striking differences in protein content of corpus and antrum tissues. 492 proteins were preferentially localized to the corpus in uninfected animals. The abundance of 91 of these proteins was reduced in H. pylori-infected corpus tissues exhibiting atrophic gastritis compared to infected corpus tissues with non-atrophic gastritis or uninfected corpus tissues; these included numerous proteins with metabolic functions. Fifty proteins localized to the corpus in uninfected animals were diffusely delocalized throughout the stomach in infected tissues with atrophic gastritis; these included numerous proteins with roles in protein processing. Corresponding alterations were not detected in animals infected with a H. pylori ∆cagT mutant (lacking Cag type IV secretion system activity). These results indicate that H. pylori can cause loss of proteins normally localized to the gastric corpus as well as diffuse delocalization of corpus-specific proteins, resulting in marked changes in the normal gastric molecular partitioning into distinct corpus and antrum regions.
Project description:DNA methylation profiles were compared between gastric mucosae samples without Helicobacter pylori (HP) infection (low risk : G1), those with HP eradication without gastric cancer (intermediate risk : G2), and those with HP eradication with gastric cancer (high risk : G3).
Project description:Helicobacter pylori infection triggers a cascade of inflammatory stages that may lead to the appearance of non-atrophic gastritis, multifocal atrophic gastritis, intestinal metaplasia, dysplasia, and cancer. Deleted in malignant brain tumors 1 (DMBT1) belongs to the group of secreted scavenger receptor cysteine-rich proteins and is considered to be involved in host defense by binding to pathogens. Recent studies have shown that DMBT1 expression is up-regulated in areas of intestinal metaplasia and in gastric tumors. Here, we examined the role of DMBT1 in the development of inflammatory response and gastric precancerous lesions in Caucasian, African American and Hispanic populations as well as in a mouse model. We found that mucosal DMBT1 expression is significantly increased in individuals with more advanced gastric precancerous lesions. We also show that H. pylori infection of Dmbt1-/- mice results in enhanced gastric inflammation and the development of mucous metaplasia that is accompanied by increased cell proliferative rates and reduced IL-33 expression levels in the inflamed mucosa. Taken together, our data suggest that DMBT1 may be mediating mucosal protection that may reduce the risk of developing gastric precancerous lesions in response to H. pylori infection
Project description:Persistent colonization of the gastric mucosa by Helicobacter pylori (Hp) elicits chronic inflammation and aberrant epithelial cell proliferation, which increases the risk of gastric cancer. We examined the ability of microRNAs to modulate gastric cell proliferation in response to persistent Hp infection and found that epigenetic silencing of miR-210 plays a key role in gastric disease progression. Importantly, DNA methylation of the miR-210 gene was increased in Hp-positive human gastric biopsies as compared to Hp-negative controls. Moreover silencing of miR-210 in gastric epithelial cells promoted proliferation. We identified STMN1 and DIMT1 as miR-210 target genes and demonstrated that inhibition of miR-210 expression augmented cell proliferation by activating STMN1 and DIMT1. Together, our results highlight inflammation-induced epigenetic silencing of miR-210 as a mechanism of induction of chronic gastric diseases, including cancer, during Hp infection.
Project description:This SuperSeries is composed of the following subset Series: GSE16390: Response of gastric epithelial progenitors to H. pylori isolates from Swedish patients with chronic atrophic gastritis 1 GSE16439: Response of gastric epithelial progenitors to H. pylori isolates from Swedish patients with chronic atrophic gastritis 2 Refer to individual Series
Project description:Gastric cancer is an important health problem because it is difficult to diagnose and treat in advanced stage. This makes that the prognosis of gastric cancer patients remains scarce. Currently it is known that the cause of gastric cancer is attributed to chronic infection with Helicobacter pylori. Its persistent infection leads to development of chronic atrophic gastritis that is considered as a predecessor stage of intestinal-type gastric cancer. The understanding of the alteration of molecular mechanisms during the early stages of the development of gastric cancer, and the identification of their potential biomarkers can allow a rapid diagnosis that leads to an improvement diagnosis and increase the patient’s prognosis. We analyzed gene expression profiles of patients with chronic atrophic gastritis and gastric cancer through microarray analysis, functional enrichment analysis and validation of gene expression by quantitative PCR. Gene expression profiles in patients with chronic atrophic gastritis showed molecular changes of the gastric mucosa, which leads to intestinal metaplasia and subsequently, gastric cancer. In gastric cancer the gene expression profile showed the stage of tumor progression, the product of these genes are potential biomarkers of early stages of cancer that can be potential therapeutic targets. Accordingly, the transcriptome analysis revealed several gene groups are related to development of chronic atrophic gastritis, some of which were inhibited in gastric cancer patients. The increased expression of CLDN1, CLDN7, OLFM4, c-Myc and MMP-9 genes in chronic atrophic gastritis and gastric cancer point outs to their use as promising biomarkers for the early diagnosis of gastric cancer.
Project description:Serum pepsinogen (PG) levels are considered reliable markers for progression of atrophic gastritis with a stepwise reduction in the serum PG I level or PG I/II ratio. A combination of serum PG levels and Helicobacter pylori serology are used as a biomarker strategy for detection of individuals at increased risk of gastric neoplasm based on Correa’s hypothesis. The investigators aimed to uncover whether this combination method could predict the risk of gastric neoplasms and the progression of chronic atrophic gastritis after 3 years. All the participants will be followed for an expected average of 3 years.