Gastric cancer (GC) is a globally prevalent malignancy with a particularly heavy burden in China. Helicobacter pylori ( H. pylori ) is a Group I carcinogen for GC, with a higher seroprevalence rate indicating a higher GC incidence. However, only approximately 3% of the individuals with H. pylori infection eventually develop GC, and about 2.6% still progress to GC even 10-20 years after the eradication of H. pylori . Thus, the pathogenic mechanism of H. pylori for GC must be elucidated, and high-risk individuals precisely identified. Furthermore, GC can occur even in individuals who have never been infected with H. pylori . As H. pylori infection rates decline, the proportion of H. pylori -negative GC cases is increasing annually, gaining significant research attention. In this review, potential pathogenic mechanisms of H. pylori infection are explored from the aspects of H. pylori virulence factors and host factors (genetic susceptibility and immune microenvironment). Possible risk factors for H. pylori -negative GC include infections by other microorganisms (e.g., bacteria, fungi, and viruses), autoimmune gastritis, bile reflux, genetic mutations, and environmental factors. We aim to review the potential mechanisms for GC with varying H. pylori infection statuses, identify the high-risk individuals, and pose questions that need to be addressed. In the future, as the prevalence of H. pylori infection gradually decreases, GC prevention and management must evolve to address host-specific factors and the growing challenge of H. pylori -negative GC by integrating multidisciplinary perspectives.
Stomach Neoplasms/genetics* ; Humans ; Helicobacter Infections/complications* ; Helicobacter pylori/pathogenicity* ; Risk Factors

A small set of gastric adenocarcinomas (9%) harbor Epstein-Barr virus (EBV) DNA within malignant cells, and the virus is not an innocent bystander but rather is intimately linked to pathogenesis and tumor maintenance. Evidence comes from unique genomic features of host DNA, mRNA, microRNA and CpG methylation profiles as revealed by recent comprehensive genomic analysis by The Cancer Genome Atlas Network. Their data show that gastric cancer is not one disease but rather comprises four major classes: EBV-positive, microsatellite instability (MSI), genomically stable and chromosome instability. The EBV-positive class has even more marked CpG methylation than does the MSI class, and viral cancers have a unique pattern of methylation linked to the downregulation of CDKN2A (p16) but not MLH1. EBV-positive cancers often have mutated PIK3CA and ARID1A and an amplified 9p24.1 locus linked to overexpression of JAK2, CD274 (PD-L1) and PDCD1LG2 (PD-L2). Multiple noncoding viral RNAs are highly expressed. Patients who fail standard therapy may qualify for enrollment in clinical trials targeting cancer-related human gene pathways or promoting destruction of infected cells through lytic induction of EBV genes. Genomic tests such as the GastroGenus Gastric Cancer Classifier are available to identify actionable variants in formalin-fixed cancer tissue of affected patients.
Adenocarcinoma/*diagnosis/*etiology/therapy ; DNA Methylation ; Epstein-Barr Virus Infections/*complications ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Gene Expression Regulation, Viral ; *Genomics/methods ; Herpesvirus 4, Human/*physiology ; Host-Pathogen Interactions/genetics ; Humans ; MicroRNAs/genetics ; Mutation ; RNA, Messenger/genetics ; Signal Transduction ; Stomach Neoplasms/*diagnosis/*etiology/therapy ; Virus Integration

BACKGROUND/AIMS: Helicobacter pylori cytotoxin-associated gene A (CagA) has been suggested to be involved in the inactivation of Runt-related transcription factor 3 (RUNX3), a known gastric carcinoma tumor suppressor gene. It remains unclear how H. pylori CagA initiates or maintains RUNX3 promoter methylation and inactivates its protein expression in gastric carcinoma. METHODS: RUNX3 promoter methylation status, RUNX3 expression, and H. pylori CagA were investigated in 76 sample pairs of gastric carcinoma tissue. The patients' medical records were reviewed. The association between RUNX3 methylation or loss of RUNX3 expression and clinicopathologic variables according to H. pylori CagA status were investigated. RESULTS: In gastric carcinoma patients with H. pylori CagA-positive infection, RUNX3 methylation did not show association with lymphatic invasion, venous invasion, and TNM stages. However RUNX3 methylation was observed more frequently in poorly differentiated adenocarcinoma and signet ring cell carcinoma (77.8% vs. 20.0%, p=0.023) in early stage. In gastric carcinoma patients with H. pylori CagA-positive infection, loss of RUNX3 expression did not show association with lymphatic invasion, venous invasion, and TNM stages. However loss of RUNX3 expression was observed more frequently in early gastric carcinoma than in advanced gastric carcinoma (84.2% vs. 75.0%, p=0.51), but this difference was not significant. CONCLUSIONS: In gastric carcinoma patients with H. pylori CagA-positive infection, RUNX3 methylation or loss of RUNX3 expression did not show correlation with lymphovascular invasion and TNM stages. In early gastric carcinoma patients with H. pylori CagA-positive infection, RUNX3 methylation was observed more in poorly differentiated adenocarcinoma and signet ring cell carcinoma.
Adult ; Aged ; Aged, 80 and over ; Antigens, Bacterial/*metabolism ; Bacterial Proteins/*metabolism ; Cell Line, Tumor ; Core Binding Factor Alpha 3 Subunit/genetics/*metabolism ; Female ; *Gene Expression Regulation, Neoplastic ; Helicobacter Infections/complications/microbiology ; Helicobacter pylori/isolation & purification/*metabolism ; Humans ; Immunohistochemistry ; Lymphatic Metastasis ; Male ; Methylation ; Middle Aged ; Neoplasm Staging ; Promoter Regions, Genetic ; Retrospective Studies ; Stomach Neoplasms/complications/microbiology/*pathology

Strongyloides stercoralis can cause systemic infection, termed strongyloidiasis, and gastrointestinal ulcer disease in immunocompromised patients. However, to our knowledge, there are no reported cases of comorbid gastric adenocarcinoma and S. stercoralis infection. Here, we report a case of an 81-year-old Korean man who presented with S. stercoralis infection coexisting with early gastric adenocarcinoma (T1aN0M0). S. stercoralis eggs, rhabditiform larvae, and adult females were observed in normal gastric and duodenal crypts. They were also observed in atypical glands representative of adenocarcinoma and adenoma. Preliminary laboratory tests revealed mild neutrophilic and eosinophilic leukocytosis. A routine stool test failed to detect rhabditiform larvae in the patient's fecal sample; however, S. stercoralis was identified by PCR amplification and 18S rRNA sequencing using genomic DNA extracted from formalin-fixed paraffin-embedded tissues. Postoperatively, the patient had a persistent fever and was treated with albendazole for 7 days, which alleviated the fever. The patient was followed-up by monitoring and laboratory testing for 4 months postoperatively, and no abnormalities were observed thus far. The fact that S. stercoralis infection may be fatal in immunocompromised patients should be kept in mind when assessing high-risk patients.
Adenocarcinoma/*complications/*diagnosis/pathology ; Aged, 80 and over ; Albendazole/therapeutic use ; Animals ; Anthelmintics/therapeutic use ; DNA, Helminth/chemistry/genetics ; DNA, Ribosomal/chemistry/genetics ; Endoscopy, Digestive System ; Female ; Histocytochemistry ; Humans ; Korea ; Male ; RNA, Ribosomal, 18S/genetics ; Sequence Analysis, DNA ; Stomach Neoplasms/*complications/*diagnosis/pathology ; Strongyloides stercoralis/*isolation & purification ; Strongyloidiasis/*complications/*diagnosis/drug therapy/pathology ; Treatment Outcome

Strongyloides stercoralis can cause systemic infection, termed strongyloidiasis, and gastrointestinal ulcer disease in immunocompromised patients. However, to our knowledge, there are no reported cases of comorbid gastric adenocarcinoma and S. stercoralis infection. Here, we report a case of an 81-year-old Korean man who presented with S. stercoralis infection coexisting with early gastric adenocarcinoma (T1aN0M0). S. stercoralis eggs, rhabditiform larvae, and adult females were observed in normal gastric and duodenal crypts. They were also observed in atypical glands representative of adenocarcinoma and adenoma. Preliminary laboratory tests revealed mild neutrophilic and eosinophilic leukocytosis. A routine stool test failed to detect rhabditiform larvae in the patient's fecal sample; however, S. stercoralis was identified by PCR amplification and 18S rRNA sequencing using genomic DNA extracted from formalin-fixed paraffin-embedded tissues. Postoperatively, the patient had a persistent fever and was treated with albendazole for 7 days, which alleviated the fever. The patient was followed-up by monitoring and laboratory testing for 4 months postoperatively, and no abnormalities were observed thus far. The fact that S. stercoralis infection may be fatal in immunocompromised patients should be kept in mind when assessing high-risk patients.
Adenocarcinoma/*complications/*diagnosis/pathology ; Aged, 80 and over ; Albendazole/therapeutic use ; Animals ; Anthelmintics/therapeutic use ; DNA, Helminth/chemistry/genetics ; DNA, Ribosomal/chemistry/genetics ; Endoscopy, Digestive System ; Female ; Histocytochemistry ; Humans ; Korea ; Male ; RNA, Ribosomal, 18S/genetics ; Sequence Analysis, DNA ; Stomach Neoplasms/*complications/*diagnosis/pathology ; Strongyloides stercoralis/*isolation & purification ; Strongyloidiasis/*complications/*diagnosis/drug therapy/pathology ; Treatment Outcome

BACKGROUND/AIMS: This study was conducted to identify microRNAs (miRNAs) that are differentially expressed in Helicobacter pylori-infected patients with an intestinal type of gastric cancer using miRNA microarray and to confirm the candidate miRNA expression levels. METHODS: Total RNA was extracted from the cancerous and noncancerous regions of formalin-fixed, paraffin-embedded tissues of H. pylori-positive (n=8) or H. pylori-negative (n=8) patients with an intestinal type of gastric cancer. RNA expression was analyzed using a 3,523 miRNA profiling microarray based on the Sanger miRBase. Validation analysis was performed using TaqMan miRNA assays. RESULTS: A total of 219 miRNAs in the aberrant miRNA profiles across the miRNA microarray showed at least a 2-fold change differential expression in H. pylori-positive and H. pylori-negative cancer tissues. After candidate miRNAs were selected using online miRNA databases, TaqMan miRNA assays confirmed that three miRNAs (miR-99b-3p, miR-564, and miR-638) were significantly increased in three H. pylori-positive cancer tissues compared to the H. pylori-negative cancer tissues. Additionally, four miRNAs (miR-204-5p, miR-338-5p, miR-375, and miR-548c-3p) were significantly increased in H. pylori-negative cancer tissues compared to H. pylori-positive cancer tissues. CONCLUSIONS: miRNA expression in the intestinal type of H. pylori infection-dependent gastric cancer suggests that different gastric cancer pathogenesis mechanisms could exist between H. pylori-positive and H. pylori-negative gastric cancer. Additional functional studies are required.
Aged ; Female ; Gene Expression Profiling ; *Gene Expression Regulation, Neoplastic ; Helicobacter Infections/complications/*genetics ; *Helicobacter pylori ; Humans ; Intestines/metabolism ; Male ; MicroRNAs/*metabolism ; Middle Aged ; RNA, Neoplasm/metabolism ; Stomach Neoplasms/complications/*genetics

BACKGROUND/AIMS: This study was conducted to identify microRNAs (miRNAs) that are differentially expressed in Helicobacter pylori-infected patients with an intestinal type of gastric cancer using miRNA microarray and to confirm the candidate miRNA expression levels. METHODS: Total RNA was extracted from the cancerous and noncancerous regions of formalin-fixed, paraffin-embedded tissues of H. pylori-positive (n=8) or H. pylori-negative (n=8) patients with an intestinal type of gastric cancer. RNA expression was analyzed using a 3,523 miRNA profiling microarray based on the Sanger miRBase. Validation analysis was performed using TaqMan miRNA assays. RESULTS: A total of 219 miRNAs in the aberrant miRNA profiles across the miRNA microarray showed at least a 2-fold change differential expression in H. pylori-positive and H. pylori-negative cancer tissues. After candidate miRNAs were selected using online miRNA databases, TaqMan miRNA assays confirmed that three miRNAs (miR-99b-3p, miR-564, and miR-638) were significantly increased in three H. pylori-positive cancer tissues compared to the H. pylori-negative cancer tissues. Additionally, four miRNAs (miR-204-5p, miR-338-5p, miR-375, and miR-548c-3p) were significantly increased in H. pylori-negative cancer tissues compared to H. pylori-positive cancer tissues. CONCLUSIONS: miRNA expression in the intestinal type of H. pylori infection-dependent gastric cancer suggests that different gastric cancer pathogenesis mechanisms could exist between H. pylori-positive and H. pylori-negative gastric cancer. Additional functional studies are required.
Aged ; Female ; Gene Expression Profiling ; *Gene Expression Regulation, Neoplastic ; Helicobacter Infections/complications/*genetics ; *Helicobacter pylori ; Humans ; Intestines/metabolism ; Male ; MicroRNAs/*metabolism ; Middle Aged ; RNA, Neoplasm/metabolism ; Stomach Neoplasms/complications/*genetics

Gastric cancer is the second leading cause of cancer-related mortality and the fourth most common cancer globally. There are, however, distinct differences in incidence rates in different geographic regions. While the incidence rate of gastric cancer has been falling, that of gastric cardia cancers is reportedly on the rise in some regions. Helicobacter pylori (H. pylori) infection is a major risk factor of non-cardia gastric cancer, and data has emerged concerning the role of H. pylori eradication for primary prevention of gastric cancer. Dietary, lifestyle and metabolic factors have also been implicated. Although addressing these other factors may contribute to health, the actual impact in terms of cancer prevention is unclear. Once irreversible histological changes have occurred, endoscopic surveillance would be necessary. A molecular classification system offers hope for molecularly tailored, personalised therapies for gastric cancer, which may improve the prognosis for patients.
Female ; Global Health ; Helicobacter Infections ; complications ; prevention & control ; Helicobacter pylori ; Humans ; Incidence ; Male ; Obesity ; complications ; Risk Factors ; Stomach Neoplasms ; epidemiology ; genetics ; microbiology ; prevention & control

OBJECTIVETo establish an animal model of gastric cancer by long-term infection of Helicobacter pylori (H.pylori) and to elucidate the pathogenesis by proteomics analysis.

METHODSFifty male Mongolian gerbils (4-5 week-old and weighted 60-100 g) were infected with H.pylori and the gastric tissues were obtained after the infection at 3, 6, 12 and 24 months. Histological changes were evaluated by H-E staining of the gastric tissue sections. Detection of H.pylori was performed by in-vitro culture of fresh gastric tissue samples, PCR amplification of H.pylori 16s rRNA and localization by silver staining. In addition, proteins extracted from gastric tissue samples were subjected to two-dimensional electrophoresis (2-DE) at various infection time points. Protein spots with increased quantity over the course of H.pylori infection were selected and analyzed by LC-MS/MS. Finally, differentially expressed proteins between human gastric cancer tissue samples and lymph nodes were analyzed by real-time RT-PCR.

RESULTSColonization of H.pylori was observed in gastric tissue of gerbils as early as 3 months after H.pylori infection, and persisted till 24 months. Pathological examination of infected animals showed various histological changes including acute gastritis, atrophic gastritis, intestinal metaplasia and gastric carcinoma. Seventy-eight differentially expressed proteins were identified by proteomics analysis, among which 36 proteins were up-regulated and 42 were down-regulated. Analyzed by LC-MS/MS, ten proteins were identified, including lactate dehydrogenase, ATP synthase, fatty acid-binding protein, COX5B, peroxiredoxin-4, peroxide reductase, transgelin, succinyl-CoA ligase, keratin and protein disulfide-isomerase A2, among which transgelin, ATP synthase and lactate dehydrogenase were highly expressed in human gastric carcinoma and lymph nodes.

CONCLUSIONSH.pylori infection induces the expression of transgelin, ATP synthase and lactate dehydrogenase, implying possible roles in the pathogenesis of gastric diseases including cancer.

Animals ; Disease Models, Animal ; Gastritis ; microbiology ; pathology ; Gerbillinae ; Helicobacter Infections ; complications ; metabolism ; Helicobacter pylori ; genetics ; Humans ; L-Lactate Dehydrogenase ; metabolism ; Male ; Metaplasia ; Microfilament Proteins ; metabolism ; Muscle Proteins ; metabolism ; Proteomics ; Proton-Translocating ATPases ; metabolism ; RNA, Ribosomal, 16S ; analysis ; Stomach Neoplasms ; metabolism ; microbiology ; Tandem Mass Spectrometry

Intestinal metaplasia (IM) has been regarded as a premalignant condition. However, the pathogenesis of IM is not fully understood. The aim of this study was to evaluate the role of CDX1 and CDX2 in the formation of IM and the progression to dysplasia and gastric cancer (GC). A total of 270 subjects included 90 with GC, dysplasia and age- and sex-matched controls. Real-time PCR (RT-PCR) was performed with body specimens for CDX1 and CDX2. The expression of CDX2 was significantly higher in H. pylori positive group than H. pylori negative group (P = 0.045). CDX1 and CDX2 expression increased proportional to the IM grade of the body (P < 0.001). CDX2 expression was significantly higher in incomplete type of IM than in complete type (P = 0.045). The expression of CDX1 in dysplasia group was significantly higher than in the control group (P = 0.001); in addition, CDX1 and CDX2 in cancer group was significantly higher than control group (P < 0.001, and P < 0.001, respectively). Aberrant expression of CDX1 and CDX2 correlated with H. pylori infection and grade of IM in the body. Furthermore, the results suggest that CDX1 and CDX2 play a role in the progression to GC and dysplasia.
Aged ; Female ; Helicobacter Infections/complications/microbiology ; Helicobacter pylori/isolation & purification ; Homeodomain Proteins/*genetics/metabolism ; Humans ; Intestinal Diseases/*genetics/microbiology/pathology ; Male ; Metaplasia/pathology ; Middle Aged ; Polymerase Chain Reaction ; Precancerous Conditions/metabolism/pathology ; Stomach Neoplasms/etiology/*genetics/microbiology