1 1321 130 DEMONSTRATION AND CHARACTERIZATION OF MUTATIONS INDUCED BY HELICOBACTER PYLORI ORGANISMS IN GASTRIC EPITHELIAL CELLS. BACKGROUND: HELICOBACTER PYLORI GASTRITIS INCREASES GASTRIC CANCER RISK. MICROSATELLITE INSTABILITY-TYPE MUTATIONS ARE SECONDARY TO DEFICIENT DNA MISMATCH REPAIR. H. PYLORI GASTRITIS IS MORE FREQUENT IN PATIENTS WITH MICROSATELLITE INSTABILITY-POSITIVE GASTRIC CANCERS, AND H. PYLORI ORGANISMS INDEPENDENTLY OF INFLAMMATION CAN REDUCE DNA MISMATCH REPAIR PROTEIN LEVELS, RAISING THE HYPOTHESIS THAT H. PYLORI ORGANISMS MIGHT LEAD TO MUTAGENESIS DURING INFECTION. MATERIALS AND METHODS: MUTATIONS WERE DETECTED USING A GREEN FLUORESCENT PROTEIN REPORTER VECTOR (PEGFP-CA13). GASTRIC CANCER AGS CELLS TRANSFECTED WITH PEGFP-CA13 WERE COCULTURED WITH H. PYLORI OR ESCHERICHIA COLI. THE NUMBERS OF GREEN FLUORESCENT PROTEIN (GFP)-POSITIVE CELLS WERE DETERMINED, AND GFP, HMSH2, AND HMLH1 PROTEIN LEVELS WERE MEASURED BY WESTERN BLOT. THE EFFECT OF H. PYLORI ON CPG METHYLATION STATUS OF HMLH1 WAS DETERMINED BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION. RESULTS: GFP LEVELS AND GFP-POSITIVE CELL NUMBERS IN AGS CELLS COCULTURED WITH H. PYLORI SIGNIFICANTLY INCREASED, AS THE LEVELS OF HMLH1 AND HMSH2 DROPPED. H. PYLORI COCULTURES INDUCED LOW-LEVEL CPG METHYLATION OF THE HMLH1 PROMOTER. SEQUENCE ANALYSIS OF CELLS COCULTURED WITH H. PYLORI SHOWED AN INCREASED NUMBER OF FRAMESHIFT MUTATIONS AND POINT MUTATIONS AS COMPARED TO CELLS NOT COCULTURED WITH H. PYLORI (P = .03 AND P = .001, RESPECTIVELY). CONCLUSIONS: THIS IS THE FIRST REPORT SHOWING THAT H. PYLORI BACTERIA MAY LEAD TO ACCUMULATION OF GENOMIC MUTATIONS, INDEPENDENTLY OF UNDERLYING INFLAMMATION. THIS IS ASSOCIATED WITH REDUCED DNA MISMATCH REPAIR, AND IS AT LEAST IN PART ASSOCIATED WITH CPG METHYLATION OF THE HMLH1 PROMOTER. THESE DATA SUPPORT THE NOTION THAT H. PYLORI-INDUCED MUTATIONS AND EPIGENETIC ALTERATIONS IN GASTRIC EPITHELIAL CELLS DURING CHRONIC GASTRITIS MAY CONTRIBUTE TO AN INCREASED RISK OF GASTRIC CANCER ASSOCIATED WITH H. PYLORI INFECTION.	2006	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
2 4725  37 NORMAL GASTRIC TISSUE HELICOBACTER PYLORI INFECTION IS ASSOCIATED WITH EPIGENETIC AGE ACCELERATION, INCREASED MITOTIC TICK RATE, TISSUE CELL COMPOSITION, AND NATURAL KILLER CELL METHYLATION ALTERATIONS. BACKGROUND: GASTRIC ADENOCARCINOMAS ARE A LEADING CAUSE OF GLOBAL MORTALITY, ASSOCIATED WITH CHRONIC INFECTION WITH HELICOBACTER PYLORI . THE MECHANISMS BY WHICH INFECTION WITH H. PYLORI CONTRIBUTES TO CARCINOGENESIS ARE NOT WELL UNDERSTOOD. RECENT STUDIES FROM SUBJECTS WITH AND WITHOUT GASTRIC CANCER HAVE IDENTIFIED SIGNIFICANT DNA METHYLATION ALTERATIONS IN NORMAL GASTRIC MUCOSA ASSOCIATED WITH H. PYLORI INFECTION AND GASTRIC CANCER RISK. HERE WE FURTHER INVESTIGATED DNA METHYLATION ALTERATIONS IN NORMAL GASTRIC MUCOSA IN GASTRIC CANCER CASES (N = 42) AND CONTROL SUBJECTS (N = 42) WITH H. PYLORI INFECTION DATA. WE ASSESSED TISSUE CELL TYPE COMPOSITION, DNA METHYLATION ALTERATIONS WITHIN CELL POPULATIONS, EPIGENETIC AGING, AND REPETITIVE ELEMENT METHYLATION. RESULTS: IN NORMAL GASTRIC MUCOSA OF BOTH GASTRIC CANCER CASES AND CONTROL SUBJECTS, WE OBSERVED INCREASED EPIGENETIC AGE ACCELERATION ASSOCIATED WITH H. PYLORI INFECTION. WE ALSO OBSERVED AN INCREASED MITOTIC TICK RATE ASSOCIATED WITH H. PYLORI INFECTION IN BOTH GASTRIC CANCER CASES AND CONTROLS. SIGNIFICANT DIFFERENCES IN IMMUNE CELL POPULATIONS ASSOCIATED WITH H. PYLORI INFECTION IN NORMAL TISSUE FROM CANCER CASES AND CONTROLS WERE IDENTIFIED USING DNA METHYLATION CELL TYPE DECONVOLUTION. WE ALSO FOUND NATURAL KILLER CELL-SPECIFIC METHYLATION ALTERATIONS IN NORMAL MUCOSA FROM GASTRIC CANCER PATIENTS WITH H. PYLORI INFECTION. CONCLUSIONS: OUR FINDINGS FROM NORMAL GASTRIC MUCOSA PROVIDE INSIGHT INTO UNDERLYING CELLULAR COMPOSITION AND EPIGENETIC ASPECTS OF H. PYLORI ASSOCIATED GASTRIC CANCER ETIOLOGY.	2023	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
3 3225  39 HELICOBACTER PYLORI INFECTION INTRODUCES DNA DOUBLE-STRAND BREAKS IN HOST CELLS. GASTRIC CANCER IS AN INFLAMMATION-RELATED MALIGNANCY RELATED TO LONG-STANDING ACUTE AND CHRONIC INFLAMMATION CAUSED BY INFECTION WITH THE HUMAN BACTERIAL PATHOGEN HELICOBACTER PYLORI. INFLAMMATION CAN RESULT IN GENOMIC INSTABILITY. HOWEVER, THERE ARE CONSIDERABLE DATA THAT H. PYLORI ITSELF CAN ALSO PRODUCE GENOMIC INSTABILITY BOTH DIRECTLY AND THROUGH EPIGENETIC PATHWAYS. OVERALL, THE MECHANISMS OF H. PYLORI-INDUCED HOST GENOMIC INSTABILITIES REMAIN POORLY UNDERSTOOD. WE USED MICROARRAY SCREENING OF H. PYLORI-INFECTED HUMAN GASTRIC BIOPSY SPECIMENS TO IDENTIFY CANDIDATE GENES INVOLVED IN H. PYLORI-INDUCED HOST GENOMIC INSTABILITIES. WE FOUND UPREGULATION OF ATM EXPRESSION IN VIVO IN GASTRIC MUCOSAL CELLS INFECTED WITH H. PYLORI. USING GASTRIC CANCER CELL LINES, WE CONFIRMED THAT THE H. PYLORI-RELATED ACTIVATION OF ATM WAS DUE TO THE ACCUMULATION OF DNA DOUBLE-STRAND BREAKS (DSBS). DSBS WERE OBSERVED FOLLOWING INFECTION WITH BOTH CAG PATHOGENICITY ISLAND (PAI)-POSITIVE AND -NEGATIVE STRAINS, BUT THE EFFECT WAS MORE ROBUST WITH CAG PAI-POSITIVE STRAINS. THESE RESULTS ARE CONSISTENT WITH THE FACT THAT INFECTIONS WITH BOTH CAG PAI-POSITIVE AND -NEGATIVE STRAINS ARE ASSOCIATED WITH GASTRIC CARCINOGENESIS, BUT THE RISK IS HIGHER IN INDIVIDUALS INFECTED WITH CAG PAI-POSITIVE STRAINS.	2014	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
4 3231  39 HELICOBACTER PYLORI-INDUCED MODULATION OF THE PROMOTER METHYLATION OF WNT ANTAGONIST GENES IN GASTRIC CARCINOGENESIS. BACKGROUND: THIS STUDY AIMED TO INVESTIGATE THE CHANGES IN THE PROMOTER METHYLATION AND GENE EXPRESSION OF MULTIPLE WNT ANTAGONISTS BETWEEN THE CHRONIC INFECTION AND ERADICATION OF HELICOBACTER PYLORI (H. PYLORI) IN GASTRIC CARCINOGENESIS. METHODS: THE LEVELS OF METHYLATION AND CORRESPONDING MRNA EXPRESSION OF SEVEN WNT ANTAGONIST GENES (SFRP1, -2, -5, DKK1, -2, -3, WIF1) WERE COMPARED AMONG THE PATIENTS WITH H. PYLORI-POSITIVE GASTRIC CANCERS (GCS), AND H. PYLORI-POSITIVE AND H. PYLORI-NEGATIVE CONTROLS, BY QUANTITATIVE METHYLIGHT ASSAY AND REAL-TIME REVERSE TRANSCRIPTION (RT)-POLYMERASE CHAIN REACTION (PCR), RESPECTIVELY. THE CHANGES OF THE METHYLATION AND EXPRESSION LEVELS OF THE GENES WERE ALSO COMPARED BETWEEN THE H. PYLORI ERADICATION AND H. PYLORI-PERSISTENT GROUPS 1 YEAR AFTER ENDOSCOPIC RESECTION OF GCS. RESULTS: THE METHYLATION LEVELS OF SFRP AND DKK FAMILY GENES WERE SIGNIFICANTLY INCREASED IN THE PATIENTS WITH H. PYLORI-POSITIVE GCS AND FOLLOWED BY H. PYLORI-POSITIVE CONTROLS COMPARED WITH H. PYLORI-NEGATIVE CONTROLS (P < 0.001). SFRP1, -2, AND DKK3 GENE EXPRESSION WAS STEPWISE DOWNREGULATED FROM H. PYLORI-NEGATIVE CONTROLS, H. PYLORI-POSITIVE CONTROLS, AND TO H. PYLORI-POSITIVE GCS (P < 0.05). AMONG THE WNT ANTAGONISTS, ONLY THE DEGREES OF METHYLATION AND DOWNREGULATION OF DKK3 WERE SIGNIFICANTLY REDUCED AFTER H. PYLORI ERADICATION (P < 0.05). CONCLUSION: EPIGENETIC SILENCING OF SFRP AND DKK FAMILY GENES MAY FACILITATE THE FORMATION OF AN EPIGENETIC FIELD DURING H. PYLORI-ASSOCIATED GASTRIC CARCINOGENESIS. THE EPIGENETIC FIELD MAY NOT BE REVERSED EVEN AFTER H. PYLORI ERADICATION EXCEPT BY DKK3 METHYLATION.	2018	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
5 3227  40 HELICOBACTER PYLORI INFECTION-INDUCED H3SER10 PHOSPHORYLATION IN STEPWISE GASTRIC CARCINOGENESIS AND ITS CLINICAL IMPLICATIONS. BACKGROUND: OUR PREVIOUS WORKS HAVE DEMONSTRATED THAT HELICOBACTER PYLORI (HP) INFECTION CAN ALTER HISTONE H3 SERINE 10 PHOSPHORYLATION STATUS IN GASTRIC EPITHELIAL CELLS. HOWEVER, WHETHER HELICOBACTER PYLORI-INDUCED HISTONE H3 SERINE 10 PHOSPHORYLATION PARTICIPATES IN GASTRIC CARCINOGENESIS IS UNKNOWN. WE INVESTIGATE THE EXPRESSION OF HISTONE H3 SERINE 10 PHOSPHORYLATION IN VARIOUS STAGES OF GASTRIC DISEASE AND EXPLORE ITS CLINICAL IMPLICATION. MATERIALS AND METHODS: STOMACH BIOPSY SAMPLES FROM 129 PATIENTS WERE COLLECTED AND STAINED WITH HISTONE H3 SERINE 10 PHOSPHORYLATION, KI67, AND HELICOBACTER PYLORI BY IMMUNOHISTOCHEMISTRY STAINING, EXPRESSED AS LABELING INDEX. THEY WERE CATEGORIZED INTO NONATROPHIC GASTRITIS, CHRONIC ATROPHIC GASTRITIS, INTESTINAL METAPLASIA, LOW-GRADE INTRAEPITHELIAL NEOPLASIA, HIGH-GRADE INTRAEPITHELIAL NEOPLASIA, AND INTESTINAL-TYPE GASTRIC CANCER GROUPS. HELICOBACTER PYLORI INFECTION WAS DETERMINED BY EITHER (13) C-UREA BREATH TEST OR IMMUNOHISTOCHEMISTRY STAINING. RESULTS: IN HELICOBACTER PYLORI-NEGATIVE PATIENTS, LABELING INDEX OF HISTONE H3 SERINE 10 PHOSPHORYLATION WAS GRADUALLY INCREASED IN NONATROPHIC GASTRITIS, CHRONIC ATROPHIC GASTRITIS, INTESTINAL METAPLASIA GROUPS, PEAKED AT LOW-GRADE INTRAEPITHELIAL NEOPLASIA, AND DECLINED IN HIGH-GRADE INTRAEPITHELIAL NEOPLASIA AND GASTRIC CANCER GROUPS. IN HELICOBACTER PYLORI-INFECTED PATIENTS, LABELING INDEX OF HISTONE H3 SERINE 10 PHOSPHORYLATION FOLLOWED THE SIMILAR PATTERN AS ABOVE, WITH INCREASED EXPRESSION OVER THE CORRESPONDING HELICOBACTER PYLORI-NEGATIVE CONTROLS EXCEPT IN NONATROPHIC GASTRITIS PATIENT WHOSE LABELING INDEX WAS DECREASED WHEN COMPARED WITH HELICOBACTER PYLORI-NEGATIVE CONTROL. LABELING INDEX OF KI67 IN HELICOBACTER PYLORI-NEGATIVE GROUPS WAS HIGHER IN GASTRIC CANCER THAN CHRONIC ATROPHIC GASTRITIS AND LOW-GRADE INTRAEPITHELIAL NEOPLASIA GROUPS, AND HIGHER IN INTESTINAL METAPLASIA GROUP COMPARED WITH CHRONIC ATROPHIC GASTRITIS GROUP. IN HELICOBACTER PYLORI-POSITIVE GROUPS, KI67 LABELING INDEX WAS INCREASED STEPWISE FROM NONATROPHIC GASTRITIS TO GASTRIC CANCER EXCEPT SLIGHTLY DECREASE IN CHRONIC ATROPHIC GASTRITIS GROUP. IN ADDITION, WE NOTED THAT HISTONE H3 SERINE 10 PHOSPHORYLATION STAINING IS ACCOMPANIED WITH ITS LOCATION CHANGES FROM GASTRIC GLAND BOTTOM EXPANDED TO WHOLE GLAND AS DISEASE STAGE PROGRESS. CONCLUSIONS: THESE RESULTS INDICATE THAT STEPWISE GASTRIC CARCINOGENESIS IS ASSOCIATED WITH ALTERED HISTONE H3 SERINE 10 PHOSPHORYLATION, HELICOBACTER PYLORI INFECTION ENHANCES HISTONE H3 SERINE 10 PHOSPHORYLATION EXPRESSION IN THESE PROCESSES; IT IS ALSO ACCOMPANIED WITH HISTONE H3 SERINE 10 PHOSPHORYLATION LOCATION CHANGE FROM GLAND BOTTOM STAINING EXPAND TO WHOLE GLAND EXPRESSION. THE RESULTS SUGGEST THAT EPIGENETIC DYSREGULATION MAY PLAY IMPORTANT ROLES IN HELICOBACTER PYLORI-INDUCED GASTRIC CANCER.	2018	

6 3134  41 GLOBAL DNA HYPOMETHYLATION IS AN EARLY EVENT IN HELICOBACTER PYLORI-RELATED GASTRIC CARCINOGENESIS. AIM: CANCER, PARTICULARLY GASTRIC CANCER (GC), IS PREVALENTLY AN EPIGENETIC PHENOMENON THAT IS DEPENDENT ON AN ALTERED DNA METHYLATION PATTERN. IN GASTRIC CARCINOGENESIS, MANY GENES SHOW ABERRANT METHYLATION; HOWEVER, NONE OF THEM MAY BE USED AS A BIOMARKER OF CANCER RISK AND PROGRESSION. THE AUTHORS AIMED TO EVALUATE THE GLOBAL DNA METHYLATION OF GASTRIC MUCOSA IN HELICOBACTER PYLORI (HP)-RELATED CHRONIC GASTRITIS, IN GC AND IN 10 PATIENTS WITH PRENEOPLASTIC LESIONS (IE, ATROPHY AND INTESTINAL METAPLASIA) FOLLOWED UP FOR 10 YEARS. METHODS: THE AUTHORS ANALYSED 93 DYSPEPTIC PATIENTS WHO UNDERWENT UPPER ENDOSCOPY, 41 SURGICAL GC SAMPLES AND 10 PATIENTS WITH PRENEOPLASTIC GASTRIC LESIONS FOLLOWED UP FOR 10 YEARS AFTER SUCCESSFUL HP ERADICATION THERAPY. GLOBAL DNA METHYLATION STATUS AND SURROGATE MARKERS OF CELL PROLIFERATION AND APOPTOSIS WERE EVALUATED BY IMMUNOHISTOCHEMISTRY USING THE ANTI-5-METHYLCYTOSINE (5-MC), ANTI-KI-67 AND ANTI-P53 (ANTI-APOPTOTIC MARKER)-SPECIFIC ANTIBODIES, RESPECTIVELY. RESULTS: GLOBAL DNA METHYLATION OF GASTRIC MUCOSA GRADUALLY DECREASED FROM NORMAL MUCOSA TO HP-POSITIVE GASTRITIS, HP-POSITIVE CHRONIC ATROPHIC GASTRITIS, INDEPENDENT OF CAG-A STATUS AND GC; HOWEVER, THE VARIATION WAS SIGNIFICANT (P<0.05) ONLY BETWEEN HP-NEGATIVE SUBJECTS AND HP-POSITIVE CHRONIC GASTRITIS. INTERESTINGLY, THE 5-MC IMMUNOSTAINING WAS ABSENT IN AREAS OF INTESTINAL METAPLASIA. IN THE 10 PATIENTS WITH PRENEOPLASTIC LESIONS, GLOBAL DNA METHYLATION DECREASED OVER TIME DESPITE THE ERADICATION OF HP INFECTION, BUT REACHED SIGNIFICANCE ONLY AT 10 YEARS VERSUS BASELINE. THE 5-MC IMMUNOSTAINING NEGATIVELY CORRELATED WITH KI-67 AND P53 EXPRESSION IN ALL GROUPS. CONCLUSION: GLOBAL DNA HYPOMETHYLATION IS AN EARLY MOLECULAR EVENT IN HP-RELATED GASTRIC CARCINOGENESIS. FURTHER STUDIES WITH MORE CASES AND A LONGER FOLLOW-UP ARE NEEDED TO ESTABLISH THE POTENTIAL GC PREDICTIVE ROLE OF DNA HYPOMETHYLATION.	2011	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
7 4114  41 MECHANISMS FOR THE INDUCTION OF GASTRIC CANCER BY HELICOBACTER PYLORI INFECTION: ABERRANT DNA METHYLATION PATHWAY. MULTIPLE PATHOGENIC MECHANISMS BY WHICH HELICOBACTER PYLORI INFECTION INDUCES GASTRIC CANCER HAVE BEEN ESTABLISHED IN THE LAST TWO DECADES. IN PARTICULAR, ABERRANT DNA METHYLATION IS INDUCED IN MULTIPLE DRIVER GENES, WHICH INACTIVATES THEM. METHYLATION PROFILES IN GASTRIC CANCER ARE ASSOCIATED WITH SPECIFIC SUBTYPES, SUCH AS MICROSATELLITE INSTABILITY. RECENT COMPREHENSIVE AND INTEGRATED ANALYSES SHOWED THAT MANY CANCER-RELATED PATHWAYS ARE MORE FREQUENTLY ALTERED BY ABERRANT DNA METHYLATION THAN BY MUTATIONS. ABERRANT DNA METHYLATION CAN EVEN BE PRESENT IN NONCANCEROUS GASTRIC MUCOSAE, PRODUCING AN "EPIGENETIC FIELD FOR CANCERIZATION." MECHANISTICALLY, H. PYLORI-INDUCED CHRONIC INFLAMMATION, BUT NOT H. PYLORI ITSELF, PLAYS A DIRECT ROLE IN THE INDUCTION OF ABERRANT DNA METHYLATION. THE EXPRESSION OF THREE INFLAMMATION-RELATED GENES, IL1B, NOS2, AND TNF, IS HIGHLY ASSOCIATED WITH THE INDUCTION OF ABERRANT DNA METHYLATION. IMPORTANTLY, THE DEGREE OF ACCUMULATED ABERRANT DNA METHYLATION IS STRONGLY CORRELATED WITH GASTRIC CANCER RISK. A RECENT MULTICENTER PROSPECTIVE COHORT STUDY DEMONSTRATED THE UTILITY OF EPIGENETIC CANCER RISK DIAGNOSIS FOR METACHRONOUS GASTRIC CANCER. SUPPRESSION OF ABERRANT DNA METHYLATION BY A DEMETHYLATING AGENT WAS SHOWN TO INHIBIT GASTRIC CANCER DEVELOPMENT IN AN ANIMAL MODEL. INDUCTION OF ABERRANT DNA METHYLATION IS THE MAJOR PATHWAY BY WHICH H. PYLORI INFECTION INDUCES GASTRIC CANCER, AND THIS CAN BE UTILIZED FOR TRANSLATIONAL OPPORTUNITIES.	2017	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
8 1540  36 DNA METHYLATION IN GASTRIC CANCER, RELATED TO HELICOBACTER PYLORI AND EPSTEIN-BARR VIRUS. GASTRIC CANCER IS A LEADING CAUSE OF CANCER DEATH WORLDWIDE, AND SIGNIFICANT EFFORT HAS BEEN FOCUSED ON CLARIFYING THE PATHOLOGY OF GASTRIC CANCER. IN PARTICULAR, THE DEVELOPMENT OF GENOME-WIDE ANALYSIS TOOLS HAS ENABLED THE DETECTION OF GENETIC AND EPIGENETIC ALTERATIONS IN GASTRIC CANCER; FOR EXAMPLE, ABERRANT DNA METHYLATION IN GENE PROMOTER REGIONS IS THOUGHT TO PLAY A CRUCIAL ROLE IN GASTRIC CARCINOGENESIS. THE ETIOLOGICAL VIEWPOINT IS ALSO ESSENTIAL FOR THE STUDY OF GASTRIC CANCERS, AND TWO DISTINCT PATHOGENS, HELICOBACTER PYLORI (H. PYLORI) AND EPSTEIN-BARR VIRUS (EBV), ARE KNOWN TO PARTICIPATE IN GASTRIC CARCINOGENESIS. CHRONIC INFLAMMATION OF THE GASTRIC EPITHELIUM DUE TO H. PYLORI INFECTION INDUCES ABERRANT POLYCLONAL METHYLATION THAT MAY LEAD TO AN INCREASED RISK OF GASTRIC CANCER. IN ADDITION, EBV INFECTION IS KNOWN TO CAUSE EXTENSIVE METHYLATION, AND EBV-POSITIVE GASTRIC CANCERS DISPLAY A HIGH METHYLATION EPIGENOTYPE, IN WHICH ABERRANT METHYLATION EXTENDS TO NOT ONLY POLYCOMB REPRESSIVE COMPLEX (PRC)-TARGET GENES IN EMBRYONIC STEM CELLS BUT ALSO NON-PRC-TARGET GENES. HERE, WE REVIEW ABERRANT DNA METHYLATION IN GASTRIC CANCER AND THE ASSOCIATION BETWEEN METHYLATION AND INFECTION WITH H. PYLORI AND EBV.	2014	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
9 5276  43 PROMOTER METHYLATION OF TUMOR-RELATED GENES IN GASTRIC CARCINOGENESIS. ABERRANT PROMOTER METHYLATION AND SUBSEQUENT SILENCING OF CANCER-RELATED GENES HAS BEEN RECOGNIZED AS AN IMPORTANT PATHWAY INVOLVED IN GASTRIC CARCINOGENESIS. IN FACT, SEVERAL FACTORS ARE BELIEVED TO CONTRIBUTE TO ITS INDUCTION IN GASTRIC EPITHELIA, INCLUDING AGING, DIET, CHRONIC INFLAMMATION AND INFECTION OF HELICOBACTER PYLORI (H. PYLORI) AND EPSTEIN-BARR VIRUS (EBV). HOWEVER, THE UNDERLING MECHANISMS ARE NOT COMPLETELY IDENTIFIED, DESPITE THE BELIEF THAT INCREASED EXPRESSION OR ACTIVITY OF DNA METHYLTRANSFERASES (DNMTS), OR DECREASED DEMETHYLATION ACTIVITY MAY CONTRIBUTE TO THE EXCESSIVE METHYLATION. A GREAT NUMBER OF GENES WITH PROMOTER METHYLATION HAVE BEEN OBSERVED IN GASTRIC CANCER (GC), AMONG WHICH P16INK4A (P16), MUT L HOMOLOGUE 1 (MLH1), EPITHELIAL-CADHERIN (E-CADHERIN), RUNT-RELATED TRANSCRIPTION FACTOR 3 (RUNX3), ADENOMATOUS POLYPOSIS COLI (APC), O(6)-METHYLGUANINE-DNA METHYLTRANSFERASE (MGMT), RAS ASSOCIATION DOMAIN FAMILY 1A (RASSF1A) AND DEATH-ASSOCIATED PROTEIN KINASE (DAPK) HAVE BEEN EXTENSIVELY STUDIED. UNLIKE THE DISTINCT METHYLATION CHARACTERIZATION IN SINGLE GENES, METHYLATION ANALYSIS OF MULTIPLE GENES MAY PROVIDE MORE INFORMATION IN RISK PREDICTION, EARLY DETECTION, PROGNOSIS ASSESSMENT AND CHEMOTHERAPY CHOICE FOR GC. SPECIFICALLY, PARTICULAR MONITORING AND SCREENING SHOULD BE PERFORMED ON THOSE OVER 45 YEARS OLD, WITH PRECANCEROUS GASTRIC DISEASE OR INFECTION OF H. PYLORI OR EBV. AS AN ALTERNATIVE TO TUMOR TISSUES, METHYLATION DETECTION IN PATIENT SERA OR GASTRIC WASHES MAY ALSO BE USED IN RISK PREDICTION AND EARLY DETECTION. HOWEVER, WHAT STILL POSES A GREAT CHALLENGE AS WELL AS A PUZZLE IS THE DETERMINATION OF THE VERY GENES THAT SHOULD BE USED IN METHYLATION ANALYSIS. BECAUSE EPIGENETIC ALTERATIONS ARE NORMALLY REVERSIBLE, DRUGS OR CHEMICAL COMPOUNDS WITH DEMETHYLATING ACTIVITY, SUCH AS 5-AZA-2'-DEOXYCYTIDINE (5-AZA-DC) COULD BE USED IN THE TREATMENT OF PATIENTS WITH MULTIPLE GENE METHYLATION. IN VIEW OF THE ADVERSE EFFECTS OF 5-AZA-DC, DNMT-TARGETED STRATEGY HAS BEEN PROPOSED AND MAY PROVE TO BE MORE EFFECTIVE THAN DEMETHYLATING AGENTS.	2012	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
10 2943  26 GENETIC AND EPIGENETIC ALTERATIONS OF TUMOR SUPPRESSOR AND TUMOR-RELATED GENES IN GASTRIC CANCER. BOTH GENETIC AND EPIGENETIC ALTERATIONS OF TUMOR SUPPRESSOR AND TUMOR-RELATED GENES INVOLVED IN THE PATHOGENESIS OF GASTRIC CANCER ARE REVIEWED HERE, AND MOLECULAR PATHWAYS OF GASTRIC CARCINOGENESIS ARE PROPOSED. GASTRIC CARCINOMAS ARE BELIEVED TO EVOLVE FROM NATIVE GASTRIC MUCOSA OR INTESTINAL METAPLASTIC MUCOSA THAT UNDERGOES GENETIC AND EPIGENETIC ALTERATIONS INVOLVING EITHER THE SUPPRESSOR PATHWAY (DEFECTS IN TUMOR SUPPRESSOR GENES) OR MUTATOR PATHWAY (DEFECTS IN DNA MISMATCH REPAIR GENES). METHYLATION OF E-CADHERIN IN NATIVE GASTRIC MUCOSA RESULTS IN UNDIFFERENTIATED CARCINOMAS (SUPPRESSOR PATHWAY), WHILE METHYLATION OF HMLHI RESULTS IN DIFFERENTIATED FOVEOLAR-TYPE CARCINOMAS (MUTATOR PATHWAY). THE MAJORITY OF DIFFERENTIATED GASTRIC CARCINOMAS HOWEVER, ARISE FROM INTESTINAL METAPLASTIC MUCOSA AND EXHIBIT STRUCTURAL ALTERATIONS OF TUMOR SUPPRESSOR GENES, ESPECIALLY P53. THEY APPEAR TO BE RELATED TO CHRONIC INJURY, PERHAPS DUE TO HELICOBACTER PYLORI INFECTION. APPROXIMATELY 20% OF DIFFERENTIATED CARCINOMAS (ORDINARY-TYPE) HAVE EVIDENCE OF MUTATOR PATHWAY TUMORIGENESIS. MUTATIONS OF E-CADHERIN ARE MAINLY INVOLVED IN THE PROGRESSION OF DIFFERENTIATED CARCINOMAS TO UNDIFFERENTIATED TUMORS. THE MOLECULAR PATHWAYS OF GASTRIC CARCINOGENESIS DEPEND ON THE HISTOLOGICAL BACKGROUND, AND GASTRIC CARCINOMAS SHOW DISTINCT BIOLOGICAL BEHAVIORS AS A RESULT OF DISCERNIBLE CELLULAR GENETIC AND EPIGENETIC ALTERATIONS.	2002	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
11 3230  38 HELICOBACTER PYLORI-INDUCED INFLAMMATION AND EPIGENETIC CHANGES DURING GASTRIC CARCINOGENESIS. THE SEQUENCE OF EVENTS ASSOCIATED WITH THE DEVELOPMENT OF GASTRIC CANCER HAS BEEN DESCRIBED AS "THE GASTRIC PRECANCEROUS CASCADE". THIS CASCADE IS A DYNAMIC PROCESS THAT INCLUDES LESIONS, SUCH AS ATROPHIC GASTRITIS, INTESTINAL METAPLASIA AND DYSPLASIA. ACCORDING TO THIS MODEL, HELICOBACTER PYLORI (H. PYLORI) INFECTION TARGETS THE NORMAL GASTRIC MUCOSA CAUSING NON-ATROPHIC GASTRITIS, AN INITIATING LESION THAT CAN BE CURED BY CLEARING H. PYLORI WITH ANTIBIOTICS OR THAT MAY THEN LINGER IN THE CASE OF CHRONIC INFECTION AND PROGRESS TO ATROPHIC GASTRITIS. THE PRESENCE OF VIRULENCE FACTORS IN THE INFECTING H. PYLORI DRIVES THE CARCINOGENESIS PROCESS. INDEPENDENT EPIDEMIOLOGICAL AND ANIMAL STUDIES HAVE CONFIRMED THE SEQUENTIAL PROGRESSION OF THESE PRECANCEROUS LESIONS. PARTICULARLY LONG-TERM FOLLOW-UP STUDIES ESTIMATED A RISK OF 0.1% FOR ATROPHIC GASTRITIS/INTESTINAL METAPLASIA AND 6% IN CASE OF DYSPLASIA FOR THE LONG-TERM DEVELOPMENT OF GASTRIC CANCER. WITH THIS IN MIND, A BETTER UNDERSTANDING OF THE GENETIC AND EPIGENETIC CHANGES ASSOCIATED WITH PROGRESSION OF THE CASCADE IS CRITICAL IN DETERMINING THE RISK OF GASTRIC CANCER ASSOCIATED WITH H. PYLORI INFECTION. IN THIS REVIEW, WE WILL SUMMARIZE SOME OF THE MOST RELEVANT MECHANISMS AND FOCUS PREDOMINANTLY BUT NOT EXCLUSIVELY ON THE DISCUSSION OF GENE PROMOTER METHYLATION AND MIRNAS IN THIS CONTEXT.	2015	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
12 6841  33 [MECHANISMS OF H. PYLORI INFECTION-INDUCED GASTRIC CARCINOGENESIS]. MANY EPIDEMIOLOGICAL STUDIES HAVE DEMONSTRATED A STRONG ASSOCIATION BETWEEN H. PYLORI (HELICOBACTER PYLORI) INFECTION AND HUMAN GASTRIC CANCER DEVELOPMENT. THE PRECISE MECHANISMS ACCOUNTING FOR GASTRIC CANCER DEVELOPMENT INDUCED BY H. PYLORI INFECTION ARE STILL NOT COMPLETELY UNDERSTOOD. HOWEVER, IT SHOULD BE REASONABLE TO ASSUME THAT THERE ARE TWO DISTINCT MOLECULAR PATHWAYS FOR GASTRIC CARCINOGENESIS BY H. PYLORI INFECTION; THE DIRECT ACTION OF THE BACTERIA ITSELF ON GASTRIC EPITHELIAL CELLS, AND THE ACCUMULATION OF GENETIC CHANGES CAUSED BY PROLONGED BACTERIAL INFECTION AND CHRONIC INFLAMMATION. AS A DIRECT ACTION OF H. PYLORI, BACTERIAL PROTEINS SUCH AS CAGA COULD BE DELIVERED INTO GASTRIC EPITHELIAL CELLS VIA THE TYPE IV SECRETION APPARATUS AND MODIFY THE HOST CELL FUNCTIONS RELATED TO CELL PROLIFERATION. IN ADDITION TO THE DIRECT BACTERIAL ACTION, H. PYLORI INFECTION AND THE RESULTANT INFLAMMATORY RESPONSE CAUSE VARIOUS GENETIC AND EPIGENETIC CHANGES IN TUMOR-RELATED GENES OF THE GASTRIC EPITHELIAL CELLS. NOTABLY, EXPRESSION OF AID (ACTIVATION-INDUCED CYTIDINE DEAMINASE), A DNA EDITING ENZYME THAT UNDERGOES SOMATIC HYPERMUTATION ON HUMAN GENES, IS INDUCED IN RESPONSE TO H. PYLORI INFECTION AND PROINFLAMMATORY CYTOKINE STIMULATION IN HUMAN GASTRIC EPITHELIAL CELLS. AS A RESULT, THE ACCUMULATION OF GENETIC ALTERATIONS WOULD PERSIST UNTIL THE CLINICAL STAGE OF ATROPHIC GASTRITIS AND EVENTUALLY TRIGGER THE MALIGNANT TRANSFORMATION OF GASTRIC CELLS.	2010	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
13 2377  43 EPIGENETIC REGULATION OF TUMOR SUPPRESSORS BY HELICOBACTER PYLORI ENHANCES EBV-INDUCED PROLIFERATION OF GASTRIC EPITHELIAL CELLS. HELICOBACTER PYLORI AND EPSTEIN-BARR VIRUS (EBV) ARE TWO WELL-KNOWN CONTRIBUTORS TO CANCER AND CAN ESTABLISH LIFELONG PERSISTENT INFECTION IN THE HOST. THIS LEADS TO CHRONIC INFLAMMATION, WHICH ALSO CONTRIBUTES TO DEVELOPMENT OF CANCER. ASSOCIATION WITH H. PYLORI INCREASES THE RISK OF GASTRIC CARCINOMA, AND COEXISTENCE WITH EBV ENHANCES PROLIFERATION OF INFECTED CELLS. FURTHER, H. PYLORI-EBV COINFECTION CAUSES CHRONIC INFLAMMATION IN PEDIATRIC PATIENTS. WE HAVE ESTABLISHED AN H. PYLORI-EBV COINFECTION MODEL SYSTEM USING HUMAN GASTRIC EPITHELIAL CELLS. WE SHOWED THAT H. PYLORI INFECTION CAN INCREASE THE ONCOGENIC PHENOTYPE OF EBV-INFECTED CELLS AND THAT THE CYTOTOXIN-ASSOCIATED GENE (CAGA) PROTEIN ENCODED BY H. PYLORI STIMULATED EBV-MEDIATED CELL PROLIFERATION IN THIS COINFECTION MODEL SYSTEM. THIS LED TO INCREASED EXPRESSION OF DNA METHYL TRANSFERASES (DNMTS), WHICH REPROGRAMMED CELLULAR TRANSCRIPTIONAL PROFILES, INCLUDING THOSE OF TUMOR SUPPRESSOR GENES (TSGS), THROUGH HYPERMETHYLATION. THESE FINDINGS PROVIDE NEW INSIGHTS INTO A MOLECULAR MECHANISM WHEREBY COOPERATIVITY BETWEEN TWO ONCOGENIC AGENTS LEADS TO ENHANCED ONCOGENIC ACTIVITY OF GASTRIC CANCER CELLS.IMPORTANCE WE HAVE STUDIED THE COOPERATIVITY BETWEEN H. PYLORI AND EBV, TWO KNOWN ONCOGENIC AGENTS. THIS LED TO AN ENHANCED ONCOGENIC PHENOTYPE IN GASTRIC EPITHELIAL CELLS. WE NOW DEMONSTRATE THAT EBV-DRIVEN EPIGENETIC MODIFICATIONS ARE ENHANCED IN THE PRESENCE OF H. PYLORI, MORE SPECIFICALLY, IN THE PRESENCE OF ITS CAGA SECRETORY ANTIGEN. THIS RESULTS IN INCREASED PROLIFERATION OF THE INFECTED GASTRIC CELLS. OUR FINDINGS NOW ELUCIDATE A MOLECULAR MECHANISM WHEREBY EXPRESSION OF CELLULAR DNA METHYL TRANSFERASES IS INDUCED INFLUENCING INFECTION BY EBV. HYPERMETHYLATION OF THE REGULATORY GENOMIC REGIONS OF TUMOR SUPPRESSOR GENES RESULTS IN THEIR SILENCING. THIS DRASTICALLY AFFECTS THE EXPRESSION OF CELL CYCLE, APOPTOSIS, AND DNA REPAIR GENES, WHICH DYSREGULATES THEIR ASSOCIATED PROCESSES, AND PROMOTION OF THE ONCOGENIC PHENOTYPE.	2018	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
14 4994  36 PERFORMANCE OF DNA METHYLATION ON THE MOLECULAR PATHOGENESIS OF HELICOBACTER PYLORI IN GASTRIC CANCER; TARGETED THERAPY APPROACH. GASTRIC CANCER (GC) IS A SIGNIFICANT CAUSE OF CANCER MORTALITY WHICH HAS LED TO FOCUSED EXPLORATION OF THE PATHOLOGY OF GC. THE ADVENT OF GENOME-WIDE ANALYSIS METHODS HAS MADE IT POSSIBLE TO UNCOVER GENETIC AND EPIGENETIC FLUCTUATION SUCH AS ABNORMAL DNA METHYLATION IN GENE PROMOTER REGIONS THAT IS EXPECTED TO PLAY A KEY ROLE IN GC. THE STUDY OF GASTRIC MALIGNANCIES REQUIRES AN ETIOLOGICAL PERSPECTIVE, AND HELICOBACTER PYLORI (H. PYLORI) WAS IDENTIFIED TO PLAY A ROLE IN GC. H. PYLORI INFECTION CAUSES CHRONIC INFLAMMATION OF THE GASTRIC EPITHELIUM CAUSING ABNORMAL POLYCLONAL METHYLATION, WHICH MIGHT RAISE THE RISK OF GC. IN THE LAST TWO DECADES, VARIOUS PATHOGENIC FACTORS BY WHICH H. PYLORI INFECTION CAUSES GC HAVE BEEN DISCOVERED. ABNORMAL DNA METHYLATION IS TRIGGERED IN SEVERAL GENES, RENDERING THEM INACTIVE. IN GC, METHYLATION PATTERNS ARE LINKED TO CERTAIN SUBTYPES INCLUDING MICROSATELLITE INSTABILITY. MULTIPLE CANCER-RELATED PROCESSES ARE MORE USUALLY CHANGED BY ABNORMAL DNA METHYLATION THAN THROUGH MUTATIONS, ACCORDING TO CURRENT GENERAL AND COMBINED INVESTIGATIONS. FURTHERMORE, THE AMOUNT OF ACQUIRED ABNORMAL DNA METHYLATION IS HEAVILY LINKED TO THE CHANCES OF DEVELOPING GC. THEREFORE, WE INVESTIGATED ABNORMAL DNA METHYLATION IN GC AND THE LINK BETWEEN METHYLATION AND H. PYLORI INFECTION.	2022	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
15 3222  34 HELICOBACTER PYLORI ASSOCIATED CHRONIC GASTRITIS, CLINICAL SYNDROMES, PRECANCEROUS LESIONS, AND PATHOGENESIS OF GASTRIC CANCER DEVELOPMENT. HELICOBACTER PYLORI (H. PYLORI) INFECTION IS WELL KNOWN TO BE ASSOCIATED WITH THE DEVELOPMENT OF PRECANCEROUS LESIONS SUCH AS CHRONIC ATROPHIC GASTRITIS (AG), OR GASTRIC INTESTINAL METAPLASIA (GIM), AND CANCER. VARIOUS MOLECULAR ALTERATIONS ARE IDENTIFIED NOT ONLY IN GASTRIC CANCER (GC) BUT ALSO IN PRECANCEROUS LESIONS. H. PYLORI TREATMENT SEEMS TO IMPROVE AG AND GIM, BUT STILL REMAINS CONTROVERSIAL. IN CONTRAST, MANY STUDIES, INCLUDING META-ANALYSIS, SHOW THAT H. PYLORI ERADICATION REDUCES GC. MOLECULAR MARKERS DETECTED BY GENETIC AND EPIGENETIC ALTERATIONS RELATED TO CARCINOGENESIS REVERSE FOLLOWING H. PYLORI ERADICATION. THIS INDICATES THAT THESE CHANGES MAY BE AN IMPORTANT FACTOR IN THE IDENTIFICATION OF HIGH RISK PATIENTS FOR CANCER DEVELOPMENT. PATIENTS WHO UNDERWENT ENDOSCOPIC TREATMENT OF GC ARE AT HIGH RISK FOR DEVELOPMENT OF METACHRONOUS GC. A RANDOMIZED CONTROLLED TRIAL FROM JAPAN CONCLUDED THAT PROPHYLACTIC ERADICATION OF H. PYLORI AFTER ENDOSCOPIC RESECTION SHOULD BE USED TO PREVENT THE DEVELOPMENT OF METACHRONOUS GC, BUT RECENT RETROSPECTIVE STUDIES DID NOT SHOW THE TENDENCY. PATIENTS WITH PRECANCEROUS LESIONS (MOLECULAR ALTERATIONS) THAT DO NOT REVERSE AFTER H. PYLORI TREATMENT, REPRESENT THE "POINT OF NO RETURN" AND MAY BE AT HIGH RISK FOR THE DEVELOPMENT OF GC. THEREFORE, EARLIER H. PYLORI ERADICATION SHOULD BE CONSIDERED FOR PREVENTING GC DEVELOPMENT PRIOR TO THE APPEARANCE OF PRECANCEROUS LESIONS.	2014	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
16 3221  26 HELICOBACTER PYLORI AND THE MOLECULAR PATHOGENESIS OF INTESTINAL-TYPE GASTRIC CARCINOMA. GASTRIC CARCINOMA IS AN INFLAMMATION-RELATED CANCER CAUSED BY LONG-TERM INFECTION WITH THE HUMAN BACTERIAL PATHOGEN, HELICOBACTER PYLORI. THE PATTERN OF ACUTE-ON-CHRONIC INFLAMMATION CAUSES PROGRESSIVE MUCOSAL DAMAGE WHICH MAY RESULT IN ATROPHY WITH METAPLASTIC EPITHELIA AND EVENTUALLY GASTRIC CANCER. RECENTLY, IT HAS BEEN RECOGNIZED THAT H. PYLORI CAN ALSO CAUSE GENETIC INSTABILITY SUCH AS DOUBLE-STRANDED DNA BREAKS AND CAN PRODUCE GENE ACTIVATION AND SILENCING VIA EPIGENETIC PATHWAYS. AS GENETIC INSTABILITY IS THE HALLMARK OF CANCER, WE HIGHLIGHT RECENT PROGRESS IN UNDERSTANDING THE GASTRIC CARCINOGENESIS IN RELATION TO H. PYLORI-RELATED INFLAMMATION, H. PYLORI-INDUCED DOUBLE-STRANDED DNA BREAKAGE AND ABERRANT GENE EXPRESSION AS WELL AS THE MECHANISMS AND ROLE OF H. PYLORI-ASSOCIATED EPIGENETIC CHANGE IN GENE EXPRESSION.	2014	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
17  762  35 CAUSAL ROLE OF HELICOBACTER PYLORI INFECTION AND ERADICATION THERAPY IN GASTRIC CARCINOGENESIS. MANY EPIDEMIOLOGICAL REPORTS INDICATE THAT HELICOBACTER PYLORI (H PYLORI) INFECTION PLAYS AN IMPORTANT ROLE IN GASTRIC CARCINOGENESIS. SEVERAL GENETIC AND EPIGENETIC ALTERATIONS CONTRIBUTE TO THE INITIATION, PROMOTION, AND PROGRESSION OF THE CANCER CELLS IN A MULTI-STEP MANNER. H PYLORI IS KNOWN TO INDUCE CHRONIC INFLAMMATION IN THE GASTRIC MUCOSA. ITS PRODUCTS, INCLUDING SUPEROXIDES, PARTICIPATE IN THE DNA DAMAGE FOLLOWED BY INITIATION, AND THE INFLAMMATION-DERIVED CYTOKINES AND GROWTH FACTORS CONTRIBUTE TO THE PROMOTION OF GASTRIC CARCINOGENESIS. BY ERADICATING H PYLORI, GASTRIC INFLAMMATION CAN BE CURED; THE THERAPY DIMINISHES THE LEVELS NOT ONLY OF INFLAMMATORY CELL INFILTRATION, BUT ALSO ATROPHY/INTESTINAL METAPLASIA IN PART. A RANDOMIZED CONTROLLED TRIAL REVEALED THAT THE ERADICATION THERAPY DIMINISHED THE GASTRIC CANCER PREVALENCE IN CASES WITHOUT PRE-CANCEROUS CONDITIONS. IN ADDITION, RECENT EPIDEMIOLOGICAL STUDIES FROM JAPANESE GROUPS DEMONSTRATED THAT THE DEVELOPMENT OF GASTRIC CANCER, ESPECIALLY OF THE INTESTINAL TYPE, WAS DECREASED BY SUCCESSFUL ERADICATION THERAPY, ALTHOUGH THESE WERE DESIGNED IN A NON-RANDOMIZED MANNER. HOWEVER, IT SHOULD BE MENTIONED THAT ENDOSCOPIC DETECTION IS THE ONLY WAY TO EVALUATE THE DEGREE OF GASTRIC CARCINOGENESIS. WE HAVE REPORTED THAT THE ENDOSCOPIC AND HISTOLOGICAL MORPHOLOGIES COULD BE MODIFIED BY ERADICATION THERAPY AND IT MIGHT CONTRIBUTE TO THE PREVALENCE OF GASTRIC CANCER DEVELOPMENT. CONSIDERING THE BIOLOGICAL NATURE OF CANCER CELL PROLIFERATION, IT IS CONSIDERED THAT A SUFFICIENTLY LONG-TERM FOLLOW-UP WOULD BE ESSENTIAL TO DISCUSS THE ANTICANCER EFFECT OF ERADICATION THERAPY.	2006	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
18  902  41 CHRONIC EXPOSURE TO ARSENIC, ESTROGEN, AND THEIR COMBINATION CAUSES INCREASED GROWTH AND TRANSFORMATION IN HUMAN PROSTATE EPITHELIAL CELLS POTENTIALLY BY HYPERMETHYLATION-MEDIATED SILENCING OF MLH1. BACKGROUND: CHRONIC EXPOSURE TO ARSENIC AND ESTROGEN IS ASSOCIATED WITH RISK OF PROSTATE CANCER, BUT THEIR MECHANISM IS NOT FULLY UNDERSTOOD. ADDITIONALLY, THE CARCINOGENIC EFFECTS OF THEIR CO-EXPOSURE ARE NOT KNOWN. THEREFORE, THE OBJECTIVE OF THIS STUDY WAS TO EVALUATE THE EFFECTS OF CHRONIC EXPOSURE TO ARSENIC, ESTROGEN, AND THEIR COMBINATION, ON CELL GROWTH AND TRANSFORMATION, AND IDENTIFY THE MECHANISM BEHIND THESE EFFECTS. METHODS: RWPE-1 HUMAN PROSTATE EPITHELIAL CELLS WERE CHRONICALLY EXPOSED TO ARSENIC AND ESTROGEN ALONE AND IN COMBINATION. CELL GROWTH WAS MEASURED BY CELL COUNT AND CELL CYCLE, WHEREAS CELL TRANSFORMATION WAS EVALUATED BY COLONY FORMATION ASSAY. GENE EXPRESSION WAS MEASURED BY QUANTITATIVE REAL-TIME PCR AND CONFIRMED AT PROTEIN LEVEL BY WESTERN BLOT ANALYSIS. MLH1 PROMOTER METHYLATION WAS DETERMINED BY PYROSEQUENCING METHOD. RESULTS: EXPOSURE TO ARSENIC, ESTROGEN, AND THEIR COMBINATIONS INCREASES CELL GROWTH AND TRANSFORMATION IN RWPE-1 CELLS. INCREASED EXPRESSION OF CYCLIN D1 AND BCL2, WHEREAS DECREASED EXPRESSION OF MISMATCH REPAIR GENES MSH4, MSH6, AND MLH1 WAS ALSO OBSERVED. HYPERMETHYLATION OF MLH1 PROMOTER FURTHER SUGGESTED THE EPIGENETIC INACTIVATION OF MLH1 EXPRESSION IN ARSENIC AND ESTROGEN TREATED CELLS. ARSENIC AND ESTROGEN COMBINATION CAUSED GREATER CHANGES THAN THEIR INDIVIDUAL TREATMENTS. CONCLUSIONS: FINDINGS OF THIS STUDY FOR THE FIRST TIME SUGGEST THAT ARSENIC AND ESTROGEN EXPOSURES CAUSE INCREASED CELL GROWTH AND SURVIVAL POTENTIALLY THROUGH EPIGENETIC INACTIVATION OF MLH1 RESULTING IN DECREASED MLH1-MEDIATED APOPTOTIC RESPONSE, AND CONSEQUENTLY INCREASED CELLULAR TRANSFORMATION.	2013	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
19 5767  30 SPECIES-SPECIFIC ROLE OF GENE-ADJACENT RETROELEMENTS IN HUMAN AND MOUSE GASTRIC CARCINOGENESIS. HELICOBACTER PYLORI (HP) INFECTION PROMOTES THE RECRUITMENT OF BONE MARROW STEM CELLS INTO CHRONIC GASTRITIS LESIONS. SOME OF THESE MARROW STEM CELLS CAN DIFFERENTIATE INTO GASTRIC EPITHELIAL CELLS AND NEOPLASTIC CELLS. WE PROPOSE THAT HP-ASSOCIATED METHYLATION COULD STABILIZE TRANS-DIFFERENTIATION OF MARROW-DERIVED STEM CELLS AND THAT AN UNSTABLE METHYLATION STATUS IS ASSOCIATED WITH A RISK OF GASTRIC CANCER. PATHOBIOLOGIC BEHAVIOR OF EXPERIMENTAL MOUSE GASTRIC CANCER IS MILD COMPARED TO INVASIVE AND METASTATIC HUMAN GASTRIC CANCER. DIFFERENCES IN EPIGENETIC STABILIZATION OF ADULT CELL PHENOTYPES BETWEEN HUMANS AND MICE COULD PROVIDE A FOUNDATION TO EXPLORE THE DEVELOPMENT OF INVASIVE AND METASTATIC GASTRIC CANCER. RETROELEMENTS ARE HIGHLY REPETITIVE SEQUENCES THAT PLAY AN ESSENTIAL ROLE IN THE GENERATION OF SPECIES DIVERSITY. IN THIS REVIEW, WE ANALYZED RETROELEMENTS ADJACENT TO HUMAN AND MOUSE HOUSEKEEPING GENES AND PROPOSED A POSSIBLE EPIGENETIC MECHANISM FOR HP-ASSOCIATED CARCINOGENESIS.	2018	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
20 4237  42 METHYLATION PATTERN OF THBS1, GATA-4, AND HIC1 IN PEDIATRIC AND ADULT PATIENTS INFECTED WITH HELICOBACTER PYLORI. BACKGROUND: HELICOBACTER PYLORI INFECTION IS USUALLY ACQUIRED IN CHILDHOOD AND PERSISTS INTO ADULTHOOD IF UNTREATED. THE BACTERIUM INDUCES A CHRONIC INFLAMMATORY RESPONSE, WHICH IS ASSOCIATED WITH EPIGENETIC ALTERATIONS IN ONCOGENES, TUMOR-SUPPRESSOR GENES, CELL-CYCLE REGULATORS, AND CELL-ADHESION MOLECULES. AIM: THE AIM OF THIS STUDY WAS TO ANALYZE THE EFFECT OF H. PYLORI INFECTION ON THE METHYLATION STATUS OF THROMBOSPONDIN-1 (THBS1), HYPERMETHYLATED IN CANCER 1 (HIC1) AND GATA BINDING PROTEIN-4 (GATA-4) IN GASTRIC BIOPSY SAMPLES FROM CHILDREN AND ADULTS INFECTED OR UNINFECTED WITH THE BACTERIUM AND IN SAMPLES OBTAINED FROM GASTRIC CANCER PATIENTS. METHODS: THE METHYLATION PATTERN WAS ANALYZED WITH METHYLATION-SPECIFIC PCR. RESULTS: OUR RESULTS SHOWED THAT H. PYLORI INFECTION WAS ASSOCIATED WITH METHYLATION OF THE PROMOTER REGIONS OF THE THBS1 AND GATA-4 GENES IN PEDIATRIC AND ADULT SAMPLES (P < 0.01). HIC1 SHOWED THE LOWEST LEVEL OF METHYLATION, WHICH WAS NOT AN EARLY EVENT DURING GASTRIC CARCINOGENESIS. CONCLUSIONS: THE RESULTS FROM THIS STUDY INDICATE THAT METHYLATION OF THBS1 AND GATA-4 OCCURS IN THE EARLY STAGES OF CHRONIC GASTRITIS AND GASTRIC CANCER IN ASSOCIATION WITH H. PYLORI INFECTION; HOWEVER, IN GASTRIC CANCER SAMPLES, OTHER MECHANISMS COOPERATE WITH THE DOWN-REGULATION OF THESE GENES. METHYLATION OF HIC1 MAY NOT BE THE PRINCIPAL MECHANISM IMPLICATED IN ITS DOWN-REGULATION IN GASTRIC CANCER SAMPLES.	2013