1 3222 112 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 2 3230 42 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 3 762 44 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 4 2895 38 GASTRIC CANCER DEVELOPMENT AFTER THE SUCCESSFUL ERADICATION OF HELICOBACTER PYLORI. GASTRIC CANCER (GC) DEVELOPS AS A RESULT OF INFLAMMATION-ASSOCIATED CARCINOGENESIS DUE TO HELICOBACTER PYLORI (H. PYLORI) INFECTION AND SUBSEQUENT DEFECTS IN GENETIC/EPIGENETIC EVENTS. ALTHOUGH THE INDICATION FOR ERADICATION THERAPY HAS BECOME WIDESPREAD, CLINICAL STUDIES HAVE REVEALED ITS LIMITED EFFECTS IN DECREASING THE INCIDENCE OF GC. MOREOVER, RESEARCH ON BIOPSY SPECIMENS OBTAINED BY CONVENTIONAL ENDOSCOPY HAS DEMONSTRATED THE FEASIBILITY OF THE RESTORATION OF SOME GENETIC/EPIGENETIC ALTERATIONS IN THE GASTRIC MUCOSA. PRACTICALLY, THE NUMBER OF SPORADIC CASES OF PRIMARY/METACHRONOUS GC THAT EMERGE AFTER SUCCESSFUL ERADICATION HAS INCREASED, WHILE ON-GOING GUIDELINES RECOMMEND ERADICATION THERAPY FOR PATIENTS WITH CHRONIC GASTRITIS AND THOSE WITH BACKGROUND MUCOSA AFTER ENDOSCOPIC RESECTION FOR GC. ACCORDINGLY, REGULAR SURVEILLANCE OF NUMEROUS INDIVIDUALS WHO HAVE RECEIVED ERADICATION THERAPY IS RECOMMENDED DESPITE THE LACK OF BIOMARKERS. RECENTLY, THE FOCUS HAS BEEN ON FUNCTIONAL REVERSIBILITY AFTER SUCCESSFUL ERADICATION AS ANOTHER CUE TO ELUCIDATE THE MECHANISMS OF RESTORATION AS WELL AS THOSE OF CARCINOGENESIS IN THE GASTRIC MUCOSA AFTER H. PYLORI ERADICATION. WE DEMONSTRATED THAT CONGO-RED CHROMOENDOSCOPY ENABLED THE IDENTIFICATION OF THE MULTI-FOCAL DISTRIBUTION OF FUNCTIONALLY IRREVERSIBLE MUCOSA COMPARED WITH THAT OF RESTORED MUCOSA AFTER SUCCESSFUL ERADICATION IN INDIVIDUALS AT EXTREMELY HIGH RISK FOR GC. FURTHER RESEARCH THAT USES FUNCTIONAL IMAGING MAY PROVIDE NEW INSIGHTS INTO THE MECHANISMS OF REGENERATION AND CARCINOGENESIS IN THE GASTRIC MUCOSA POST-ERADICATION AND MAY ALLOW FOR THE DEVELOPMENT OF USEFUL BIOMARKERS. 2016 5 4725 31 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 6 5180 30 PREMALIGNANT CONDITIONS OF GASTRIC CANCER. PREMALIGNANT LESIONS OF GASTRIC CANCER ENCOMPASS A VARIETY OF CONDITIONS SUCH AS CHRONIC GASTRITIS, INTESTINAL METAPLASIA AND DYSPLASIA, IN WHICH ELEVATED RISK OF DEVELOPING GASTRIC CANCER HAVE BEEN DOCUMENTED. AMONG THEM, INTESTINAL METAPLASIA IS FREQUENTLY ENCOUNTERED IN OUR DAILY ENDOSCOPIC EXAMINATION, YET ITS CLINICAL SIGNIFICANCE IS OFTEN UNDERESTIMATED DESPITE OF A NUMBER OF REPORTS DEMONSTRATING GENETIC AND EPIGENETIC ALTERATIONS IN THE INTESTINAL METAPLASTIC MUCOSA. IN THIS REVIEW, I WILL DESCRIBE THE MOLECULAR MECHANISMS OF PHENOTYPIC CHANGES FROM GASTRIC MUCOSA TO INTESTINAL METAPLASIA BASED ON OUR ANALYSIS OF MOUSE MODEL OF INTESTINAL METAPLASIA GENERATED BY ECTOPIC EXPRESSION OF CDX2 IN CONJUNCTION WITH THE STUDIES WITH HUMAN INTESTINAL METAPLASIA. 2013 7 4960 44 PATHOGENESIS OF PRE-NEOPLASTIC LESIONS OF THE STOMACH: TARGETS FOR PREVENTION. GASTRIC ATROPHY AND INTESTINAL METAPLASIA ARE GENERALLY CONSIDERED TO BE PRECANCEROUS LESIONS OF THE STOMACH. CHRONIC HELICOBACTER PYLORI INFECTION IS ONE THE MOST IMPORTANT FACTORS IN THE DEVELOPMENT OF THESE PRE-MALIGNANT GASTRIC LESIONS. IN ADDITION TO BACTERIAL FACTORS, POLYMORPHISMS IN THE CYTOKINE GENES OF THE HOST THAT MODULATE INFLAMMATORY RESPONSES ARE FOUND TO HAVE A SYNERGISTIC EFFECT IN THE DEVELOPMENT OF GASTRIC CANCER AS WELL AS PRE-NEOPLASTIC LESIONS. RECENTLY, INAPPROPRIATE ACTIVATION OF THE INTESTINE-SPECIFIC TRANSCRIPTION FACTOR LIKE THE HOMEOBOX GENE COMPLEX CDX1 AND CDX2 ARE FOUND TO BE AN IMPORTANT CONTRIBUTING FACTOR IN THE INDUCTION OF INTESTINAL METAPLASIA IN THE STOMACH. ABERRANT EXPRESSION OF CYCLOOXYGENASE-2 AND EPIGENETIC CHANGES ARE ALSO FREQUENTLY DETECTED IN PRE-NEOPLASTIC GASTRIC LESIONS. ONE OF THE MOST IMPORTANT QUESTIONS RELATING TO THESE PRE-NEOPLASTIC GASTRIC LESIONS IS THAT WHETHER H. PYLORI ERADICATION COULD REVERSE THESE CHANGES. HOWEVER, MOST CONTROLLED STUDIES SHOWED NO OR JUST MODEST IMPROVEMENT IN INTESTINAL METAPLASIA AFTER H. PYLORI ERADICATION. FURTHER STUDIES SHOULD EVALUATE THE ROLE OF OTHER CHEMOPREVENTIVE AGENTS, PARTICULARLY CYCLOOXYGENASE-2 INHIBITOR, ON REGRESSION OF PRE-NEOPLASTIC LESIONS. 2004 8 4994 31 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 9 4114 35 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 10 6841 39 [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 11 3219 46 HELICOBACTER PYLORI AND GASTRIC CANCER. INFECTION WITH HELICOBACTER PYLORI IS ESTABLISHED AS THE MAJOR RISK FACTOR FOR GASTRIC CANCER DEVELOPMENT. DAMAGE OF THE MUCOSAL BARRIER DUE TO H. PYLORI-INDUCED INFLAMMATION ENHANCES THE CARCINOGENIC EFFECT OF OTHER RISK FACTORS SUCH AS SALT INTAKE OR TOBACCO SMOKING. THE GENETIC DISPOSITION OF BOTH THE BACTERIAL STRAIN AND THE HOST CAN INCREASE THE POTENTIAL TOWARDS GASTRIC CANCER FORMATION. GENETIC VARIANCE OF THE BACTERIAL PROTEINS CAGA AND VACA IS ASSOCIATED WITH A HIGHER GASTRIC CANCER RISK, AS ARE POLYMORPHISMS AND EPIGENETIC CHANGES IN HOST GENE CODING FOR INTERLEUKINS (IL1BETA, IL8), TRANSCRIPTION FACTORS (CDX2, RUNX3) AND DNA REPAIR ENZYMES. APPLICATION OF HIGH-THROUGHPUT ASSAYS FOR GENOME-WIDE ASSESSMENT OF EITHER GENETIC STRUCTURAL VARIANCE OR GENE EXPRESSION PATTERNS MAY LEAD TO A BETTER UNDERSTANDING OF THE PATHOBIOLOGICAL BACKGROUND OF THESE PROCESSES, INCLUDING THE UNDERLYING SIGNALING PATHWAYS. UNDERSTANDING OF THE STEPWISE ALTERATIONS THAT TAKE PLACE IN THE TRANSITION FROM CHRONIC ATROPHIC GASTRITIS, VIA METAPLASTIC CHANGES, TO INVASIVE NEOPLASIA IS VITAL TO DEFINE THE 'POINT OF NO RETURN' BEFORE WHICH ERADICATION OF H. PYLORI HAS THE POTENTIAL TO PREVENT GASTRIC CANCER. CURRENTLY, ERADICATION AS PREVENTIVE STRATEGY IS ONLY RECOMMENDED FOR HIGH-INCIDENCE REGIONS IN ASIA; LARGE POPULATION STUDIES WITH AN ADEQUATE FOLLOW-UP ARE REQUIRED TO DEMONSTRATE THE EFFECTIVENESS OF SUCH AN APPROACH IN WESTERN POPULATIONS. 2014 12 4751 45 NOVEL RISK MARKERS FOR GASTRIC CANCER SCREENING: PRESENT STATUS AND FUTURE PROSPECTS. INITIAL IDENTIFICATION OF POPULATIONS AT HIGH RISK OF GASTRIC CANCER (GC) IS IMPORTANT FOR ENDOSCOPIC SCREENING OF GC. AS SERUM PEPSINOGEN (PG) TEST-POSITIVE SUBJECTS WITH PROGRESSION OF CHRONIC ATROPHIC GASTRITIS (CAG) SHOW A HIGH LIKELIHOOD OF FUTURE CANCER DEVELOPMENT, THIS POPULATION WARRANTS CAREFUL FOLLOW-UP OBSERVATION AS A HIGH-RISK GC GROUP. BY COMBINING THE PG TEST WITH HELICOBACTER PYLORI (HP) ANTIBODY TITERS, THE HP-RELATED CHRONIC GASTRITIS STAGE CAN BE CLASSIFIED, THUS IDENTIFYING NOT ONLY A GC HIGH-RISK GROUP BUT ALSO A LOW-RISK GROUP. AMONG PG TEST-NEGATIVE PATIENTS WITHOUT CAG, THOSE WITH HIGH SERUM PG II LEVELS AND HP ANTIBODY TITERS ARE THOUGHT TO HAVE SEVERE GASTRIC MUCOSAL INFLAMMATION AND THE RISK OF DIFFUSE-TYPE GC IS ALSO HIGH. MEANWHILE, IN GASTRIC MUCOSAE OBTAINED BY ENDOSCOPIC BIOPSY, HP INFECTION INDUCES ABERRANT DNA METHYLATION IN CPG ISLANDS IN MULTIPLE GENE REGIONS AND THE EXTENT OF METHYLATION CLEARLY CORRELATES WITH GC RISK. BY QUANTIFYING ABERRANT DNA METHYLATION IN SUITABLE GENE MARKERS, WE CAN DETERMINE THE EXTENT OF THE EPIGENETIC FIELD FOR CANCERIZATION. THESE NOVEL CONCEPTS AND RISK MARKERS WILL HAVE MANY CLINICAL APPLICATIONS IN GASTROINTESTINAL ENDOSCOPY, INCLUDING MORE EFFICIENT ENDOSCOPIC GC SCREENING AND A STRATEGIC APPROACH TO METACHRONOUS MULTIPLE GCS AFTER ENDOSCOPIC TREATMENT. 2010 13 2852 44 FROM GASTRIC INFLAMMATION TO GASTRIC CANCER. THE MAJORITY OF GASTRIC ADENOCARCINOMAS ARE RELATED TO CHRONIC INFLAMMATION INDUCED BY HELICOBACTER PYLORI INFECTION. FOR INTESTINAL-TYPE GASTRIC CANCER, A MULTISTEP PROCESS OF MUCOSAL ALTERATIONS LEADING FROM GASTRITIS VIA GLANDULAR ATROPHY, INTESTINAL METAPLASIA AND DYSPLASIA TO INVASIVE CARCINOMA IS WELL RECOGNIZED. ONGOING CLINICAL STUDIES FOCUS ON A 'POINT OF NO RETURN'. IT IS DEFINED AS A SITUATION WHEN CERTAIN ALTERATIONS ARE NO LONGER REVERSIBLE BY H. PYLORI ERADICATION AND PROGRESSION TO GASTRIC CANCER MAY CONTINUE. H. PYLORI AFFECTS THE MUCOSAL AS WELL AS THE SYSTEMIC IMMUNE RESPONSE BY SECRETION OF CYTOKINES AND THE RECRUITMENT OF DISTINCT INFLAMMATORY CELLS. THE IMMUNE RESPONSE IS CHARACTERIZED BY A BALANCE BETWEEN A TH1-DOMINATED RESPONSE AND THE RECRUITMENT OF ANTIGEN-SPECIFIC REGULATORY T CELLS THAT ALLOW THE BACTERIA TO PERSIST IN HUMAN GASTRIC MUCOSA. BESIDES IMMUNE-MEDIATED EFFECTS, H. PYLORI INDUCES CELLULAR ALTERATIONS AS WELL AS GENETIC ALTERATIONS IN GENES THAT ARE ESSENTIAL FOR THE EPIGENETIC INTEGRITY AND MUCOSAL HOMEOSTASIS. THESE GENETIC ALTERATIONS DURING GASTRIC CANCER DEVELOPMENT ARE IN FOCUS OF INTENSIVE RESEARCH AND SHOULD ULTIMATELY ALLOW THE IDENTIFICATION OF RISK FACTORS INVOLVED IN GASTRIC CARCINOGENESIS. THE DETECTION OF INDIVIDUALS AT HIGH RISK FOR GASTRIC CANCER WOULD HELP TO DESIGN APPROPRIATE STRATEGIES FOR PREVENTION AND SURVEILLANCE. 2010 14 3229 32 HELICOBACTER PYLORI-INDUCED GASTRIC INFLAMMATION AND GASTRIC CANCER. HELICOBACTER PYLORI (H. PYLORI) INFECT OVER HALF OF THE WORLD'S POPULATION. THE PREVALENCE OF H. PYLORI INFECTION AND THE PREDOMINANT GENOTYPE OF H. PYLORI VIRULENCE FACTORS VARY CONSIDERABLY ACROSS DIFFERENT GEOGRAPHICAL REGIONS. H. PYLORI COULD UNIQUELY PERSIST FOR DECADES IN THE HARSH STOMACH ENVIRONMENT, WHERE IT DAMAGES THE GASTRIC MUCOSA AND CHANGES THE PATTERN OF GASTRIC HORMONE RELEASE, THEREBY AFFECTS GASTRIC PHYSIOLOGY. BY UTILIZING VARIOUS VIRULENCE FACTORS, H. PYLORI TARGETS DIFFERENT CELLULAR PROTEINS TO MODULATE THE HOST INFLAMMATORY RESPONSE AND INITIATE MULTIPLE "HITS" ON THE GASTRIC MUCOSA, RESULTING IN CHRONIC GASTRITIS AND PEPTIC ULCERATION. AMONG THE LONG-TERM CONSEQUENCES OF H. PYLORI INFECTION IS GASTRIC MALIGNANCIES, PARTICULARLY GASTRIC CANCER (GC) AND GASTRIC MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT) LYMPHOMA. AS SUCH, H. PYLORI HAS BEEN RECOGNIZED AS A CLASS I CARCINOGEN BY THE INTERNATIONAL AGENCY FOR RESEARCH ON CANCER. DESPITE A CLOSE CAUSAL LINK BETWEEN H. PYLORI INFECTION AND THE DEVELOPMENT OF GASTRIC MALIGNANCIES, THE PRECISE MECHANISMS INVOLVED IN THIS PROCESS ARE STILL OBSCURE. STUDIES OVER THE PAST TWO DECADES HAVE REVEALED THAT H. PYLORI EXERT ONCOGENIC EFFECTS ON GASTRIC MUCOSA THROUGH A COMPLEX INTERACTION BETWEEN BACTERIAL FACTORS, HOST FACTORS, AND ENVIRONMENTAL FACTORS. NUMEROUS SIGNALING PATHWAYS CAN BE ACTIVATED BY H. PYLORI. IN THIS REVIEW, WE AIM TO ELABORATE ON THE RECENT DEVELOPMENTS IN THE PATHOPHYSIOLOGICAL MECHANISMS OF H. PYLORI-INDUCED GASTRIC INFLAMMATION AND GASTRIC CANCER. 2014 15 1540 35 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 16 1799 35 EFFECT OF HELICOBACTER PYLORI INFECTION ON THE COMPOSITION OF GASTRIC MICROBIOTA IN THE DEVELOPMENT OF GASTRIC CANCER. BACKGROUND: GASTRIC CANCER IS ONE OF THE MOST COMMON CANCER TYPES WORLDWIDE. IN CHINA, GASTRIC CANCER HAS BECOME ONE OF THE MAJOR THREATS FOR PUBLIC HEALTH, RANKING SECOND ON INCIDENCE AND THIRD ON CAUSE OF CANCER DEATH. DESPITE THE COMMON RISK FACTORS THAT PROMOTE THE DEVELOPMENT OF GASTRIC CANCER, THE HUGE QUANTITY OF MICROORGANISM COLONIES WITHIN THE GASTROINTESTINAL TRACT, PARTICULARLY HELICOBACTER PYLORI INFECTION, DEMONSTRATES A CORRELATION WITH CHRONIC INFLAMMATION AND GASTRIC CARCINOGENESIS, AS EPIDEMIOLOGICAL STUDIES HAVE DETERMINED THAT H. PYLORI INFECTION CONFERS APPROXIMATELY 75% OF THE ATTRIBUTABLE RISK FOR GASTRIC CANCER. SUMMARY: THE CURRENT ARTICLE DRAWS AN OVERVIEW ON THE CORRELATION BETWEEN THE MICROBIOTA, INFLAMMATION AND GASTRIC TUMORIGENESIS. H. PYLORI INFECTION HAS BEEN IDENTIFIED AS THE MAIN RISK FACTOR AS IT TRIGGERS EPITHELIAL BARRIER DISRUPTION, SURVIVAL SIGNALING AS WELL AS GENETIC/EPIGENETIC MODULATION. APART FROM H. PYLORI, THE EXISTENCE OF A DIVERSE AND COMPLEX COMPOSITION OF MICROBIOTA IN THE STOMACH HAS BEEN IDENTIFIED, WHICH SUPPORTS A ROLE OF MICROBIOTA IN THE DEVELOPMENT OF GASTRIC CANCER. MOREOVER, METAGENOMICS STUDIES FOCUSED ON THE COMPOSITION AND FUNCTION OF THE MICROBIOTA HAVE ASSOCIATED MICROBIOTA WITH GASTRIC METABOLIC DISEASES AND EVEN TUMORIGENESIS. APART FROM THE GASTRIC MICROBIOTA, INFLAMMATION IS ANOTHER IDENTIFIED CONTRIBUTOR TO CANCER DEVELOPMENT AS WELL. KEY MESSAGE: THOUGH H. PYLORI INFECTION AND THE NON-H. PYLORI MICROBIOTA PLAY A ROLE IN GASTRIC CANCER, THE PROPERTIES OF GASTRIC MICROBIOTA AND MECHANISMS BY WHICH THEY PARTICIPATE IN THE GENESIS OF GASTRIC CANCER ARE STILL NOT CLEARLY DEPICTED. MOREOVER, IT REMAINS TO BE UNDERSTOOD HOW THE PRESENCE OF MICROBIOTA ALONG WITH H. PYLORI INFECTION AFFECTS THE PROGRESS FROM GASTRIC DISEASE TO CANCER. PRACTICAL IMPLICATIONS: THIS ARTICLE SUMMARIZED A CLUE OF THE CURRENT STUDIES ON MICROBIOTA, H. PYLORI INFECTION AND THE PROGRESSION FROM GASTRIC DISEASE TO CANCER. 2015 17 5181 38 PREMALIGNANT LESIONS IN GASTRIC CANCER. DESPITE A PLATEAU IN INCIDENCE, GASTRIC CANCER IS ONE OF THE MOST COMMON CANCERS WORLDWIDE AND CAUSES CONSIDERABLE MORBIDITY AND MORTALITY. PREMALIGNANT GASTRIC LESIONS ARE WELL KNOWN RISK FACTORS FOR THE DEVELOPMENT OF INTESTINAL-TYPE GASTRIC ADENOCARCINOMAS. IN THIS MULTISTEP MODEL OF GASTRIC CARCINOGENESIS, HELICOBACTER PYLORI CAUSES CHRONIC ACTIVE INFLAMMATION OF THE GASTRIC MUCOSA, WHICH SLOWLY PROGRESSES THROUGH THE PREMALIGNANT STAGES OF ATROPHIC GASTRITIS, INTESTINAL METAPLASIA, AND ADENOMA/DYSPLASIA TO GASTRIC CARCINOMA. THIS PROGRESSION IS PARALLELED BY A STEPWISE ACCUMULATION OF MULTIPLE GENETIC AND EPIGENETIC ABNORMALITIES. DETECTION, TREATMENT, AND MOLECULAR ANALYSES OF PREMALIGNANT LESIONS MAY THUS PROVIDE A BASIS FOR GASTRIC CANCER PREVENTION. THIS REVIEW DESCRIBES AN OVERVIEW OF CURRENT KNOWLEDGE ON PREMALIGNANT GASTRIC LESIONS. IT ALSO REVIEWS THE ISSUE OF SURVEILLANCE OF PATIENTS WITH PREMALIGNANT LESIONS IN ORDER TO IMPROVE THE SURVIVAL OF PATIENTS WITH GASTRIC CANCER. 2010 18 3221 29 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 19 3232 30 HELICOBACTER PYLORI-INDUCED SIGNALING PATHWAYS CONTRIBUTE TO INTESTINAL METAPLASIA AND GASTRIC CARCINOGENESIS. HELICOBACTER PYLORI (H. PYLORI) INDUCES CHRONIC GASTRIC INFLAMMATION, ATROPHIC GASTRITIS, INTESTINAL METAPLASIA, AND CANCER. ALTHOUGH THE RISK OF GASTRIC CANCER INCREASES EXPONENTIALLY WITH THE EXTENT OF ATROPHIC GASTRITIS, THE PRECISE MECHANISMS OF GASTRIC CARCINOGENESIS HAVE NOT BEEN FULLY ELUCIDATED. H. PYLORI INDUCES GENETIC AND EPIGENETIC CHANGES IN GASTRIC EPITHELIAL CELLS THROUGH ACTIVATING INTRACELLULAR SIGNALING PATHWAYS IN A CAGPAI-DEPENDENT MANNER. H. PYLORI EVENTUALLY INDUCES GASTRIC CANCER WITH CHROMOSOMAL INSTABILITY (CIN) OR MICROSATELLITE INSTABILITY (MSI), WHICH ARE CLASSIFIED AS TWO MAJOR SUBTYPES OF GASTRIC CANCER. ELUCIDATION OF THE PRECISE MECHANISMS OF GASTRIC CARCINOGENESIS WILL ALSO BE IMPORTANT FOR CANCER THERAPY. 2015 20 3849 39 IS ERADICATION OF HELICOBACTER PYLORI THE FEASIBLE WAY TO PREVENT GASTRIC CANCER? NEW EVIDENCE AND PROGRESS, BUT STILL A LONG WAY TO GO. EPIDEMIOLOGICAL, ANIMAL AND BIOLOGICAL STUDIES PROVIDE COMPELLING EVIDENCE FOR THE ROLE OF HELICOBACTER PYLORI INFECTION IN GASTRIC CARCINOGENESIS. THE FINDING THAT H. PYLORI-INDUCED CHRONIC ATROPHIC GASTRITIS IS THE MAJOR CAUSE OF GASTRIC CANCER SUGGESTS THAT ERADICATION OF THE BACTERIUM MAY PREVENT THIS MALIGNANCY. COMPUTER-SIMULATION STUDIES HAVE CONFIRMED THE COST-EFFECTIVENESS OF ERADICATION IN HIGH-RISK SUBJECTS; HOWEVER, UNRESOLVED ISSUES COMPLICATE ACTIVE TESTING FOR AND TREATMENT OF H. PYLORI INFECTION AMONG ASYMPTOMATIC CARRIERS. CONCERNS INCLUDE THE ENORMOUS COSTS FOR DEVELOPING COUNTRIES TO IMPLEMENT STRATEGIES, THE INCONCLUSIVENESS OF DATA FROM RANDOMIZED CONTROLLED STUDIES, THE POTENTIAL INDUCTION OF ANTIMICROBIAL RESISTANCE, AND THE UNCERTAIN EFFECT OF ELIMINATING THIS ORGANISM ON THE SPECTRUM OF MODERN DISEASE. ALTHOUGH CURRENT EVIDENCE IS INSUFFICIENT TO RECOMMEND UNIVERSAL TESTING AND TREATMENT, IT IS POSSIBLE TO IDENTIFY HIGHLY SUSCEPTIBLE INDIVIDUALS WHO ARE MOST LIKELY TO BENEFIT FROM TREATMENT. NOVEL BIOMARKERS FOR PREDICTING RISK ARE UNDER EXTENSIVE INVESTIGATION, INCLUDING GENETIC, EPIGENETIC AND PROTEINOMIC FACTORS. THE EMERGING EVIDENCE SUGGESTS THAT TREATMENT OF H. PYLORI INFECTION IN ASYMPTOMATIC CARRIERS MAY DECREASE THE BURDEN OF GASTRIC CANCER. HOWEVER, CONFIRMATION OF LONG-TERM BENEFITS REMAINS A LONG WAY OFF. 2008