1 2894 133 GASTRIC CANCER AS A STEM-CELL DISEASE: DATA AND HYPOTHESES. THE MAIN FUNCTION OF GASTRIC STEM CELLS IS TO MAINTAIN THE INTEGRITY OF THE GASTROINTESTINAL EPITHELIUM AND REPLENISH ALL THE MATURE CELL LINEAGES. IN ORDER TO ACCOMPLISH THIS, GASTRIC STEM CELLS PROLIFERATE AND SELF-RENEW, GIVING RISE TO TRANSIENT AMPLIFYING CELLS WHICH REPLACE THE CONSTANTLY RENEWING EPITHELIUM, ESPECIALLY AFTER INJURY INDUCED BY LONG-TERM INFLAMMATION. GASTRIC CANCER (GC) REMAINS THE FOURTH MOST COMMON CANCER AND THE SECOND LEADING CAUSE OF DEATH FOR CANCER IN THE WORLD. THE MOST ACCEPTED MODEL OF GASTRIC CARCINOGENESIS PROVIDES A MULTIFACTORIAL AND MULTISTEP PATHOGENESIS, INVOLVING A NUMBER OF INITIATORS AND OTHER CONTINUATOR AGENTS. HELICOBACTER PYLORI INFECTION IS RECOGNIZED AS A NECESSARY BUT INSUFFICIENT CAUSE OF GC. RECENT ADVANCES IN GASTRIC STEM CELL BIOLOGY POINT OUT TO TWO HYPOTHESES. IN THE FIRST, IT IS POSTULATED THAT RESIDENT STEM CELLS MAY, IN A CHRONICALLY INFLAMED ENVIRONMENT, AS IN THE CASE OF HELICOBACTER PYLORI-INDUCED GASTRITIS, ACCUMULATE OVER TIME A SERIES OF GENETIC AND EPIGENETIC CHANGES THAT LEAD TO THE EMERGENCE OF GC STEM CELLS. ALTERNATIVELY, THE SETTING OF CHRONIC INFLAMMATORY STRESS MAY LEAD TO LOSS OF THE INDIGENOUS GASTRIC STEM CELLS FROM THEIR NICHES, FOLLOWED BY RECRUITMENT AND ENGRAFTMENT OF BONE MARROW DERIVED STEM CELLS (BMDCS) INTO THE GASTRIC EPITHELIUM. IN THE MOUSE MODEL, INCREASING EVIDENCE SUPPORTS THE HYPOTHESIS THAT BMDCS ARE IMPORTANT CELLULAR SOURCE OF HELICOBACTER-INDUCED GC. THIS REVIEW HIGHLIGHTS DATA AND HYPOTHESES ABOUT GC AS A MODEL OF STEM-CELL DISEASE. 2014 2 3224 43 HELICOBACTER PYLORI INFECTION AND STEM CELLS AT THE ORIGIN OF GASTRIC CANCER. HELICOBACTER PYLORI INFECTION IS NOW RECOGNIZED AS THE MAIN AND SPECIFIC INFECTIOUS CAUSE OF CANCER IN THE WORLD. IT IS RESPONSIBLE FOR GASTRIC ADENOCARCINOMAS OF BOTH INTESTINAL AND DIFFUSE TYPES, WHICH ARE THE LONG-TERM CONSEQUENCES OF THE CHRONIC INFECTION OF THE GASTRIC MUCOSA. CASE-CONTROL STUDIES HAVE SHOWN AN ASSOCIATION BETWEEN THE TWO, RECOGNIZED AS EARLY AS 1994 AND FURTHER SUBSTANTIATED BY INTERVENTIONAL STUDIES IN WHICH H. PYLORI ERADICATION HAS LED TO THE PREVENTION OF AT LEAST PART OF THE GASTRIC CANCERS. EXPERIMENTAL STUDIES HAVE HIGHLIGHTED THE ROLE OF BONE MARROW-DERIVED CELLS (BMDCS) AND PARTICULARLY MESENCHYMAL STEM CELLS, IN THE NEOPLASTIC PROCESS IN ABOUT A QUARTER OF THE CASES AND POSSIBLY AN EPITHELIAL-MESENCHYMAL TRANSITION (EMT) IN THE OTHER CASES. DIFFERENT STUDIES HAVE CONFIRMED THAT CHRONIC INFECTION WITH H. PYLORI INDUCES A CHRONIC INFLAMMATION AND SUBSEQUENT DAMAGE OF THE GASTRIC EPITHELIAL MUCOSA, LEADING TO BMDC RECRUITMENT. ONCE RECRUITED, THESE CELLS HOME AND DIFFERENTIATE BY CELL-CELL FUSION WITH LOCAL GASTRIC EPITHELIAL CELLS, BEARING LOCAL STEM CELL FAILURE AND PARTICIPATING IN TISSUE REGENERATION. THE CONTEXT OF CHRONIC INFECTION AND INFLAMMATION LEADS TO AN EMT AND ALTERED TISSUE REGENERATION AND DIFFERENTIATION FROM BOTH LOCAL EPITHELIAL STEM CELLS AND BMDC. EMT INDUCES THE EMERGENCE OF CD44+ CELLS POSSESSING MESENCHYMAL AND STEM CELL PROPERTIES, RESULTING IN METAPLASTIC AND DYSPLASTIC LESIONS TO GIVE RISE, AFTER ADDITIONAL EPIGENETIC AND MUTATIONAL EVENTS, TO THE EMERGENCE OF CANCER STEM CELLS (CSCS) AND ADENOCARCINOMA. 2015 3 6273 33 THE ORIGINS OF GASTRIC CANCER FROM GASTRIC STEM CELLS: LESSONS FROM MOUSE MODELS. THE CELLULAR ORIGIN OF DIGESTIVE CANCERS HAS BEEN A LONG-STANDING QUESTION IN THE CANCER FIELD. MOUSE MODELS HAVE IDENTIFIED LONG-LIVED STEM CELLS IN MOST ORGAN SYSTEMS, INCLUDING THE LUMINAL GASTROINTESTINAL TRACT, AND NUMEROUS STUDIES HAVE POINTED TO TISSUE RESIDENT STEM CELLS AS THE MAIN CELLULAR ORIGIN OF CANCER. DURING GASTRIC CARCINOGENESIS, CHRONIC INFLAMMATION INDUCES GENETIC AND EPIGENETIC ALTERATIONS IN LONG-LIVED STEM CELLS, ALONG WITH EXPANSION OF STEM CELL NICHES, EVENTUALLY LEADING TO INVASIVE CANCER. THE GASTRIC CORPUS AND ANTRUM HAVE DISTINCT STEM CELLS AND STEM CELL NICHES, SUGGESTING DIFFERENTIAL REGULATION OF CANCER INITIATION AT THE 2 SITES. IN THIS SHORT REVIEW, WE DISCUSS RECENT EXPERIMENTAL MODELS AND HUMAN STUDIES, WHICH PROVIDE IMPORTANT INSIGHTS INTO THE PATHOGENESIS OF GASTRIC CANCER. 2017 4 2852 36 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 5 6466 61 TISSUE STEM CELLS AND CANCER STEM CELLS: POTENTIAL IMPLICATIONS FOR GASTRIC CANCER. GASTRIC CANCER REMAINS THE SECOND LEADING CAUSE OF DEATH IN THE WORLD TODAY, MAKING THE SEARCH FOR ITS MOLECULAR AND CELLULAR BASIS AN IMPORTANT PRIORITY. THOUGH RECOGNITION OF THE TIGHT LINK BETWEEN INFLAMMATION AND TUMORIGENESIS IS CENTURIES OLD, ONLY RECENTLY ARE THE PIECES OF THE ETIOLOGICAL PUZZLE BEGINNING TO FALL TOGETHER. RECENT ADVANCES IN GASTRIC STEM CELL BIOLOGY APPEAR TO BE CENTRAL TO THIS SLOWLY RESOLVING PUZZLE. AT LEAST TWO TYPES OF STEM CELLS MAY BE IMPORTANT. RESIDENT ADULT OR TISSUE STEM CELLS MAY, IN A CHRONICALLY INFLAMED ENVIRONMENT, SLOWLY ACQUIRE A SERIES OF GENETIC AND EPIGENETIC CHANGES THAT LEAD TO THEIR EMERGENCE AS ''CANCER STEM CELLS''. THIS SCENARIO HAS NOT YET BEEN PROVEN EXPERIMENTALLY, ALTHOUGH THE FIRST STEP, PROSPECTIVE RECOGNITION OF A GASTRIC STEM CELL HAS RECENTLY BEEN CONQUERED. ALTERNATIVELY, THE SETTING OF CHRONIC INFLAMMATORY STRESS AND INJURY MAY LEAD TO LOSS OF THE INDIGENOUS GASTRIC STEM CELLS FROM THEIR NICHES; BONE MARROW DERIVED STEM CELLS MAY THEN BE RECRUITED TO AND ENGRAFT INTO THE GASTRIC EPITHELIUM. SUCH RECRUITED CELLS HAVE THE POTENTIAL TO CONTRIBUTE TO THE TUMOR MASS. INDEED, EVIDENCE SUPPORTING THIS SCENARIO HAS BEEN PUBLISHED. HERE, WE REVIEW THESE RECENT FINDINGS AND DISCUSS IMPLICATIONS FOR THE FUTURE. 2008 6 762 30 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 7 3220 41 HELICOBACTER PYLORI AND MICRORNAS: RELATION WITH INNATE IMMUNITY AND PROGRESSION OF PRENEOPLASTIC CONDITIONS. THE ACCEPTED PARADIGM FOR INTESTINAL-TYPE GASTRIC CANCER PATHOGENESIS IS A MULTISTEP PROGRESSION FROM CHRONIC GASTRITIS INDUCED BY HELICOBACTER PYLORI (H. PYLORI) TO GASTRIC ATROPHY, INTESTINAL METAPLASIA, DYSPLASIA AND ULTIMATELY GASTRIC CANCER. THE GENETIC AND MOLECULAR MECHANISMS UNDERLYING DISEASE PROGRESSION ARE STILL NOT COMPLETELY UNDERSTOOD AS ONLY A FRACTION OF COLONIZED INDIVIDUALS EVER DEVELOP NEOPLASIA SUGGESTING THAT BACTERIAL, HOST AND ENVIRONMENTAL FACTORS ARE INVOLVED. MICRORNAS ARE NONCODING RNAS THAT MAY INFLUENCE H. PYLORI-RELATED PATHOLOGY THROUGH THE REGULATION OF THE TRANSCRIPTION AND EXPRESSION OF VARIOUS GENES, PLAYING AN IMPORTANT ROLE IN INFLAMMATION, CELL PROLIFERATION, APOPTOSIS AND DIFFERENTIATION. INDEED, H. PYLORI HAVE BEEN SHOWN TO MODIFY MICRORNA EXPRESSION IN THE GASTRIC MUCOSA AND MICRORNAS ARE INVOLVED IN THE IMMUNE HOST RESPONSE TO THE BACTERIA AND IN THE REGULATION OF THE INFLAMMATORY RESPONSE. MICRORNAS HAVE A KEY ROLE IN THE REGULATION OF INFLAMMATORY PATHWAYS AND H. PYLORI MAY INFLUENCE INFLAMMATION-MEDIATED GASTRIC CARCINOGENESIS POSSIBLY THROUGH DNA METHYLATION AND EPIGENETIC SILENCING OF TUMOR SUPPRESSOR MICRORNAS. FURTHERMORE, MICRORNAS INFLUENCED BY H. PYLORI ALSO HAVE BEEN FOUND TO BE INVOLVED IN CELL CYCLE REGULATION, APOPTOSIS AND EPITHELIAL-MESENCHYMAL TRANSITION. ALTOGETHER, MICRORNAS SEEM TO HAVE AN IMPORTANT ROLE IN THE PROGRESSION FROM GASTRITIS TO PRENEOPLASTIC CONDITIONS AND NEOPLASTIC LESIONS AND SINCE EACH MICRORNA CAN CONTROL THE EXPRESSION OF HUNDREDS TO THOUSANDS OF GENES, KNOWLEDGE OF MICRORNAS TARGET GENES AND THEIR FUNCTIONS ARE OF PARAMOUNT IMPORTANCE. IN THIS ARTICLE WE PRESENT A COMPREHENSIVE REVIEW ABOUT THE ROLE OF MICRORNAS IN H. PYLORI GASTRIC CARCINOGENESIS, IDENTIFYING THE MICRORNAS DOWNREGULATED AND UPREGULATED IN THE INFECTION AND CLARIFYING THEIR BIOLOGICAL ROLE IN THE LINK BETWEEN IMMUNE HOST RESPONSE, INFLAMMATION, DNA METHYLATION AND GASTRIC CARCINOGENESIS. 2015 8 2853 30 FROM HELICOBACTER PYLORI INFECTION TO GASTRIC CANCER: CURRENT EVIDENCE ON THE IMMUNE RESPONSE. GASTRIC CANCER (GC) IS THE RESULT OF A MULTIFACTORIAL PROCESS WHOSE MAIN COMPONENTS ARE INFECTION BY HELICOBACTER PYLORI (H. PYLORI), BACTERIAL VIRULENCE FACTORS, HOST IMMUNE RESPONSE AND ENVIRONMENTAL FACTORS. THE DEVELOPMENT OF THE NEOPLASTIC MICROENVIRONMENT ALSO DEPENDS ON GENETIC AND EPIGENETIC CHANGES IN ONCOGENES AND TUMOR SUPPRESSOR GENES, WHICH RESULTS IN DEREGULATION OF CELL SIGNALING PATHWAYS AND APOPTOSIS PROCESS. THIS REVIEW SUMMARIZES THE MAIN ASPECTS OF THE PATHOGENESIS OF GC AND THE IMMUNE RESPONSE INVOLVED IN CHRONIC INFLAMMATION GENERATED BY H. PYLORI. 2022 9 1180 31 CONVERGENCE OF GENETIC, NUTRITIONAL AND INFLAMMATORY FACTORS IN GASTROINTESTINAL CANCERS. GASTROINTESTINAL CANCERS ACCOUNT FOR 20% OF ALL CANCER INCIDENCES WORLDWIDE. COLORECTAL CANCER IS THE SECOND MOST COMMON CAUSE OF ALL CANCER-RELATED MORTALITY AND IS INCREASING IN WESTERN SOCIETIES. INFECTION AND INFLAMMATION CONTRIBUTE TO 15-20% OF ALL MALIGNANCIES, AND ARE PREDISPOSING RISK FACTORS FOR GASTROINTESTINAL CANCERS. HELICOBACTER PYLORI INFECTION IS COMMONLY ASSOCIATED WITH GASTRIC CANCERS, AND CHRONIC INFLAMMATION INCREASES THE RISK OF COLORECTAL CANCER BY 1% PER YEAR. MICRONUTRIENT STATUS AND COMMON GENETIC VARIATIONS IN HUMAN POPULATIONS MODIFY RISK FOR GASTROINTESTINAL CANCER. CHRONIC INFLAMMATION PROMOTES CARCINOGENESIS BY INDUCING GENE MUTATIONS, INHIBITING APOPTOSIS, AND STIMULATING ANGIOGENESIS AND CELL PROLIFERATION. INFLAMMATION ALSO INDUCES EPIGENETIC ALTERATIONS THAT ARE ASSOCIATED WITH CANCER DEVELOPMENT. TWO KEY GENES IN THE INFLAMMATORY PROCESS, CYCLOOXYGENASE-2 (COX-2) AND NUCLEAR FACTOR-KAPPA B (NF-KAPPAB), PROVIDE A MECHANISTIC LINK BETWEEN INFLAMMATION AND CANCER AND ARE TARGETS FOR CHEMOPREVENTION. DIETARY COMPONENTS, AND HUMAN GENETIC VARIATION THAT AFFECTS NUTRIENT UTILIZATION, CAN DIRECTLY MODIFY INFLAMMATORY PROCESSES AND/OR SUPPRESS GENOMIC ALTERATIONS THAT ARE THE MOLECULAR ANTECEDENTS OF CANCERS. THE PRESENT REPORT FOCUSES ON THE CONVERGENCE OF GENETIC, NUTRITIONAL, AND INFLAMMATORY FACTORS IN THE INITIATION AND PROGRESSION OF GASTROINTESTINAL CANCERS, AND THE EMERGING DIETARY STRATEGIES FOR CANCER PREVENTION. 2007 10 1799 36 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 11 6841 35 [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 12 4994 27 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 13 2658 27 EPITHELIAL METAPLASIA: ADULT STEM CELL REPROGRAMMING AND (PRE)NEOPLASTIC TRANSFORMATION MEDIATED BY INFLAMMATION? THROUGHOUT ADULT LIFE, NEW DEVELOPMENTAL COMMITMENT OF ADULT STEM CELLS CAUSES METAPLASTIC CONVERSIONS TO OCCUR FREQUENTLY IN SOME ORGANS. THESE REVERSIBLE EPITHELIAL REPLACEMENTS ARE ALMOST ALWAYS OBSERVED IN ASSOCIATION WITH CHRONIC INFLAMMATION AND PERSISTENT IRRITATION. ALTHOUGH METAPLASIA IS NOT SYNONYMOUS WITH DYSPLASIA, CLINICAL SURVEILLANCE HAS DEMONSTRATED THAT THESE ADAPTIVE PROCESSES HAVE AN INCREASED SUSCEPTIBILITY TO EVOLVE INTO CANCER. WE PROPOSE THAT CYTOKINES AND OTHER SOLUBLE FACTORS RELEASED BY BOTH EPITHELIAL AND INFLAMMATORY CELLS MIGHT ALTER THE TRANSCRIPTION-FACTOR EXPRESSION PROFILE OF STEM CELLS AND LEAD TO THE DEVELOPMENT OF METAPLASIA. FURTHERMORE, INFLAMMATORY MEDIATORS MIGHT ALSO PROMOTE THE MALIGNANT TRANSFORMATION OF EPITHELIAL METAPLASIA BY INDUCING GENETIC AND EPIGENETIC CHANGES AND BY PREVENTING THE IMMUNE SYSTEM FROM MOUNTING AN EFFICIENT ANTI-TUMOUR IMMUNE RESPONSE. A BETTER UNDERSTANDING OF THE MOLECULAR MECHANISMS LEADING TO METAPLASIA MIGHT HELP IN THE DESIGN OF NEW THERAPIES FOR NEOPLASTIC AND DEGENERATIVE DISEASES. 2009 14 928 30 CHRONIC INFLAMMATION, THE TUMOR MICROENVIRONMENT AND CARCINOGENESIS. CHRONIC INFLAMMATION OFTEN PRECEDES OR ACCOMPANIES A SUBSTANTIAL NUMBER OF CANCERS. INDEED, ANTI-INFLAMMATORY THERAPIES HAVE SHOWN EFFICACY IN CANCER PREVENTION AND TREATMENT. THE EXACT MECHANISMS THAT TURN A WOUND HEALING PROCESS INTO A CANCER PRECURSOR ARE TOPICS OF INTENSE RESEARCH. A PATHOGENIC LINK HAS BEEN IDENTIFIED BETWEEN INFLAMMATORY MEDIATORS, INFLAMMATION RELATED GENE POLYMORPHISMS AND CARCINOGENESIS. ANIMAL MODELS OF CANCER HAVE BEEN INSTRUMENTAL IN DEMONSTRATING THE DIVERSITY OF MECHANISMS THROUGH WHICH EVERY TUMOR COMPARTMENT AND TUMOR STAGE MAY BE AFFECTED BY THE UNDERLYING INFLAMMATORY PROCESS. IN THIS REVIEW, WE FOCUS ON THE INTERACTION BETWEEN CHRONIC INFLAMMATION, TUMOR STEM CELLS AND THE TUMOR MICROENVIRONMENT. WE SUMMARIZE THE PROPOSED MECHANISMS THAT LEAD TO THE RECRUITMENT OF BONE MARROW DERIVED CELLS AND EXPLORE THE GENETIC AND EPIGENETIC ALTERATIONS THAT MAY OCCUR IN INFLAMMATION ASSOCIATED CANCERS. 2009 15 736 40 CANCER STEM CELLS--NEW APPROACH TO CANCEROGENENSIS AND TREATMENT. RECENTLY, THERE IS AN INCREASING EVIDENCE SUPPORTING THE THEORY OF CANCER STEM CELLS NOT ONLY IN LEUKEMIA BUT ALSO IN SOLID CANCER. TO DATE, THE EXISTENCE OF CANCER STEM CELLS HAS BEEN PROVEN IN ACUTE AND CHRONIC MYELOID LEUKEMIA, IN BREAST CANCER, IN BRAIN TUMORS, IN LUNG CANCER AND GASTROINTESTINAL TUMORS. THIS REVIEW IS FOCUSING ON THE RECENT DISCOVERY OF STEM CELLS IN LEUKEMIA, HUMAN BRAIN TUMORS AND BREAST CANCER. A SMALL POPULATION OF CELLS IN THE TUMOR (LESS THAN 1%) SHOWS THE POTENTIAL TO GIVE RISE TO THE TUMOR AND ITS GROWTH. THESE CELLS HAVE A SUBSTANTIAL CHARACTERISTIC OF STEM CELLS--ABILITY FOR SELF-RENEWAL WITHOUT LOSS OF PROLIFERATION CAPACITY WITH EACH CELL DIVISION. FURTHERMORE THEY ARE IMMORTAL, RATHER RESISTANT TO TREATMENT AND EXPRESS TYPICAL MARKERS OF STEM CELLS. THE ORIGIN OF THESE RESIDENT CANCER STEM CELLS IS NOT CLEAR. WHETHER THE CANCER STEM CELLS ORIGINATE FROM NORMAL STEM CELLS IN CONSEQUENCE OF GENETIC AND EPIGENETIC CHANGES AND/OR REDIFFERENTIATION FROM SOMATIC TUMOR CELLS TO THE STEM-LIKE CELLS REMAINS TO BE INVESTIGATED. WE PROPOSE THE IDEA OF THE RELATION BETWEEN NORMAL TISSUE STEM CELLS AND CANCER STEM CELLS AND THEIR POPULATIONS--PROGENITOR CELLS. BASED ON THIS WE HIGHLIGHT ONE OF THE MAJOR CHARACTERISTIC OF STEM CELL--PLASTICITY, WHICH IS EQUALLY IMPORTANT IN THE PHYSIOLOGICAL REGENERATION PROCESS AS WELL AS CARCINOGENESIS. FURTHERMORE, WE CONSIDER THE MICROENVIRONMENT AS A LIMITING FACTOR FOR TUMOR GENESIS IN AML, BREAST CANCER AND BRAIN TUMORS. THUS THE BIOLOGICAL PROPERTIES OF CANCER STEM CELLS ARE JUST BEGINNING TO BE REVEALED, THE CONTINUATION OF THESE STUDIES SHOULD LEAD TO THE DEVELOPMENT OF CANCER STEM CELLS TARGET THERAPIES FOR CANCER TREATMENT. 2008 16 4733 24 NOVEL BIOMARKERS FOR THE IDENTIFICATION AND TARGETED THERAPY OF GASTRIC CANCER. GASTRIC CANCER DEVELOPMENT FOLLOWS THE PATHOLOGIC PATTERN SUCH THAT CHRONIC INFLAMMATION IN THE GASTRIC MUCOSA PROGRESSIVELY TRANSFORMS NORMAL MUCOSA INTO ATROPHY, INTESTINAL METAPLASIA, ADENOMA/DYSPLASIA AND EVENTUALLY INVASIVE AND METASTATIC TUMORS. THE ACCUMULATION OF MULTIPLE GENETIC AND EPIGENETIC ALTERATIONS LEADS TO THE DYSREGULATION OF ONCOGENES AND TUMOR SUPPRESSORS, WHICH WAS CONSIDERED AS THE DRIVER BEHIND EVENTS DURING THE TUMORIGENESIS. ALMOST ALL GASTRIC CANCERS ARE ADENOCARCINOMAS, WHICH SHARE CONSIDERABLE HETEROGENEITY WITH DISTINCT MORPHOLOGY, PATHOGENESIS AND CLINICAL BEHAVIOR. THEREFORE, IDENTIFYING SUBTYPES OF GASTRIC CANCERS WITH MOLECULAR AND GENETIC FEATURES WILL BE BENEFICIAL FOR THE EARLY IDENTIFICATION AND SELECTION OF NEW EFFECTIVE AGENTS FOR TARGETED TREATMENT. HIGH-THROUGHPUT SEQUENCING TECHNIQUES SUCH AS WHOLE GENOMIC, EPIGENOME AND TRANSCRIPTOME SEQUENCING AND PROTEOMICS PLATFORMS HAVE IDENTIFIED MAJOR GENOMIC CHARACTERISTICS THAT EXHIBIT IDENTIFICATION AND PROGNOSTIC IMPACTS AND DISTINCT RESPONSE PATTERNS. IN THIS ARTICLE, THE AUTHORS AIM TO SUMMARIZE THE INFORMATION REGARDING THE MOST PROMISING MOLECULES THAT MAY HAVE CLINICAL APPLICATION AS NON-INVASIVE BIOMARKERS AND THERAPY TARGETS. 2015 17 3233 30 HELICOBACTER, INFLAMMATION, AND GASTRIC CANCER. HELICOBACTER PYLORI INFECTION LEADS TO LONG-LASTING CHRONIC INFLAMMATION AND REPRESENTS THE MOST COMMON RISK FACTOR UNDERLYING GASTRIC CANCER. RECENTLY, NEW INSIGHTS INTO THE MECHANISMS THROUGH WHICH H. PYLORI AND MUCOSAL INFLAMMATION LEAD TO CANCER DEVELOPMENT HAVE EMERGED. H. PYLORI VIRULENCE FACTORS, IN PARTICULAR SPECIFIC CAGA GENOTYPES, REPRESENT MAIN FACTORS IN GASTRIC CANCER, INDUCING ALTERED INTRACELLULAR SIGNALING IN EPITHELIAL CELLS. THE CHRONIC NATURE OF H. PYLORI INFECTION APPEARS TO RELATE TO THE VACA VIRULENCE FACTOR AND TH17/TREG MECHANISMS. A ROLE OF H. PYLORI INFECTION IN EPIGENETIC AND MICRORNA DEREGULATION HAS BEEN SHOWN. MUTATION OF THE EPITHELIAL CELL GENOME, A HALLMARK OF CANCER, WAS DEMONSTRATED TO ACCUMULATE IN H. PYLORI INFECTED STOMACH PARTLY DUE TO INADEQUATE DNA REPAIR. GASTRIC STEM CELLS WERE SHOWN TO BE TARGETS OF OXIDATIVE INJURY IN THE HELICOBACTER-INFLAMMATORY MILIEU. RECENT ADVANCES EMPHASIZING THE CONTRIBUTION OF BACTERIAL FACTORS, INFLAMMATORY MEDIATORS, AND THE HOST EPITHELIAL RESPONSE IN GASTRIC CARCINOGENESIS ARE REVIEWED. 2013 18 737 42 CANCER STEM CELLS. THERE IS AN INCREASING EVIDENCE SUPPORTING THE CANCER STEM CELL HYPOTHESIS. NORMAL STEM CELLS IN THE ADULT ORGANISM ARE RESPONSIBLE FOR TISSUE RENEWAL AND REPAIR OF AGED OR DAMAGED TISSUE. A SUBSTANTIAL CHARACTERISTIC OF STEM CELLS IS THEIR ABILITY FOR SELF-RENEWAL WITHOUT LOSS OF PROLIFERATION CAPACITY WITH EACH CELL DIVISION. THE STEM CELLS ARE IMMORTAL, AND RATHER RESISTANT TO ACTION OF DRUGS. THEY ARE ABLE TO DIFFERENTIATE AND FORM SPECIFIC TYPES OF TISSUE DUE TO THE INFLUENCE OF MICROENVIRONMENTAL AND SOME OTHER FACTORS. STEM CELLS DIVIDE ASYMMETRICALLY PRODUCING TWO DAUGHTER CELLS -- ONE IS A NEW STEM CELL AND THE SECOND IS PROGENITOR CELL, WHICH HAS THE ABILITY FOR DIFFERENTIATION AND PROLIFERATION, BUT NOT THE CAPABILITY FOR SELF-RENEWAL. CANCER STEM CELLS ARE IN MANY ASPECTS SIMILAR TO THE STEM CELLS. IT HAS BEEN PROVEN THAT TUMOR CELLS ARE HETEROGENEOUS COMPRISING RARE TUMOR INITIATING CELLS AND ABUNDANT NON-TUMOR INITIATING CELLS. TUMOR INITIATING CELLS -- CANCER STEM CELLS HAVE THE ABILITY OF SELF-RENEWAL AND PROLIFERATION, ARE RESISTANT TO DRUGS, AND EXPRESS TYPICAL MARKERS OF STEM CELLS. IT IS NOT CLEAR WHETHER CANCER STEM CELLS ORIGINATE FROM NORMAL STEM CELLS IN CONSEQUENCE OF GENETIC AND EPIGENETIC CHANGES AND/OR BY REDIFFERENTIATION FROM SOMATIC TUMOR CELLS TO THE STEM-LIKE CELLS. PROBABLY BOTH MECHANISMS ARE INVOLVED IN THE ORIGIN OF CANCER STEM CELLS. DYSREGULATION OF STEM CELL SELF-RENEWAL IS A LIKELY REQUIREMENT FOR THE DEVELOPMENT OF CANCER. ISOLATION AND IDENTIFICATION OF CANCER STEM CELLS IN HUMAN TUMORS AND IN TUMOR CELL LINES HAS BEEN SUCCESSFUL. TO DATE, THE EXISTENCE OF CANCER STEM CELLS HAS BEEN PROVEN IN ACUTE AND CHRONIC MYELOID LEUKEMIA, IN BREAST CANCER, IN BRAIN TUMORS, IN LUNG CANCER AND GASTROINTESTINAL TUMORS. CANCER STEM CELL MODEL IS ALSO CONSISTENT WITH SOME CLINICAL OBSERVATIONS. ALTHOUGH STANDARD CHEMOTHERAPY KILLS MOST CELLS IN A TUMOR, CANCER STEM CELLS REMAIN VIABLE. DESPITE THE SMALL NUMBER OF SUCH CELLS, THEY MIGHT BE THE CAUSE OF TUMOR RECURRENCE, SOMETIMES MANY YEARS AFTER THE "SUCCESSFUL" TREATMENT OF PRIMARY TUMOR. GROWTH OF METASTASES IN DISTINCT AREAS OF BODY AND THEIR CELLULAR HETEROGENEITY MIGHT BE CONSEQUENCE OF CANCER STEM CELL DIFFERENTIATION AND/OR DEDIFFERENTIATION AND ASYMMETRIC DIVISION OF CANCER STEM CELLS. FURTHER CHARACTERIZATION OF CANCER STEM CELLS IS NEEDED IN ORDER TO FIND WAYS TO DESTROY THEM, WHICH MIGHT CONTRIBUTE SIGNIFICANTLY TO THE THERAPEUTIC MANAGEMENT OF MALIGNANT TUMORS. 2005 19 4539 35 MULTISTAGE CARCINOGENESIS IN MOUSE SKIN. THE MOUSE SKIN MODEL OF MULTISTAGE CARCINOGENESIS HAS FOR MANY YEARS PROVIDED A CONCEPTUAL FRAMEWORK FOR STUDYING CARCINOGENESIS MECHANISMS AND POTENTIAL MEANS FOR INHIBITING SPECIFIC STAGES OF CARCINOGENESIS. THE PROCESS OF SKIN CARCINOGENESIS INVOLVES THE STEPWISE ACCUMULATION OF GENETIC CHANGE ULTIMATELY LEADING TO MALIGNANCY. INITIATION, THE FIRST STEP IN MULTISTAGE SKIN CARCINOGENESIS INVOLVES CARCINOGEN-INDUCED GENETIC CHANGES. A TARGET GENE IDENTIFIED FOR SOME SKIN TUMOR INITIATORS IS C-HA-RAS. THE SECOND STEP, THE PROMOTION STAGE, INVOLVES PROCESSES WHEREBY INITIATED CELLS UNDERGO SELECTIVE CLONAL EXPANSION TO FORM VISIBLE PREMALIGNANT LESIONS TERMED PAPILLOMAS. THE PROCESS OF TUMOR PROMOTION INVOLVES THE PRODUCTION AND MAINTENANCE OF A SPECIFIC AND CHRONIC HYPERPLASIA CHARACTERIZED BY A SUSTAINED CELLULAR PROLIFERATION OF EPIDERMAL CELLS. THESE CHANGES ARE BELIEVED TO RESULT FROM EPIGENETIC MECHANISMS SUCH AS ACTIVATION OF THE CELLULAR RECEPTOR, PROTEIN KINASE C, BY SOME CLASSES OF TUMOR PROMOTERS. THE PROGRESSION STAGE INVOLVES THE CONVERSION OF PAPILLOMAS TO MALIGNANT TUMORS, SQUAMOUS CELL CARCINOMAS. THE ACCUMULATION OF ADDITIONAL GENETIC CHANGES IN CELLS COMPRISING PAPILLOMAS HAS BEEN CORRELATED WITH TUMOR PROGRESSION, INCLUDING TRISOMIES OF CHROMOSOMES 6 AND 7 AND LOSS OF HETEROZYGOSITY. THE CURRENT REVIEW FOCUSES ON THE MECHANISMS INVOLVED IN MULTISTAGE SKIN CARCINOGENESIS, A SUMMARY OF KNOWN INHIBITORS OF SPECIFIC STAGES AND THEIR PROPOSED MECHANISMS OF ACTION, AND THE RELEVANCE OF THIS MODEL SYSTEM TO HUMAN CANCER. 1992 20 2994 32 GENETIC PATHOGENESIS OF INFLAMMATION-ASSOCIATED CANCERS IN DIGESTIVE ORGANS. EPIDEMIOLOGICAL, CLINICAL, AND BIOLOGICAL STUDIES CONVINCINGLY DEMONSTRATE THAT CHRONIC INFLAMMATION PREDISPOSES TO THE DEVELOPMENT OF HUMAN CANCERS. IN DIGESTIVE ORGANS, INFLAMMATION-ASSOCIATED CANCERS INCLUDE COLITIS-ASSOCIATED COLORECTAL CANCERS, HELICOBACTER PYLORI-ASSOCIATED GASTRIC CANCER, AS WELL AS BARRETT'S ESOPHAGUS AND ESOPHAGEAL ADENOCARCINOMA ASSOCIATED WITH CHRONIC DUODENOGASTRIC-ESOPHAGEAL REFLUX. CANCER IS A GENOMIC DISEASE, AND STEPWISE ACCUMULATION OF GENETIC AND EPIGENETIC ALTERATIONS OF TUMOR-RELATED GENES LEADS TO THE DEVELOPMENT OF TUMOR CELLS. RECENT GENOME ANALYSES SHOW THAT GENETIC ALTERATIONS, WHICH ARE EVOKED BY INFLAMMATION, ARE LATENTLY ACCUMULATED IN INFLAMED EPITHELIAL CELLS OF DIGESTIVE ORGANS. PRODUCTION OF REACTIVE OXYGEN AND ABERRANT EXPRESSION OF ACTIVATION-INDUCED CYTIDINE DEAMINASE, A NUCLEOTIDE-EDITING ENZYME, COULD BE INDUCED IN INFLAMED GASTROINTESTINAL EPITHELIAL CELLS AND PLAY A ROLE AS A GENOMIC MODULATOR OF INFLAMMATION-ASSOCIATED CARCINOGENESIS. UNDERSTANDING THE MOLECULAR LINKAGE BETWEEN INFLAMMATION AND GENETIC ALTERATIONS WILL OPEN UP A NEW FIELD OF TUMOR BIOLOGY AND PROVIDE A NOVEL STRATEGY FOR THE PREVENTION OF INFLAMMATION-ASSOCIATED TUMORIGENESIS. 2021