1 2391 131 EPIGENETIC REPRESSION OF DNA MISMATCH REPAIR BY INFLAMMATION AND HYPOXIA IN INFLAMMATORY BOWEL DISEASE-ASSOCIATED COLORECTAL CANCER. SPORADIC HUMAN MISMATCH REPAIR (MMR)-DEFICIENT COLORECTAL CANCERS ACCOUNT FOR APPROXIMATELY 12.5% OF ALL CASES OF COLORECTAL CANCER. MMR-DEFICIENT COLORECTAL CANCERS ARE CLASSICALLY CHARACTERIZED BY RIGHT-SIDED LOCATION, MULTIFOCALITY, MUCINOUS HISTOLOGY, AND LYMPHOCYTIC INFILTRATION. HOWEVER, TUMORS IN GERM-LINE MMR-DEFICIENT MOUSE MODELS LACK THESE HISTOPATHOLOGIC FEATURES. MICE LACKING THE HETEROTRIMERIC G PROTEIN ALPHA SUBUNIT GIALPHA2 DEVELOP CHRONIC COLITIS AND MULTIFOCAL, RIGHT-SIDED CANCERS WITH MUCINOUS HISTOPATHOLOGY, SIMILAR TO HUMAN MMR-DEFICIENT COLORECTAL CANCER. YOUNG GIALPHA2-/- COLONIC EPITHELIUM HAS NORMAL MMR EXPRESSION BUT SELECTIVELY LOSES MLH1 AND CONSEQUENTLY PMS2 EXPRESSION FOLLOWING INFLAMMATION. GIALPHA2-/- CANCERS HAVE MICROSATELLITE INSTABILITY. MLH1 IS EPIGENETICALLY SILENCED NOT BY PROMOTER HYPERMETHYLATION BUT BY DECREASED HISTONE ACETYLATION. CHRONICALLY INFLAMED GIALPHA2-/- COLONIC MUCOSA CONTAINS PATCHY HYPOXIA, WITH INCREASED CRYPT EXPRESSION OF THE HYPOXIA MARKERS DEC-1 AND BNIP3. CHROMATIN IMMUNOPRECIPITATION IDENTIFIED INCREASED BINDING OF THE TRANSCRIPTIONAL REPRESSOR DEC-1 TO THE PROXIMAL MLH1 PROMOTER IN HYPOXIC YAMC CELLS AND COLITIC GIALPHA2-/- CRYPTS. TREATING GIALPHA2-/- MICE WITH THE HISTONE DEACETYLASE INHIBITOR SUBEROYLANILIDE HYDROXAMIC ACID SIGNIFICANTLY DECREASED COLITIS ACTIVITY AND RESCUED MLH1 EXPRESSION IN CRYPT EPITHELIAL CELLS, WHICH WAS ASSOCIATED WITH INCREASED ACETYL HISTONE H3 LEVELS AND DECREASED DEC-1 BINDING AT THE PROXIMAL MLH1 PROMOTER, CONSISTENT WITH A HISTONE DEACETYLASE-DEPENDENT MECHANISM. THESE DATA LINK CHRONIC HYPOXIC INFLAMMATION, EPIGENETIC MMR PROTEIN DOWN-REGULATION, DEVELOPMENT OF MMR-DEFICIENT COLORECTAL CANCER, AND THE FIRSTMOUSE MODEL OF SOMATICALLY ACQUIRED MMR-DEFICIENT COLORECTAL CANCER. 2009 2 5404 23 REGENERATIVE INTESTINAL STEM CELLS INDUCED BY ACUTE AND CHRONIC INJURY: THE SAVING GRACE OF THE EPITHELIUM? THE INTESTINAL EPITHELIUM IS REPLENISHED EVERY 3-4 DAYS THROUGH AN ORDERLY PROCESS THAT MAINTAINS IMPORTANT SECRETORY AND ABSORPTIVE FUNCTIONS WHILE PRESERVING A CONTINUOUS MUCOSAL BARRIER. INTESTINAL EPITHELIAL CELLS (IECS) DERIVE FROM A STABLE POPULATION OF INTESTINAL STEM CELLS (ISCS) THAT RESIDE IN THE BASAL CRYPTS. WHEN INTESTINAL INJURY REACHES THE CRYPTS AND DAMAGES IECS, A MECHANISM TO REPLACE THEM IS NEEDED. RECENT RESEARCH HAS HIGHLIGHTED THE EXISTENCE OF DISTINCT POPULATIONS OF ACUTE AND CHRONIC DAMAGE-ASSOCIATED ISCS AND THEIR ROLES IN MAINTAINING HOMEOSTASIS IN SEVERAL INTESTINAL PERTURBATION MODELS. WHAT REMAINS UNKNOWN IS HOW THE DAMAGE-ASSOCIATED REGENERATIVE ISC POPULATION FUNCTIONS IN THE SETTING OF CHRONIC INFLAMMATION, AS OPPOSED TO ACUTE INJURY. WHAT LONG-TERM CONSEQUENCES RESULT FROM PERSISTENT INFLAMMATION AND OTHER CELLULAR INSULTS TO THE ISC NICHE? WHAT PARTICULAR "REGENERATIVE" CELL TYPES PROVIDE THE MOST EFFICACIOUS RESTORATIVE PROPERTIES? WHICH DIFFERENTIATED IECS MAINTAIN THE ABILITY TO DE-DIFFERENTIATE AND RESTORE THE ISC NICHE? THIS REVIEW WILL COVER THE LATEST RESEARCH ON DAMAGE-ASSOCIATED REGENERATIVE ISCS AND EPIGENETIC FACTORS THAT DETERMINE ISC FATE, AS WELL AS PROVIDE OPINIONS ON FUTURE STUDIES THAT NEED TO BE UNDERTAKEN TO UNDERSTAND THE REPERCUSSIONS OF THE EMERGENCE OF THESE CELLS, THEIR CONTRIBUTION TO RELAPSES IN INFLAMMATORY BOWEL DISEASE, AND THEIR POTENTIAL USE IN THERAPEUTICS FOR CHRONIC INTESTINAL DISEASES. 2020 3 1863 28 EMERGENCE OF MUC1 IN MAMMALS FOR ADAPTATION OF BARRIER EPITHELIA. THE MUCIN 1 (MUC1) GENE WAS DISCOVERED BASED ON ITS OVEREXPRESSION IN HUMAN BREAST CANCERS. SUBSEQUENT WORK DEMONSTRATED THAT MUC1 IS ABERRANTLY EXPRESSED IN CANCERS ORIGINATING FROM OTHER DIVERSE ORGANS, INCLUDING SKIN AND IMMUNE CELLS. THESE FINDINGS SUPPORTED A ROLE FOR MUC1 IN THE ADAPTATION OF BARRIER TISSUES TO INFECTION AND ENVIRONMENTAL STRESS. OF FUNDAMENTAL IMPORTANCE FOR THIS EVOLUTIONARY ADAPTATION WAS INCLUSION OF A SEA DOMAIN, WHICH CATALYZES AUTOPROTEOLYSIS OF THE MUC1 PROTEIN AND FORMATION OF A NON-COVALENT HETERODIMERIC COMPLEX. THE RESULTING MUC1 HETERODIMER IS POISED AT THE APICAL CELL MEMBRANE TO RESPOND TO LOSS OF HOMEOSTASIS. DISRUPTION OF THE COMPLEX RELEASES THE MUC1 N-TERMINAL (MUC1-N) SUBUNIT INTO A PROTECTIVE MUCOUS GEL. CONVERSELY, THE TRANSMEMBRANE C-TERMINAL (MUC1-C) SUBUNIT ACTIVATES A PROGRAM OF LINEAGE PLASTICITY, EPIGENETIC REPROGRAMMING AND REPAIR. THIS MUC1-C-ACTIVATED PROGRAM APPARENTLY EVOLVED FOR BARRIER TISSUES TO MOUNT SELF-REGULATING PROLIFERATIVE, INFLAMMATORY AND REMODELING RESPONSES ASSOCIATED WITH WOUND HEALING. EMERGING EVIDENCE INDICATES THAT MUC1-C UNDERPINS INFLAMMATORY ADAPTATION OF TISSUE STEM CELLS AND IMMUNE CELLS IN THE BARRIER NICHE. THIS REVIEW FOCUSES ON HOW PROLONGED ACTIVATION OF MUC1-C BY CHRONIC INFLAMMATION IN THESE NICHES PROMOTES THE CANCER STEM CELL (CSC) STATE BY ESTABLISHING AUTO-INDUCTIVE NODES THAT DRIVE SELF-RENEWAL AND TUMORIGENICITY. 2022 4 866 32 CHRONIC ACTIVATION OF MUC1-C IN WOUND REPAIR PROMOTES PROGRESSION TO CANCER STEM CELLS. THE MUCIN 1 (MUC1) GENE EMERGED IN MAMMALS TO AFFORD PROTECTION OF BARRIER EPITHELIAL TISSUES FROM THE EXTERNAL ENVIRONMENT. MUC1 ENCODES A TRANSMEMBRANE C-TERMINAL (MUC1-C) SUBUNIT THAT IS ACTIVATED BY LOSS OF HOMEOSTASIS AND INDUCES INFLAMMATORY, PROLIFERATIVE, AND REMODELING PATHWAYS ASSOCIATED WITH WOUND REPAIR. AS A CONSEQUENCE, CHRONIC ACTIVATION OF MUC1-C PROMOTES LINEAGE PLASTICITY, EPIGENETIC REPROGRAMMING, AND CARCINOGENESIS. IN DRIVING CANCER PROGRESSION, MUC1-C IS IMPORTED INTO THE NUCLEUS, WHERE IT INDUCES NF-KAPPAB INFLAMMATORY SIGNALING AND THE EPITHELIAL-MESENCHYMAL TRANSITION (EMT). MUC1-C REPRESSES GENE EXPRESSION BY ACTIVATING (I) DNA METHYLTRANSFERASE 1 (DNMT1) AND DNMT3B, (II) POLYCOMB REPRESSIVE COMPLEX 1 (PRC1) AND PRC2, AND (III) THE NUCLEOSOME REMODELING AND DEACETYLASE (NURD) COMPLEX. PRC1/2-MEDIATED GENE REPRESSION IS COUNTERACTED BY THE SWI/SNF CHROMATIN REMODELING COMPLEXES. MUC1-C ACTIVATES THE SWI/SNF BAF AND PBAF COMPLEXES IN CANCER STEM CELL (CSC) MODELS WITH THE INDUCTION OF GENOME-WIDE DIFFERENTIALLY ACCESSIBLE REGIONS AND EXPRESSED GENES. MUC1-C REGULATES CHROMATIN ACCESSIBILITY OF ENHANCER-LIKE SIGNATURES IN ASSOCIATION WITH THE INDUCTION OF THE YAMANAKA PLURIPOTENCY FACTORS AND RECRUITMENT OF JUN AND BAF, WHICH PROMOTE INCREASES IN HISTONE ACTIVATION MARKS AND OPENING OF CHROMATIN. THESE AND OTHER FINDINGS DESCRIBED IN THIS REVIEW HAVE UNCOVERED A PIVOTAL ROLE FOR MUC1-C IN INTEGRATING LINEAGE PLASTICITY AND EPIGENETIC REPROGRAMMING, WHICH ARE TRANSIENT IN WOUND REPAIR AND SUSTAINED IN PROMOTING CSC PROGRESSION. 2022 5 4116 21 MECHANISMS OF AIRWAY EPITHELIAL INJURY AND ABNORMAL REPAIR IN ASTHMA AND COPD. THE AIRWAY EPITHELIUM COMPRISES OF DIFFERENT CELL TYPES AND ACTS AS A PHYSICAL BARRIER PREVENTING PATHOGENS, INCLUDING INHALED PARTICLES AND MICROBES, FROM ENTERING THE LUNGS. GOBLET CELLS AND SUBMUCOSAL GLANDS PRODUCE MUCUS THAT TRAPS PATHOGENS, WHICH ARE EXPELLED FROM THE RESPIRATORY TRACT BY CILIATED CELLS. BASAL CELLS ACT AS PROGENITOR CELLS, DIFFERENTIATING INTO DIFFERENT EPITHELIAL CELL TYPES, TO MAINTAIN HOMEOSTASIS FOLLOWING INJURY. ADHERENS AND TIGHT JUNCTIONS BETWEEN CELLS MAINTAIN THE EPITHELIAL BARRIER FUNCTION AND REGULATE THE MOVEMENT OF MOLECULES ACROSS IT. IN THIS REVIEW WE DISCUSS HOW ABNORMAL EPITHELIAL STRUCTURE AND FUNCTION, CAUSED BY CHRONIC INJURY AND ABNORMAL REPAIR, DRIVES AIRWAY DISEASE AND SPECIFICALLY ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). IN BOTH DISEASES, INHALED ALLERGENS, POLLUTANTS AND MICROBES DISRUPT JUNCTIONAL COMPLEXES AND PROMOTE CELL DEATH, IMPAIRING THE BARRIER FUNCTION AND LEADING TO INCREASED PENETRATION OF PATHOGENS AND A CONSTANT AIRWAY IMMUNE RESPONSE. IN ASTHMA, THE INFLAMMATORY RESPONSE PRECIPITATES THE EPITHELIAL INJURY AND DRIVES ABNORMAL BASAL CELL DIFFERENTIATION. THIS LEADS TO REDUCED CILIATED CELLS, GOBLET CELL HYPERPLASIA AND INCREASED EPITHELIAL MESENCHYMAL TRANSITION, WHICH CONTRIBUTE TO IMPAIRED MUCOCILIARY CLEARANCE AND AIRWAY REMODELLING. IN COPD, CHRONIC OXIDATIVE STRESS AND INFLAMMATION TRIGGER PREMATURE EPITHELIAL CELL SENESCENCE, WHICH CONTRIBUTES TO LOSS OF EPITHELIAL INTEGRITY AND AIRWAY INFLAMMATION AND REMODELLING. INCREASED NUMBERS OF BASAL CELLS SHOWING DEREGULATED DIFFERENTIATION, CONTRIBUTES TO CILIARY DYSFUNCTION AND MUCOUS HYPERPRODUCTION IN COPD AIRWAYS. DEFECTIVE ANTIOXIDANT, ANTIVIRAL AND DAMAGE REPAIR MECHANISMS, POSSIBLY DUE TO GENETIC OR EPIGENETIC FACTORS, MAY CONFER SUSCEPTIBILITY TO AIRWAY EPITHELIAL DYSFUNCTION IN THESE DISEASES. THE CURRENT EVIDENCE SUGGESTS THAT A CONSTANT CYCLE OF INJURY AND ABNORMAL REPAIR OF THE EPITHELIUM DRIVES CHRONIC AIRWAY INFLAMMATION AND REMODELLING IN ASTHMA AND COPD. MECHANISTIC UNDERSTANDING OF INJURY SUSCEPTIBILITY AND DAMAGE RESPONSE MAY LEAD TO IMPROVED THERAPIES FOR THESE DISEASES. 2023 6 4512 20 MUC1-C IN CHRONIC INFLAMMATION AND CARCINOGENESIS; EMERGENCE AS A TARGET FOR CANCER TREATMENT. CHRONIC INFLAMMATION IS A HIGHLY PREVALENT CONSEQUENCE OF CHANGES IN ENVIRONMENTAL AND LIFESTYLE FACTORS THAT CONTRIBUTE TO THE DEVELOPMENT OF CANCER. THE BASIS FOR THIS CRITICAL ASSOCIATION HAS LARGELY REMAINED UNCLEAR. THE MUC1 GENE EVOLVED IN MAMMALS TO PROTECT EPITHELIA FROM THE EXTERNAL ENVIRONMENT. THE MUC1-C SUBUNIT PROMOTES RESPONSES FOUND IN WOUND HEALING AND CANCER. MUC1-C INDUCES EMT, EPIGENETIC REPROGRAMMING, DEDIFFERENTIATION AND PLURIPOTENCY FACTOR EXPRESSION, WHICH WHEN PROLONGED IN CHRONIC INFLAMMATION PROMOTE CANCER PROGRESSION. AS DISCUSSED IN THIS REVIEW, MUC1-C ALSO DRIVES DRUG RESISTANCE AND IMMUNE EVASION, AND IS AN IMPORTANT TARGET FOR CANCER THERAPEUTICS NOW UNDER DEVELOPMENT. 2020 7 234 29 ADDICTION OF CANCER STEM CELLS TO MUC1-C IN TRIPLE-NEGATIVE BREAST CANCER PROGRESSION. TRIPLE-NEGATIVE BREAST CANCER (TNBC) IS AN AGGRESSIVE MALIGNANCY WITH LIMITED TREATMENT OPTIONS. TNBC PROGRESSION IS ASSOCIATED WITH EXPANSION OF CANCER STEM CELLS (CSCS). FEW INSIGHTS ARE AVAILABLE REGARDING DRUGGABLE TARGETS THAT DRIVE THE TNBC CSC STATE. THIS REVIEW SUMMARIZES THE LITERATURE ON TNBC CSCS AND THE COMPELLING EVIDENCE THAT THEY ARE ADDICTED TO THE MUC1-C TRANSMEMBRANE PROTEIN. IN NORMAL EPITHELIA, MUC1-C IS ACTIVATED BY LOSS OF HOMEOSTASIS AND INDUCES REVERSIBLE WOUND-HEALING RESPONSES OF INFLAMMATION AND REPAIR. HOWEVER, IN SETTINGS OF CHRONIC INFLAMMATION, MUC1-C PROMOTES CARCINOGENESIS. MUC1-C INDUCES EMT, EPIGENETIC REPROGRAMMING AND CHROMATIN REMODELING IN TNBC CSCS, WHICH ARE DEPENDENT ON MUC1-C FOR SELF-RENEWAL AND TUMORIGENICITY. MUC1-C-INDUCED LINEAGE PLASTICITY IN TNBC CSCS CONFERS DNA DAMAGE RESISTANCE AND IMMUNE EVASION BY CHRONIC ACTIVATION OF INFLAMMATORY PATHWAYS AND GLOBAL CHANGES IN CHROMATIN ARCHITECTURE. OF THERAPEUTIC SIGNIFICANCE, AN ANTIBODY GENERATED AGAINST THE MUC1-C EXTRACELLULAR DOMAIN HAS BEEN ADVANCED IN A CLINICAL TRIAL OF ANTI-MUC1-C CAR T CELLS AND IN IND-ENABLING STUDIES FOR DEVELOPMENT AS AN ANTIBODY-DRUG CONJUGATE (ADC). AGENTS TARGETING THE MUC1-C CYTOPLASMIC DOMAIN HAVE ALSO ENTERED THE CLINIC AND ARE UNDERGOING FURTHER DEVELOPMENT AS CANDIDATES FOR ADVANCING TNBC TREATMENT. ELIMINATING TNBC CSCS WILL BE NECESSARY FOR CURING THIS RECALCITRANT CANCER AND MUC1-C REPRESENTS A PROMISING DRUGGABLE TARGET FOR ACHIEVING THAT GOAL. 2022 8 2065 25 EPIGENETIC CONTROL OF INTESTINAL BARRIER FUNCTION AND INFLAMMATION IN ZEBRAFISH. THE INTESTINAL EPITHELIUM FORMS A BARRIER PROTECTING THE ORGANISM FROM MICROBES AND OTHER PROINFLAMMATORY STIMULI. THE INTEGRITY OF THIS BARRIER AND THE PROPER RESPONSE TO INFECTION REQUIRES PRECISE REGULATION OF POWERFUL IMMUNE HOMING SIGNALS SUCH AS TUMOR NECROSIS FACTOR (TNF). DYSREGULATION OF TNF LEADS TO INFLAMMATORY BOWEL DISEASES (IBD), BUT THE MECHANISM CONTROLLING THE EXPRESSION OF THIS POTENT CYTOKINE AND THE EVENTS THAT TRIGGER THE ONSET OF CHRONIC INFLAMMATION ARE UNKNOWN. HERE, WE SHOW THAT LOSS OF FUNCTION OF THE EPIGENETIC REGULATOR UBIQUITIN-LIKE PROTEIN CONTAINING PHD AND RING FINGER DOMAINS 1 (UHRF1) IN ZEBRAFISH LEADS TO A REDUCTION IN TNFA PROMOTER METHYLATION AND THE INDUCTION OF TNFA EXPRESSION IN INTESTINAL EPITHELIAL CELLS (IECS). THE INCREASE IN IEC TNFA LEVELS IS MICROBE-DEPENDENT AND RESULTS IN IEC SHEDDING AND APOPTOSIS, IMMUNE CELL RECRUITMENT, AND BARRIER DYSFUNCTION, CONSISTENT WITH CHRONIC INFLAMMATION. IMPORTANTLY, TNFA KNOCKDOWN IN UHRF1 MUTANTS RESTORES IEC MORPHOLOGY, REDUCES CELL SHEDDING, AND IMPROVES BARRIER FUNCTION. WE PROPOSE THAT LOSS OF EPIGENETIC REPRESSION AND TNF INDUCTION IN THE INTESTINAL EPITHELIUM CAN LEAD TO IBD ONSET. 2015 9 3544 25 IMMUNOMETABOLIC CONTROL OF TRAINED IMMUNITY. INNATE IMMUNE CELLS CAN ADOPT LONG-TERM INFLAMMATORY PHENOTYPES FOLLOWING BRIEF ENCOUNTERS WITH EXOGENOUS (MICROBIAL) OR ENDOGENOUS STIMULI. THIS PHENOMENON IS NAMED TRAINED IMMUNITY AND CAN IMPROVE HOST DEFENSE AGAINST (RECURRENT) INFECTIONS. IN CONTRAST, TRAINED IMMUNITY CAN ALSO BE MALADAPTIVE IN THE CONTEXT OF CHRONIC INFLAMMATORY DISORDERS, SUCH AS ATHEROSCLEROSIS. KEY TO FUTURE THERAPEUTIC EXPLOITATION OF THIS MECHANISM IS THOROUGH KNOWLEDGE OF THE MECHANISMS DRIVING TRAINED IMMUNITY, WHICH CAN BE USED AS PHARMACOLOGICAL TARGETS. THESE MECHANISMS INCLUDE PROFOUND CHANGES IN INTRACELLULAR METABOLISM, WHICH ARE CLOSELY INTERTWINED WITH EPIGENETIC REPROGRAMMING AT THE LEVEL OF HISTONE MODIFICATIONS. GLYCOLYSIS, GLUTAMINE REPLENISHMENT OF THE TRICARBOXYLIC ACID CYCLE WITH ACCUMULATION OF FUMARATE, AND THE MEVALONATE PATHWAY HAVE ALL BEEN IDENTIFIED AS CRITICAL PATHWAYS FOR TRAINED IMMUNITY IN MONOCYTES AND MACROPHAGES. IN THIS REVIEW, WE PROVIDE A STATE-OF-THE-ART OVERVIEW OF HOW THESE METABOLIC PATHWAYS INTERACT WITH EPIGENETIC PROGRAMS TO DEVELOP TRAINED IMMUNITY. 2021 10 2894 25 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 11 6273 21 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 12 5631 24 SENESCENCE-INFLAMMATORY REGULATION OF REPARATIVE CELLULAR REPROGRAMMING IN AGING AND CANCER. THE INABILITY OF ADULT TISSUES TO TRANSITORILY GENERATE CELLS WITH FUNCTIONAL STEM CELL-LIKE PROPERTIES IS A MAJOR OBSTACLE TO TISSUE SELF-REPAIR. NUCLEAR REPROGRAMMING-LIKE PHENOMENA THAT INDUCE A TRANSIENT ACQUISITION OF EPIGENETIC PLASTICITY AND PHENOTYPE MALLEABILITY MAY CONSTITUTE A REPARATIVE ROUTE THROUGH WHICH HUMAN TISSUES RESPOND TO INJURY, STRESS, AND DISEASE. HOWEVER, TISSUE REJUVENATION SHOULD INVOLVE NOT ONLY THE TRANSIENT EPIGENETIC REPROGRAMMING OF DIFFERENTIATED CELLS, BUT ALSO THE COMMITTED RE-ACQUISITION OF THE ORIGINAL OR ALTERNATIVE COMMITTED CELL FATE. CHRONIC OR UNRESTRAINED EPIGENETIC PLASTICITY WOULD DRIVE AGING PHENOTYPES BY IMPAIRING THE REPAIR OR THE REPLACEMENT OF DAMAGED CELLS; SUCH UNCONTROLLED PHENOMENA OF IN VIVO REPROGRAMMING MIGHT ALSO GENERATE CANCER-LIKE CELLULAR STATES. WE HEREIN PROPOSE THAT THE ABILITY OF SENESCENCE-ASSOCIATED INFLAMMATORY SIGNALING TO REGULATE IN VIVO REPROGRAMMING CYCLES OF TISSUE REPAIR OUTLINES A THRESHOLD MODEL OF AGING AND CANCER. THE DEGREE OF SENESCENCE/INFLAMMATION-ASSOCIATED DEVIATION FROM THE HOMEOSTATIC STATE MAY DELINEATE A TYPE OF THRESHOLDING ALGORITHM DISTINGUISHING BENEFICIAL FROM DELETERIOUS EFFECTS OF IN VIVO REPROGRAMMING. FIRST, TRANSIENT ACTIVATION OF NF-KAPPAB-RELATED INNATE IMMUNITY AND SENESCENCE-ASSOCIATED INFLAMMATORY COMPONENTS (E.G., IL-6) MIGHT FACILITATE REPARATIVE CELLULAR REPROGRAMMING IN RESPONSE TO ACUTE INFLAMMATORY EVENTS. SECOND, PARA-INFLAMMATION SWITCHES MIGHT PROMOTE LONG-LASTING BUT REVERSIBLE REFRACTORINESS TO REPARATIVE CELLULAR REPROGRAMMING. THIRD, CHRONIC SENESCENCE-ASSOCIATED INFLAMMATORY SIGNALING MIGHT LOCK CELLS IN HIGHLY PLASTIC EPIGENETIC STATES DISABLED FOR REPARATIVE DIFFERENTIATION. THE CONSIDERATION OF A CELLULAR REPROGRAMMING-CENTERED VIEW OF EPIGENETIC PLASTICITY AS A FUNDAMENTAL ELEMENT OF A TISSUE'S CAPACITY TO UNDERGO SUCCESSFUL REPAIR, AGING DEGENERATION OR MALIGNANT TRANSFORMATION SHOULD PROVIDE CHALLENGING STOCHASTIC INSIGHTS INTO THE CURRENT DETERMINISTIC GENETIC PARADIGM FOR MOST CHRONIC DISEASES, THEREBY INCREASING THE SPECTRUM OF THERAPEUTIC APPROACHES FOR PHYSIOLOGICAL AGING AND CANCER. 2017 13 1378 18 DEVELOPMENTAL PROGRAMS ARE KEPT ALIVE DURING ADULTHOOD BY STEM CELLS: THE AGING ASPECT. STEM CELLS ARE FUNDAMENTAL FOR LIFE-LONG PRESERVATION OF CELLULAR SOMATIC MAINTENANCE. TISSUE-BORNE STEM CELLS REPLENISH WORN-OUT CRITICAL ELEMENTS. PROVIDED THEY REMAIN FIT OVER LIFETIME, ENDURING STEM CELL ACTIVITIES AVERT THE EMERGENCE OF AGE-ASSOCIATED CHRONIC DEGENERATIVE DISEASES AND PATHOLOGIES. ALTHOUGH EXPERIMENTALLY STILL UNCLEAR, IT IS ASSUMED THAT STEM CELLS RESIDE IN PROTECTED NICHES. FRESHLY ISOLATED MESENCHYMAL STEM CELLS EXHIBIT DONOR-SPECIFIC ABERRATIONS, WHICH CANNOT SOLELY BE ASCRIBED TO DIFFERENCES IN GENETIC BACKGROUND. BESIDES INEVITABLY ACCUMULATING INTRINSIC MODIFICATIONS, THE SYSTEMIC ENVIRONMENT ALSO IMPACTS ON BASIC PROPERTIES OF MESENCHYMAL STEM CELLS SUCH AS THEIR INHERENT MULTI-LINEAGE DIFFERENTIATION POTENTIAL. CHRONIC SYSTEMIC ABERRATIONS OVER TIME COMPRISE UNWHOLESOME INFLUENCES, IN PARTICULAR IN TERMS OF REGENERATION AND REPAIR WHEN STEM CELLS RECAPITULATE DISTINCT DEVELOPMENTAL PROGRAMS. DURING OR THEREAFTER, STEM CELLS CAN DIVERSIFY EITHER BECAUSE OF INSUFFICIENTLY SILENCING ACTIVATED BUILDING CYCLES, OR BY ACQUIRING EPIGENETIC DEVIATIONS. 2013 14 6452 21 THERAPIES TARGETING TRAINED IMMUNE CELLS IN INFLAMMATORY AND AUTOIMMUNE DISEASES. THE CONCEPT OF TRAINED IMMUNITY HAS RECENTLY EMERGED AS A MECHANISM CONTRIBUTING TO SEVERAL IMMUNE MEDIATED INFLAMMATORY CONDITIONS. TRAINED IMMUNITY IS DEFINED BY THE IMMUNOLOGICAL MEMORY DEVELOPED IN INNATE IMMUNE CELLS AFTER A PRIMARY NON-SPECIFIC STIMULUS THAT, IN TURN, PROMOTES A HEIGHTENED INFLAMMATORY RESPONSE UPON A SECONDARY CHALLENGE. THE MOST CHARACTERISTIC CHANGES ASSOCIATED TO THIS PROCESS INVOLVE THE REWIRING OF CELL METABOLISM AND EPIGENETIC REPROGRAMMING. UNDER PHYSIOLOGICAL CONDITIONS, THE ROLE OF TRAINED IMMUNE CELLS ENSURES A PROMPT RESPONSE. THIS ACTION IS LIMITED BY EFFECTIVE RESOLUTION OF INFLAMMATION AND TISSUE REPAIR IN ORDER TO RESTORE HOMEOSTASIS. HOWEVER, UNRESTRAINED ACTIVATION OF INNATE IMMUNE CELLS CONTRIBUTES TO THE DEVELOPMENT OF CHRONIC INFLAMMATION AND TISSUE DESTRUCTION THROUGH THE SECRETION OF INFLAMMATORY CYTOKINES, PROTEASES AND GROWTH FACTORS. THEREFORE, INTERVENTIONS AIMED AT REVERSING THE CHANGES INDUCED BY TRAINED IMMUNITY PROVIDE POTENTIAL THERAPEUTIC APPROACHES TO TREAT INFLAMMATORY AND AUTOIMMUNE DISEASES LIKE RHEUMATOID ARTHRITIS (RA). WE REVIEW CELLULAR APPROACHES THAT TARGET METABOLISM AND THE EPIGENETIC REPROGRAMMING OF DENDRITIC CELLS, MACROPHAGES, NATURAL KILLER CELLS, AND OTHER TRAINED CELLS IN THE CONTEXT OF AUTOIMMUNE INFLAMMATORY DISEASES. 2020 15 2657 21 EPITHELIAL DYSFUNCTION IN CHRONIC RESPIRATORY DISEASES, A SHARED ENDOTYPE? PURPOSE OF REVIEW: EPITHELIAL BARRIER DEFECTS ARE BEING APPRECIATED IN VARIOUS INFLAMMATORY DISORDERS; HOWEVER, CAUSAL UNDERLYING MECHANISMS ARE LACKING. IN THIS REVIEW, WE DESCRIBE THE DISRUPTION OF THE AIRWAY EPITHELIUM WITH REGARD TO UPPER AND LOWER AIRWAY DISEASES, THE ROLE OF EPIGENETIC ALTERATIONS UNDERLYING THIS PROCESS, AND POTENTIAL NOVEL WAYS OF INTERFERING WITH DYSFUNCTIONAL EPITHELIAL BARRIERS AS A NOVEL THERAPEUTIC APPROACH. RECENT FINDINGS: A DEFECTIVE EPITHELIAL BARRIER, IMPAIRED INNATE DEFENCE MECHANISMS OR HAMPERED EPITHELIAL CELL RENEWAL ARE FOUND IN UPPER AND LOWER AIRWAY DISEASES. BARRIER DYSFUNCTION MIGHT FACILITATE THE ENTRANCE OF FOREIGN SUBSTANCES, INITIATING AND FACILITATING THE ONSET OF DISEASE. LATEST DATA PROVIDED NOVEL INSIGHTS FOR POSSIBLE INVOLVEMENT OF EPIGENETIC ALTERATIONS INDUCED BY INFLAMMATION OR OTHER UNKNOWN MECHANISMS AS A POTENTIAL MECHANISM RESPONSIBLE FOR EPITHELIAL DEFECTS. ADDITIONALLY, THESE MECHANISMS MIGHT PRECEDE DISEASE DEVELOPMENT, AND REPRESENT A NOVEL THERAPEUTIC APPROACH FOR RESTORING EPITHELIAL DEFECTS. SUMMARY: A BETTER UNDERSTANDING OF THE ROLE OF EPIGENETICS IN DRIVING AND MAINTAINING EPITHELIAL DEFECTS IN VARIOUS INFLAMMATORY DISEASES, USING STATE-OF-THE-ART BIOLOGY TOOLS WILL BE CRUCIAL IN DESIGNING NOVEL THERAPIES TO PROTECT OR RECONSTITUTE A DEFECTIVE AIRWAY EPITHELIAL BARRIER. 2020 16 714 25 CADMIUM IS A MUTAGEN THAT ACTS BY INHIBITING MISMATCH REPAIR. MOST ERRORS THAT ARISE DURING DNA REPLICATION CAN BE CORRECTED BY DNA POLYMERASE PROOFREADING OR BY POST-REPLICATION MISMATCH REPAIR (MMR). INACTIVATION OF BOTH MUTATION-AVOIDANCE SYSTEMS RESULTS IN EXTREMELY HIGH MUTABILITY THAT CAN LEAD TO ERROR CATASTROPHE. HIGH MUTABILITY AND THE LIKELIHOOD OF CANCER CAN BE CAUSED BY MUTATIONS AND EPIGENETIC CHANGES THAT REDUCE MMR. HYPERMUTABILITY CAN ALSO BE CAUSED BY EXTERNAL FACTORS THAT DIRECTLY INHIBIT MMR. IDENTIFYING SUCH FACTORS HAS IMPORTANT IMPLICATIONS FOR UNDERSTANDING THE ROLE OF THE ENVIRONMENT IN GENOME STABILITY. WE FOUND THAT CHRONIC EXPOSURE OF YEAST TO ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF CADMIUM, A KNOWN HUMAN CARCINOGEN, CAN RESULT IN EXTREME HYPERMUTABILITY. THE MUTATION SPECIFICITY ALONG WITH RESPONSES IN PROOFREADING-DEFICIENT AND MMR-DEFICIENT MUTANTS INDICATE THAT CADMIUM REDUCES THE CAPACITY FOR MMR OF SMALL MISALIGNMENTS AND BASE-BASE MISMATCHES. IN EXTRACTS OF HUMAN CELLS, CADMIUM INHIBITED AT LEAST ONE STEP LEADING TO MISMATCH REMOVAL. TOGETHER, OUR DATA SHOW THAT A HIGH LEVEL OF GENETIC INSTABILITY CAN RESULT FROM ENVIRONMENTAL IMPEDIMENT OF A MUTATION-AVOIDANCE SYSTEM. 2003 17 6502 20 TRAINED IMMUNITY: LONG-TERM ADAPTATION IN INNATE IMMUNE RESPONSES. ADAPTIVE IMMUNE RESPONSES ARE CHARACTERIZED BY ANTIGEN SPECIFICITY AND INDUCTION OF LIFELONG IMMUNOLOGIC MEMORY. RECENTLY, IT HAS BEEN REPORTED THAT INNATE IMMUNE CELLS CAN ALSO BUILD IMMUNE MEMORY CHARACTERISTICS-A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY DESCRIBES THE PERSISTENT HYPERRESPONSIVE PHENOTYPE THAT INNATE IMMUNE CELLS CAN DEVELOP AFTER BRIEF STIMULATION. PATHOGENIC STIMULI SUCH AS MICROORGANISMS, AND ALSO ENDOGENOUS MOLECULES INCLUDING URIC ACID, OXIDIZED LDL (LOW-DENSITY LIPOPROTEIN), AND CATECHOLAMINES, ARE CAPABLE OF INDUCING MEMORY IN MONOCYTES AND MACROPHAGES. WHILE TRAINED IMMUNITY PROVIDES FAVORABLE CROSS-PROTECTION IN THE CONTEXT OF INFECTIOUS DISEASES, THE HEIGHTENED IMMUNE RESPONSE CAN BE MALADAPTIVE IN DISEASES DRIVEN BY CHRONIC SYSTEMIC INFLAMMATION, SUCH AS ATHEROSCLEROSIS. TRAINED IMMUNITY IS MAINTAINED BY DISTINCT EPIGENETIC AND METABOLIC MECHANISMS AND PERSISTS FOR AT LEAST SEVERAL MONTHS IN VIVO DUE TO REPROGRAMMING OF MYELOID PROGENITOR CELLS. ADDITIONALLY, CERTAIN NONIMMUNE CELLS ARE ALSO FOUND TO EXHIBIT TRAINED IMMUNITY CHARACTERISTICS. THUS, TRAINED IMMUNITY PRESENTS AN EXCITING FRAMEWORK TO DEVELOP NEW APPROACHES TO VACCINATION AND ALSO NOVEL PHARMACOLOGICAL TARGETS IN THE TREATMENT OF INFLAMMATORY DISEASES. 2021 18 5602 37 RORGAMMAT(+) HEMATOPOIETIC CELLS ARE NECESSARY FOR TUMOR CELL PROLIFERATION DURING COLITIS-ASSOCIATED TUMORIGENESIS IN MICE. COLORECTAL CANCER (CRC) IS ONE OF THE MOST COMMON TUMOR ENTITIES. IN PATIENTS WITH INFLAMMATORY BOWEL DISEASES, THE DEVELOPMENT OF COLITIS-ASSOCIATED COLON CANCER IS CONSIDERED A DANGEROUS LONG-TERM COMPLICATION. IL-17A AND THE TRANSCRIPTION FACTOR RETINOIC ACID RECEPTOR-RELATED ORPHAN RECEPTOR GAMMAT (RORGAMMAT) PLAY FUNDAMENTAL ROLES IN THE PATHOGENESIS OF INFLAMMATORY BOWEL DISEASES; IN HUMAN STUDIES, WE DETECTED A DENSE INFILTRATION OF RORGAMMAT-DEPENDENT CD4(+) IL17A(+) T HELPER (TH)17 CELLS IN SPECIMENS OF CRC, ULCERATIVE COLITIS, AND ULCERATIVE COLITIS-ASSOCIATED COLORECTAL CANCER. HOWEVER, THE MECHANISTIC ROLE OF RORGAMMAT(+) HEMATOPOIETIC CELLS IN COLITIS-ASSOCIATED TUMORIGENESIS REMAINS UNCLEAR. TO INVESTIGATE COLITIS-ASSOCIATED COLON TUMORIGENESIS, WE CONDUCTED STUDIES IN THE AOM+DSS MOUSE MODEL THAT REVEALED THE IMPORTANCE OF RORGAMMAT FOR COLON TUMOR PROGRESSION. IN THE ABSENCE OF RORGAMMAT-DEPENDENT TH17 LYMPHOCYTES, MICE SHOWED SIGNS OF INTENSE CHRONIC COLITIS, BUT DEVELOPED SIGNIFICANTLY FEWER MACROSCOPIC TUMOR NODULES. THE REDUCTION OF TUMOR DEVELOPMENT IN RORGAMMAT(-/-) MICE WAS NOT DUE TO REDUCED COLON TUMOR INITIATION. HOWEVER, THE PROLIFERATION RATE OF TUMOR CELLS WAS REDUCED IN THE ABSENCE OF RORGAMMAT-DEPENDENT TH17 CELLS AND TUMOR CELLS SHOWED PRONOUNCED SIGNS OF SENESCENCE-ASSOCIATED EPIGENETIC AND LYSOSOMAL CHANGES. THESE RESULTS INDICATE AN IMPORTANT ROLE FOR THE IMMUNOLOGICAL MILIEU IN COLITIS-ASSOCIATED CANCER, WHICH IS SHAPED IN-PART BY RORGAMMAT-DEPENDENT TH17 LYMPHOCYTES THAT SUPPORT CRC GROWTH. 2015 19 1300 25 DEDIFFERENTIATION AND IN VIVO REPROGRAMMING OF COMMITTED CELLS IN WOUND REPAIR (REVIEW). ACCUMULATING EVIDENCE HAS SHOWN THAT CELL DEDIFFERENTIATION OR REPROGRAMMING IS A PIVOTAL PROCEDURE FOR ANIMALS TO DEAL WITH INJURY AND PROMOTE ENDOGENOUS TISSUE REPAIR. TISSUE DAMAGE IS A CRITICAL FACTOR THAT TRIGGERS CELL DEDIFFERENTIATION OR REPROGRAMMING IN VIVO. BY CONTRAST, MICROENVIRONMENTAL CHANGES, INCLUDING THE LOSS OF STEM CELLS, HYPOXIA, CELL SENESCENCE, INFLAMMATION AND IMMUNITY, CAUSED BY TISSUE DAMAGE CAN RETURN CELLS TO AN UNSTABLE STATE. IF THE WOUND PERSISTS IN THE LONG?TERM DUE TO CHRONIC DAMAGE, THEN DEDIFFERENTIATION OR REPROGRAMMING OF THE SURROUNDING CELLS MAY LEAD TO CARCINOGENESIS. IN RECENT YEARS, EXTENSIVE RESEARCH HAS BEEN PERFORMED INVESTIGATING CELL DEDIFFERENTIATION OR REPROGRAMMING IN VIVO, WHICH CAN HAVE SIGNIFICANT IMPLICATIONS FOR WOUND REPAIR, TREATMENT AND PREVENTION OF CANCER IN THE FUTURE. THE CURRENT REVIEW SUMMARIZES THE MOLECULAR EVENTS THAT ARE KNOWN TO DRIVE CELL DEDIFFERENTIATION DIRECTLY FOLLOWING TISSUE INJURY AND THE EFFECTS OF EPIGENETIC MODIFICATION ON DEDIFFERENTIATION OR REPROGRAMMING IN VIVO. IN ADDITION, THE PRESENT REVIEW EXPLORES THE INTRACELLULAR MECHANISM OF ENDOGENOUS TISSUE REPAIR AND ITS RELATIONSHIP WITH CANCER, WHICH IS ESSENTIAL FOR BALANCING THE RISK BETWEEN TISSUE REPAIR AND MALIGNANT TRANSFORMATION AFTER INJURY. 2022 20 4154 29 MECHANISTIC ROLES OF EPITHELIAL AND IMMUNE CELL SIGNALING DURING THE DEVELOPMENT OF COLITIS-ASSOCIATED CANCER. TO DATE, SUBSTANTIAL EVIDENCE HAS SHOWN A SIGNIFICANT ASSOCIATION BETWEEN INFLAMMATORY BOWEL DISEASES (IBD) AND DEVELOPMENT OF COLITIS-ASSOCIATED CANCER (CAC). THE INCIDENCE/PREVALENCE OF IBD IS HIGHER IN WESTERN COUNTRIES INCLUDING THE US, AUSTRALIA, AND THE UK. ALTHOUGH CAC DEVELOPMENT IS GENERALLY CHARACTERIZED BY STEPWISE ACCUMULATION OF GENETIC AS WELL AS EPIGENETIC CHANGES, PRECISE MECHANISMS OF HOW CHRONIC INFLAMMATION LEADS TO THE DEVELOPMENT OF CAC ARE LARGELY UNKNOWN. PRECEDING INTESTINAL INFLAMMATION IS ONE OF THE MAJOR INFLUENTIAL FACTORS FOR CAC TUMORIGENESIS. MUCOSAL IMMUNE RESPONSES INCLUDING ACTIVATION OF ABERRANT SIGNALING PATHWAYS BOTH IN INNATE AND ADAPTIVE IMMUNE CELLS PLAY A PIVOTAL ROLE IN CAC. TUMOR PROGRESSION AND METASTASIS ARE SHAPED BY A TIGHTLY CONTROLLED TUMOR MICROENVIRONMENT WHICH IS ORCHESTRATED BY SEVERAL IMMUNE CELLS AND STROMAL CELLS INCLUDING MACROPHAGES, NEUTROPHILS, DENDRITIC CELLS, MYELOID DERIVED SUPPRESSOR CELLS, T CELLS, AND MYOFIBROBLASTS. IN THIS ARTICLE, WE WILL DISCUSS THE CONTRIBUTING FACTORS OF EPITHELIAL AS WELL AS IMMUNE CELL SIGNALING IN INITIATION OF CAC TUMORIGENESIS AND MUCOSAL IMMUNE REGULATORY FACTORS IN THE COLONIC TUMOR MICROENVIRONMENT. IN DEPTH UNDERSTANDING OF THESE FACTORS IS NECESSARY TO DEVELOP NOVEL ANTI-INFLAMMATORY AND ANTI-CANCER THERAPIES FOR CAC IN THE NEAR FUTURE. 2016