1 2786 89 EZH2 RESTRICTS THE SMOOTH MUSCLE LINEAGE DURING MOUSE LUNG MESOTHELIAL DEVELOPMENT. DURING DEVELOPMENT, THE LUNG MESODERM GENERATES A VARIETY OF CELL LINEAGES, INCLUDING AIRWAY AND VASCULAR SMOOTH MUSCLE. EPIGENETIC CHANGES IN ADULT LUNG MESODERMAL LINEAGES ARE THOUGHT TO CONTRIBUTE TOWARDS DISEASES SUCH AS IDIOPATHIC PULMONARY FIBROSIS AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE, ALTHOUGH THE FACTORS THAT REGULATE EARLY LUNG MESODERM DEVELOPMENT ARE UNKNOWN. WE SHOW IN MOUSE THAT THE PRC2 COMPONENT EZH2 IS REQUIRED TO RESTRICT SMOOTH MUSCLE DIFFERENTIATION IN THE DEVELOPING LUNG MESOTHELIUM. MESODERMAL LOSS OF EZH2 LEADS TO THE FORMATION OF ECTOPIC SMOOTH MUSCLE IN THE SUBMESOTHELIAL REGION OF THE DEVELOPING LUNG MESODERM. LOSS OF EZH2 SPECIFICALLY IN THE DEVELOPING MESOTHELIUM REVEALS A MESOTHELIAL CELL-AUTONOMOUS ROLE FOR EZH2 IN REPRESSION OF THE SMOOTH MUSCLE DIFFERENTIATION PROGRAM. LOSS OF EZH2 DEREPRESSES EXPRESSION OF MYOCARDIN AND TBX18, WHICH ARE IMPORTANT REGULATORS OF SMOOTH MUSCLE DIFFERENTIATION FROM THE MESOTHELIUM AND RELATED CELL LINEAGES. TOGETHER, THESE FINDINGS UNCOVER AN EZH2-DEPENDENT MECHANISM TO RESTRICT THE SMOOTH MUSCLE GENE EXPRESSION PROGRAM IN THE DEVELOPING MESOTHELIUM AND ALLOW APPROPRIATE CELL FATE DECISIONS TO OCCUR IN THIS MULTIPOTENT MESODERM LINEAGE. 2016 2 2169 34 EPIGENETIC MECHANISMS IN PARENCHYMAL LUNG DISEASES: BYSTANDERS OR THERAPEUTIC TARGETS? EPIGENETIC RESPONSES DUE TO ENVIRONMENTAL CHANGES ALTER CHROMATIN STRUCTURE, WHICH IN TURN MODIFIES THE PHENOTYPE, GENE EXPRESSION PROFILE, AND ACTIVITY OF EACH CELL TYPE THAT HAS A ROLE IN THE PATHOPHYSIOLOGY OF A DISEASE. PULMONARY DISEASES ARE ONE OF THE MAJOR CAUSES OF DEATH IN THE WORLD, INCLUDING LUNG CANCER, IDIOPATHIC PULMONARY FIBROSIS (IPF), CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), PULMONARY HYPERTENSION (PH), LUNG TUBERCULOSIS, PULMONARY EMBOLISM, AND ASTHMA. SEVERAL LINES OF EVIDENCE INDICATE THAT EPIGENETIC MODIFICATIONS MAY BE ONE OF THE MAIN FACTORS TO EXPLAIN THE INCREASING INCIDENCE AND PREVALENCE OF LUNG DISEASES INCLUDING IPF AND COPD. INTERESTINGLY, ISOLATED FIBROBLASTS AND SMOOTH MUSCLE CELLS FROM PATIENTS WITH PULMONARY DISEASES SUCH AS IPF AND PH THAT WERE CULTURED EX VIVO MAINTAINED THE DISEASE PHENOTYPE. THE CELLS OFTEN SHOW A HYPER-PROLIFERATIVE, APOPTOSIS-RESISTANT PHENOTYPE WITH INCREASED EXPRESSION OF EXTRACELLULAR MATRIX (ECM) AND ACTIVATED FOCAL ADHESIONS SUGGESTING THE PRESENCE OF AN EPIGENETICALLY IMPRINTED PHENOTYPE. MOREOVER, MANY ABNORMALITIES OBSERVED IN MOLECULAR PROCESSES IN IPF PATIENTS ARE SHOWN TO BE EPIGENETICALLY REGULATED, SUCH AS INNATE IMMUNITY, CELLULAR SENESCENCE, AND APOPTOTIC CELL DEATH. DNA METHYLATION, HISTONE MODIFICATION, AND MICRORNA REGULATION CONSTITUTE THE MOST COMMON EPIGENETIC MODIFICATION MECHANISMS. 2022 3 1326 19 DEPLETION OF NUCLEAR HISTONE H2A VARIANTS IS ASSOCIATED WITH CHRONIC DNA DAMAGE SIGNALING UPON DRUG-EVOKED SENESCENCE OF HUMAN SOMATIC CELLS. CELLULAR SENESCENCE IS ASSOCIATED WITH GLOBAL CHROMATIN CHANGES, ALTERED GENE EXPRESSION, AND ACTIVATION OF CHRONIC DNA DAMAGE SIGNALING. THESE EVENTS ULTIMATELY LEAD TO MORPHOLOGICAL AND PHYSIOLOGICAL TRANSFORMATIONS IN PRIMARY CELLS. IN THIS STUDY, WE SHOW THAT CHRONIC DNA DAMAGE SIGNALS CAUSED BY GENOTOXIC STRESS IMPACT THE EXPRESSION OF HISTONES H2A FAMILY MEMBERS AND LEAD TO THEIR DEPLETION IN THE NUCLEI OF SENESCENT HUMAN FIBROBLASTS. OUR DATA REINFORCE THE HYPOTHESIS THAT PROGRESSIVE CHROMATIN DESTABILIZATION MAY LEAD TO THE LOSS OF EPIGENETIC INFORMATION AND IMPAIRED CELLULAR FUNCTION ASSOCIATED WITH CHRONIC DNA DAMAGE UPON DRUG-EVOKED SENESCENCE. WE PROPOSE THAT CHANGES IN THE HISTONE BIOSYNTHESIS AND CHROMATIN ASSEMBLY MAY DIRECTLY CONTRIBUTE TO CELLULAR AGING. IN ADDITION, WE ALSO OUTLINE THE METHOD THAT ALLOWS FOR QUANTITATIVE AND UNBIASED MEASUREMENT OF THESE CHANGES. 2012 4 4111 31 MECHANISMS CONTRIBUTING TO PERSISTENTLY ACTIVATED CELL PHENOTYPES IN PULMONARY HYPERTENSION. CHRONIC PULMONARY HYPERTENSION (PH) IS CHARACTERIZED BY THE ACCUMULATION OF PERSISTENTLY ACTIVATED CELL TYPES IN THE PULMONARY VESSEL EXHIBITING ABERRANT EXPRESSION OF GENES INVOLVED IN APOPTOSIS RESISTANCE, PROLIFERATION, INFLAMMATION AND EXTRACELLULAR MATRIX (ECM) REMODELLING. CURRENT THERAPIES FOR PH, FOCUSING ON VASODILATATION, DO NOT NORMALIZE THESE ACTIVATED PHENOTYPES. FURTHERMORE, CURRENT APPROACHES TO DEFINE ADDITIONAL THERAPEUTIC TARGETS HAVE FOCUSED ON DETERMINING THE INITIATING SIGNALS AND THEIR DOWNSTREAM EFFECTORS THAT ARE IMPORTANT IN PH ONSET AND DEVELOPMENT. ALTHOUGH THESE APPROACHES HAVE PRODUCED A LARGE NUMBER OF COMPELLING PH TREATMENT TARGETS, MANY PROMISING HUMAN DRUGS HAVE FAILED IN PH CLINICAL TRIALS. HEREIN, WE PROPOSE THAT ONE CONTRIBUTING FACTOR TO THESE FAILURES IS THAT PROCESSES IMPORTANT IN PH DEVELOPMENT MAY NOT BE GOOD TREATMENT TARGETS IN THE ESTABLISHED PHASE OF CHRONIC PH. WE HYPOTHESIZE THAT THIS IS DUE TO ALTERATIONS OF CHROMATIN STRUCTURE IN PH CELLS, RESULTING IN FUNCTIONAL DIFFERENCES BETWEEN THE SAME FACTOR OR PATHWAY IN NORMAL OR EARLY PH CELLS VERSUS CELLS IN CHRONIC PH. WE PROPOSE THAT THE HIGH EXPRESSION OF GENES INVOLVED IN THE PERSISTENTLY ACTIVATED PHENOTYPE OF PH VASCULAR CELLS IS PERPETUATED BY AN OPEN CHROMATIN STRUCTURE AND MULTIPLE TRANSCRIPTION FACTORS (TFS) VIA THE RECRUITMENT OF HIGH LEVELS OF EPIGENETIC REGULATORS INCLUDING THE HISTONE ACETYLASES P300/CBP, HISTONE ACETYLATION READERS INCLUDING BRDS, THE MEDIATOR COMPLEX AND THE POSITIVE TRANSCRIPTION ELONGATION FACTOR (ABSTRACT FIGURE). THUS, DETERMINING HOW GENE EXPRESSION IS CONTROLLED BY EXAMINING CHROMATIN STRUCTURE, TFS AND EPIGENETIC REGULATORS ASSOCIATED WITH ABERRANTLY EXPRESSED GENES IN PULMONARY VASCULAR CELLS IN CHRONIC PH, MAY UNCOVER NEW PH THERAPEUTIC TARGETS. 2019 5 4 26 "MIX OF MICS"- PHENOTYPIC AND BIOLOGICAL HETEROGENEITY OF "MULTIPOTENT" MUSCLE INTERSTITIAL CELLS (MICS). THE CAPACITY OF ADULT SKELETAL MUSCLE FOR REGENERATION APPEARS TO BE LIMITED, WITH PROGRESSIVE IMPAIRMENT IN REPAIR EFFICIENCY OF INJURED MUSCLES OBSERVED IN CHRONIC MUSCULAR DISORDERS AND DURING AGING. WHILE SATELLITE CELLS, THE COMMITTED ADULT MUSCLE STEM CELLS, ARE THE MAIN DIRECT CELL SOURCE SUPPORTING THE REGENERATIVE POTENTIAL OF ADULT SKELETAL MUSCLES, THE CHARACTERIZATION OF THE CELL TYPES AND SIGNALS THAT CONSTITUTE THE FUNCTIONAL "NICHE" OF SATELLITE CELLS IS CURRENTLY THE OBJECT OF INTENSE INVESTIGATION. RECENT STUDIES HAVE IDENTIFIED A FUNCTIONAL RELATIONSHIP BETWEEN SATELLITE CELLS AND VARIOUS CELL TYPES LOCATED IN KEY ANATOMICAL POSITION, SUCH AS THE INTERSTITIUM OF SKELETAL MUSCLES. THIS HETEROGENEOUS POPULATION OF MUSCLE INTERSTITIAL CELLS (MICS) APPEARS TO RETAIN AN INTRINSIC MULTIPOTENCY WITHIN THE MESODERMAL LINEAGE, AND THEIR DIRECT OR INDIRECT CONTRIBUTION TO MYOFIBER TURNOVER, REPAIR AND DEGENERATION HAS BEEN SUGGESTED BY MANY STUDIES THAT WILL BE REVIEWED HERE. GIVEN THE EXISTING GAP OF KNOWLEDGE ON LINEAGE IDENTITY AND FUNCTIONAL PROPERTIES OF MICS, THEIR DETAILED CHARACTERIZATION AT THE SINGLE CELL LEVEL HOLDS THE PROMISE TO PROVIDE KEY INSIGHT INTO THE COMPOSITION OF THIS HETEROGENEOUS POPULATION AND THE DYNAMIC TRANSITION THROUGH DISTINCT SUB-POPULATIONS IN HEALTHY, DISEASED AND AGING MUSCLES. THIS REVIEW PROVIDES AN OVERVIEW OF THE RESULTS OF VARIOUS STUDIES DESCRIBING THE PHENOTYPE AND THE FUNCTION OF CELLS ISOLATED FROM SKELETAL MUSCLE INTERSTITIUM, AND DISCUSSES THE IMPORTANCE OF SINGLE CELL TRANSCRIPTION PROFILING IN ORDER TO DECIPHER THE FUNCTIONAL AND PHENOTYPICAL HETEROGENEITY OF MUSCLE INTERSTITIAL CELLS (MICS). 2012 6 2022 31 EPIGENETIC CHANGES ASSOCIATED WITH DISEASE PROGRESSION IN A MOUSE MODEL OF CHILDHOOD ALLERGIC ASTHMA. DEVELOPMENT OF ASTHMA IN CHILDHOOD IS LINKED TO VIRAL INFECTIONS OF THE LOWER RESPIRATORY TRACT IN EARLY LIFE, WITH SUBSEQUENT CHRONIC EXPOSURE TO ALLERGENS. PROGRESSION TO PERSISTENT ASTHMA IS ASSOCIATED WITH A TH2-BIASED IMMUNOLOGICAL RESPONSE AND STRUCTURAL REMODELLING OF THE AIRWAYS. THE UNDERLYING MECHANISMS ARE UNCLEAR, BUT COULD INVOLVE EPIGENETIC CHANGES. TO INVESTIGATE THIS, WE EMPLOYED A RECENTLY DEVELOPED MOUSE MODEL IN WHICH SELF-LIMITED NEONATAL INFECTION WITH A PNEUMOVIRUS, FOLLOWED BY SENSITISATION TO OVALBUMIN VIA THE RESPIRATORY TRACT AND LOW-LEVEL CHRONIC CHALLENGE WITH AEROSOLISED ANTIGEN, LEADS TO DEVELOPMENT OF AN ASTHMATIC PHENOTYPE. WE ASSESSED EXPRESSION OF MICRORNA BY CELLS IN THE PROXIMAL AIRWAYS, COMPARING CHANGES OVER THE PERIOD OF DISEASE PROGRESSION, AND USED TARGET PREDICTION DATABASES TO IDENTIFY GENES LIKELY TO BE UP- OR DOWNREGULATED AS A CONSEQUENCE OF ALTERED REGULATION OF MICRORNA. IN PARALLEL, WE ASSESSED DNA METHYLATION IN PULMONARY CD4(+) T CELLS. WE FOUND THAT A LIMITED NUMBER OF MICRORNAS EXHIBITED MARKED UP- OR DOWNREGULATION FOLLOWING EARLY-LIFE INFECTION AND SENSITISATION, FOR MANY OF WHICH THE LEVELS OF EXPRESSION WERE FURTHER CHANGED FOLLOWING CHRONIC CHALLENGE WITH THE SENSITIZING ANTIGEN. TARGETS OF THESE MICRORNAS INCLUDED GENES INVOLVED IN IMMUNE OR INFLAMMATORY RESPONSES (E.G. GATA3, KITL) AND IN TISSUE REMODELLING (E.G. IGF1, TGFBR1), AS WELL AS GENES FOR VARIOUS TRANSCRIPTION FACTORS AND SIGNALLING PROTEINS. IN PULMONARY CD4(+) T CELLS, THERE WAS SIGNIFICANT DEMETHYLATION AT PROMOTER SITES FOR INTERLEUKIN-4 AND INTERFERON-GAMMA, THE LATTER INCREASING FOLLOWING CHRONIC CHALLENGE. WE CONCLUDE THAT, IN THIS MODEL, PROGRESSION TO AN ASTHMATIC PHENOTYPE IS LINKED TO EPIGENETIC REGULATION OF GENES ASSOCIATED WITH INFLAMMATION AND STRUCTURAL REMODELLING, AND WITH T-CELL COMMITMENT TO A TH2 IMMUNOLOGICAL RESPONSE. EPIGENETIC CHANGES ASSOCIATED WITH THIS PATTERN OF GENE ACTIVATION MIGHT PLAY A ROLE IN THE DEVELOPMENT OF CHILDHOOD ASTHMA. 2013 7 6533 29 TRANSCRIPTIONAL REGULATION OF INFLAMMATORY GENES ASSOCIATED WITH SEVERE ASTHMA. THE 10% OF PATIENTS WITH THE MOST SEVERE ASTHMA ARE RESPONSIBLE FOR A LARGE PART OF HEALTHCARE EXPENDITURE AND MORBIDITY. UNDERSTANDING THE PROCESSES INVOLVED IS KEY IF NEW THERAPEUTIC APPROACHES ARE TO BE DEVELOPED. EVIDENCE IS ACCUMULATING THAT CHRONIC DISEASES SUCH AS ASTHMA ARE ASSOCIATED WITH TEMPORAL AND SPATIAL ALTERATIONS IN THE PATTERN OF INFLAMMATORY GENE EXPRESSION WITHIN THE AIRWAYS. EXPRESSION OF THESE GENES CAN BE REGULATED BY TRANSCRIPTIONAL, POSTTRANSCRIPTIONAL, TRANSLATIONAL AND EPIGENETIC MECHANISMS. IT IS WELL ESTABLISHED THAT BINDING OF ACTIVATED TRANSCRIPTION FACTORS TO SPECIFIC INDUCIBLE GENE PROMOTER SITES IS TIGHTLY CONTROLLED BY CHROMATIN STATE AS A RESULT OF HISTONE MODIFICATIONS, PARTICULARLY THE BALANCE BETWEEN HISTONE ACETYLATION AND DEACETYLATION [1]. THE INTERACTION BETWEEN TRANSCRIPTION FACTORS AND THE PROMOTER IS KEY TO THE DIVERSIFICATION OF GENE EXPRESSION IN A TIME DEPENDENT MANNER LEADING TO ALTERED GENE EXPRESSION PROFILES. ALTERATIONS OF THE ACCESSIBILITY OF TRANSCRIPTION FACTORS TO THE DNA CAN HAVE RESIDING EFFECTS UPON GENE TRANSCRIPTION. THIS REVIEW WILL FOCUS ON THE REGULATION OF SEVERAL GROUPS OF KEY GENES WHICH ARE INVOLVED IN CHRONIC AIRWAY INFLAMMATION AND REMODELLING IN ASTHMA DRAWING MAINLY FROM OUR EXPERIENCE OF STUDYING THESE PROCESSES IN AIRWAY SMOOTH MUSCLE CELLS. AN OVERVIEW IS SHOWN IN FIGURE 1. 2011 8 2914 32 GENE REGULATORY NETWORK UNDERLYING THE IMMORTALIZATION OF EPITHELIAL CELLS. BACKGROUND: TUMORIGENIC TRANSFORMATION OF HUMAN EPITHELIAL CELLS IN VITRO HAS BEEN DESCRIBED EXPERIMENTALLY AS THE POTENTIAL RESULT OF SPONTANEOUS IMMORTALIZATION. THIS PROCESS IS CHARACTERIZED BY A SERIES OF CELL-STATE TRANSITIONS, IN WHICH NORMAL EPITHELIAL CELLS ACQUIRE FIRST A SENESCENT STATE WHICH IS LATER SURPASSED TO ATTAIN A MESENCHYMAL STEM-LIKE PHENOTYPE WITH A POTENTIALLY TUMORIGENIC BEHAVIOR. IN THIS PAPER WE AIM TO PROVIDE A SYSTEM-LEVEL MECHANISTIC EXPLANATION TO THE EMERGENCE OF THESE CELL TYPES, AND TO THE TIME-ORDERED TRANSITION PATTERNS THAT ARE COMMON TO NEOPLASIAS OF EPITHELIAL ORIGIN. TO THIS END, WE FIRST INTEGRATE PUBLISHED FUNCTIONAL AND WELL-CURATED MOLECULAR DATA OF THE COMPONENTS AND INTERACTIONS THAT HAVE BEEN FOUND TO BE INVOLVED IN SUCH CELL STATES AND TRANSITIONS INTO A NETWORK OF 41 MOLECULAR COMPONENTS. WE THEN REDUCE THIS INITIAL NETWORK BY REMOVING SIMPLE MEDIATORS (I.E., LINEAR PATHWAYS), AND FORMALIZE THE RESULTING REGULATORY CORE INTO LOGICAL RULES THAT GOVERN THE DYNAMICS OF EACH OF THE NETWORK COMPONENTS AS A FUNCTION OF THE STATES OF ITS REGULATORS. RESULTS: COMPUTATIONAL DYNAMIC ANALYSIS SHOWS THAT OUR PROPOSED GENE REGULATORY NETWORK MODEL RECOVERS EXACTLY THREE ATTRACTORS, EACH OF THEM DEFINED BY A SPECIFIC GENE EXPRESSION PROFILE THAT CORRESPONDS TO THE EPITHELIAL, SENESCENT, AND MESENCHYMAL STEM-LIKE CELLULAR PHENOTYPES, RESPECTIVELY. WE SHOW THAT ALTHOUGH A MESENCHYMAL STEM-LIKE STATE CAN BE ATTAINED EVEN UNDER UNPERTURBED PHYSIOLOGICAL CONDITIONS, THE LIKELIHOOD OF CONVERGING TO THIS STATE IS INCREASED WHEN PRO-INFLAMMATORY CONDITIONS ARE SIMULATED, PROVIDING A SYSTEMS-LEVEL MECHANISTIC EXPLANATION FOR THE CARCINOGENIC ROLE OF CHRONIC INFLAMMATORY CONDITIONS OBSERVED IN THE CLINIC. WE ALSO FOUND THAT THE REGULATORY CORE YIELDS AN EPIGENETIC LANDSCAPE THAT RESTRICTS TEMPORAL PATTERNS OF PROGRESSION BETWEEN THE STEADY STATES, SUCH THAT RECOVERED PATTERNS RESEMBLE THE TIME-ORDERED TRANSITIONS OBSERVED DURING THE SPONTANEOUS IMMORTALIZATION OF EPITHELIAL CELLS, BOTH IN VIVO AND IN VITRO. CONCLUSION: OUR STUDY STRONGLY SUGGESTS THAT THE IN VITRO TUMORIGENIC TRANSFORMATION OF EPITHELIAL CELLS, WHICH STRONGLY CORRELATES WITH THE PATTERNS OBSERVED DURING THE PATHOLOGICAL PROGRESSION OF EPITHELIAL CARCINOGENESIS IN VIVO, EMERGES FROM UNDERLYING REGULATORY NETWORKS INVOLVED IN EPITHELIAL TRANS-DIFFERENTIATION DURING DEVELOPMENT. 2017 9 2589 26 EPIGENETICS OF PROGRESSION OF CHRONIC KIDNEY DISEASE: FACT OR FANTASY? EPIGENETIC MODIFICATIONS ARE IMPORTANT IN THE NORMAL FUNCTIONING OF THE CELL, FROM REGULATING DYNAMIC EXPRESSION OF ESSENTIAL GENES AND ASSOCIATED PROTEINS TO REPRESSING THOSE THAT ARE UNNEEDED. EPIGENETIC CHANGES ARE ESSENTIAL FOR DEVELOPMENT AND FUNCTIONING OF THE KIDNEY, AND ABERRANT METHYLATION, HISTONE MODIFICATIONS, AND EXPRESSION OF MICRORNA COULD LEAD TO CHRONIC KIDNEY DISEASE (CKD). HERE, EPIGENETIC MODIFICATIONS MODULATE TRANSFORMING GROWTH FACTOR BETA SIGNALING, INFLAMMATION, PROFIBROTIC GENES, AND THE EPITHELIAL-TO-MESENCHYMAL TRANSITION, PROMOTING RENAL FIBROSIS AND PROGRESSION OF CKD. IDENTIFICATION OF THESE EPIGENETIC CHANGES IS IMPORTANT BECAUSE THEY ARE POTENTIALLY REVERSIBLE AND MAY SERVE AS THERAPEUTIC TARGETS IN THE FUTURE TO PREVENT SUBSEQUENT RENAL FIBROSIS AND CKD. IN THIS REVIEW WE DISCUSS THE DIFFERENT TYPES OF EPIGENETIC CONTROL, METHODS TO STUDY EPIGENETIC MODIFICATIONS, AND HOW EPIGENETICS PROMOTES PROGRESSION OF CKD. 2013 10 5292 28 PROSTATIC INFLAMMATION ENHANCES BASAL-TO-LUMINAL DIFFERENTIATION AND ACCELERATES INITIATION OF PROSTATE CANCER WITH A BASAL CELL ORIGIN. CHRONIC INFLAMMATION HAS BEEN SHOWN TO PROMOTE THE INITIATION AND PROGRESSION OF DIVERSE MALIGNANCIES BY INDUCING GENETIC AND EPIGENETIC ALTERATIONS. IN THIS STUDY, WE INVESTIGATE AN ALTERNATIVE MECHANISM THROUGH WHICH INFLAMMATION PROMOTES THE INITIATION OF PROSTATE CANCER. ADULT MURINE PROSTATE EPITHELIA ARE COMPOSED PREDOMINANTLY OF BASAL AND LUMINAL CELLS. PREVIOUS STUDIES REVEALED THAT THE TWO LINEAGES ARE LARGELY SELF-SUSTAINED WHEN RESIDING IN THEIR NATIVE MICROENVIRONMENT. TO INTERROGATE WHETHER TISSUE INFLAMMATION ALTERS THE DIFFERENTIATION PROGRAM OF BASAL CELLS, WE CONDUCTED LINEAGE TRACING OF BASAL CELLS USING A K14-CREER;MTMG MODEL IN CONCERT WITH A MURINE MODEL OF PROSTATITIS INDUCED BY INFECTION FROM THE UROPATHOGENIC BACTERIA CP9. WE SHOW THAT ACUTE PROSTATITIS CAUSES TISSUE DAMAGE AND CREATES A TISSUE MICROENVIRONMENT THAT INDUCES THE DIFFERENTIATION OF BASAL CELLS INTO LUMINAL CELLS, AN ALTERATION THAT RARELY OCCURS UNDER NORMAL PHYSIOLOGICAL CONDITIONS. PREVIOUSLY WE SHOWED THAT A MOUSE MODEL WITH PROSTATE BASAL CELL-SPECIFIC DELETION OF PHOSPHATASE AND TENSIN HOMOLOG (K14-CREER;PTEN(FL/FL)) DEVELOPS PROSTATE CANCER WITH A LONG LATENCY, BECAUSE DISEASE INITIATION IN THIS MODEL REQUIRES AND IS LIMITED BY THE DIFFERENTIATION OF TRANSFORMATION-RESISTANT BASAL CELLS INTO TRANSFORMATION-COMPETENT LUMINAL CELLS. HERE, WE SHOW THAT CP9-INDUCED PROSTATITIS SIGNIFICANTLY ACCELERATES THE INITIATION OF PROSTATIC INTRAEPITHELIAL NEOPLASIA IN THIS MODEL. OUR RESULTS DEMONSTRATE THAT INFLAMMATION RESULTS IN A TISSUE MICROENVIRONMENT THAT ALTERS THE NORMAL PROSTATE EPITHELIAL CELL DIFFERENTIATION PROGRAM AND THAT THROUGH THIS CELLULAR PROCESS INFLAMMATION ACCELERATES THE INITIATION OF PROSTATE CANCER WITH A BASAL CELL ORIGIN. 2014 11 2033 29 EPIGENETIC CHANGES IN SOLID AND HEMATOPOIETIC TUMORS. THERE ARE THREE CONNECTED MOLECULAR MECHANISMS OF EPIGENETIC CELLULAR MEMORY IN MAMMALIAN CELLS: DNA METHYLATION, HISTONE MODIFICATIONS, AND RNA INTERFERENCE. THE FIRST TWO HAVE NOW BEEN FIRMLY LINKED TO NEOPLASTIC TRANSFORMATION. HYPERMETHYLATION OF CPG-RICH PROMOTERS TRIGGERS LOCAL HISTONE CODE MODIFICATIONS RESULTING IN A CELLULAR CAMOUFLAGE MECHANISM THAT SEQUESTERS GENE PROMOTERS AWAY FROM TRANSCRIPTION FACTORS AND RESULTS IN STABLE SILENCING. THIS NORMALLY RESTRICTED MECHANISM IS UBIQUITOUSLY USED IN CANCER TO SILENCE HUNDREDS OF GENES, AMONG WHICH SOME CRITICALLY CONTRIBUTE TO THE NEOPLASTIC PHENOTYPE. VIRTUALLY EVERY PATHWAY IMPORTANT TO CANCER FORMATION IS AFFECTED BY THIS PROCESS. METHYLATION PROFILING OF HUMAN CANCERS REVEALS TISSUE-SPECIFIC EPIGENETIC SIGNATURES, AS WELL AS TUMOR-SPECIFIC SIGNATURES, REFLECTING IN PARTICULAR THE PRESENCE OF EPIGENETIC INSTABILITY IN A SUBSET OF CANCERS AFFECTED BY THE CPG ISLAND METHYLATOR PHENOTYPE. GENERALLY, METHYLATION PATTERNS CAN BE TRACED TO A TISSUE-SPECIFIC, PROLIFERATION-DEPENDENT ACCUMULATION OF ABERRANT PROMOTER METHYLATION IN AGING TISSUES, A PROCESS THAT CAN BE ACCELERATED BY CHRONIC INFLAMMATION AND LESS WELL-DEFINED MECHANISMS INCLUDING, POSSIBLY, DIET AND GENETIC PREDISPOSITION. THE EPIGENETIC MACHINERY CAN ALSO BE ALTERED IN CANCER BY SPECIFIC LESIONS IN EPIGENETIC EFFECTOR GENES, OR BY ABERRANT RECRUITMENT OF THESE GENES BY MUTANT TRANSCRIPTION FACTORS AND COACTIVATORS. EPIGENETIC PATTERNS ARE PROVING CLINICALLY USEFUL IN HUMAN ONCOLOGY VIA RISK ASSESSMENT, EARLY DETECTION, AND PROGNOSTIC CLASSIFICATION. PHARMACOLOGIC MANIPULATION OF THESE PATTERNS-EPIGENETIC THERAPY-IS ALSO POISED TO CHANGE THE WAY WE TREAT CANCER IN THE CLINIC. 2005 12 2933 30 GENESIS OF THE MYOFIBROBLAST IN LUNG INJURY AND FIBROSIS. TISSUE INJURY INCITES A REPAIR RESPONSE WITH A KEY MESENCHYMAL COMPONENT THAT PROVIDES THE ESSENTIAL CONNECTIVE TISSUE FOR SUBSEQUENT REGENERATION OR PATHOLOGICAL FIBROSIS. THE FIBROBLAST IS THE MAJOR MESENCHYMAL CELL TYPE TO BE IMPLICATED IN THIS CONNECTIVE TISSUE RESPONSE, AND IT IS IN ITS ACTIVATED OR DIFFERENTIATED FORM THAT IT PARTICIPATES IN THE REPAIR PROCESS. THE MYOFIBROBLAST REPRESENTS SUCH AN ACTIVATED MESENCHYMAL CELL AND IS A KEY SOURCE OF EXTRACELLULAR MATRIX AND INFLAMMATORY/FIBROGENIC CYTOKINES AS WELL AS PARTICIPATING IN WOUND CONTRACTION. ALTHOUGH SUCCESSFUL HEALING RESULTS IN GRADUAL DISAPPEARANCE OF MYOFIBROBLASTS, THEIR PERSISTENCE IS ASSOCIATED WITH CHRONIC AND PROGRESSIVE FIBROSIS. THUS, ELUCIDATION OF THE MECHANISM INVOLVED IN THE GENESIS OF THE MYOFIBROBLAST SHOULD PROVIDE INSIGHT INTO BOTH PATHOGENESIS OF CHRONIC FIBROTIC DISEASES AND THERAPEUTIC STRATEGIES FOR THEIR MANAGEMENT AND CONTROL. ALTHOUGH THE FIBROBLAST IS A WELL-DOCUMENTED PROGENITOR CELL FOR THE MYOFIBROBLAST, RECENT STUDIES HAVE SUGGESTED ADDITIONAL PRECURSOR CELLS THAT HAVE THE POTENTIAL TO GIVE RISE TO THE MYOFIBROBLAST. MANY OF THE STUDIES FOCUSED ON MECHANISMS AND FACTORS THAT REGULATE INDUCTION OF ALPHA-SMOOTH MUSCLE ACTIN EXPRESSION, A KEY AND COMMONLY USED MARKER OF THE MYOFIBROBLAST. THESE REVEAL COMPLEX AND MULTIFACTORIAL MECHANISMS INVOLVING TRANSCRIPTIONAL AND EPIGENETIC REGULATION AND IMPLICATING DIVERSE CELL-SIGNALING PATHWAYS, INCLUDING THOSE ACTIVATED BY THE POTENT FIBROGENIC CYTOKINE TRANSFORMING GROWTH FACTOR BETA. DESPITE THESE EXTENSIVE STUDIES, MANY ASPECTS REMAIN POORLY UNDERSTOOD, WITH THE SUGGESTION THAT ADDITIONAL NOVEL MECHANISMS REMAIN TO BE DISCOVERED. FUTURE STUDIES WITH THE HELP OF NEWLY DEVELOPED TECHNICAL ADVANCEMENTS SHOULD EXPEDITE DISCOVERY IN THIS DIRECTION. 2012 13 2055 27 EPIGENETIC CONTROL DURING LYMPHOID DEVELOPMENT AND IMMUNE RESPONSES: ABERRANT REGULATION, VIRUSES, AND CANCER. METHYLATION OF CYTOSINES CONTROLS A NUMBER OF BIOLOGIC PROCESSES SUCH AS IMPRINTING AND X CHROMOSOMAL INACTIVATION. DNA HYPERMETHYLATION IS CLOSELY ASSOCIATED WITH TRANSCRIPTIONAL SILENCING, WHILE DNA HYPOMETHYLATION IS ASSOCIATED WITH TRANSCRIPTIONAL ACTIVATION. HYPOACETYLATION OF HISTONES LEADS TO COMPACT CHROMATIN WITH REDUCED ACCESSIBILITY TO THE TRANSCRIPTIONAL MACHINERY. METHYL-CPG BINDING PROTEINS CAN RECRUIT COREPRESSORS AND HISTONE DEACETYLASES; THUS, THE INTERPLAY BETWEEN THESE EPIGENETIC MECHANISMS REGULATES GENE ACTIVATION. METHYLATION HAS BEEN IMPLICATED AS AN IMPORTANT MECHANISM DURING IMMUNE DEVELOPMENT, CONTROLLING VDJ RECOMBINATION, LINEAGE-SPECIFIC EXPRESSION OF CELL SURFACE ANTIGENS, AND TRANSCRIPTIONAL REGULATION OF CYTOKINE GENES DURING IMMUNE RESPONSES. ABERRATIONS IN EPIGENETIC MACHINERY, EITHER BY GENETIC MUTATIONS OR BY SOMATIC CHANGES SUCH AS VIRAL INFECTIONS, ARE ASSOCIATED WITH EARLY ALTERATIONS IN CHRONIC DISEASES SUCH AS IMMUNODEFICIENCY AND CANCER. 2003 14 4164 25 MEDIATORS OF CAPILLARY-TO-VENULE CONVERSION IN THE CHRONIC INFLAMMATORY SKIN DISEASE PSORIASIS. PSORIASIS IS A CHRONIC INFLAMMATORY SKIN DISEASE CHARACTERIZED BY EPIDERMAL HYPERPLASIA AND HYPERKERATOSIS, IMMUNE CELL INFILTRATION AND VASCULAR REMODELING. DESPITE THE EMERGING RECOGNITION OF VASCULAR NORMALIZATION AS A POTENTIAL STRATEGY FOR MANAGING PSORIASIS, AN IN-DEPTH DELINEATION OF THE REMODELED DERMAL VASCULATURE HAS BEEN MISSING. IN THIS STUDY, WE EXPLOITED 5' SINGLE-CELL RNA SEQUENCING TO INVESTIGATE THE TRANSCRIPTOMIC ALTERATIONS IN DIFFERENT SUBPOPULATIONS OF BLOOD VASCULAR AND LYMPHATIC ENDOTHELIAL CELLS DIRECTLY ISOLATED FROM PSORIATIC AND HEALTHY HUMAN SKIN. INDIVIDUAL SUBTYPES OF ENDOTHELIAL CELLS UNDERWENT SPECIFIC MOLECULAR REPATTERNING ASSOCIATED WITH CELL ADHESION AND EXTRACELLULAR MATRIX ORGANIZATION. BLOOD CAPILLARIES, IN PARTICULAR, SHOWED UPREGULATION OF THE MELANOMA CELL ADHESION MOLECULE AS WELL AS ITS BINDING PARTNERS AND ADOPTED POSTCAPILLARY VENULE?LIKE CHARACTERISTICS DURING CHRONIC INFLAMMATION THAT ARE MORE PERMISSIVE TO LEUKOCYTE TRANSMIGRATION. WE ALSO IDENTIFIED PSORIASIS-SPECIFIC INTERACTIONS BETWEEN CIS-REGULATORY ENHANCERS AND PROMOTERS FOR EACH ENDOTHELIAL CELL SUBTYPE, REVEALING THE DYSREGULATED GENE REGULATORY NETWORKS IN PSORIASIS. TOGETHER, OUR RESULTS PROVIDE MORE INSIGHTS INTO THE SPECIFIC TRANSCRIPTIONAL RESPONSES AND EPIGENETIC SIGNATURES OF ENDOTHELIAL CELLS LINING DIFFERENT VESSEL COMPARTMENTS IN CHRONIC SKIN INFLAMMATION. 2022 15 4738 29 NOVEL FIBROBLAST PHENOTYPES IN HOMEOSTASIS AND CHRONIC INFLAMMATION: FROM FUNCTIONS TO POTENTIAL REGULATORS. FIBROBLASTS ARE ESSENTIAL COMPONENTS OF THE STROMA, SUSTAINING A VARIETY OF TISSUES AND BEING KEY TO THE PROCESS OF TISSUE REPAIR AFTER INJURY. THEIR ROLE IN TISSUE REPAIR HAS BEEN ATTRIBUTED TO THEIR ABILITY TO ACQUIRE A CONTRACTILE, EXTRACELLULAR MATRIX-PRODUCING PHENOTYPE KNOWN AS MYOFIBROBLASTS. THIS PROPERTY IS PRIMARILY DEPENDENT ON THEIR RESPONSE TO THE PLEIOTROPIC CYTOKINE TRANSFORMING GROWTH FACTOR-BETA1. UNTIL RECENTLY, THE POTENTIAL ROLE OF FIBROBLASTS IN OTHER HOMEOSTATIC AND DISEASE-RELATED PROCESSES WAS LESS WELL UNDERSTOOD. ALTHOUGH IN VITRO STUDIES INDICATED THAT FIBROBLASTS ARE ABLE TO RESPOND TO AND SECRETE INFLAMMATORY MEDIATORS, DEFINITIVE EVIDENCE OF THEIR CONTRIBUTION TO CHRONIC INFLAMMATION WAS LIMITED. HOWEVER, THE EMERGENCE OF TECHNIQUES THAT ALLOW EXPLORATION OF TISSUES AT THE SINGLE CELL LEVEL HAS CHALLENGED THE PREVIOUS PARADIGMS ON FIBROBLAST IDENTITY AND FUNCTIONS, AND HAS LED TO THE DISCOVERY OF SIGNIFICANT DIVERSITY, SHOWING THE PRESENCE OF FIBROBLASTS WITH ALTERNATE TRANSCRIPTIONAL PROFILES IN A VARIETY OF TISSUES. THESE STUDIES HAVE ALSO SUGGESTED POTENTIAL ROLES OF NOVEL FIBROBLAST SUBTYPES AS REGULATORS OF EPITHELIAL HOMEOSTASIS AND RENEWAL, INFLAMMATORY CELL INFILTRATION AND ACTIVATION, AND ANTIGEN PRESENTATION. HERE, WE PROVIDE A COMPREHENSIVE REVIEW OF THE RECENT LITERATURE ON FIBROBLAST DIVERSITY IN THE DIGESTIVE TRACT, SKIN, LUNGS AND JOINTS. WE ALSO REVIEW EVIDENCE OF THEIR CONTRIBUTION TO THE REGULATION OF HOMEOSTASIS AND CHRONIC INFLAMMATION, AS WELL AS THEIR INTERACTIONS WITH OTHER CELLS IN VARIOUS TISSUE COMPARTMENTS. WE DISCUSS EVIDENCE OF DIFFERENT FACTORS INVOLVED IN THE CONTROL OF FIBROBLAST FUNCTION, ADDRESSING THE ROLE OF VARIOUS CYTOKINES, TRANSCRIPTION FACTORS AND EPIGENETIC CHANGES, AS WELL AS MICROENVIRONMENTAL FACTORS, INCLUDING EXTRACELLULAR MATRIX STIFFNESS, HYPOXIA, AND METABOLIC SHIFTS. 2023 16 172 29 ABSENCE OF HDAC3 BY MATRIX STIFFNESS PROMOTES CHROMATIN REMODELING AND FIBROBLAST ACTIVATION IN IDIOPATHIC PULMONARY FIBROSIS. IDIOPATHIC PULMONARY FIBROSIS (IPF) IS A CHRONIC AND FATAL DISEASE CHARACTERIZED BY PROGRESSIVE AND IRREVERSIBLE LUNG SCARRING ASSOCIATED WITH PERSISTENT ACTIVATION OF FIBROBLASTS. EPIGENETICS COULD INTEGRATE DIVERSE MICROENVIRONMENTAL SIGNALS, SUCH AS STIFFNESS, TO DIRECT PERSISTENT FIBROBLAST ACTIVATION. HISTONE MODIFICATIONS BY DEACETYLASES (HDAC) MAY PLAY AN ESSENTIAL ROLE IN THE GENE EXPRESSION CHANGES INVOLVED IN THE PATHOLOGICAL REMODELING OF THE LUNG. PARTICULARLY, HDAC3 IS CRUCIAL FOR MAINTAINING CHROMATIN AND REGULATING GENE EXPRESSION, BUT LITTLE IS KNOWN ABOUT ITS ROLE IN IPF. IN THE STUDY, CONTROL AND IPF-DERIVED FIBROBLASTS WERE USED TO DETERMINE THE INFLUENCE OF HDAC3 ON CHROMATIN REMODELING AND GENE EXPRESSION ASSOCIATED WITH IPF SIGNATURE. ADDITIONALLY, THE CELLS WERE GROWN ON HYDROGELS TO MIMIC THE STIFFNESS OF A FIBROTIC LUNG. OUR RESULTS SHOWED A DECREASED HDAC3 IN THE NUCLEUS OF IPF FIBROBLASTS, WHICH CORRELATES WITH CHANGES IN NUCLEUS SIZE AND HETEROCHROMATIN LOSS. THE INHIBITION OF HDAC3 WITH A PHARMACOLOGICAL INHIBITOR CAUSES HYPERACETYLATION OF H3K9 AND PROVOKES AN INCREASED EXPRESSION OF COL1A1, ACTA2, AND P21. COMPARABLE RESULTS WERE FOUND IN HYDROGELS, WHERE MATRIX STIFFNESS PROMOTES THE LOSS OF NUCLEAR HDAC3 AND INCREASES THE PROFIBROTIC SIGNATURE. FINALLY, LATRUNCULIN B WAS USED TO CONFIRM THAT CHANGES BY STIFFNESS DEPEND ON THE MECHANOTRANSDUCTION SIGNALS. TOGETHER, THESE RESULTS SUGGEST THAT HDAC3 COULD BE A LINK BETWEEN EPIGENETIC MECHANISMS AND THE FIBROTIC MICROENVIRONMENT. 2023 17 2566 34 EPIGENETICS MECHANISMS IN RENAL DEVELOPMENT. APPRECIATION FOR THE ROLE OF EPIGENETIC MODIFICATIONS IN THE DIAGNOSIS AND TREATMENT OF DISEASES IS FAST GAINING ATTENTION. TREATMENT OF CHRONIC KIDNEY DISEASE STEMMING FROM DIABETES OR HYPERTENSION AS WELL AS WILMS TUMOR WILL ALL PROFIT FROM KNOWLEDGE OF THE CHANGES IN THE EPIGENOMIC LANDSCAPES. TO DO SO, IT IS ESSENTIAL TO CHARACTERIZE THE EPIGENOMIC MODIFIERS AND THEIR MODIFICATIONS UNDER NORMAL PHYSIOLOGICAL CONDITIONS. THE TRANSCRIPTION FACTOR PAX2 WAS IDENTIFIED AS A MAJOR EPIGENETIC PLAYER IN THE EARLY SPECIFICATION OF THE KIDNEY. NOTABLY, THE PROGENITORS OF ALL NEPHRONS THAT RESIDE IN THE CAP MESENCHYME DISPLAY A UNIQUE BIVALENT HISTONE SIGNATURE (EXPRESSING REPRESSIVE EPIGENETIC MARKS ALONGSIDE ACTIVATION MARKS) ON LINEAGE-SPECIFIC GENES. THESE CELLS ARE DEEMED POISED FOR DIFFERENTIATION AND COMMITMENT TO THE NEPHROGENIC LINEAGE. IN RESPONSE TO THE APPROPRIATE INDUCING SIGNAL, THESE GENES LOSE THEIR REPRESSIVE HISTONE MARKS, WHICH ALLOW FOR THEIR EXPRESSION IN NASCENT NEPHRON PRECURSORS. SUCH KNOWLEDGE OF THE EPIGENETIC LANDSCAPE AND THE RESULTANT CELL FATE OR BEHAVIOR IN THE DEVELOPING KIDNEY WILL GREATLY IMPROVE THE OVERALL SUCCESS IN DESIGNING REGENERATIVE STRATEGIES AND TISSUE REPROGRAMMING METHODOLOGIES FROM PLURIPOTENT CELLS. 2016 18 3772 32 INTERACTION BETWEEN MICRORNA AND DNA METHYLATION IN ATHEROSCLEROSIS. ATHEROSCLEROSIS (AS) IS A CHRONIC INFLAMMATORY DISEASE ACCOMPANIED BY COMPLEX PATHOLOGICAL CHANGES, SUCH AS ENDOTHELIAL DYSFUNCTION, FOAM CELL FORMATION, AND VASCULAR SMOOTH MUSCLE CELL PROLIFERATION. MANY APPROACHES, INCLUDING REGULATING AS-RELATED GENE EXPRESSION IN THE TRANSCRIPTIONAL OR POST-TRANSCRIPTIONAL LEVEL, CONTRIBUTE TO ALLEVIATING AS DEVELOPMENT. THE DNA METHYLATION IS A CRUCIAL EPIGENETIC MODIFICATION IN REGULATING CELL FUNCTION BY SILENCING THE RELATIVE GENE EXPRESSION. THE MICRORNA (MIRNA) IS A TYPE OF NONCODING RNA THAT PLAYS AN IMPORTANT ROLE IN GENE POST-TRANSCRIPTIONAL REGULATION AND DISEASE DEVELOPMENT. THE DNA METHYLATION AND THE MIRNA ARE IMPORTANT EPIGENETIC FACTORS IN AS. HOWEVER, RECENT STUDIES HAVE FOUND A MUTUAL REGULATION BETWEEN THESE TWO FACTORS IN AS DEVELOPMENT. IN THIS STUDY, RECENT INSIGHTS INTO THE ROLES OF MIRNA AND DNA METHYLATION AND THEIR INTERACTION IN THE AS PROGRESSION ARE REVIEWED. 2021 19 2541 28 EPIGENETICS IN KIDNEY DEVELOPMENT AND RENAL DISEASE. THE STUDY OF EPIGENETICS IS INTIMATELY LINKED AND INSEPARABLE FROM DEVELOPMENTAL BIOLOGY. MANY OF THE GENES THAT IMPRINT EPIGENETIC INFORMATION ON CHROMATIN FUNCTION DURING THE SPECIFICATION OF CELL LINEAGES IN THE DEVELOPING EMBRYO. THESE INCLUDE THE HISTONE METHYLTRANSFERASES AND THEIR COFACTORS OF THE POLYCOMB AND TRITHORAX GENE FAMILIES. HOW HISTONE METHYLATION IS ESTABLISHED AND WHAT REGULATES THE TISSUE AND LOCUS SPECIFICITY OF HISTONE METHYLATION IS AN EMERGING AREA OF RESEARCH. THE EMBRYONIC KIDNEY IS USED AS A MODEL TO UNDERSTAND HOW DNA-BINDING PROTEINS CAN SPECIFY CELL LINEAGES AND HOW SUCH PROTEINS INTERACT DIRECTLY WITH THE HISTONE METHYLATION MACHINERY TO GENERATE A UNIQUE EPIGENOME FOR PARTICULAR TISSUES AND CELL TYPES. IN ADULT TISSUES, HISTONE METHYLATION MARKS MUST BE MAINTAINED FOR NORMAL GENE EXPRESSION PATTERNS. IN CHRONIC AND ACUTE RENAL DISEASE, EPIGENETIC MARKS ARE BEING CHARACTERIZED AND CORRELATED WITH THE ESTABLISHMENT OF METABOLIC MEMORY, IN PART TO EXPLAIN THE PERSISTENCE OF PATHOLOGIES EVEN WHEN OPTIMAL TREATMENT MODALITIES ARE USED. THUS, THE STATE OF THE EPIGENOME IN ADULT CELLS MUST BE CONSIDERED WHEN ATTEMPTING TO ALLEVIATE OR ALTER GENE EXPRESSION PATTERNS IN DISEASE. 2015 20 6151 23 THE FIRE WITHIN: CELL-AUTONOMOUS MECHANISMS IN INFLAMMATION-DRIVEN CANCER. INFLAMMATORY CELLS ARE IMPORTANT FOR TUMOR INITIATION AND PROMOTION, PROVIDING CANCER CELLS WITH CYTOKINES THAT ENHANCE CELL PROLIFERATION AND SURVIVAL. ALTHOUGH MALIGNANT EPITHELIAL CELLS WERE TRADITIONALLY CONSIDERED TO BE ON THE RECEIVING END OF THESE MICROENVIRONMENTAL INTERACTIONS, RECENT STUDIES SHOW THAT EPITHELIAL CELLS CAN UNDERGO INFLAMMATORY REPROGRAMMING ON THEIR OWN. SUCH EPIGENETIC SWITCHES ARE OFTEN TRIGGERED BY CHRONIC TISSUE INJURY AND PLAY IMPORTANT ROLES IN TISSUE REPAIR. BY CONVERTING TERMINALLY DIFFERENTIATED CELLS THAT HARBOR EVEN A SINGLE ONCOGENIC MUTATION TO A LESS DIFFERENTIATED STATE WITH A HIGHER PROLIFERATIVE POTENTIAL, CELL-AUTONOMOUS INFLAMMATION IS AN IMPORTANT CONTRIBUTOR TO TUMOR INITIATION. 2019