1 4267 126 MICROARRAY DATASET OF TRANSIENT AND PERMANENT DNA METHYLATION CHANGES IN HELA CELLS UNDERGOING INORGANIC ARSENIC-MEDIATED EPITHELIAL-TO-MESENCHYMAL TRANSITION. THE NOVEL DATASET PRESENTED HERE REPRESENTS THE RESULTS OF THE CHANGING PATTERN OF DNA METHYLATION PROFILES IN HELA CELLS EXPOSED TO CHRONIC LOW DOSE (0.5 MICROM) SODIUM ARSENITE, RESULTING IN EPITHELIAL-TO-MESENCHYMAL TRANSITION, AS WELL AS DNA METHYLATION PATTERNS IN CELLS WHERE INORGANIC ARSENIC HAS BEEN REMOVED. INORGANIC ARSENIC IS A KNOWN CARCINOGEN, THOUGH NOT MUTAGENIC. SEVERAL MECHANISMS HAVE BEEN PROPOSED AS TO HOW INORGANIC ARSENIC DRIVES CARCINOGENESIS SUCH AS REGULATION OF THE CELL?S REDOX POTENTIAL AND/OR EPIGENETICS. IN FACT, THERE ARE GENE SPECIFIC STUDIES AND LIMITED GENOME-WIDE STUDIES THAT HAVE IMPLICATED EPIGENETIC FACTORS SUCH AS DNA METHYLATION IN INORGANIC ARSENIC-MEDIATED EPITHELIAL-TO-MESENCHYMAL TRANSITION (EMT). HOWEVER, GENOME-WIDE STUDIES ABOUT THE IMPACT OF 1) CHRONIC, LOW-DOSE INORGANIC ARSENIC EXPOSURE ON DNA METHYLATION PATTERNS DURING INORGANIC ARSENIC-INDUCED EPITHELIAL-TO-MESENCHYMAL TRANSITION, AND 2) THE REMOVAL INORGANIC ARSENIC (REVERSAL) ON DNA METHYLATION PATTERNS, IS LACKING. FOR THIS DATASET, TWO REPLICATES WERE PERFORMED WITH EACH OF THE SAMPLES - NON-TREATED, INORGANIC ARSENIC-TREATED, AND REVERSE-TREATED CELLS. WE PROVIDE NORMALIZED AND PROCESSED DATA, AND LOG2 FOLD CHANGE IN DNA METHYLATION. THE RAW MICROARRAY DATA ARE AVAILABLE THROUGH NCBI GEO, ACCESSION NUMBER GSE95232 AND A RELATED RESEARCH PAPER HAS BEEN ACCEPTED FOR PUBLISHED IN TOXICOLOGY AND APPLIED PHARMACOLOGY (ECKSTEIN ET AL., 2017) [1]. 2017 2 480 30 ARSENIC-INDUCED CARCINOGENESIS: THE IMPACT OF MIRNA DYSREGULATION. ARSENIC IS A TOXIC METALLOID WIDELY PRESENT IN THE EARTH'S CRUST, AND IS A PROVEN HUMAN CARCINOGEN. CHRONIC ARSENIC EXPOSURE MAINLY THROUGH DRINKING WATER CAUSES SKIN, LUNG, AND URINARY BLADDER CANCERS, AND IS ASSOCIATED WITH LIVER, PROSTATE, AND KIDNEY CANCERS, CARDIOVASCULAR AND NEUROLOGICAL DISORDERS, AND DIABETES. SEVERAL MODES OF ACTION HAVE BEEN SUGGESTED IN ARSENIC CARCINOGENESIS. HOWEVER, THE MOLECULAR ETIOLOGY OF ARSENIC-INDUCED CANCER REMAINS UNCLEAR. RECENT EVIDENCE CLEARLY INDICATES THAT GENE EXPRESSION MODIFICATIONS INDUCED BY ARSENIC MAY INVOLVE EPIGENETIC ALTERATIONS, INCLUDING MIRNA DYSREGULATION. MANY MIRNAS HAVE BEEN IMPLICATED IN DIFFERENT HUMAN CANCERS AS A CONSEQUENCE OF LOSSES AND OR GAINS OF MIRNA FUNCTION THAT CONTRIBUTE TO CANCER DEVELOPMENT. PROGRESS IN IDENTIFYING MIRNA DYSREGULATION INDUCED BY ARSENIC HAS BEEN MADE USING DIFFERENT APPROACHES AND MODELS. THE PRESENT REVIEW DISCUSSES THE RECENT DATA REGARDING DYSREGULATED EXPRESSION OF MIRNA IN ARSENIC-INDUCED MALIGNANT TRANSFORMATION IN VITRO, GAPS IN CURRENT UNDERSTANDING AND DEFICIENCIES IN CURRENT MODELS FOR ARSENIC-INDUCED CARCINOGENESIS, AND FUTURE DIRECTIONS OF RESEARCH THAT WOULD IMPROVE OUR KNOWLEDGE REGARDING THE MECHANISMS INVOLVED IN ARSENIC-INDUCED CARCINOGENESIS. 2018 3 4840 30 ONCOGENOMIC DISRUPTIONS IN ARSENIC-INDUCED CARCINOGENESIS. CHRONIC EXPOSURE TO ARSENIC AFFECTS MORE THAN 200 MILLION PEOPLE WORLDWIDE, AND HAS BEEN ASSOCIATED WITH MANY ADVERSE HEALTH EFFECTS, INCLUDING CANCER IN SEVERAL ORGANS. THERE IS ACCUMULATING EVIDENCE THAT ARSENIC BIOTRANSFORMATION, A STEP IN THE ELIMINATION OF ARSENIC FROM THE HUMAN BODY, CAN INDUCE CHANGES AT A GENETIC AND EPIGENETIC LEVEL, LEADING TO CARCINOGENESIS. AT THE GENETIC LEVEL, ARSENIC INTERFERES WITH KEY CELLULAR PROCESSES SUCH AS DNA DAMAGE-REPAIR AND CHROMOSOMAL STRUCTURE, LEADING TO GENOMIC INSTABILITY. AT THE EPIGENETIC LEVEL, ARSENIC PLACES A HIGH DEMAND ON THE CELLULAR METHYL POOL, LEADING TO GLOBAL HYPOMETHYLATION AND HYPERMETHYLATION OF SPECIFIC GENE PROMOTERS. THESE ARSENIC-ASSOCIATED DNA ALTERATIONS RESULT IN THE DEREGULATION OF BOTH ONCOGENIC AND TUMOUR-SUPPRESSIVE GENES. FURTHERMORE, RECENT REPORTS HAVE IMPLICATED ABERRANT EXPRESSION OF NON-CODING RNAS AND THE CONSEQUENTIAL DISRUPTION OF SIGNALING PATHWAYS IN THE CONTEXT OF ARSENIC-INDUCED CARCINOGENESIS. THIS ARTICLE PROVIDES AN OVERVIEW OF THE ONCOGENOMIC ANOMALIES ASSOCIATED WITH ARSENIC EXPOSURE AND CONVEYS THE IMPORTANCE OF NON-CODING RNAS IN THE ARSENIC-INDUCED CARCINOGENIC PROCESS. 2017 4 474 24 ARSENIC BIOTRANSFORMATION AS A CANCER PROMOTING FACTOR BY INDUCING DNA DAMAGE AND DISRUPTION OF REPAIR MECHANISMS. CHRONIC EXPOSURE TO ARSENIC IN DRINKING WATER POSES A MAJOR GLOBAL HEALTH CONCERN. POPULATIONS EXPOSED TO HIGH CONCENTRATIONS OF ARSENIC-CONTAMINATED DRINKING WATER SUFFER SERIOUS HEALTH CONSEQUENCES, INCLUDING ALARMING CANCER INCIDENCE AND DEATH RATES. ARSENIC IS BIOTRANSFORMED THROUGH SEQUENTIAL ADDITION OF METHYL GROUPS, ACQUIRED FROM S-ADENOSYLMETHIONINE (SAM). METABOLISM OF ARSENIC GENERATES A VARIETY OF GENOTOXIC AND CYTOTOXIC SPECIES, DAMAGING DNA DIRECTLY AND INDIRECTLY, THROUGH THE GENERATION OF REACTIVE OXIDATIVE SPECIES AND INDUCTION OF DNA ADDUCTS, STRAND BREAKS AND CROSS LINKS, AND INHIBITION OF THE DNA REPAIR PROCESS ITSELF. SINCE SAM IS THE METHYL GROUP DONOR USED BY DNA METHYLTRANSFERASES TO MAINTAIN NORMAL EPIGENETIC PATTERNS IN ALL HUMAN CELLS, ARSENIC IS ALSO POSTULATED TO AFFECT MAINTENANCE OF NORMAL DNA METHYLATION PATTERNS, CHROMATIN STRUCTURE, AND GENOMIC STABILITY. THE BIOLOGICAL PROCESSES UNDERLYING THE CANCER PROMOTING FACTORS OF ARSENIC METABOLISM, RELATED TO DNA DAMAGE AND REPAIR, WILL BE DISCUSSED HERE. 2011 5 1917 40 ENVIRONMENTAL ARSENIC EXPOSURE: FROM GENETIC SUSCEPTIBILITY TO PATHOGENESIS. MORE THAN 200 MILLION PEOPLE IN 70 COUNTRIES ARE EXPOSED TO ARSENIC THROUGH DRINKING WATER. CHRONIC EXPOSURE TO THIS METALLOID HAS BEEN ASSOCIATED WITH THE ONSET OF MANY DISEASES, INCLUDING CANCER. EPIDEMIOLOGICAL EVIDENCE SUPPORTS ITS CARCINOGENIC POTENTIAL, HOWEVER, DETAILED MOLECULAR MECHANISMS REMAIN TO BE ELUCIDATED. DESPITE THE GLOBAL MAGNITUDE OF THIS PROBLEM, NOT ALL INDIVIDUALS FACE THE SAME RISK. SUSCEPTIBILITY TO THE TOXIC EFFECTS OF ARSENIC IS INFLUENCED BY ALTERATIONS IN GENES INVOLVED IN ARSENIC METABOLISM, AS WELL AS BIOLOGICAL FACTORS, SUCH AS AGE, GENDER AND NUTRITION. MOREOVER, CHRONIC ARSENIC EXPOSURE RESULTS IN SEVERAL GENOTOXIC AND EPIGENETIC ALTERATIONS TIGHTLY ASSOCIATED WITH THE ARSENIC BIOTRANSFORMATION PROCESS, RESULTING IN AN INCREASED CANCER RISK. IN THIS REVIEW, WE: 1) REVIEW THE ROLES OF INTER-INDIVIDUAL DNA-LEVEL VARIATIONS INFLUENCING THE SUSCEPTIBILITY TO ARSENIC-INDUCED CARCINOGENESIS; 2) DISCUSS THE CONTRIBUTION OF ARSENIC BIOTRANSFORMATION TO CANCER INITIATION; 3) PROVIDE INSIGHTS INTO EMERGING RESEARCH AREAS AND THE CHALLENGES IN THE FIELD; AND 4) COMPILE A RESOURCE OF PUBLICLY AVAILABLE ARSENIC-RELATED DNA-LEVEL VARIATIONS, TRANSCRIPTOME AND METHYLATION DATA. UNDERSTANDING THE MOLECULAR MECHANISMS OF ARSENIC EXPOSURE AND ITS SUBSEQUENT HEALTH EFFECTS WILL SUPPORT EFFORTS TO REDUCE THE WORLDWIDE HEALTH BURDEN AND ENCOURAGE THE DEVELOPMENT OF STRATEGIES FOR MANAGING ARSENIC-RELATED DISEASES IN THE ERA OF PERSONALIZED MEDICINE. 2018 6 6562 51 TRANSIENT AND PERMANENT CHANGES IN DNA METHYLATION PATTERNS IN INORGANIC ARSENIC-MEDIATED EPITHELIAL-TO-MESENCHYMAL TRANSITION. CHRONIC LOW DOSE INORGANIC ARSENIC EXPOSURE CAUSES CELLS TO TAKE ON AN EPITHELIAL-TO-MESENCHYMAL PHENOTYPE, WHICH IS A CRUCIAL PROCESS IN CARCINOGENESIS. INORGANIC ARSENIC IS NOT A MUTAGEN AND THUS EPIGENETIC ALTERATIONS HAVE BEEN IMPLICATED IN THIS PROCESS. INDEED, DURING THE EPITHELIAL-TO-MESENCHYMAL TRANSITION, MORPHOLOGIC CHANGES TO CELLS CORRELATE WITH CHANGES IN CHROMATIN STRUCTURE AND GENE EXPRESSION, ULTIMATELY DRIVING THIS PROCESS. HOWEVER, STUDIES ON THE EFFECTS OF INORGANIC ARSENIC EXPOSURE/WITHDRAWAL ON THE EPITHELIAL-TO-MESENCHYMAL TRANSITION AND THE IMPACT OF EPIGENETIC ALTERATIONS IN THIS PROCESS ARE LIMITED. IN THIS STUDY WE USED HIGH-RESOLUTION MICROARRAY ANALYSIS TO MEASURE THE CHANGES IN DNA METHYLATION IN CELLS UNDERGOING INORGANIC ARSENIC-INDUCED EPITHELIAL-TO-MESENCHYMAL TRANSITION, AND ON THE REVERSAL OF THIS PROCESS, AFTER REMOVAL OF THE INORGANIC ARSENIC EXPOSURE. WE FOUND THAT CELLS EXPOSED TO CHRONIC, LOW-DOSE INORGANIC ARSENIC EXPOSURE SHOWED 30,530 SITES WERE DIFFERENTIALLY METHYLATED, AND WITH INORGANIC ARSENIC WITHDRAWAL SEVERAL DIFFERENTIAL METHYLATED SITES WERE REVERSED, ALBEIT NOT COMPLETELY. FURTHERMORE, THESE CHANGES IN DNA METHYLATION MAINLY CORRELATED WITH CHANGES IN GENE EXPRESSION AT MOST SITES TESTED BUT NOT AT ALL. THIS STUDY SUGGESTS THAT DNA METHYLATION CHANGES ON GENE EXPRESSION ARE NOT CLEAR-CUT AND PROVIDE A PLATFORM TO BEGIN TO UNCOVER THE RELATIONSHIP BETWEEN DNA METHYLATION AND GENE EXPRESSION, SPECIFICALLY WITHIN THE CONTEXT OF INORGANIC ARSENIC TREATMENT. 2017 7 759 30 CASE REPORT OF CUTANEOUS SQUAMOUS CELL CARCINOMA AT THE WRIST JOINT AND THE PUBLIC HEALTH CRISIS OF ARSENICOSIS. CONTEXT: ARSENICOSIS IS CAUSED BY LONG TERM (6 MONTHS PLUS) INGESTION OF ARSENIC ABOVE A SAFE DOSE, CHARACTERIZED BY SKIN LESIONS AND POSSIBLE INVOLVEMENT OF INTERNAL ORGANS. ARSENICOSIS IS COMMON IN INDIA AND BANGLADESH WHERE NATURALLY OCCURRING HIGH CONCENTRATIONS OF ARSENIC IN THE EARTH'S CRUST CONTAMINATE GROUND WATER, CAUSING ADVERSE HEALTH EFFECTS. CASE PRESENTATION: WE REPORT A CASE OF A 55-YEAR-OLD INDIAN MALE, RESIDENT OF A KNOWN ARSENIC ENDEMIC REGION OF UTTAR PRADESH WHO SUFFERED FROM CHARACTERISTIC PULMONARY AND CUTANEOUS FEATURES OF CHRONIC ARSENIC TOXICITY WHICH INCLUDED RADIOLOGICAL FINDINGS OF INTERSTITIAL LUNG DISEASE, HYPERKERATOTIC LESIONS OVER THE PALMS AND SOLES, RAIN DROP LIKE PIGMENTATION OVER THE TRUNK, AND CARCINOMATOUS CHANGES AT THE WRIST JOINT. THE PATIENT WAS STARTED ON CHELATING AGENTS (D-PENICILLAMINE) AND ORAL RETINOIDS (ISOTRETINOIN) FOLLOWED BY THE SURGICAL EXCISION OF THE CARCINOMA. DISCUSSION: ENVIRONMENTAL CONTAMINATION WITH ARSENIC IS A WELL-KNOWN HEALTH HAZARD IN SOUTH ASIAN COUNTRIES. THE MAIN SOURCE IS CONSUMPTION OF CONTAMINATED GROUND WATER FOR DOMESTIC PURPOSES. CUTANEOUS LESIONS, INTERNAL ORGAN INVOLVEMENT INCLUDING INTERSTITIAL LUNG DISEASE AND CARCINOMAS AS OBSERVED IN OUR PATIENT HAVE BEEN REPORTED IN THE LITERATURE. VARIOUS MECHANISMS LIKE EPIGENETIC CHANGES AND ARSENIC-INDUCED IMMUNE SUPPRESSION HAVE BEEN PROPOSED FOR THE DEVELOPMENT OF CUTANEOUS CARCINOMAS WITH PROLONGED EXPOSURE TO ARSENIC. RELEVANCE TO CLINICAL PRACTICE: AMONG THE VARIOUS CAUSES OF PALMO-PLANTAR HYPERKERATOSIS, ARSENICOSIS SHOULD BE KEPT IN MIND WHEN PRESENTING IN COMBINATION WITH PIGMENTARY CHANGES AND CARCINOMATOUS GROWTH FROM AN ARSENIC-ENDEMIC REGION. CONCLUSIONS: PEOPLE RESIDING IN ARSENIC-ENDEMIC REGIONS SHOULD BE MADE AWARE OF ARSENIC-RELATED HEALTH HAZARDS. RAINWATER HARVESTING AND GOOD NUTRITION ARE THE SIMPLEST MEASURES WHICH COULD BE ADOPTED BY THE EXPOSED POPULATION IN AFFECTED AREAS. SEVERAL METHODS HAVE ALSO BEEN EMPLOYED BY GOVERNMENTAL AND NON-GOVERNMENT ORGANIZATIONS TO SEPARATE ARSENIC FROM CONTAMINATED WATER TO COMBAT ARSENIC-RELATED DISEASES AND CARCINOMAS. COMPETING INTERESTS: THE AUTHORS DECLARE NO COMPETING FINANCIAL INTERESTS. 2021 8 2655 34 EPIMUTAGENESIS: A PROSPECTIVE MECHANISM TO REMEDIATE ARSENIC-INDUCED TOXICITY. ARSENIC TOXICITY IS A GLOBAL ISSUE, ADDRESSED BY THE WORLD HEALTH ORGANIZATION AS ONE OF THE MAJOR NATURAL CALAMITIES FACED BY HUMANS. MORE THAN 137 MILLION INDIVIDUALS IN 70 NATIONS ARE AFFECTED BY ARSENIC MAINLY THROUGH DRINKING WATER AND ALSO THROUGH DIET. CHRONIC ARSENIC EXPOSURE LEADS TO VARIOUS TYPES OF PATHO-PHYSIOLOGICAL END POINTS IN HUMANS INCLUDING CANCERS. ARSENIC, A XENOBIOTIC SUBSTANCE, IS BIOTRANSFORMED IN THE BODY TO ITS METHYLATED SPECIES BY USING THE PHYSIOLOGICAL S-ADENOSYL METHIONINE (SAM). SAM DICTATES METHYLATION STATUS OF THE GENOME AND ARSENIC METABOLISM LEADS TO DEPLETION OF SAM LEADING TO AN EPIGENETIC DISEQUILIBRIUM. SINCE EPIGENETICS IS ONE OF THE MAJOR PHENOMENON AT THE INTERFACE BETWEEN THE ENVIRONMENT AND HUMAN HEALTH IMPACT, ITS DISEQUILIBRIUM BY ARSENIC INFLICTS UPON THE CHROMATIN COMPACTION, GENE EXPRESSION, GENOMIC STABILITY AND A HOST OF BIOMOLECULAR INTERACTIONS, THE INTERACTOME WITHIN THE CELL. SINCE ARSENIC IS NOT MUTAGENIC BUT IS CARCINOGENIC IN NATURE, ARSENIC INDUCED EPIMUTAGENESIS HAS COME TO THE FOREFRONT SINCE IT DETERMINES THE TRANSCRIPTIONAL AND GENOMIC INTEGRITY OF THE CELL. ARSENIC TOXICITY BRINGS FORTH SEVERAL PATHOPHYSIOLOGICAL MANIFESTATIONS LIKE DERMATOLOGICAL NON-CANCEROUS, PRE-CANCEROUS AND CANCEROUS LESIONS, PERIPHERAL NEUROPATHY, DNA DAMAGE, RESPIRATORY DISORDERS AND CANCERS OF SEVERAL INTERNAL ORGANS. RECENTLY, SEVERAL DISEASES OF SIMILAR MANIFESTATIONS HAVE BEEN EXPLAINED WITH THE RELEVANT EPIGENETIC PERSPECTIVES REGARDING THE POSSIBLE MOLECULAR MECHANISM FOR THEIR ONSET. HENCE, IN THE CURRENT REVIEW, WE COMPREHENSIVELY TRY TO INTERCALATE THE INFORMATION ON ARSENIC-INDUCED EPIGENETIC ALTERATIONS OF DNA, HISTONES AND MICRORNA SO AS TO UNDERSTAND WHETHER THE ARSENIC-INDUCED TOXIC MANIFESTATIONS ARE BROUGHT ABOUT BY THE EPIGENETIC CHANGES. WE HIGHLIGHT THE NEED TO UNDERSTAND THE ASPECT OF EPIMUTAGENESIS AND SUBSEQUENT ALTERATIONS IN THE CELLULAR INTERACTOME DUE TO ARSENIC-INDUCED MOLECULAR CHANGES, WHICH MAY BE UTILIZED TO DEVELOP PUTATIVE THERAPEUTIC STRATEGIES TARGETING BOTH OXIDATIVE POTENTIAL AND EPIMUTAGENESIS IN HUMANS. 2015 9 3508 28 IDENTIFYING A PANEL OF GENES/PROTEINS/MIRNAS MODULATED BY ARSENICALS IN BLADDER, PROSTATE, KIDNEY CANCERS. ARSENIC AND ARSENIC-DERIVATIVE COMPOUNDS, NAMED AS ARSENICALS, REPRESENT A WORLDWIDE PROBLEM FOR THEIR EFFECT ON THE HUMAN HEALTH AND, IN PARTICULAR, FOR THEIR CAPABILITY TO INCREASE THE RISK OF DEVELOPING CANCER SUCH AS KIDNEY, BLADDER AND PROSTATE CANCER. THE MAIN SOURCE OF ARSENICAL EXPOSURE IS DRINKING WATER. NOWADAYS, IT IS WELL KNOWN THAT THE CHRONIC EXPOSURE TO ARSENICALS LEADS TO A SERIES OF EPIGENETIC ALTERATIONS THAT HAVE A ROLE IN ARSENIC-INDUCED EFFECTS ON HUMAN HEALTH INCLUDING CANCER. BASED ON THESE OBSERVATIONS, THE AIM OF OUR STUDY WAS TO SELECT BY NETWORK ANALYSIS THE GENES/PROTEINS/MIRNAS IMPLICATED IN KIDNEY, BLADDER AND PROSTATE CANCER DEVELOPMENT UPON ARSENICAL EXPOSURE. FROM THIS ANALYSIS WE IDENTIFIED: (I) THE NODES LINKING THE THREE MOLECULAR NETWORKS SPECIFIC FOR KIDNEY, BLADDER AND PROSTATE CANCER; (II) THE RELATIVE HUB NODES (RXRA, MAP3K7, NR3C1, PABPC1, NDRG1, RELA AND CTNNB1) THAT LINK THE THREE CANCER NETWORKS; (III) THE MIRNAS ABLE TO TARGET THESE HUB NODES. IN CONCLUSION, WE HIGHLIGHTED A PANEL OF POTENTIAL MOLECULES RELATED TO THE MOLECULAR MECHANISMS OF ARSENICAL-INDUCED CANCEROGENESIS AND SUGGEST THEIR UTILITY AS BIOMARKERS OR THERAPEUTIC TARGETS. 2018 10 633 23 BIOLOGICAL EFFECTS AND EPIDEMIOLOGICAL CONSEQUENCES OF ARSENIC EXPOSURE, AND REAGENTS THAT CAN AMELIORATE ARSENIC DAMAGE IN VIVO. THROUGH CONTAMINATED DIET, WATER, AND OTHER FORMS OF ENVIRONMENTAL EXPOSURE, ARSENIC AFFECTS HUMAN HEALTH. THERE ARE MANY U.S. AND WORLDWIDE "HOT SPOTS" WHERE THE ARSENIC LEVEL IN PUBLIC WATER EXCEEDS THE MAXIMUM EXPOSURE LIMIT. THE BIOLOGICAL EFFECTS OF CHRONIC ARSENIC EXPOSURE INCLUDE GENERATION OF REACTIVE OXYGEN SPECIES (ROS), LEADING TO OXIDATIVE STRESS AND DNA DAMAGE, EPIGENETIC DNA MODIFICATION, INDUCTION OF GENOMIC INSTABILITY, AND INFLAMMATION AND IMMUNOMODULATION, ALL OF WHICH CAN INITIATE CARCINOGENESIS. HIGH ARSENIC EXPOSURE IS EPIDEMIOLOGICALLY ASSOCIATED WITH SKIN, LUNG, BLADDER, LIVER, KIDNEY AND PANCREATIC CANCER, AND CARDIOVASCULAR, NEURONAL, AND OTHER DISEASES. THIS REVIEW BRIEFLY SUMMARIZES THE BIOLOGICAL EFFECTS OF ARSENIC EXPOSURE AND EPIDEMIOLOGICAL CANCER STUDIES WORLDWIDE, AND PROVIDES AN OVERVIEW FOR EMERGING RODENT-BASED STUDIES OF REAGENTS THAT CAN AMELIORATE THE EFFECTS OF ARSENIC EXPOSURE IN VIVO. THESE REAGENTS MAY BE TRANSLATED TO HUMAN POPULATIONS FOR DISEASE PREVENTION. WE PROPOSE THE IMPORTANCE OF DEVELOPING A BIOMARKER-BASED PRECISION PREVENTION APPROACH FOR THE HEALTH ISSUES ASSOCIATED WITH ARSENIC EXPOSURE THAT AFFECTS MILLIONS OF PEOPLE WORLDWIDE. 2017 11 2099 36 EPIGENETIC EFFECTS OF LOW-LEVEL SODIUM ARSENITE EXPOSURE ON HUMAN LIVER HEPARG CELLS. CHRONIC EXPOSURE TO INORGANIC ARSENIC IS ASSOCIATED WITH A VARIETY OF ADVERSE HEALTH EFFECTS, INCLUDING LUNG, BLADDER, KIDNEY, AND LIVER CANCER. SEVERAL MECHANISMS HAVE BEEN PROPOSED FOR ARSENIC-INDUCED TUMORIGENESIS; HOWEVER, INSUFFICIENT KNOWLEDGE AND MANY UNANSWERED QUESTIONS REMAIN TO EXPLAIN THE INTEGRATED MOLECULAR PATHOGENESIS OF ARSENIC CARCINOGENICITY. IN THE PRESENT STUDY, USING NON-TUMORIGENIC HUMAN LIVER HEPARG CELLS, WE INVESTIGATED EPIGENETIC ALTERATIONS UPON PROLONGED EXPOSURE TO A NONCYTOTOXIC CONCENTRATION OF SODIUM ARSENITE (NAASO(2)). WE DEMONSTRATE THAT CONTINUOUS EXPOSURE OF HEPARG CELLS TO 1 MICROM SODIUM ARSENITE (NAASO(2)) FOR 14 DAYS RESULTED IN SUBSTANTIAL CYTOSINE DNA DEMETHYLATION AND HYPERMETHYLATION ACROSS THE GENOME, AMONG WHICH THE CLAUDIN 14 (CLDN14) GENE WAS HYPERMETHYLATED AND THE MOST DOWN-REGULATED GENE. ANOTHER IMPORTANT FINDING WAS A PROFOUND LOSS OF HISTONE H3 LYSINE 36 (H3K36) TRIMETHYLATION, WHICH WAS ACCOMPANIED BY INCREASED DAMAGE TO GENOMIC DNA AND AN ELEVATED DE NOVO MUTATION FREQUENCY. THESE RESULTS DEMONSTRATE THAT CONTINUOUS EXPOSURE OF HEPARG CELLS TO A NONCYTOTOXIC CONCENTRATION OF NAASO(2) RESULTS IN SUBSTANTIAL EPIGENETIC ABNORMALITIES ACCOMPANIED BY SEVERAL CARCINOGENESIS-RELATED EVENTS, INCLUDING INDUCTION OF EPITHELIAL-TO-MESENCHYMAL TRANSITION, DAMAGE TO DNA, INHIBITION OF DNA REPAIR GENES, AND INDUCTION OF DE NOVO MUTATIONS. IMPORTANTLY, THIS STUDY HIGHLIGHTS THE INTIMATE MECHANISTIC LINK AND INTERPLAY BETWEEN TWO FUNDAMENTAL CANCER-ASSOCIATED EVENTS, EPIGENETIC AND GENETIC ALTERATIONS, IN ARSENIC-ASSOCIATED CARCINOGENESIS. 2020 12 502 35 ASSOCIATION OF ARSENIC EXPOSURE WITH WHOLE BLOOD DNA METHYLATION: AN EPIGENOME-WIDE STUDY OF BANGLADESHI ADULTS. BACKGROUND: ARSENIC EXPOSURE AFFECTS [FORMULA: SEE TEXT] PEOPLE WORLDWIDE, INCLUDING [FORMULA: SEE TEXT] IN BANGLADESH. ARSENIC EXPOSURE INCREASES THE RISK OF CANCER AND OTHER CHRONIC DISEASES, AND ONE POTENTIAL MECHANISM OF ARSENIC TOXICITY IS EPIGENETIC DYSREGULATION. OBJECTIVE: WE ASSESSED ASSOCIATIONS BETWEEN ARSENIC EXPOSURE AND GENOME-WIDE DNA METHYLATION MEASURED AT BASELINE AMONG 396 BANGLADESHI ADULTS PARTICIPATING IN THE HEALTH EFFECTS OF ARSENIC LONGITUDINAL STUDY (HEALS) WHO WERE EXPOSED BY DRINKING NATURALLY CONTAMINATED WELL WATER. METHODS: METHYLATION IN WHOLE BLOOD DNA WAS MEASURED AT [FORMULA: SEE TEXT] USING THE ILLUMINA INFINIUMMETHYLATIONEPIC (EPIC) ARRAY. TO ASSESS ASSOCIATIONS BETWEEN ARSENIC EXPOSURE AND CPG METHYLATION, WE USED LINEAR REGRESSION MODELS ADJUSTED FOR COVARIATES AND SURROGATE VARIABLES (SVS) (CAPTURING UNKNOWN TECHNICAL AND BIOLOGIC FACTORS). WE ATTEMPTED REPLICATION AND CONDUCTED A META-ANALYSIS USING AN INDEPENDENT DATASET OF [FORMULA: SEE TEXT] FROM 400 BANGLADESHI INDIVIDUALS WITH ARSENICAL SKIN LESIONS. RESULTS: WE IDENTIFIED 34 CPGS ASSOCIATED WITH [FORMULA: SEE TEXT] CREATININE-ADJUSTED URINARY ARSENIC [[FORMULA: SEE TEXT]]. SIXTEEN OF THESE CPGS ANNOTATED TO THE [FORMULA: SEE TEXT] ARRAY, AND 10 ASSOCIATIONS WERE REPLICATED ([FORMULA: SEE TEXT]). THE TOP TWO CPGS ANNOTATED UPSTREAM OF THE ABR GENE (CG01912040, CG10003262 ). ALL URINARY ARSENIC-ASSOCIATED CPGS WERE ALSO ASSOCIATED WITH ARSENIC CONCENTRATION MEASURED IN DRINKING WATER ([FORMULA: SEE TEXT]). META-ANALYSIS ([FORMULA: SEE TEXT] SAMPLES) IDENTIFIED 221 URINARY ARSENIC-ASSOCIATED CPGS ([FORMULA: SEE TEXT]). THE ARSENIC-ASSOCIATED CPGS FROM THE META-ANALYSIS WERE ENRICHED IN NON-CPG ISLANDS AND SHORES ([FORMULA: SEE TEXT]) AND DEPLETED IN PROMOTER REGIONS ([FORMULA: SEE TEXT]). AMONG THE ARSENIC-ASSOCIATED CPGS ([FORMULA: SEE TEXT]), WE OBSERVED SIGNIFICANT ENRICHMENT OF GENES ANNOTATING TO THE REACTIVE OXYGEN SPECIES PATHWAY, INFLAMMATORY RESPONSE, AND TUMOR NECROSIS FACTOR [FORMULA: SEE TEXT] ([FORMULA: SEE TEXT]) SIGNALING VIA NUCLEAR FACTOR KAPPA-B ([FORMULA: SEE TEXT]) HALLMARKS ([FORMULA: SEE TEXT]). CONCLUSIONS: THE NOVEL AND REPLICABLE ASSOCIATIONS BETWEEN ARSENIC EXPOSURE AND DNA METHYLATION AT SPECIFIC CPGS OBSERVED IN THIS WORK SUGGEST THAT EPIGENETIC ALTERATIONS SHOULD BE FURTHER INVESTIGATED AS POTENTIAL MEDIATORS IN ARSENIC TOXICITY AND AS BIOMARKERS OF EXPOSURE AND EFFECT IN EXPOSED POPULATIONS. HTTPS://DOI.ORG/10.1289/EHP3849. 2019 13 192 32 ACETYLATED H4K16 BY MYST1 PROTECTS UROTSA CELLS FROM ARSENIC TOXICITY AND IS DECREASED FOLLOWING CHRONIC ARSENIC EXPOSURE. ARSENIC, A HUMAN CARCINOGEN THAT IS ASSOCIATED WITH AN INCREASED RISK OF BLADDER CANCER, IS COMMONLY FOUND IN DRINKING WATER. AN IMPORTANT MECHANISM BY WHICH ARSENIC IS THOUGHT TO BE CARCINOGENIC IS THROUGH THE INDUCTION OF EPIGENETIC CHANGES THAT LEAD TO ABERRANT GENE EXPRESSION. PREVIOUSLY, WE REPORTED THAT THE SAS2 GENE IS REQUIRED FOR OPTIMAL GROWTH OF YEAST IN THE PRESENCE OF ARSENITE (AS(III)). YEAST SAS2P IS ORTHOLOGOUS TO HUMAN MYST1, A HISTONE 4 LYSINE 16 (H4K16) ACETYLTRANSFERASE. HERE, WE SHOW THAT H4K16 ACETYLATION IS NECESSARY FOR THE RESISTANCE OF YEAST TO AS(III) THROUGH THE MODULATION OF CHROMATIN STATE. WE FURTHER EXPLORED THE ROLE OF MYST1 AND H4K16 ACETYLATION IN ARSENIC TOXICITY AND CARCINOGENESIS IN HUMAN BLADDER EPITHELIAL CELLS. THE EXPRESSION OF MYST1 WAS KNOCKED DOWN IN UROTSA CELLS, A MODEL OF BLADDER EPITHELIUM THAT HAS BEEN USED TO STUDY ARSENIC-INDUCED CARCINOGENESIS. SILENCING OF MYST1 REDUCED ACETYLATION OF H4K16 AND INDUCED SENSITIVITY TO AS(III) AND TO ITS MORE TOXIC METABOLITE MONOMETHYLARSONOUS ACID (MMA(III)) AT DOSES RELEVANT TO HIGH ENVIRONMENTAL HUMAN EXPOSURES. IN ADDITION, BOTH AS(III) AND MMA(III) TREATMENTS DECREASED GLOBAL H4K16 ACETYLATION LEVELS IN A DOSE- AND TIME-DEPENDENT MANNER. THIS INDICATES THAT ACETYLATED H4K16 IS REQUIRED FOR RESISTANCE TO ARSENIC AND THAT A REDUCTION IN ITS LEVELS AS A CONSEQUENCE OF ARSENIC EXPOSURE MAY CONTRIBUTE TO TOXICITY IN UROTSA CELLS. BASED ON THESE FINDINGS, WE PROPOSE A NOVEL ROLE FOR THE MYST1 GENE IN HUMAN SENSITIVITY TO ARSENIC. 2009 14 6387 26 THE ROLE OF REACTIVE OXYGEN SPECIES IN ARSENIC TOXICITY. ARSENIC POISONING IS A GLOBAL HEALTH PROBLEM. CHRONIC EXPOSURE TO ARSENIC HAS BEEN ASSOCIATED WITH THE DEVELOPMENT OF A WIDE RANGE OF DISEASES AND HEALTH PROBLEMS IN HUMANS. ARSENIC EXPOSURE INDUCES THE GENERATION OF INTRACELLULAR REACTIVE OXYGEN SPECIES (ROS), WHICH MEDIATE MULTIPLE CHANGES TO CELL BEHAVIOR BY ALTERING SIGNALING PATHWAYS AND EPIGENETIC MODIFICATIONS, OR CAUSE DIRECT OXIDATIVE DAMAGE TO MOLECULES. ANTIOXIDANTS WITH THE POTENTIAL TO REDUCE ROS LEVELS HAVE BEEN SHOWN TO AMELIORATE ARSENIC-INDUCED LESIONS. HOWEVER, EMERGING EVIDENCE SUGGESTS THAT CONSTRUCTIVE ACTIVATION OF ANTIOXIDATIVE PATHWAYS AND DECREASED ROS LEVELS CONTRIBUTE TO CHRONIC ARSENIC TOXICITY IN SOME CASES. THIS REVIEW DETAILS THE PATHWAYS INVOLVED IN ARSENIC-INDUCED REDOX IMBALANCE, AS WELL AS CURRENT STUDIES ON PROPHYLAXIS AND TREATMENT STRATEGIES USING ANTIOXIDANTS. 2020 15 2961 34 GENETIC AND EPIGENETIC MECHANISMS IN METAL CARCINOGENESIS AND COCARCINOGENESIS: NICKEL, ARSENIC, AND CHROMIUM. CHRONIC EXPOSURE TO NICKEL(II), CHROMIUM(VI), OR INORGANIC ARSENIC (IAS) HAS LONG BEEN KNOWN TO INCREASE CANCER INCIDENCE AMONG AFFECTED INDIVIDUALS. RECENT EPIDEMIOLOGICAL STUDIES HAVE FOUND THAT CARCINOGENIC RISKS ASSOCIATED WITH CHROMATE AND IAS EXPOSURES WERE SUBSTANTIALLY HIGHER THAN PREVIOUSLY THOUGHT, WHICH LED TO MAJOR REVISIONS OF THE FEDERAL STANDARDS REGULATING AMBIENT AND DRINKING WATER LEVELS. GENOTOXIC EFFECTS OF CR(VI) AND IAS ARE STRONGLY INFLUENCED BY THEIR INTRACELLULAR METABOLISM, WHICH CREATES SEVERAL REACTIVE INTERMEDIATES AND BYPRODUCTS. TOXIC METALS ARE CAPABLE OF POTENT AND SURPRISINGLY SELECTIVE ACTIVATION OF STRESS-SIGNALING PATHWAYS, WHICH ARE KNOWN TO CONTRIBUTE TO THE DEVELOPMENT OF HUMAN CANCERS. DEPENDING ON THE METAL, ASCORBATE (VITAMIN C) HAS BEEN FOUND TO ACT EITHER AS A STRONG ENHANCER OR SUPPRESSOR OF TOXIC RESPONSES IN HUMAN CELLS. IN ADDITION TO GENETIC DAMAGE VIA BOTH OXIDATIVE AND NONOXIDATIVE (DNA ADDUCTS) MECHANISMS, METALS CAN ALSO CAUSE SIGNIFICANT CHANGES IN DNA METHYLATION AND HISTONE MODIFICATIONS, LEADING TO EPIGENETIC SILENCING OR REACTIVATION OF GENE EXPRESSION. IN VITRO GENOTOXICITY EXPERIMENTS AND RECENT ANIMAL CARCINOGENICITY STUDIES PROVIDED STRONG SUPPORT FOR THE IDEA THAT METALS CAN ACT AS COCARCINOGENS IN COMBINATION WITH NONMETAL CARCINOGENS. COCARCINOGENIC AND COMUTAGENIC EFFECTS OF METALS ARE LIKELY TO STEM FROM THEIR ABILITY TO INTERFERE WITH DNA REPAIR PROCESSES. OVERALL, METAL CARCINOGENESIS APPEARS TO REQUIRE THE FORMATION OF SPECIFIC METAL COMPLEXES, CHROMOSOMAL DAMAGE, AND ACTIVATION OF SIGNAL TRANSDUCTION PATHWAYS PROMOTING SURVIVAL AND EXPANSION OF GENETICALLY/EPIGENETICALLY ALTERED CELLS. 2008 16 3775 26 INTERACTIONS BETWEEN ARSENIC-INDUCED TOXICITY AND NUTRITION IN EARLY LIFE. EXPOSURE TO ARSENIC THROUGH DRINKING WATER IS A MAJOR PUBLIC HEALTH PROBLEM AFFECTING MOST COUNTRIES, ALTHOUGH THE SITUATION IS PARTICULARLY SEVERE IN LOW-INCOME NATIONS. THE HEALTH CONSEQUENCES OF CHRONIC ARSENIC EXPOSURE INCLUDE INCREASED RISK FOR VARIOUS FORMS OF CANCER AND NUMEROUS NONCANCER EFFECTS, INCLUDING DIABETES, SKIN DISEASES, CHRONIC COUGH, AND TOXIC EFFECTS ON LIVER, KIDNEY, CARDIOVASCULAR SYSTEM, AND PERIPHERAL AND CENTRAL NERVOUS SYSTEMS. IN RECENT YEARS INCREASING REPORTS OF EFFECTS ON FETAL AND CHILD DEVELOPMENT HAVE APPEARED. THERE SEEMS TO BE A WIDE VARIATION IN SUSCEPTIBILITY TO ARSENIC TOXICITY, WHICH IS LIKELY TO BE RELATED TO FACTORS SUCH AS VARIATION IN ARSENIC METABOLISM, NUTRITION, HOST-RELATED DEFENSE MECHANISMS, AND GENETIC PREDISPOSITION. THE MAIN MECHANISMS OF ARSENIC-NUTRITION INTERACTIONS INCLUDE ARSENIC-INDUCED OXIDATIVE STRESS, WHICH REQUIRES NUTRIENT-DEPENDENT DEFENSE SYSTEMS, AND ARSENIC METABOLISM (METHYLATION) VIA 1-CARBON METABOLISM, WHICH REQUIRES METHYL GROUPS, FOLIC ACID, VITAMIN B-12, AND BETAINE FOR THE REMETHYLATION OF HOMOCYSTEINE TO METHIONINE. AN EFFICIENT FIRST METHYLATION STEP IN COMBINATION WITH A SLOW SECOND METHYLATION STEP SEEMS TO BE MOST CRITICAL FROM A TOXICOLOGICAL POINT OF VIEW. A THIRD MODE OF ARSENIC-NUTRITION INTERACTION INVOLVES EPIGENETIC EFFECTS AND FETAL PROGRAMMING VIA DNA METHYLATION. 2007 17 2947 40 GENETIC AND EPIGENETIC CHANGES INDUCED BY CHRONIC LOW DOSE EXPOSURE TO ARSENIC OF MOUSE TESTICULAR LEYDIG CELLS. ARSENIC IS AN IMPORTANT ENVIRONMENTAL CARCINOGEN THAT AFFECTS MILLIONS OF PEOPLE WORLDWIDE THROUGH CONTAMINATED WATER SUPPLIES. GENOTOXICITY OF ARSENIC HAS BEEN A TOPIC OF CONTROVERSY. BOTH GENETIC ALTERATIONS (MUTATIONS) AND EPIGENETIC CHANGES (METHYLATION) HAVE BEEN SHOWN TO PLAY A CRUCIAL ROLE IN ENVIRONMENTAL CARCINOGENESIS. CHRONIC EXPOSURE TO ARSENIC HAS BEEN SHOWN TO INDUCE MALIGNANT TRANSFORMATION OF MAMMALIAN CELLS. HOWEVER, THE GENETIC ABERRATIONS INDUCED BY ARSENIC IN THIS PROCESS ARE UNCLEAR. THE PURPOSE OF THIS STUDY WAS TO DETERMINE IF BOTH LOWER (1 PG/ML) AND HIGHER CONCENTRATIONS (100 NG/ML) OF ARSENIC INDUCES EITHER MUTATIONS OR METHYLATION CHANGES THAT COULD LEAD TO THE DEVELOPMENT OF GENOMIC INSTABILITY IN TM3 CELLS, IMMORTALIZED LEYDIG CELLS DERIVED FROM NORMAL MOUSE TESTIS. TWO INDEPENDENT EXPOSURE TIMES WERE USED IN THIS STUDY WHICH RESULTED IN CELLS OF 33 AND 100 GENERATIONS IN AGE. ARSENIC-INDUCED GENETIC AND EPIGENETIC CHANGES WERE SCREENED AT A GENOME-WIDE LEVEL BY RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD), ALSO KNOWN AS AP-PCR METHOD WITH UNDIGESTED DNA AS WELL AS DNA DIGESTED BY THE METHYLATION SENSITIVE ISOSIZOMERIC RESTRICTION ENZYMES MSPI AND HPAII AND UNTREATED CONTROLS. CHANGES IN THE DNA FINGERPRINT OF BOTH, THE RESTRICTION ENZYME DIGESTED DNA (INDICATING METHYLATION CHANGES) AS WELL AS UNDIGESTED DNA (INDICATING MUTATIONS) FROM ARSENIC-TREATED (LOW AS WELL AS HIGH DOSE) SAMPLES WERE OBSERVED AS COMPARED TO THEIR CONTROLS. THUS, THIS STUDY PROVIDES THE FIRST EVIDENCE AT DNA SEQUENCE LEVEL FOR MUTAGENIC POTENTIAL OF ARSENIC. FURTHER CHARACTERIZATION OF THESE ALTERED GENOMIC REGIONS IS UNDERWAY. THE UNDERSTANDING OF THESE GENETIC AND EPIGENETIC CHANGES IN ARSENIC-INDUCED CARCINOGENESIS WILL PROVIDE A BASIS FOR BETTER INTERVENTIONAL APPROACHES IN BOTH THE TREATMENT AND PREVENTION OF ARSENIC-INDUCED CANCER. 2007 18 876 25 CHRONIC ARSENIC INTOXICATION DIAGNOSTIC SCORE (CASIDS). ARSENIC AND ITS COMPOUNDS ARE WELL-ESTABLISHED, POTENT, ENVIRONMENTALLY WIDESPREAD AND PERSISTENT TOXICANTS WITH METABOLIC, GENOTOXIC, MUTAGENIC, TERATOGENIC, EPIGENETIC AND CARCINOGENIC EFFECTS. ARSENIC OCCURS NATURALLY IN THE EARTH'S CRUST, BUT ANTHROPOGENIC ARSENIC EMISSIONS HAVE SURMOUNTED THE EMISSIONS FROM IMPORTANT NATURAL SOURCES SUCH AS VOLCANISM. INORGANIC ARSENICALS EXHIBIT ACUTE AND CHRONIC TOXICITIES IN VIRTUALLY ALL CELL TYPES AND TISSUES, AND HENCE ARSENIC INTOXICATION AFFECTS MULTIPLE SYSTEMS. WHEREAS ACUTE ARSENIC INTOXICATION IS RARE AND RELATIVELY EASY TO DIAGNOSE, CHRONIC ARSENIC INTOXICATION (CASI) IS COMMON BUT GOES OFTEN MISDIAGNOSED. BASED ON A REVIEW OF THE LITERATURE AS WELL AS OUR OWN CLINICAL EXPERIENCE, WE PROPOSE A CHRONIC ARSENIC INTOXICATION DIAGNOSTIC SCORE (CASIDS). A DISTINCTIVE FEATURE OF CASIDS IS THE USE OF BONE ARSENIC LOAD AS AN ESSENTIAL CRITERION FOR THE INDIVIDUAL RISK ASSESSMENT OF CHRONIC ARSENIC INTOXICATION, COMBINED WITH A SYSTEMIC CLINICAL ASSESSMENT. WE PRESENT CLINICAL EXAMPLES WHERE CASIDS IS APPLIED FOR THE DIAGNOSIS OF CASI, REVIEW THE MAIN TOPICS OF THE TOXICITY OF ARSENIC IN DIFFERENT CELL AND ORGAN SYSTEMS AND DISCUSS THE THERAPY AND PREVENTION OF DISEASE CAUSED OR AGGRAVATED BY CHRONIC ARSENIC INTOXICATION. CASIDS CAN HELP PHYSICIANS ESTABLISH THE DIAGNOSIS OF CASI AND ASSOCIATED CONDITIONS. 2018 19 1993 35 EPIGENETIC AND EPITRANSCRIPTOMIC MECHANISMS OF CHROMIUM CARCINOGENESIS. HEXAVALENT CHROMIUM [CR(VI)], A GROUP I CARCINOGEN CLASSIFIED BY THE INTERNATIONAL AGENCY FOR RESEARCH ON CANCER (IARC), REPRESENTS ONE OF THE MOST COMMON OCCUPATIONAL AND ENVIRONMENTAL POLLUTANTS. THE FINDINGS FROM HUMAN EPIDEMIOLOGICAL AND LABORATORY ANIMAL STUDIES SHOW THAT LONG-TERM EXPOSURE TO CR(VI) CAUSES LUNG CANCER AND OTHER CANCER. ALTHOUGH CR(VI) IS A WELL-RECOGNIZED CARCINOGEN, THE MECHANISM OF CR(VI) CARCINOGENESIS HAS NOT BEEN WELL UNDERSTOOD. DUE TO THE FACT THAT CR(VI) UNDERGOES A SERIES OF METABOLIC REDUCTIONS ONCE ENTERING CELLS TO GENERATE REACTIVE CR METABOLITES AND REACTIVE OXYGEN SPECIES (ROS) CAUSING GENOTOXICITY, CR(VI) IS GENERALLY CONSIDERED AS A GENOTOXIC CARCINOGEN. HOWEVER, MORE AND MORE STUDIES HAVE DEMONSTRATED THAT ACUTE OR CHRONIC CR(VI) EXPOSURE ALSO CAUSES EPIGENETIC DYSREGULATIONS INCLUDING CHANGING DNA METHYLATION, HISTONE POSTTRANSLATIONAL MODIFICATIONS AND REGULATORY NON-CODING RNA (MICRORNA AND LONG NON-CODING RNA) EXPRESSIONS. MOREOVER, EMERGING EVIDENCE SHOWS THAT CR(VI) EXPOSURE IS ALSO CAPABLE OF ALTERING CELLULAR EPITRANSCRIPTOME. GIVEN THE INCREASINGLY RECOGNIZED IMPORTANCE OF EPIGENETIC AND EPITRANSCRIPTOMIC DYSREGULATIONS IN CANCER INITIATION AND PROGRESSION, IT IS BELIEVED THAT CR(VI) EXPOSURE-CAUSED EPIGENETIC AND EPITRANSCRIPTOMIC CHANGES COULD PLAY IMPORTANT ROLES IN CR(VI) CARCINOGENESIS. THE GOAL OF THIS CHAPTER IS TO REVIEW THE EPIGENETIC AND EPITRANSCRIPTOMIC EFFECTS OF CR(VI) EXPOSURE AND DISCUSS THEIR ROLES IN CR(VI) CARCINOGENESIS. BETTER UNDERSTANDING THE MECHANISM OF CR(VI) CARCINOGENESIS MAY IDENTIFY NEW MOLECULAR TARGETS FOR MORE EFFICIENT PREVENTION AND TREATMENT OF CANCER RESULTING FROM CR(VI) EXPOSURE. 2023 20 6078 29 THE EFFECT OF CHRONIC ARSENIC EXPOSURE IN ZEBRAFISH. ARSENIC IS A PREVALENT ENVIRONMENTAL TOXIN AND A GROUP ONE HUMAN CARCINOGENIC AGENT. CHRONIC ARSENIC EXPOSURE HAS BEEN ASSOCIATED WITH MANY HUMAN DISEASES. THE AIM OF THIS STUDY IS TO EVALUATE ZEBRAFISH AS AN ANIMAL MODEL TO ASSESS ARSENIC TOXICITY IN ELEVATED LONG-TERM ARSENIC EXPOSURE. WITH PROLONGED EXPOSURE (6 MONTHS) TO VARIOUS CONCENTRATIONS OF ARSENIC FROM 50 PPB TO 300 PPB, EFFECTS OF ARSENIC ACCUMULATION IN ZEBRAFISH TISSUES, AND PHENOTYPES WERE INVESTIGATED. RESULTS SHOWED THAT THERE ARE NO SIGNIFICANT CHANGES OF ARSENIC RETENTION IN ZEBRAFISH TISSUES, AND ZEBRAFISH DID NOT EXHIBIT ANY VISIBLE TUMOR FORMATION UNDER ARSENIC EXPOSURE CONDITIONS. HOWEVER, THE ZEBRAFISH DEMONSTRATE A DYSFUNCTION IN THEIR NEUROLOGICAL SYSTEM, WHICH IS REFLECTED BY A REDUCTION OF LOCOMOTIVE ACTIVITY. MOREOVER, ELEVATED LEVELS OF THE SUPEROXIDE DISMUTASE (SOD2) PROTEIN WERE DETECTED IN THE EYE AND LIVER, SUGGESTING INCREASED OXIDATIVE STRESS. IN ADDITION, THE PROGENIES OF ARSENIC-TREATED PARENTS DISPLAYED A SMALLER BIOMASS (FOUR-FOLD REDUCTION IN BODY WEIGHT) COMPARED WITH THOSE FROM THEIR PARENTAL CONTROLS. THIS RESULT INDICATES THAT ARSENIC MAY INDUCE GENETIC OR EPIGENETIC CHANGES THAT ARE THEN PASSED ON TO THE NEXT GENERATION. OVERALL, THIS STUDY DEMONSTRATES THAT ZEBRAFISH IS A CONVENIENT VERTEBRATE MODEL WITH ADVANTAGES IN THE EVALUATION OF ARSENIC-ASSOCIATED NEUROLOGICAL DISORDERS AS WELL AS ITS INFLUENCES ON THE OFFSPRING. 2016