1  2840 149 FRAMEWORK ANALYSIS FOR THE CARCINOGENIC MODE OF ACTION OF NITROBENZENE. NITROBENZENE (CASRN: 98-95-3) HAS BEEN SHOWN TO INDUCE CANCERS IN MANY TISSUES INCLUDING KIDNEY, LIVER, AND THYROID, FOLLOWING CHRONIC INHALATION IN ANIMALS. HOWEVER, WITH A FEW EXCEPTIONS, GENOTOXICITY ASSAYS USING NITROBENZENE HAVE GIVEN NEGATIVE RESULTS. SOME DNA BINDING/ADDUCT STUDIES HAVE BROUGHT FORTH QUESTIONABLE RESULTS AND, CONSIDERING THE AVAILABLE WEIGHT OF EVIDENCE, IT DOES NOT APPEAR THAT NITROBENZENE CAUSES CANCER VIA A GENOTOXIC MODE OF ACTION. NITROBENZENE PRODUCES A NUMBER OF FREE RADICALS DURING ITS REDUCTIVE METABOLISM, IN THE GUT AS WELL AS AT THE CELLULAR LEVEL, AND GENERATES SUPEROXIDE ANION AS A BY-PRODUCT DURING OXIDATIVE MELABOLISM. THE REACTIVE SPECIES GENERATED DURING NITROBENZENE METABOLISM ARE CONSIDERED CANDIDATES FOR CARCINOGENICITY. FURTHERMORE, SEVERAL LINES OF EVIDENCE SUGGEST THAT NITROBENZENE EXERTS ITS CARCINOGENICITY THROUGH A NON-DNA REACTIVE (EPIGENETIC) FASHION, SUCH AS A STRONG TEMPORAL RELATIONSHIP BETWEEN NON-, PRE-, AND NEOPLASTIC LESIONS LEADING TO CARCINOGENESIS. IN THIS REPORT, WE FIRST DESCRIBE THE ABSORPTION, DISTRIBUTION, METABOLISM, AND EXCRETION OF NITROBENZENE FOLLOWED BY A SUMMARY OF THE AVAILABLE GENOTOXICITY STUDIES AND THE ONLY AVAILABLE CANCER BIOASSAY. WE SUBSEQUENTLY REFER TO THE MODE OF ACTION FRAMEWORK OF THE U.S. ENVIRONMENTAL PROTECTION AGENCY'S 2005 GUIDELINES FOR CARCINOGEN RISK ASSESSMENT AS A BASIS FOR PRESENTING POSSIBLE MODES OF ACTION FOR NITROBENZENE-INDUCED CANCERS OF THE LIVER, THYROID, AND KIDNEY, AS SUPPORTED BY THE AVAILABLE EXPERIMENTAL DATA. THE RATIONALE(S) REGARDING HUMAN RELEVANCE OF EACH MODE OF ACTION IS ALSO PRESENTED. FINALLY, WE HYPOTHESIZE THAT THE CARCINOGENIC MODE OF ACTION FOR NITROBENZENE IS MULTIFACTORIAL IN NATURE AND REFLECTIVE OF FREE RADICALS, INFLAMMATION, AND/OR ALTERED METHYLATION.	2007	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
2  4258  29 METHYLOMICS OF NITROXIDATIVE STRESS ON PRECANCEROUS CELLS REVEALS DNA METHYLATION ALTERATION AT THE TRANSITION FROM IN SITU TO INVASIVE CERVICAL CANCER. EPIGENETIC DYSREGULATION IS IMPORTANT IN CERVICAL CANCER DEVELOPMENT, BUT THE UNDERLYING MECHANISM IS LARGELY UNKNOWN. INCREASING EVIDENCE INDICATES THAT DNA METHYLATION IS SENSITIVE TO CHANGES IN MICROENVIRONMENTAL FACTORS, SUCH AS NITRIC OXIDE (NO) IN THE CHRONIC INFLAMMATORY CERVIX. HOWEVER, THE EPIGENOMIC EFFECTS OF NO IN CANCER HAVE NOT BEEN INVESTIGATED. IN THIS STUDY, WE EXPLORED THE METHYLOMIC EFFECTS OF NITROXIDATIVE STRESS IN HPV-IMMORTALIZED PRECANCEROUS CELLS. CHRONIC NO EXPOSURE PROMOTED THE ACQUISITION OF MALIGNANT PHENOTYPES SUCH AS CELL GROWTH, MIGRATION, INVASION, AND ANCHORAGE-INDEPENDENT GROWTH. EPIGENETIC ANALYSIS CONFIRMED HYPERMETHYLATION OF PTPRR. WHOLE-GENOME METHYLATION ANALYSIS SHOWED BOLA2B, FGF8, HSPA6, LYPD2, AND SHE WERE HYPERMETHYLATED IN CELLS. THE HYPERMETHYLATION BOLA2B, FGF8, HSPA6, AND SHE WAS CONFIRMED IN CERVICAL SCRAPINGS FROM INVASIVE CANCER, BUT NOT IN CIN3/CIS, CIN2 AND CIN1 (P=0.019, 0.023, 0.023 AND 0.027 RESPECTIVELY), SUGGESTING THE ROLE IN THE TRANSITION FROM IN SITU TO INVASIVE PROCESS. OUR RESULTS REVEAL THAT NITROXIDATIVE STRESS CAUSES EPIGENETIC CHANGES IN HPV-INFECTED CELLS. INVESTIGATION OF THESE METHYLATION CHANGES IN PERSISTENT HPV INFECTION MAY HELP IDENTIFY NEW BIOMARKERS OF DNA METHYLATION FOR CERVICAL CANCER SCREENING, ESPECIALLY FOR PRECANCEROUS LESIONS.	2017	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
3  3671  40 INFLAMMATION AND CANCER. INFECTION AND INFLAMMATION ACCOUNT FOR APPROXIMATELY 25% OF CANCER-CAUSING FACTORS. INFLAMMATION-RELATED CANCERS ARE CHARACTERIZED BY MUTAGENIC DNA LESIONS, SUCH AS 8-OXO-7,8-DIHYDRO-2'-DEOXYGUANOSINE (8-OXODG) AND 8-NITROGUANINE. OUR PREVIOUS STUDIES DEMONSTRATED THE FORMATION OF 8-OXODG AND 8-NITROGUANINE IN THE TISSUES OF CANCER AND PRECANCEROUS LESIONS DUE TO INFECTION (E.G., OPISTHORCHIS VIVERRINI-RELATED CHOLANGIOCARCINOMA, SCHISTOSOMA HAEMATOBIUM-ASSOCIATED BLADDER CANCER, HELICOBACTER PYLORI-INFECTED GASTRIC CANCER, HUMAN PAPILLOMAVIRUS-RELATED CERVICAL CANCER, EPSTEIN-BARR VIRUS-INFECTED NASOPHARYNGEAL CARCINOMA) AND PRO-INFLAMMATORY FACTORS (E.G., ASBESTOS, NANOMATERIALS, AND INFLAMMATORY DISEASES SUCH AS BARRETT'S ESOPHAGUS AND ORAL LEUKOPLAKIA). INTERESTINGLY, SEVERAL OF OUR STUDIES SUGGESTED THAT INFLAMMATION-ASSOCIATED DNA DAMAGE IN CANCER STEM-LIKE CELLS LEADS TO CANCER DEVELOPMENT WITH AGGRESSIVE CLINICAL FEATURES. REACTIVE OXYGEN/NITROGEN SPECIES FROM INFLAMMATION DAMAGE NOT ONLY DNA BUT ALSO OTHER BIOMACROMOLECULES, SUCH AS PROTEINS AND LIPIDS, RESULTING IN THEIR DYSFUNCTION. WE IDENTIFIED OXIDATIVELY DAMAGED PROTEINS IN CANCER TISSUES BY 2D OXYBLOT FOLLOWED BY MALDI-TOF/TOF. AS AN EXAMPLE, OXIDATIVELY DAMAGED TRANSFERRIN RELEASED IRON ION, WHICH MAY MEDIATE FENTON REACTIONS AND GENERATE ADDITIONAL REACTIVE OXYGEN SPECIES. DYSFUNCTION OF ANTI-OXIDATIVE PROTEINS DUE TO THIS DAMAGE MIGHT INCREASE OXIDATIVE STRESS. SUCH DAMAGE IN BIOMACROMOLECULES MAY FORM A VICIOUS CYCLE OF OXIDATIVE STRESS, LEADING TO CANCER DEVELOPMENT. EPIGENETIC ALTERATIONS SUCH AS DNA METHYLATION AND MICRORNA DYSREGULATION PLAY VITAL ROLES IN CARCINOGENESIS, ESPECIALLY IN INFLAMMATION-RELATED CANCERS. WE EXAMINED EPIGENETIC ALTERATIONS, DNA METHYLATION AND MICRORNA DYSREGULATION, IN EPSTEIN-BARR VIRUS-RELATED NASOPHARYNGEAL CARCINOMA IN THE ENDEMIC AREA OF SOUTHERN CHINA AND FOUND SEVERAL DIFFERENTIALLY METHYLATED TUMOR SUPPRESSOR GENE CANDIDATES BY USING A NEXT-GENERATION SEQUENCER. AMONG THESE CANDIDATES, WE REVEALED HIGHER METHYLATION RATES OF RAS-LIKE ESTROGEN-REGULATED GROWTH INHIBITOR (RERG) IN BIOPSY SPECIMENS OF NASOPHARYNGEAL CARCINOMA MORE CONVENIENTLY BY USING RESTRICTION ENZYME-BASED REAL-TIME PCR. THIS RESULT MAY HELP TO IMPROVE CANCER SCREENING STRATEGIES. WE PROFILED MICRORNAS OF NASOPHARYNGEAL CARCINOMA TISSUES USING MICROARRAYS. QUANTITATIVE RT-PCR ANALYSIS CONFIRMED THE CONCORDANT DOWNREGULATION OF MIR-497 IN CANCER TISSUES AND PLASMA, SUGGESTING THAT PLASMA MIR-497 COULD BE USED AS A DIAGNOSTIC BIOMARKER FOR NASOPHARYNGEAL CARCINOMA. CHRONIC INFLAMMATION PROMOTES GENETIC AND EPIGENETIC ABERRATIONS, WITH VARIOUS PATHOGENESES. THESE CHANGES MAY BE USEFUL BIOMARKERS IN LIQUID BIOPSY FOR EARLY DETECTION AND PREVENTION OF CANCER.	2018	

4  5057  31 PHENOBARBITAL MECHANISTIC DATA AND RISK ASSESSMENT: ENZYME INDUCTION, ENHANCED CELL PROLIFERATION, AND TUMOR PROMOTION. CHRONIC EXPOSURE TO HIGH DOSES OF PHENOBARBITAL (PB) CAUSES HEPATOCELLULAR ADENOMAS IN BOTH MICE AND RATS AND HEPATOCELLULAR CARCINOMAS IN SOME STRAINS OF MICE. LONG-TERM PB THERAPY HAS NOT BEEN FOUND TO CAUSE HUMAN TUMORS. PB IS NOT DNA REACTIVE, AND MOST GENOTOXICITY TESTS HAVE YIELDED NEGATIVE RESULTS. PB HAS BEEN EXTENSIVELY STUDIED AS AN EPIGENETIC, RODENT LIVER TUMOR PROMOTER. AT EXPOSURES CAUSING RODENT LIVER TUMORS, PB HAS MEASURABLE EFFECTS ON HEPATOCYTES: PB INHIBITS CELL-TO-CELL COMMUNICATION; PB INDUCES ENZYMES, INCLUDING P450 CYTOCHROMES; PB STIMULATES PROLIFERATION AND INHIBITS APOPTOSIS OF HEPATOCYTES IN NEOPLASTIC FOCI. THRESHOLD EXPOSURES FOR SOME OF THESE ENDPOINTS COINCIDE WITH THE THRESHOLD EXPOSURE FOR TUMORIGENESIS.	1996	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
5  5010  41 PEROXIDATION OF LINOLEIC, ARACHIDONIC AND OLEIC ACID IN RELATION TO THE INDUCTION OF OXIDATIVE DNA DAMAGE AND CYTOGENETIC EFFECTS. IN THE PRESENT STUDY, THE POSSIBLE ROLE OF THE POLYUNSATURATED FATTY ACIDS LINOLEIC AND ARACHIDONIC ACID IN THE CHEMICAL INDUCTION OF CARCINOGENESIS HAS BEEN INVESTIGATED. ANALYSIS OF 7,8-DIHYDRO-8-OXO-2'-DEOXYGUANOSINE (8-OXODG) LEVELS IN 2'-DEOXYGUANOSINE (DG) AND ISOLATED DNA HAS DEMONSTRATED THAT LINOLEIC AND ARACHIDONIC ACID ARE CAPABLE OF INDUCING THIS SPECIFIC GENOTOXIC DAMAGE. THIS EFFECT APPEARS TO BE RELATED TO THE DEGREE OF FATTY ACID UNSATURATION, SINCE IT WAS NOT INDUCED BY MONOUNSATURATED OLEIC ACID. ENZYMATIC PEROXIDATION OF LINOLEIC AND ARACHIDONIC ACID RESULTED IN A SIGNIFICANT INCREASE IN OXIDATIVE DNA DAMAGE. STUDIES ON THE INTERFERENCE OF RADICAL SCAVENGERS WITH THE INDUCTION OF 8-OXODG IN COMBINATION WITH ELECTRON SPIN RESONANCE SPECTROSCOPY DEMONSTRATED THAT THE SUPEROXIDE ANION WAS GENERATED DURING PEROXIDATION OF THESE FATTY ACIDS AND THAT SINGLET OXYGEN IS MOST LIKELY INVOLVED IN THE FORMATION OF OXIDATIVE DNA DAMAGE. THE LEVEL OF OXIDATIVE DAMAGE IN DG AND SINGLE-STRANDED DNA WAS HIGHER AS COMPARED TO THAT IN NATIVE DNA AFTER EQUIMOLAR TREATMENT. EXPOSURE OF HUMAN LYMPHOCYTES TO LINOLEIC OR ARACHIDONIC ACID DID NOT RESULT IN A SIGNIFICANT INCREASE IN LEVELS OF 8-OXODG. THIS MAY INDICATE THAT THE RATE OF INTRACELLULAR PEROXIDATION IS RELATIVELY LOW AND/OR THAT NUCLEAR DNA IN INTACT CELLS IS EFFECTIVELY PROTECTED AGAINST GENETIC DAMAGE INDUCED BY REACTIVE OXYGEN SPECIES. IT IS THEREFORE CONCLUDED THAT RELATIVELY SHORT PERIODS OF LINOLEIC OR ARACHIDONIC ACID ADMINISTRATION ARE NOT LIKELY TO IMPOSE A DIRECT GENOTOXIC RISK. IT CAN, HOWEVER, NOT BE EXCLUDED THAT CHRONIC EXPOSURE TO POLYUNSATURATED FATTY ACIDS INDUCES OXIDATIVE DNA DAMAGE OR IS RELATED TO CANCER RISK BY EPIGENETIC MECHANISMS, AS IS ALSO INDICATED BY THE OBSERVED CYTOTOXIC EFFECTS OF LINOLEIC AND ARACHIDONIC ACID.	1994	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
6  5582  37 ROLE OF NITRATIVE AND OXIDATIVE DNA DAMAGE IN INFLAMMATION-RELATED CARCINOGENESIS. CHRONIC INFLAMMATION INDUCED BY BIOLOGICAL, CHEMICAL, AND PHYSICAL FACTORS HAS BEEN FOUND TO BE ASSOCIATED WITH THE INCREASED RISK OF CANCER IN VARIOUS ORGANS. WE REVEALED THAT INFECTIOUS AGENTS INCLUDING LIVER FLUKE, HELICOBACTER PYLORI, AND HUMAN PAPILLOMA VIRUS AND NONINFECTIOUS AGENTS SUCH AS ASBESTOS FIBER INDUCED INOS-DEPENDENT FORMATION OF 8-NITROGUANINE AND 8-OXO-7, 8-DIHYDRO-2'-DEOXYGUANOSINE (8-OXODG) IN CANCER TISSUES AND PRECANCEROUS REGIONS. OUR RESULTS WITH THE COLOCALIZATION OF PHOSPHORYLATED ATM AND GAMMA-H2AX WITH 8-OXODG AND 8-NITROGUANINE IN INFLAMMATION-RELATED CANCER TISSUES SUGGEST THAT DNA BASE DAMAGE LEADS TO DOUBLE-STRANDED BREAKS. IT IS INTERESTING FROM THE ASPECT OF GENETIC INSTABILITY. WE ALSO DEMONSTRATED IL-6-MODULATED INOS EXPRESSION VIA STAT3 AND EGFR IN EPSTEIN-BARR-VIRUS-ASSOCIATED NASOPHARYNGEAL CARCINOMA AND FOUND PROMOTER HYPERMETHYLATION IN SEVERAL TUMOR SUPPRESSOR GENES. SUCH EPIGENETIC ALTERATION MAY OCCUR BY CONTROLLING THE DNA METHYLATION THROUGH IL-6-MEDIATED JAK/STAT3 PATHWAYS. COLLECTIVELY, 8-NITROGUANINE WOULD BE A USEFUL BIOMARKER FOR PREDICTING THE RISK OF INFLAMMATION-RELATED CANCERS.	2012	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
7  6663  33 UPREGULATION OF HISTONE-LYSINE METHYLTRANSFERASES PLAYS A CAUSAL ROLE IN HEXAVALENT CHROMIUM-INDUCED CANCER STEM CELL-LIKE PROPERTY AND CELL TRANSFORMATION. WHILE HEXAVALENT CHROMIUM [CR(VI)] IS GENERALLY CONSIDERED AS A GENOTOXIC ENVIRONMENTAL CARCINOGEN, STUDIES SHOWED THAT CR(VI) EXPOSURE ALSO CAUSES EPIGENETIC CHANGES. HOWEVER, WHETHER CR(VI)-CAUSED EPIGENETIC DYSREGULATIONS PLAYS AN IMPORTANT ROLE IN CR(VI) CARCINOGENICITY REMAIN LARGELY UNKNOWN. THE AIM OF THIS STUDY WAS TO DETERMINE IF CHRONIC LOW DOSE CR(VI) EXPOSURE CAUSES EPIGENETIC CHANGES, THE UNDERLYING MECHANISM AND WHETHER CHRONIC LOW DOSE CR(VI) EXPOSURE-CAUSED EPIGENETIC DYSREGULATION CONTRIBUTES CAUSALLY TO CR(VI)-INDUCED CANCER STEM CELL (CSC)-LIKE PROPERTY AND CELL TRANSFORMATION. TWO IMMORTALIZED HUMAN BRONCHIAL EPITHELIAL CELL LINES (BEAS-2B AND 16HBE) WERE EXPOSED TO 0.25 MUM OF K(2)CR(2)O(7) FOR 20 AND 40 WEEKS TO INDUCE CELL TRANSFORMATION, RESPECTIVELY. CR(VI)-INDUCED EPIGENETIC CHANGES WERE EXAMINED IN CR(VI)-TRANSFORMED CELLS AND CR(VI) EXPOSURE-CAUSED HUMAN LUNG CANCER TISSUES. PHARMACOLOGICAL INHIBITORS AND GENE KNOCKDOWN EXPERIMENTS WERE USED TO DETERMINE THE ROLE OF EPIGENETIC DYSREGULATION IN CR(VI) CARCINOGENICITY. WE FOUND THAT CHRONIC CR(VI) EXPOSURE CAUSES EPIGENETIC DYSREGULATION AS EVIDENCED BY THE INCREASED LEVELS OF HISTONE H3 REPRESSIVE METHYLATION MARKS (H3K9ME2 AND H3K27ME3) AND THE RELATED HISTONE-LYSING METHYLTRANSFERASES (HMTASES). PHARMACOLOGICAL INHIBITION OR KNOCKDOWN OF HMTASES REDUCES H3 REPRESSIVE METHYLATION MARKS AND MALIGNANT PHENOTYPES OF CR(VI)-TRANSFORMED CELLS. MOREOVER, KNOCKDOWN OF HMTASES IN PARENTAL CELLS SIGNIFICANTLY REDUCES CHRONIC CR(VI) EXPOSURE-INDUCED CSC-LIKE PROPERTY AND CELL TRANSFORMATION. FURTHER MECHANISTIC STUDY REVEALED THAT KNOCKDOWN OF HMTASES DECREASES CR(VI) EXPOSURE-CAUSED DNA DAMAGE. OUR FINDINGS INDICATE THAT CHRONIC CR(VI) EXPOSURE INCREASES H3 REPRESSIVE METHYLATION MARKS BY INCREASING THE RELATED HMTASES EXPRESSION; AND THAT INCREASED EXPRESSION OF HMTASES PLAYS A CAUSAL ROLE IN CR(VI)-INDUCED CSC-LIKE PROPERTY AND CELL TRANSFORMATION.	2018	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
8  5960  31 TELOMERE LENGTH IN HEPATOCELLULAR CARCINOMA AND PAIRED ADJACENT NON-TUMOR TISSUES BY QUANTITATIVE PCR. TELOMERE SHORTENING LIMITS THE PROLIFERATIVE CAPACITY OF HUMAN CELLS, RESTRAINS THE REGENERATIVE CAPACITY OF ORGAN SYSTEMS DURING CHRONIC DISEASES AND AGING AND ALSO INDUCES CHROMOSOMAL INSTABILITY AS WELL AS INITIATION OF CANCER. PREVIOUS STUDIES DEMONSTRATED THAT TELOMERES ARE OFTEN SIGNIFICANTLY SHORTER IN TUMOR TISSUE, INCLUDING HEPATOCELLULAR CARCINOMA (HCC), COMPARED TO THE SURROUNDING TISSUE, BUT TELOMERE LENGTH IN HCC TISSUES WAS NOT CORRELATED WITH SEVERAL CLINICAL PARAMETERS, SUCH AS AGE, SEX, HBV OR HCV INFECTIONS AND TUMOR SIZE. IN THE PRESENT STUDY, THE TELOMERE LENGTH RATIO OF 36 PAIRED HCC, AND THEIR ADJACENT NON-TUMOR TISSUES WAS MEASURED BY QUANTITATIVE PCR (Q-PCR). THE MEAN TELOMERE LENGTHS (SD) FOR HCC AND ADJACENT NON-TUMOR TISSUES WERE 0.26 (0.10) AND 0.47 (0.20) RESPECTIVELY (T = 6.22, P < 0.0001). THERE WAS A LARGE DIFFERENCE IN THE DISTRIBUTION OF SUBJECTS BASED ON TELOMERE LENGTH IN TUMOR AND ADJACENT NON-TUMOR TISSUES. THE NUMBER OF TUMORS WITH TELOMERE LENGTH SHORTER THAN 0.50 WAS MUCH HIGHER THAN THAT OF ADJACENT NON-TUMOR TISSUES; MORE THAN 90% OF THE TISSUES WITH TELOMERE LENGTH > OR = 0.50 WERE ADJACENT NON-TUMOR TISSUES. THE CORRELATIONS BETWEEN TELOMERE LENGTH AND AFLATOXIN B1- AND POLYCYCLIC AROMATIC HYDROCARBON-DNA ADDUCTS LEVEL, P53 MUTATIONS AND P16 HYPERMETHYLATION STATUS WERE ALSO TESTED, BUT NO SIGNIFICANT ASSOCIATIONS WERE FOUND. THE RELATIONSHIP BETWEEN TELOMERE LENGTH SHORTENING, CHEMICAL CARCINOGEN EXPOSURE, AND GENETIC AND EPIGENETIC CHANGES IN HEPATOCARCINOGENESIS NEEDS FURTHER INVESTIGATION.	2007	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
9  2099  31 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	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
10   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	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
11  1321  33 DEMONSTRATION AND CHARACTERIZATION OF MUTATIONS INDUCED BY HELICOBACTER PYLORI ORGANISMS IN GASTRIC EPITHELIAL CELLS. BACKGROUND: HELICOBACTER PYLORI GASTRITIS INCREASES GASTRIC CANCER RISK. MICROSATELLITE INSTABILITY-TYPE MUTATIONS ARE SECONDARY TO DEFICIENT DNA MISMATCH REPAIR. H. PYLORI GASTRITIS IS MORE FREQUENT IN PATIENTS WITH MICROSATELLITE INSTABILITY-POSITIVE GASTRIC CANCERS, AND H. PYLORI ORGANISMS INDEPENDENTLY OF INFLAMMATION CAN REDUCE DNA MISMATCH REPAIR PROTEIN LEVELS, RAISING THE HYPOTHESIS THAT H. PYLORI ORGANISMS MIGHT LEAD TO MUTAGENESIS DURING INFECTION. MATERIALS AND METHODS: MUTATIONS WERE DETECTED USING A GREEN FLUORESCENT PROTEIN REPORTER VECTOR (PEGFP-CA13). GASTRIC CANCER AGS CELLS TRANSFECTED WITH PEGFP-CA13 WERE COCULTURED WITH H. PYLORI OR ESCHERICHIA COLI. THE NUMBERS OF GREEN FLUORESCENT PROTEIN (GFP)-POSITIVE CELLS WERE DETERMINED, AND GFP, HMSH2, AND HMLH1 PROTEIN LEVELS WERE MEASURED BY WESTERN BLOT. THE EFFECT OF H. PYLORI ON CPG METHYLATION STATUS OF HMLH1 WAS DETERMINED BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION. RESULTS: GFP LEVELS AND GFP-POSITIVE CELL NUMBERS IN AGS CELLS COCULTURED WITH H. PYLORI SIGNIFICANTLY INCREASED, AS THE LEVELS OF HMLH1 AND HMSH2 DROPPED. H. PYLORI COCULTURES INDUCED LOW-LEVEL CPG METHYLATION OF THE HMLH1 PROMOTER. SEQUENCE ANALYSIS OF CELLS COCULTURED WITH H. PYLORI SHOWED AN INCREASED NUMBER OF FRAMESHIFT MUTATIONS AND POINT MUTATIONS AS COMPARED TO CELLS NOT COCULTURED WITH H. PYLORI (P = .03 AND P = .001, RESPECTIVELY). CONCLUSIONS: THIS IS THE FIRST REPORT SHOWING THAT H. PYLORI BACTERIA MAY LEAD TO ACCUMULATION OF GENOMIC MUTATIONS, INDEPENDENTLY OF UNDERLYING INFLAMMATION. THIS IS ASSOCIATED WITH REDUCED DNA MISMATCH REPAIR, AND IS AT LEAST IN PART ASSOCIATED WITH CPG METHYLATION OF THE HMLH1 PROMOTER. THESE DATA SUPPORT THE NOTION THAT H. PYLORI-INDUCED MUTATIONS AND EPIGENETIC ALTERATIONS IN GASTRIC EPITHELIAL CELLS DURING CHRONIC GASTRITIS MAY CONTRIBUTE TO AN INCREASED RISK OF GASTRIC CANCER ASSOCIATED WITH H. PYLORI INFECTION.	2006	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
12   865  35 CHRONIC ACRYLAMIDE EXPOSURE IN MALE MICE RESULTS IN ELEVATED DNA DAMAGE IN THE GERMLINE AND HERITABLE INDUCTION OF CYP2E1 IN THE TESTES. ACUTE ACRYLAMIDE EXPOSURE IN MALE RODENTS RESULTS IN REDUCED REPRODUCTIVE PERFORMANCE AND DOMINANT LETHALITY. HOWEVER, THE REPRODUCTIVE EFFECTS OF LOW DOSE CHRONIC EXPOSURE, WHICH BETTER REFLECTS THE NATURE OF HUMAN EXPOSURE, REMAIN FAR LESS CERTAIN. HUMAN DIETARY CONSUMPTION OF ACRYLAMIDE HAS BEEN ESTIMATED AT AN AVERAGE OF 1-4 MICROG/KG BW/DAY. IN ORDER TO SIMULATE THIS EXPOSURE, MALE MICE WERE PROVIDED WITH ACRYLAMIDE (1 MICROG/ML) VIA THEIR DRINKING WATER CONTINUOUSLY FOR SIX MONTHS, WHICH WAS EQUIVALENT TO A HUMAN DOSE OF 10.5 MICROG/ KG BW/DAY. THIS EXPOSURE REGIME INCREASED DNA DAMAGE IN THE SPERMATOZOA, WITHOUT AFFECTING A CONCOMITANT REDUCTION IN OVERALL FERTILITY. THE OFFSPRING OF ACRYLAMIDE TREATED MICE DID NOT HAVE AN INCREASED INCIDENCE OF SKIN PAPILLOMA FORMATION FOLLOWING THE TWO-STAGE TUMOR INDUCTION PROTOCOL. HOWEVER, THE MALE OFFSPRING OF ACRYLAMIDE TREATED FATHERS HAD SIGNIFICANTLY INCREASED LEVELS OF DNA DAMAGE IN THEIR SPERMATOZOA, DESPITE HAVING HAD NO DIRECT TOXICANT EXPOSURE. IT WAS ALSO FOUND THAT THE F0, AND MOST CRUCIALLY, F1 MICE HAD INCREASED LEVELS OF CYP2E1 PROTEIN IN THEIR GERM CELLS. THIS IS SIGNIFICANT AS CYP2E1 IS THE SOLE ENZYME RESPONSIBLE FOR CONVERSION OF ACRYLAMIDE TO ITS HARMFUL METABOLITE GLYCIDAMIDE. THIS ALTERED EXPRESSION MAY BE DUE TO EPIGENETIC ALTERATIONS. ADDITIONALLY, THE F0 AND F1 MICE HAD INCREASED OXIDATIVE ADDUCTS IN THE DNA OF THEIR GERM CELLS, WHICH WAS HYPOTHESIZED TO ARISE AS A BYPRODUCT OF INCREASED CYP2E1 ACTIVITY. THEREFORE, CHRONIC PATERNAL ACRYLAMIDE EXPOSURE IN MICE HAS CONSEQUENCES FOR THEIR OFFSPRING, AND RAISES CONCERNS FOR THE EFFECTS OF ACRYLAMIDE EXPOSURE IN THE HUMAN POPULATION AND THE ACCUMULATED EFFECTS WITH MULTIPLE GENERATIONS OF EXPOSURE.	2016	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
13  3796  34 INTERLEUKIN-6 PROMOTES TUMORIGENESIS BY ALTERING DNA METHYLATION IN ORAL CANCER CELLS. WORLDWIDE ORAL SQUAMOUS CELL CARCINOMA (OSCC) ACCOUNTS FOR MORE THAN 100,000 DEATHS EACH YEAR. CHRONIC INFLAMMATION CONSTITUTES ONE OF THE KEY RISK FACTORS FOR OSCC. ACCUMULATING EVIDENCE SUGGESTS THAT ABERRANT DNA METHYLATION MAY CONTRIBUTE TO OSCC TUMORIGENESIS. THIS STUDY INVESTIGATED WHETHER CHRONIC INFLAMMATION ALTERS DNA METHYLATION AND EXPRESSION OF CANCER-ASSOCIATED GENES IN OSCC. WE ESTABLISHED AN IN VITRO MODEL OF INTERLEUKIN (IL)-6 MEDIATING CHRONIC INFLAMMATION IN OSCC CELL LINES. THEREAFTER, WE MEASURED THE ABILITY OF IL-6 TO INDUCE GLOBAL HYPOMETHYLATION OF LONG INTERSPERSED NUCLEAR ELEMENT-1 (LINE-1) SEQUENCES, AS WELL AS CPG METHYLATION CHANGES USING MULTIPLE METHODOLOGIES INCLUDING QUANTITATIVE PYROSEQUENCING, METHYLATION-SPECIFIC MULTIPLEX LIGATION-DEPENDENT PROBE AMPLIFICATION AND SENSITIVE MELTING ANALYSIS AFTER REAL-TIME-METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION (PCR). GENE EXPRESSION WAS INVESTIGATED BY QUANTITATIVE REVERSE TRANSCRIPTASE-PCR. IL-6 INDUCED SIGNIFICANT GLOBAL LINE-1 HYPOMETHYLATION (P=0.016) IN OUR IN VITRO MODEL OF INFLAMMATORY STRESS IN OSCC CELL LINES. SIMULTANEOUSLY, IL-6 INDUCED CPG PROMOTER METHYLATION CHANGES IN SEVERAL IMPORTANT PUTATIVE TUMOR SUPPRESSOR GENES INCLUDING CHFR, GATA5 AND PAX6. METHYLATION CHANGES CORRELATED INVERSELY WITH THE CHANGES IN THE EXPRESSION OF CORRESPONDING GENES. OUR RESULTS INDICATE THAT IL-6-INDUCED INFLAMMATION PROMOTES TUMORIGENESIS IN THE ORAL CAVITY BY ALTERING GLOBAL LINE-1 HYPOMETHYLATION. IN ADDITION, CONCURRENT HYPERMETHYLATION OF MULTIPLE TUMOR SUPPRESSOR GENES BY IL-6 SUGGESTS THAT EPIGENETIC GENE SILENCING MAY BE AN IMPORTANT CONSEQUENCE OF CHRONIC INFLAMMATION IN THE ORAL CAVITY. THESE FINDINGS HAVE CLINICAL RELEVANCE, AS BOTH METHYLATION AND INFLAMMATION ARE SUITABLE TARGETS FOR DEVELOPING NOVEL PREVENTIVE AND THERAPEUTIC MEASURES.	2011	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
14  2961  35 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	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
15  4267  37 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	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
16  1993  41 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	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
17   907  25 CHRONIC EXPOSURE TO ENVIRONMENTALLY RELEVANT CONCENTRATION OF FLUORIDE ALTERS OGG1 AND RAD51 EXPRESSIONS IN MICE: INVOLVEMENT OF EPIGENETIC REGULATION. CHRONIC EXPOSURE TO FLUORIDE (F) BEYOND THE PERMISSIBLE LIMIT (1.5 PPM) IS KNOWN TO CAUSE DETRIMENTAL HEALTH EFFECTS BY INDUCTION OF OXIDATIVE STRESS-MEDIATED DNA DAMAGE OVERPOWERING THE DNA REPAIR MACHINERY. IN THE PRESENT STUDY, WE ASSESSED F INDUCED OXIDATIVE STRESS THROUGH MONITORING BIOCHEMICAL PARAMETERS AND LOOKED INTO THE EFFECT OF CHRONIC F EXPOSURE ON TWO CRUCIAL DNA REPAIR GENES OGG1 AND RAD51 HAVING IMPORTANT ROLE AGAINST ROS INDUCED DNA DAMAGES. TO ADDRESS THIS ISSUE, WE EXPOSED SWISS ALBINO MICE TO AN ENVIRONMENTALLY RELEVANT CONCENTRATION OF FLUORIDE (15 PPM NAF) FOR 8 MONTHS. RESULTS REVEALED HISTOARCHITECTURAL DAMAGES IN LIVER, BRAIN, KIDNEY AND SPLEEN. DEPLETION OF GSH, INCREASE IN LIPID PEROXIDATION AND CATALASE ACTIVITY IN LIVER AND BRAIN CONFIRMED THE GENERATION OF OXIDATIVE STRESS. QRT-PCR RESULT SHOWED THAT EXPRESSIONS OF OGG1 AND RAD51 WERE ALTERED AFTER F EXPOSURE IN THE AFFECTED ORGANS. PROMOTER HYPERMETHYLATION WAS ASSOCIATED WITH THE DOWNREGULATION OF RAD51. F-INDUCED DNA DAMAGE AND THE COMPROMISED DNA REPAIR MACHINERY TRIGGERED INTRINSIC PATHWAY OF APOPTOSIS IN LIVER AND BRAIN. THE PRESENT STUDY INDICATES THE POSSIBLE ASSOCIATION OF EPIGENETIC REGULATION WITH F INDUCED NEUROTOXICITY.	2020	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
18  1781  22 EFFECT OF 1 YEAR B AND D VITAMIN SUPPLEMENTATION ON LINE-1 REPETITIVE ELEMENT METHYLATION IN OLDER SUBJECTS. BACKGROUND: DISTURBED DNA METHYLATION IS CAUSALLY RELATED TO CHRONIC DISEASES LIKE CANCER AND ATHEROSCLEROSIS. B VITAMINS ARE COFACTORS REQUIRED FOR METHYL GROUP SYNTHESIS AND MAY THEREFORE AFFECT DNA METHYLATION. VITAMIN D HAS EPIGENETIC EFFECTS. WE TESTED IF B AND D VITAMIN SUPPLEMENTATION HAS AN EFFECT ON GENOMIC LONG INTERSPERSED NUCLEAR ELEMENT-1 (LINE-1) METHYLATION AND THE METABOLITES S-ADENOSYLMETHIONINE (SAM) AND S-ADENOSYLHOMOCYSTEINE (SAH). METHODS: FIFTY SUBJECTS (MEDIAN AGE 68.0 YEARS) WERE SUPPLEMENTED WITH A DAILY ORAL DOSE OF B VITAMINS (500 MICROG FOLIC ACID, 500 MICROG VITAMIN B12 AND 50 MG VITAMIN B6), 1200 IU VITAMIN D AND 456 MG CALCIUM. FASTING BLOOD SAMPLES WERE COLLECTED BEFORE AND AFTER 1 YEAR OF SUPPLEMENTATION. LINE-1 METHYLATION WAS DETERMINED IN GENOMIC DNA FROM BLOOD CELLS AS A SURROGATE FOR WHOLE GENOME METHYLATION. IN ADDITION, SAM, SAH AND TOTAL HOMOCYSTEINE (THCY) WERE MEASURED IN PLASMA SAMPLES. RESULTS: PLASMA HOMOCYSTEINE DECREASED SIGNIFICANTLY AFTER SUPPLEMENTATION (12.8 VS. 9.1 MICROMOL/L; P<0.05), WHEREAS SAM, SAH, THE SAM/SAH RATIO AND LINE-1 METHYLATION DID NOT CHANGE SIGNIFICANTLY. LINE-1 METHYLATION WAS NOT SIGNIFICANTLY CORRELATED WITH SAH, HOMOCYSTEINE OR B VITAMINS. CONCLUSIONS: LONG-TERM VITAMIN B SUPPLEMENTATION HAD NO EFFECT ON LINE-1 METHYLATION IN BLOOD CELLS NOR ON PLASMA LEVELS OF SAM AND SAH. VITAMIN B AND D SUPPLEMENTATION SEEMS TO HAVE NO EFFECT ON DNA METHYLATION, ESPECIALLY IN CASES WHERE NO SEVERE DEFICIENCY EXISTS.	2013	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
19   122  27 A SYSTEMATIC REVIEW ON FLUORIDE-INDUCED EPIGENETIC TOXICITY IN MAMMALS. FLUORIDE, ONE OF THE GLOBAL GROUNDWATER CONTAMINANTS, IS UBIQUITOUS IN OUR DAY-TO-DAY LIFE FROM VARIOUS NATURAL AND ANTHROPOGENIC SOURCES. NUMEROUS IN VITRO, IN VIVO, AND EPIDEMIOLOGICAL STUDIES ARE CONDUCTED TO UNDERSTAND THE EFFECT OF FLUORIDE ON BIOLOGICAL SYSTEMS. A LOW CONCENTRATION OF FLUORIDE IS REPORTED TO INCREASE ORAL HEALTH, WHEREAS CHRONIC EXPOSURE TO HIGHER CONCENTRATIONS CAUSES FLUORIDE TOXICITY (FLUOROSIS). IT INCLUDES DENTAL FLUOROSIS, SKELETAL FLUOROSIS, AND FLUORIDE TOXICITY IN SOFT TISSUES. THE MECHANISM OF FLUORIDE TOXICITY HAS BEEN REVIEWED EXTENSIVELY. HOWEVER, EPIGENETIC REGULATION IN FLUORIDE TOXICITY HAS NOT BEEN REVIEWED. THIS SYSTEMATIC REVIEW SUMMARIZES THE CURRENT KNOWLEDGE REGARDING FLUORIDE-INDUCED EPIGENETIC TOXICITY IN THE IN VITRO, IN VIVO, AND EPIDEMIOLOGICAL STUDIES IN MAMMALIAN SYSTEMS. WE EXAMINED FOUR DATABASES FOR THE ASSOCIATION BETWEEN EPIGENETICS AND FLUORIDE EXPOSURE. OUT OF 932 ARTICLES (AS OF 31 MARCH 2022), 39 MET OUR INCLUSION CRITERIA. MOST OF THE STUDIES FOCUSED ON DIFFERENT GENES, AND OVERALL, PRELIMINARY EVIDENCE FOR EPIGENETIC REGULATION OF FLUORIDE TOXICITY WAS IDENTIFIED. WE FURTHER HIGHLIGHT THE NEED FOR EPIGENOME STUDIES RATHER THAN CANDIDATE GENES AND PROVIDE RECOMMENDATIONS FOR FUTURE RESEARCH. OUR RESULTS INDICATE A CORRELATION BETWEEN FLUORIDE EXPOSURE AND EPIGENETIC PROCESSES. FURTHER STUDIES ARE WARRANTED TO ELUCIDATE AND CONFIRM THE MECHANISM OF EPIGENETIC ALTERATIONS MEDIATED FLUORIDE TOXICITY.	2022	
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
20  2656  30 EPIMUTATION AND CANCER: A NEW CARCINOGENIC MECHANISM OF LYNCH SYNDROME (REVIEW). EPIMUTATION IS DEFINED AS ABNORMAL TRANSCRIPTIONAL REPRESSION OF ACTIVE GENES AND/OR ABNORMAL ACTIVATION OF USUALLY REPRESSED GENES CAUSED BY ERRORS IN EPIGENETIC GENE REPRESSION. EPIMUTATION ARISES IN SOMATIC CELLS AND THE GERMLINE, AND CONSTITUTIONAL EPIMUTATION MAY ALSO OCCUR. EPIMUTATION IS THE FIRST STEP OF TUMORIGENESIS AND CAN BE A DIRECT CAUSE OF CARCINOGENESIS. CANCERS ASSOCIATED WITH EPIMUTATION INCLUDE LYNCH SYNDROME (HEREDITARY NON-POLYPOSIS COLORECTAL CANCER, HNPCC), CHRONIC LYMPHOCYTIC LEUKEMIA, BREAST CANCER AND OVARIAN CANCER. EPIMUTATION HAS BEEN SHOWN FOR MANY TUMOR SUPPRESSOR GENES, INCLUDING RB, VHL, HMLH1, APC AND BRCA1, IN SPORADIC CANCERS. METHYLATION HAS RECENTLY BEEN SHOWN IN DNA FROM NORMAL TISSUES AND PERIPHERAL BLOOD IN CASES OF SPORADIC COLORECTAL CANCER AND MANY STUDIES SHOW CONSTITUTIVE EPIMUTATION IN CANCERS. EPIMUTATION OF DNA MISMATCH REPAIR (MMR) GENES (BRCA1, HMLH1 AND HMSH2) INVOLVED IN DEVELOPMENT FAMILIAL CANCERS HAS ALSO BEEN FOUND. THESE RESULTS HAVE LED TO A FOCUS ON EPIMUTATION AS A NOVEL ONCOGENIC MECHANISM.	2012