1 145 142 ABERRANT DNA METHYLATION STATUS AND MRNA EXPRESSION LEVEL OF SMG1 GENE IN CHRONIC MYELOID LEUKEMIA: A CASE-CONTROL STUDY. OOBJECTIVE: CHRONIC MYELOID LEUKEMIA (CML) IS A MYELOPROLIFERATIVE MALIGNANCY WITH DIFFERENT STAGES. ABERRANT EPIGENETIC MODIFICATIONS, SUCH AS DNA METHYLATION, HAVE BEEN INTRODUCED AS A SIGNATURE FOR DIVERSE CANCERS WHICH ALSO PLAYS A CRUCIAL ROLE IN CML PATHOGENESIS AND DEVELOPMENT. SUPPRESSOR WITH MORPHOGENETIC EFFECT ON GENITALIA (SMG1) GENE RECENTLY HAS BEEN BROUGHT TO THE SPOTLIGHT AS A POTENT TUMOR SUPPRESSOR GENE THAT CAN BE SUPPRESSED BY TUMORS FOR FURTHER PROGRESS. THE PRESENT STUDY AIMS TO INVESTIGATE SMG1 STATUS IN CML PATIENTS. MATERIALS AND METHODS: IN THIS CASE-CONTROL STUDY, PERIPHERAL BLOOD FROM 30 PATIENTS WITH DIFFERENT PHASES OF CML [NEW CASE (N)=10, COMPLETE MOLECULAR REMISSION (CMR)=10, BLASTIC PHASE (BP)=10] AND 10 HEALTHY SUBJECTS WERE COLLECTED. METHYLATION STATUS AND EXPRESSION LEVEL OF SMG1 GENE PROMOTER WAS ASSESSED BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION (MSP) AND QUANTITATIVE REVERSE-TRANSCRIPTION PCR, RESPECTIVELY. RESULTS: MSP RESULTS OF SMG1 GENE PROMOTOR IN THE NEW CASE GROUP WERE METHYLATED (60% METHYLATED, 30% HEMIMETHYLATED AND 10% UNMETHYLATED). ALL CMR AND CONTROL GROUP PATIENTS WERE UNMETHYLATED IN THE SMG1 GENE PROMOTER. IN THE BP GROUP, METHYLATED SMG1 PROMOTER WAS SEEN (50% OF PATIENTS HAD A METHYLATED STATUS AND 50% HAD HEMIMETHYLATED STATUS). IN COMPARISON WITH THE HEALTHY SUBJECTS, EXPRESSION LEVEL OF SMG1 IN THE NEW CASE GROUP WAS DECREASED (P<0.01); IN THE CMR GROUP AND BP-CML GROUPS, IT WAS INCREASED (P<0.05). NO SIGNIFICANT CORRELATION BETWEEN PATIENTS' HEMATOLOGICAL FEATURES AND SMG1 METHYLATION WAS SEEN. CONCLUSION: OUR RESULTS DEMONSTRATED THAT ABERRANT METHYLATION OF SMG1 OCCURRED IN CML PATIENTS AND IT HAD A SIGNIFICANT ASSOCIATION WITH SMG1 EXPRESSION. SMG1 GENE PROMOTER SHOWED DIVERSE METHYLATED STATUS AND SUBSEQUENT EXPRESSION LEVELS IN DIFFERENT PHASES OF CML. THESE FINDINGS SUGGESTED POSSIBLE PARTICIPATION OF SMG1 SUPPRESSION IN THE CML PATHOGENESIS. 2022 2 2304 45 EPIGENETIC REGULATION OF CATHEPSIN L EXPRESSION IN CHRONIC MYELOID LEUKAEMIA. THE EXPRESSION AND SIGNIFICANCE OF CATHEPSIN L (CTSL) HAS BEEN EXTENSIVELY STUDIED IN SOLID TUMOURS. HOWEVER NO SUCH INFORMATION IN CHRONIC MYELOID LEUKAEMIA (CML) WAS AVAILABLE. WE INVESTIGATED THE ACTIVITY AND EXPRESSION OF THIS PROTEASE IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMCS) OF 47 ADULT CML PATIENTS. THIRTY ADULTS SUFFERING FROM SYSTEMIC DISEASES AND 50 HEALTHY VOLUNTEERS SERVED AS CONTROLS. THE MRNA LEVELS OF CTSL, ITS SPECIFIC ENDOGENOUS INHIBITOR CYSTATIN C AND TRANSCRIPTIONAL UP-REGULATOR VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF) WERE QUANTITATED BY REAL-TIME QPCR. CTSL PROTEASE ACTIVITY AND ITS MRNA EXPRESSION WERE SIGNIFICANTLY HIGHER IN CML CHRONIC PHASE (CP) PATIENTS COMPARED TO CML ACCELERATED PHASE/BLAST CRISIS (AP/BC) PATIENTS AND CONTROLS (P0.05). THE FREQUENCY OF DDX43 HYPOMETHYLATION IN PATIENTS IN THE CHRONIC PHASE, IN THE ACCELERATED PHASE, AND IN BLAST CRISIS WAS 23.4% (15/64), 25.0% (2/8), AND 33.3% (5/15), RESPECTIVELY (P>0.05). THERE WAS A SIGNIFICANT CORRELATION BETWEEN DDX43 HYPOMETHYLATION AND DDX43 TRANSCRIPT (R=0.469, P=0.004). OUR DATA SUGGEST THAT HYPOMETHYLATION OF THE DDX43 PROMOTER MAY BE AN EARLY AND FREQUENT MOLECULAR EVENT IN THE DEVELOPMENT OF CML IN CHINESE PATIENTS. 2013 5 3168 50 GTPASE REGULATOR ASSOCIATED WITH THE FOCAL ADHESION KINASE (GRAF) TRANSCRIPT WAS DOWN-REGULATED IN PATIENTS WITH MYELOID MALIGNANCIES. BACKGROUND: GTPASE REGULATOR ASSOCIATED WITH THE FOCAL ADHESION KINASE (GRAF), A PUTATIVE TUMOR SUPPRESSOR GENE, IS FOUND INACTIVATED IN HEMATOPOIETIC MALIGNANCIES BY EITHER GENETIC OR EPIGENETIC ABNORMALITIES. HOWEVER, THE EXPRESSION LEVEL OF GRAF GENE HAS NOT YET BEEN STUDIED IN LEUKEMIA. THE AIM OF THIS STUDY WAS TO INVESTIGATE THE EXPRESSION LEVEL OF GRAF GENE IN THOSE PATIENTS WITH MYELOID MALIGNANCIES INCLUDING ACUTE MYELOID LEUKEMIA (AML), MYELODYSPLASTIC SYNDROME (MDS) AND CHRONIC MYELOID LEUKEMIA (CML). METHODS: THE EXPRESSION LEVELS OF GRAF TRANSCRIPT WERE DETERMINED IN 94 PATIENTS USING REAL-TIME QUANTITATIVE PCR (RQ-PCR). CLINICAL AND LABORATORY DATA OF THESE PATIENTS WERE COLLECTED AND ANALYZED. RESULTS: THE SIGNIFICANTLY DECREASED LEVEL OF GRAF TRANSCRIPT WAS OBSERVED IN THREE MYELOID MALIGNANCIES COMPARED TO CONTROLS. WITHIN AML, THERE WAS NO DIFFERENCE IN THE LEVEL OF GRAF TRANSCRIPT AMONG DIFFERENT FAB SUBTYPES (P > 0.05). DIFFERENCE WAS NOT OBSERVED IN THE AMOUNT OF GRAF MRNA BETWEEN CML AT CHRONIC PHASE AND CONTROLS. AS CML PROGRESSED, GRAF TRANSCRIPT SIGNIFICANTLY DECREASED. IN MDS, THREE CASES WITH 5Q DELETION HAD LOWER GRAF TRANSCRIPT THAN FOUR WITHOUT 5Q DELETION (MEDIAN 0.76 VS 2.99) (P > 0.05). CONCLUSION: OUR RESULTS DEMONSTRATE THAT THE GRAF TRANSCRIPT IS DECREASED IN MYELOID MALIGNANCIES. 2010 6 3484 49 IDENTIFICATION OF CHROMATIN REMODELING GENES ARID4A AND ARID4B AS LEUKEMIA SUPPRESSOR GENES. BACKGROUND: LEUKEMIA EVOLVES THROUGH A MULTISTEP PROCESS FROM PREMALIGNANCY TO MALIGNANCY. EPIGENETIC ALTERATIONS, INCLUDING HISTONE MODIFICATIONS, HAVE BEEN PROPOSED TO PLAY AN IMPORTANT ROLE IN TUMORIGENESIS. THE INVOLVEMENT OF TWO CHROMATIN REMODELING GENES, RETINOBLASTOMA-BINDING PROTEIN 1 (RBBP1/ARID4A) AND RBBP1-LIKE 1 (RBBP1L1/ARID4B), IN LEUKEMOGENESIS WAS NOT CHARACTERIZED. METHODS: THE LEUKEMIC PHENOTYPE OF MICE DEFICIENT FOR ARID4A WITH OR WITHOUT HAPLOINSUFFICIENCY FOR ARID4B WAS INVESTIGATED BY SERIALLY MONITORING COMPLETE BLOOD COUNTS TOGETHER WITH MICROSCOPIC HISTOLOGIC ANALYSIS AND FLOW CYTOMETRIC ANALYSIS OF BONE MARROW AND SPLEEN FROM THE ARID4A(-/-) MICE OR ARID4A(-/-)ARID4B(+/-) MICE. REGULATION IN BONE MARROW CELLS OF DOWNSTREAM GENES IMPORTANT FOR NORMAL HEMATOPOIESIS WAS ANALYZED BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN REACTION. GENOTYPIC EFFECTS ON HISTONE MODIFICATIONS WERE EXAMINED BY WESTERN BLOTTING AND IMMUNOFLUORESCENCE ANALYSIS. ALL STATISTICAL TESTS WERE TWO-SIDED. RESULTS: YOUNG (2-5 MONTHS OLD) ARID4A-DEFICIENT MICE HAD INEFFECTIVE BLOOD CELL PRODUCTION IN ALL HEMATOPOIETIC LINEAGES. BEYOND 5 MONTHS OF AGE, THE ARID4A(-/-) MICE MANIFESTED MONOCYTOSIS, ACCOMPANIED BY SEVERE ANEMIA AND THROMBOCYTOPENIA. THESE SICK ARID4A(-/-) MICE SHOWED BONE MARROW FAILURE WITH MYELOFIBROSIS ASSOCIATED WITH SPLENOMEGALY AND HEPATOMEGALY. FIVE OF 42 ARID4A(-/-) MICE AND 10 OF 12 ARID4A(-/-)ARID4B(+/-) MICE PROGRESSED TO ACUTE MYELOID LEUKEMIA (AML) AND HAD RAPID FURTHER INCREASES OF LEUKOCYTE COUNTS. EXPRESSION OF HOX GENES (HOXB3, HOXB5, HOXB6, AND HOXB8) WAS DECREASED IN ARID4A-DEFICIENT BONE MARROW CELLS WITH OR WITHOUT ARID4B HAPLOINSUFFICIENCY, AND FOXP3 EXPRESSION WAS REDUCED IN ARID4A(-/-)ARID4B(+/-) BONE MARROW. INCREASES OF HISTONE TRIMETHYLATION OF H3K4, H3K9, AND H4K20 (FOLD INCREASES IN TRIMETHYLATION = 32, 95% CONFIDENCE INTERVAL [CI] = 27 TO 32; 45, 95% CI = 41 TO 49; AND 2.2, 95% CI = 1.7 TO 2.7, RESPECTIVELY) WERE OBSERVED IN THE BONE MARROW OF ARID4A-DEFICIENT MICE. CONCLUSIONS: ARID4A-DEFICIENT MICE INITIALLY DISPLAY INEFFECTIVE HEMATOPOIESIS, FOLLOWED BY TRANSITION TO CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML)-LIKE MYELODYSPLASTIC/MYELOPROLIFERATIVE DISORDER, AND THEN TRANSFORMATION TO AML. THE DISEASE PROCESSES IN THE ARID4A-DEFICIENT MICE ARE VERY SIMILAR TO THE COURSE OF EVENTS IN HUMANS WITH CMML AND AML. THIS MOUSE MODEL HAS THE POTENTIAL TO FURNISH ADDITIONAL INSIGHTS INTO THE ROLE OF EPIGENETIC ALTERATIONS IN LEUKEMOGENESIS, AND IT MAY BE USEFUL IN DEVELOPING NOVEL PHARMACOLOGICAL APPROACHES TO TREATMENT OF PRELEUKEMIC AND LEUKEMIC STATES. 2008 7 2761 41 EXPRESSION OF TESTIS-SPECIFIC GENES, TEX101 AND ODF4, IN CHRONIC MYELOID LEUKEMIA AND EVALUATION OF TEX101 IMMUNOGENICITY. BACKGROUND AND OBJECTIVES: CANCER-TESTIS (CT) ANTIGENS ARE A GROUP OF ANTIGENS WITH A RESTRICTED EXPRESSION IN NORMAL TISSUES, EXCEPT TESTIS, AND THEY HAVE ABERRANT EXPRESSION IN DIFFERENT TUMORS. THIS PATTERN OF EXPRESSION HAS MADE THEM PROMISING TARGETS FOR IMMUNOTHERAPY AND CANCER DETECTION. OUR AIM WAS TO FIND NEW MEMBERS OF THIS GROUP THAT MIGHT BE USEFUL AS MARKERS IN THE DETECTION OF CANCER AND IMMUNOTHERAPY. DESIGN AND SETTING: A DESCRIPTIVE STUDY CONDUCTED IN REFERRAL CENTERS OF TEHRAN UNIVERSITY OF MEDICAL SCIENCE FROM JANUARY 2008 TO JANUARY 2009. PATIENTS AND METHODS: WE ANALYZED THE EXPRESSION OF TWO TESTIS-SPECIFIC GENES NAMED ODF4 (OUTER DENSE FIBER OF SPERM TAILS 4) AND TEX101 (TESTIS EXPRESSED 101) IN 20 CHRONIC MYELOID LEUKEMIA (CML) AND 20 NORMAL SAMPLES BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN REACTION AND SEQUENCING. IMMUNOGENICITY OF TEX101 WAS EVALUATED BY MEANS OF ENZYME-LINKED IMMUNOSORBENT ASSAY. RESULTS: THESE TWO GENES WERE EXPRESSED IN 30% OF CML PATIENTS BUT NOT IN ANY OF THE HEALTHY DONORS. HUMORAL RESPONSE AGAINST TEX101 WAS NOT DETECTED IN ANY SAMPLES. CONCLUSIONS: TEX101 AND ODF4 ARE CT GENES USEFUL FOR DETECTION OF CML. UNLIKE MANY CT GENES, OVEREXPRESSION OF TEX101 WAS NOT SHOWN TO INDUCE IMMUNOLOGIC RESPONSES IN THESE SAMPLES. ACCORDING TO THE PREVIOUS STUDIES, OVEREXPRESSION OF TEX101 LEADS TO SUPPRESSION OF CANCER INVASION AND METASTASIS; THUS, THE INDUCTION OF THE EXPRESSION OF TEX101 IN CANCER BY EPIGENETIC MECHANISMS MAY BE A TREATMENT STRATEGY. 2012 8 1622 40 DNA METHYLTRANSFERASES IN MALAR MELASMA AND THEIR MODIFICATION BY SUNSCREEN IN COMBINATION WITH 4% NIACINAMIDE, 0.05% RETINOIC ACID, OR PLACEBO. BACKGROUND: MALAR MELASMA HAS A CHRONIC AND RECURRENT CHARACTER THAT MAY BE RELATED TO EPIGENETIC CHANGES. OBJECTIVE: TO RECOGNIZE THE EXPRESSION AND DNA METHYLATION OF DNA METHYLTRANSFERASES (DNMTS) IN MALAR MELASMA AND PERILESIONAL SKIN, AS WELL AS THE CHANGES IN DNMTS AFTER THEIR TREATMENT WITH SUNSCREEN IN COMBINATION WITH 4% NIACINAMIDE, 0.05% RETINOIC ACID, OR PLACEBO. METHODS: THIRTY FEMALE PATIENTS WERE CLINICALLY EVALUATED FOR THE EXPRESSION OF DNMT1 AND DNMT3B USING REAL-TIME PCR AND IMMUNOFLUORESCENCE. THESE INITIAL RESULTS WERE COMPARED TO RESULTS AFTER EIGHT WEEKS OF TREATMENT WITH SUNSCREEN IN COMBINATION WITH NIACINAMIDE, RETINOIC ACID, OR PLACEBO. RESULTS: THE RELATIVE EXPRESSION OF DNMT1 WAS SIGNIFICANTLY ELEVATED IN MELASMA COMPARED WITH UNAFFECTED SKIN IN ALL SUBJECTS, INDICATING DNA HYPERMETHYLATION. AFTER TREATMENT, IT WAS DECREASED IN ALL GROUPS: NIACINAMIDE (7 VERSUS 1; P<0.01), RETINOIC ACID (7 VERSUS 2; P<0.05), AND PLACEBO (7 VERSUS 3; P<0.05), WHICH CORRELATES WITH CLINICAL IMPROVEMENT. DNMT3B WAS NOT OVEREXPRESSED IN LESIONAL SKIN BUT REDUCED IN ALL GROUPS. CONCLUSIONS: WE FOUND DNA HYPERMETHYLATION IN MELASMA LESIONS. ENVIRONMENTAL FACTORS SUCH AS SOLAR RADIATION MAY INDUCE CELLULAR CHANGES THAT TRIGGER HYPERPIGMENTATION THROUGH THE ACTIVATION OF PATHWAYS REGULATED BY EPIGENETIC MODIFICATIONS. HOWEVER, LIMITING OR DECREASING DNA METHYLATION THROUGH SUNSCREEN, NIACINAMIDE, AND RETINOIC ACID TREATMENTS THAT PROVIDE PHOTOPROTECTION AND GENETIC TRANSCRIPTION CAN COUNTERACT THIS. 2019 9 1067 34 CLINICAL UTILITY OF PDSS2 EXPRESSION TO STRATIFY PATIENTS AT RISK FOR RECURRENCE OF HEPATOCELLULAR CARCINOMA. IDENTIFICATION OF NOVEL GENETIC AND EPIGENETIC ALTERATIONS IS REQUIRED FOR OPTIMAL STRATIFICATION OF PATIENTS WITH HEPATOCELLULAR CARCINOMA (HCC) AT RISK FOR RECURRENCE AND ADVERSE PROGNOSIS. COENZYME Q10 (COQ10), WHICH MEDIATES APOPTOSIS, IS SYNTHESIZED BY PRENYL DIPHOSPHATE SYNTHASE SUBUNIT 2 (PDSS2). IN THE PRESENT STUDY WE EVALUATED THE CLINICAL SIGNIFICANCE AND REGULATORY MECHANISMS OF PDSS2 EXPRESSION IN HCC. PDSS2 EXPRESSION LEVELS AND THOSE OF GENES ENCODING POTENTIALLY INTERACTING PROTEINS AS WELL AS THE METHYLATION STATUS OF THE PDSS2 PROMOTER REGION WERE ANALYZED IN HCC CELL LINES. PDSS2 MRNA LEVELS IN 151 PAIRS OF RESECTED SPECIMENS WERE DETERMINED TO EVALUATE THE ASSOCIATION OF PDSS2 EXPRESSION AND CLINICOPATHOLOGICAL FACTORS. THE EXPRESSION AND DISTRIBUTION OF PDSS2 WERE DETERMINED USING IMMUNOHISTOCHEMISTRY. PDSS2 MRNA EXPRESSION WAS DECREASED IN SIX OF NINE HCC CELL LINES AND SIGNIFICANTLY CORRELATED WITH THOSE OF HEPATOCYTE NUCLEAR FACTOR 4ALPHA. PDSS2 TRANSCRIPTION IN HCC CELLS WITH DECREASED PDSS2 EXPRESSION ACCOMPANYING HYPERMETHYLATION WAS REACTIVATED AFTER TREATING THESE CELLS WITH A METHYLATION INHIBITOR. MEAN EXPRESSION LEVELS OF PDSS2 MRNA RELATIVE TO THAT OF UNINVOLVED LIVER DIMINISHED GRADUALLY IN THE ORDER OF CHRONIC HEPATITIS TO CIRRHOSIS, AND EACH WAS SIGNIFICANTLY HIGHER THAN THOSE OF HCCS. PDSS2 AND PDSS2 MRNA LEVELS WERE CONSISTENT. DECREASED PDSS2 MRNA LEVELS WERE DETECTED IN HCC TISSUES OF 56 PATIENTS, CORRELATED WITH SHORTER DISEASE-SPECIFIC SURVIVAL, AND WAS IDENTIFIED AS AN INDEPENDENT PROGNOSTIC FACTOR. PDSS2 IS A PUTATIVE TUMOR SUPPRESSOR, AND PROMOTER HYPERMETHYLATION IS A KEY REGULATORY MECHANISM IN HCC. DECREASED LEVELS OF PDSS2 MRNA EXPRESSION MAY REPRESENT A NOVEL BIOMARKER OF HCC. 2014 10 2974 42 GENETIC AND METHYLATION STATUS OF CDKN2A (P14(ARF)/P16(INK4A)) AND TP53 GENES IN RECURRENT RESPIRATORY PAPILLOMATOSIS. RECURRENT RESPIRATORY PAPILLOMATOSIS (RRP) IS A RARE AND CHRONIC DISEASE AFFECTING THE UPPER AIRWAY WITH PAPILLOMATOUS LESIONS CAUSED BY THE HUMAN PAPILLOMAVIRUS (HPV) INFECTION, ESPECIALLY HPV-6 AND/OR HPV-11 TYPES. LITTLE IS KNOWN ABOUT THE GENETIC AND EPIGENETIC DRIVERS IN RRP PATHOPHYSIOLOGY. FOR THIS PURPOSE, WE ANALYZED 27 PAPILLOMATOUS LESIONS FROM PATIENTS WITH RRP TO EVALUATE SOMATIC MUTATIONS AND METHYLATION STATUS IN CDKN2A (P14(ARF)/P16(INK4A)) AND TP53, WHICH ARE KEY TUMOR SUPPRESSOR GENES FOR THE CELL CYCLE CONTROL. SANGER SEQUENCING ANALYSIS REVEALED ONE SOMATIC MUTATION IN TP53 (C.733_734INSA) AND FOUR MUTATIONS IN CDKN2A (C.-30G > T, C.29_30INSA, C.69DELT, AND C.300C > A). THESE MUTATIONS WERE OBSERVED IN 10 PATIENTS, 6 OF WHICH CARRIED DOUBLE MUTATION. FURTHERMORE, 50% (5/10) OF THESE PATIENTS CARRYING SOMATIC MUTATIONS HAD RRP SEVERITY, REPRESENTING 62.5% (5/8) OF THE SEVERITY CASES IN THIS STUDY, ALBEIT NO SIGNIFICANT ASSOCIATION WAS FOUND BETWEEN SOMATIC MUTATIONS AND DISEASE SEVERITY. METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION ASSAYS REVEALED P14(ARF) PROMOTER HYPERMETHYLATION IN 100% OF CASES, FOLLOWED BY TP53 (96.3%) AND P16(INK4A) (55.6%), SUGGESTING THE INFLUENCE OF HPV IN THE DNA METHYLATION MACHINERY. IN CONCLUSION, SOMATIC MUTATIONS WERE NOT COMMON EVENTS IDENTIFIED IN PATIENTS WITH RRP. HOWEVER, EPIGENETIC MODULATION BY HIGH METHYLATION RATES, PARTICULARLY FOR THE P14(ARF)/TP53 PATHWAY, SEEMS TO BE IN THE COURSE OF RRP DEVELOPMENT. 2022 11 5775 44 SPERMIDINE/SPERMINE N(1)-ACETYLTRANSFERASE ACTIVITY ASSOCIATES WITH WHITE BLOOD CELL COUNT IN MYELOID LEUKEMIAS. THE METABOLISM OF POLYAMINES, THE CATIONIC SMALL MOLECULES ESSENTIAL FOR CELL PROLIFERATION AND DIFFERENTIATION, IS ALTERED IN CANCER CELLS AND CAN BE EXPLOITED IN CANCER DIAGNOSIS AND THERAPY. SPERMIDINE/SPERMINE N(1)-ACETYLTRANSFERASE (SSAT), WHICH REGULATES INTRACELLULAR LEVELS OF POLYAMINES BY CATABOLIZING SPERMIDINE AND SPERMINE, HAS A CONTROVERSIAL ROLE IN THE DEVELOPMENT OF CANCERS. IN THIS STUDY, THE POLYAMINE METABOLISM AND FUNCTION OF SSAT WERE CHARACTERIZED IN ACUTE MYELOID LEUKEMIA (AML), CHRONIC MYELOID LEUKEMIA (CML), AND ACUTE LYMPHOID LEUKEMIA PATIENT SAMPLES. ALSO, MICE OVEREXPRESSING SSAT AND HAVING A MYELOPROLIFERATIVE PHENOTYPE WERE ANALYZED FOR THEIR RESPONSE TO DECITABINE AND HISTONE DEACETYLASE INHIBITOR TRICHOSTATIN A. THE PRESENCE OF EPIGENETIC FACTORS IN THE BONE MARROW CELLS OF SSAT MICE WAS ANALYZED. ELEVATED LEVELS OF SPERMIDINE AND SPERMINE, AS WELL AS INCREASED ACTIVITY OF SSAT, WERE DETECTED IN AML, CML, AND ACUTE LYMPHOID LEUKEMIA PATIENTS COMPARED WITH THE CONTROLS. HOWEVER, WE FOUND SSAT ACTIVITY TO BE ASSOCIATED WITH WHITE BLOOD CELL COUNT ONLY IN AML AND CML PATIENTS. DECITABINE TREATMENT BROUGHT THE PERIPHERAL BLOOD AND BONE MARROW CELL COUNTS OF SSAT MICE TO THE LEVEL OF WILD-TYPE MICE. SPERMIDINE/SPERMINE N(1)-ACETYLTRANSFERASE MICE HAD INCREASED HISTONE METHYLATION AND AN INCREASED LEVEL OF HISTONE DEACETYLASE 1 IN THEIR BONE MARROW CELLS. THE STUDY SUGGESTS THAT SSAT INFLUENCES THE DEVELOPMENT OF MYELOID MALIGNANCIES, AND EPIGENETIC FACTORS PARTLY CONTRIBUTE TO THE SSAT OVEREXPRESSION-INDUCED MYELOPROLIFERATIVE DISEASE IN MICE. 2014 12 2626 47 EPIGENOME-WIDE ASSOCIATION STUDY IDENTIFIES DNA METHYLATION MARKERS FOR ASTHMA REMISSION IN WHOLE BLOOD AND NASAL EPITHELIUM. BACKGROUND: ASTHMA IS A CHRONIC RESPIRATORY DISEASE WHICH IS NOT CURABLE, YET SOME PATIENTS EXPERIENCE SPONTANEOUS REMISSION. WE HYPOTHESIZED THAT EPIGENETIC MECHANISMS MAY BE INVOLVED IN ASTHMA REMISSION. METHODS: CLINICAL REMISSION (CLINR) WAS DEFINED AS THE ABSENCE OF ASTHMA SYMPTOMS AND MEDICATION FOR AT LEAST 12 MONTHS, AND COMPLETE REMISSION (COMR) WAS DEFINED AS CLINR WITH NORMAL LUNG FUNCTION AND ABSENCE OF AIRWAY HYPERRESPONSIVENESS. WE ANALYZED DIFFERENTIAL DNA METHYLATION OF CLINR AND COMR COMPARING TO PERSISTENT ASTHMA (PERSA) IN WHOLE BLOOD SAMPLES (N = 72) AND NASAL BRUSHING SAMPLES (N = 97) IN A LONGITUDINAL COHORT OF WELL CHARACTERIZED ASTHMA PATIENTS. SIGNIFICANT FINDINGS OF WHOLE BLOOD DNA METHYLATION WERE TESTED FOR REPLICATION IN TWO INDEPENDENT COHORTS, LIFELINES AND EPIDEMIOLOGICAL STUDY ON THE GENETICS AND ENVIRONMENT OF ASTHMA (EGEA). RESULTS: WE IDENTIFIED DIFFERENTIALLY METHYLATED CPG SITES ASSOCIATED WITH CLINR (7 CPG SITES) AND COMR (129 CPG SITES) IN WHOLE BLOOD. ONE CPG (CG13378519, CHR1) ASSOCIATED WITH CLINR WAS REPLICATED AND ANNOTATED TO PEX11 (PEROXISOMAL BIOGENESIS FACTOR 11 BETA). THE WHOLE BLOOD DNA METHYLATION LEVELS OF THIS CPG WERE ALSO DIFFERENT BETWEEN CLINR AND HEALTHY SUBJECTS. ONE COMR-ASSOCIATED CPG (CG24788483, CHR10) THAT ANNOTATED TO TCF7L2 (TRANSCRIPTION FACTOR 7 LIKE 2) WAS REPLICATED AND ASSOCIATED WITH EXPRESSION OF TCF7L2 GENE. ONE OUT OF SEVEN CLINR-ASSOCIATED CPG SITES AND 8 OUT OF 129 COMR-ASSOCIATED CPG SITES IDENTIFIED FROM WHOLE BLOOD SAMPLES SHOWED NOMINAL SIGNIFICANCE (P < 0.05) AND THE SAME DIRECTION OF EFFECT IN NASAL BRUSHES. CONCLUSION: WE IDENTIFIED DNA METHYLATION MARKERS POSSIBLY ASSOCIATED WITH CLINICAL AND COMPLETE ASTHMA REMISSION IN NASAL BRUSHES AND WHOLE BLOOD, AND TWO CPG SITES IDENTIFIED FROM WHOLE BLOOD CAN BE REPLICATED IN INDEPENDENT COHORTS AND MAY PLAY A ROLE IN PEROXISOME PROLIFERATION AND WNT SIGNALING PATHWAY. 2020 13 2125 47 EPIGENETIC INACTIVATION OF DLX4 IS ASSOCIATED WITH DISEASE PROGRESSION IN CHRONIC MYELOID LEUKEMIA. ABERRANT DNA METHYLATION OF VARIOUS GENES HAS BEEN IDENTIFIED TO BE ASSOCIATED WITH DISEASE PROGRESSION IN CHRONIC MYELOID LEUKEMIA (CML). OUR STUDY WAS INTENDED TO INVESTIGATE DLX4 METHYLATION PATTERN IN DIFFERENT CLINICAL STAGES OF CML AND FURTHER DETERMINE ITS ROLE IN REGULATING DLX4 EXPRESSION. REAL-TIME QUANTITATIVE METHYLATION-SPECIFIC PCR AND BISULFITE SEQUENCING PCR WERE APPLIED TO DETECT DLX4 METHYLATION. 5-AZA-2'-DEOXYCYTIDINE (5-AZA-DC) WAS USED FOR DEMETHYLATION STUDIES. DLX4 WAS SIGNIFICANTLY HYPERMETHYLATED IN CML PATIENTS (P = 0.002) ESPECIALLY IN BLASTIC PHASE (BC) STAGE (P < 0.001) AS COMPARED WITH CONTROLS. MOREOVER, DLX4 METHYLATION LEVEL IN BC STAGE WAS SIGNIFICANTLY HIGHER THAN IN CHRONIC PHASE (CP) STAGE (P < 0.001). DLX4 METHYLATION DENSITY WAS SIGNIFICANTLY INCREASED DURING THE PROGRESSION OF CML AMONG THE TESTED TWO PATIENTS (P < 0.001). DLX4 HYPERMETHYLATION OCCURRED WITH THE HIGHEST INCIDENCE IN BC STAGE (83%), LOWER INCIDENCE IN ACUTE PHASE (AP) STAGE (43%), AND THE LOWEST INCIDENCE IN CP STAGE (26%) (P = 0.001). MOREOVER, T(9; 22) WITH ADDITIONAL ALTERATION CASES HAD SIGNIFICANTLY HIGHER FREQUENCY OF DLX4 HYPERMETHYLATION COMPARED WITH THE OTHER CYTOGENETICS (P = 0.010). SIGNIFICANTLY NEGATIVE CORRELATION WAS OBSERVED BETWEEN DLX4 METHYLATION AND DLX4-TV2 (THE SHORTER DLX4 ISOFORM) EXPRESSION (R = -0.382, P = 0.001, N = 78) BUT NOT BETWEEN DLX4 METHYLATION AND BP1 (THE LONGER DLX4 ISOFORM) EXPRESSION (R = 0.134, P = 0.244, N = 78) IN CML PATIENTS. BOTH DLX4-TV2 AND BP1 MRNA WERE SIGNIFICANTLY INCREASED AFTER 5-AZA-DC TREATMENT IN K562 CELL LINE (P < 0.001). OUR STUDY INDICATED THAT HYPERMETHYLATION OF DLX4 CORRELATED WITH DISEASE PROGRESSION OF CML. MOREOVER, DLX4 EXPRESSION WAS REGULATED BY ITS METHYLATION IN CML. 2015 14 154 34 ABERRANT METHYLATION OF NUCLEOTIDE EXCISION REPAIR GENES IS ASSOCIATED WITH CHRONIC ARSENIC POISONING. OBJECTIVE: TO DEFINE WHETHER ABERRANT METHYLATION OF DNA REPAIR GENES IS ASSOCIATED WITH CHRONIC ARSENIC POISONING. METHODS: HUNDRED AND TWO ENDEMIC ARSENICOSIS PATIENTS AND 36 HEALTHY SUBJECTS WERE RECRUITED. METHYLIGHT AND BISULFITE SEQUENCING (BSP) ASSAYS WERE USED TO EXAMINE THE METHYLATION STATUS OF ERCC1, ERCC2 AND XPC GENES IN PERIPHERAL BLOOD LYMPHOCYTES (PBLS) AND SKIN LESIONS OF ARSENICOSIS PATIENTS AND NAASO(2)-TREATED HACAT CELLS. RESULTS: HYPERMETHYLATION OF ERCC1 AND ERCC2 AND SUPPRESSED GENE EXPRESSION WERE FOUND IN PBLS AND SKIN LESIONS OF ARSENICOSIS PATIENTS AND WAS CORRELATED WITH THE LEVEL OF ARSENIC EXPOSURE. PARTICULARLY, THE EXPRESSION OF ERCC1 AND ERCC2 WAS ASSOCIATED WITH THE SEVERITY OF SKIN LESIONS. IN VITRO STUDIES REVEALED AN INDUCTION OF ERCC2 HYPERMETHYLATION AND DECREASED MRNA EXPRESSION IN RESPONSE TO NAASO(2) TREATMENT. CONCLUSION: HYPERMETHYLATION OF ERCC1 AND ERCC2 AND CONCOMITANT SUPPRESSION OF GENE EXPRESSION MIGHT BE SERVED AS THE EPIGENETIC MARKS ASSOCIATED WITH ARSENIC EXPOSURE AND ADVERSE HEALTH EFFECTS. 2017 15 2327 54 EPIGENETIC REGULATION OF HUMAN CANCER/TESTIS ANTIGEN GENE, HAGE, IN CHRONIC MYELOID LEUKEMIA. BACKGROUND AND OBJECTIVES: CANCER TESTIS ANTIGENS (CTA) PROVIDE ATTRACTIVE TARGETS FOR CANCER-SPECIFIC IMMUNOTHERAPY. ALTHOUGH CTA GENES ARE EXPRESSED IN SOME NORMAL TISSUES, SUCH AS THE TESTIS, THIS IMMUNOLOGICALLY PROTECTED SITE LACKS MHC I EXPRESSION AND AS SUCH, DOES NOT PRESENT SELF ANTIGENS TO T CELLS. TO DATE, CTA GENES HAVE BEEN SHOWN TO BE EXPRESSED IN A RANGE OF SOLID TUMORS VIA DEMETHYLATION OF THEIR PROMOTER CPG ISLANDS, BUT RARELY IN CHRONIC MYELOID LEUKEMIA (CML) OR OTHER HEMATOLOGIC MALIGNANCIES. DESIGN AND METHODS: IN THIS STUDY, THE METHYLATION STATUS OF THE HAGE CTA GENE PROMOTER WAS ANALYZED BY QUANTITATIVE METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION (MSP) AND SEQUENCING IN FOUR PHILADELPHIA-POSITIVE CELL LINES (TCC-S, K562, KU812 AND KYO-1) AND IN CML SAMPLES TAKEN FROM PATIENTS IN CHRONIC PHASE (CP N=215) OR BLAST CRISIS (BC N=47). HAGE EXPRESSION WAS ASSESSED BY QUANTITATIVE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN REACTION. RESULTS: THE TCC-S CELL LINE SHOWED DEMETHYLATION OF HAGE THAT WAS ASSOCIATED WITH OVER-EXPRESSION OF THIS GENE. HAGE HYPOMETHYLATION WAS SIGNIFICANTLY MORE FREQUENT IN BC (46%) THAN IN CP (22%) (P=0.01) AND WAS CORRELATED WITH HIGH EXPRESSION LEVELS OF HAGE TRANSCRIPTS (P<0.0001). OF NOTE, IN CP-CML, EXTENSIVE HAGE HYPOMETHYLATION WAS ASSOCIATED WITH POORER PROGNOSIS IN TERMS OF CYTOGENETIC RESPONSE TO INTERFERON (P=0.01) OR IMATINIB (P=0.01), MOLECULAR RESPONSE TO IMATINIB (P=0.003) AND PROGRESSION-FREE SURVIVAL (P=0.05). INTERPRETATIONS AND CONCLUSION: THE METHYLATION STATUS OF THE HAGE PROMOTER DIRECTLY CORRELATES WITH ITS EXPRESSION IN BOTH CML CELL LINES AND PATIENTS AND IS ASSOCIATED WITH ADVANCED DISEASE AND POOR OUTCOME. 2007 16 5934 35 TARGETING FEATURES OF CURAXIN CBL0137 ON HEMATOLOGICAL MALIGNANCIES IN VITRO AND IN VIVO. THE ANTICANCER ACTIVITY OF CURAXIN CBL0137, A DNA-BINDING SMALL MOLECULE WITH CHROMATIN REMODULATING EFFECT, HAS BEEN DEMONSTRATED IN DIFFERENT CANCERS. HEREIN, A COMPARATIVE EVALUATION OF CBL0137 ACTIVITY WAS PERFORMED IN RESPECT TO ACUTE MYELOID LEUKEMIA (AML), ACUTE LYMPHOBLASTIC LEUKEMIA (ALL), CHRONIC MYELOID LEUKEMIA AND MULTIPLE MYELOMA (MM) CULTURED IN VITRO. MTT ASSAY SHOWED AML AND MM HIGHER SENSITIVITY TO CBL0137'S CYTOSTATIC EFFECT COMPARATIVELY TO OTHER HEMATOLOGICAL MALIGNANCY CELLS. FLOW CYTOMETRY CELL CYCLE ANALYSIS REVEALED AN INCREASE IN SUBG1 AND G2/M POPULATIONS AFTER CBL0137 CELL TREATMENT, BUT THE PREVALENT TYPE OF ARREST VARIED. APOPTOSIS ACTIVATION BY CBL0137 MEASURED BY ANNEXIN-V/PI DUAL STAINING WAS MORE ACTIVE IN AML AND MM CELLS. RT2 PCR ARRAY SHOWED THAT CHANGES CAUSED BY CBL0137 IN SIGNALING PATHWAYS INVOLVED IN CANCER PATHOGENESIS WERE MORE INTENSIVE IN AML AND MM CELLS. ON THE MURINE MODEL OF AML WEHI-3, CBL0137 SHOWED SIGNIFICANT ANTICANCER EFFECTS IN VIVO, WHICH WERE EVALUATED BY CORRESPONDING CHANGES IN SPLEEN AND LIVER. THUS, MORE PRONOUNCED ANTICANCER EFFECTS OF CBL0137 IN VITRO WERE OBSERVED IN RESPECT TO AML AND MM. EXPERIMENTS IN VIVO ALSO INDICATED THE PERSPECTIVE OF CBL0137 USE FOR AML TREATMENT. THIS IN ACCORDANCE WITH THE FRONTLINE TREATMENT APPROACH IN AML USING EPIGENETIC DRUGS. 2023 17 1843 37 EFFECTS OF TELOMERASE INHIBITOR ON EPIGENETIC CHROMATIN MODIFICATION ENZYMES IN MALIGNANCIES. TELOMERASE HAS A CRITICAL ROLE IN CELL PROLIFERATION, TUMOR MAINTAINING, AND THERAPY RESISTANCE, WHICH ACT BY MODIFYING MANY SIGNALING PATHWAYS. 2-[(E)-3-NAPHTALEN-2-YL-BUT-2-ENOYLAMINO]-BENZOIC ACID (BIBR1532) IS ONE OF THE MOST STUDIED TELOMERASE INHIBITORS, AND IT TARGETS TELOMERASE COMPONENTS TERC AND TERT. IN THIS NOVEL STUDY, WE AIMED TO INVESTIGATE THE EPIGENETIC EFFECTS OF BIBR1532 ON BOTH HEMATOLOGIC MALIGNANCIES AND SOLID TUMORS. K-562 HUMAN CHRONIC MYELOID LEUKEMIA CELL LINE AND U87MG GLIOBLASTOMA CELL LINE WERE COMPARED WITH CONTROL GROUPS WITHOUT BIBR1532 TREATMENT. CYTOTOXIC EFFECTS OF BIBR1532 WERE DETERMINED BY USING WST-1 ASSAY. APOPTOTIC EFFECTS OF BIBR1532 WERE DETECTED BY USING ANNEXIN V METHOD. TO ASSESS EXPRESSION CHANGES IN THE HUMAN EPIGENETIC CHROMATIN MODIFICATION ENZYME GENES, TOTAL RNA WAS ISOLATED FROM K-562 AND U87MG CELLS TREATED WITH BIBR1532 AND UNTREATED CONTROL CELLS. BIBR1532 INDUCED 2.41-FOLD APOPTOTIC CELL DEATH IN U87MG CELL LINES COMPARED WITH CONTROL GROUPS. APOPTOSIS WAS SLIGHTLY INDUCED IN K-562 CELLS WITH BIBR1532 TREATMENT COMPARED WITH CONTROL CELLS. WE OBSERVED THAT BIBR1532 ALSO REGULATES SIMILAR GENES IN BOTH CELL LINES, AND IT IS USEFUL ON EPIGENETIC MECHANISMS. AS A RESULT, TELOMERASE INHIBITOR BIBR1532 HAS A SIGNIFICANT EFFECT ON BOTH HEMATOLOGICAL MALIGNANCIES AND SOLID TUMORS. 2018 18 4225 40 METHYLATION DEGREE OF METALLOPROTEINASE INHIBITOR RECK GENE: LINKS TO RECK PROTEIN LEVEL AND HEPATOCELLULAR CARCINOMA IN CHRONIC HCV INFECTION PATIENTS. THE RECK GENE, A TUMOR SUPPRESSOR GENE, INHIBITS ANGIOGENESIS, INVASION, AND TUMOR METASTASIS. EPIGENETIC REGULATION OF THE RECK GENE CONSTITUTES A POTENT APPROACH TO THE MOLECULAR BASIS OF LIVER MALIGNANCY. THIS STUDY AIMS TO EVALUATE THE PROMOTER METHYLATION STATUS OF THE RECK GENE AND ITS SERUM LEVEL IN PATIENTS WITH HEPATITIS C VIRUS (HCV)-RELATED HEPATOCELLULAR CARCINOMA (HCC) AND THE POTENTIAL ASSOCIATION OF RECK GENE METHYLATION WITH CLINICAL CRITERIA OF HCC. ONE HUNDRED AND FIFTY-FIVE SUBJECTS WERE INCLUDED (HEALTHY CONTROL [55], CHRONIC HCV PATIENTS [55], HCV-RELATED HCC PATIENTS [45]). THE METHYLATION STATUS OF THE RECK GENE PROMOTER AND SERUM RECK LEVEL WERE INVESTIGATED BY METHYLATION-SPECIFIC PCR AND ENZYME-LINKED IMMUNOSORBENT ASSAY TECHNIQUES, RESPECTIVELY. RECK GENE PROMOTER HYPERMETHYLATION WAS RECORDED IN 46.7% OF HCC PATIENTS, AND 10.9% OF HCV PATIENTS, BUT NOT IN CONTROL SUBJECTS (0%). IT WAS RELATED TO RECK PROTEIN LEVEL, VARICES, EDEMA, ASCITES, LYMPH NODE METASTASIS, VASCULAR INVASION, AND THE LARGEST DIAMETER OF FOCAL LESIONS. MEANWHILE, IT WAS NOT ASSOCIATED WITH FOCAL LESION NUMBER NOR DISTANT METASTASIS OF HCC. IN CONCLUSION, RECK GENE PROMOTER HYPERMETHYLATION IS LINKED TO HCV GENOTYPE-4-RELATED HCC. MOREOVER, DIFFERENT DEGREES OF RECK GENE PROMOTER METHYLATION ARE ASSOCIATED WITH SERUM RECK LEVEL, LYMPH NODE METASTASIS, AND VASCULAR INVASION, WHICH COULD PROVE ITS PATHOGENIC ROLE IN HEPATOCARCINOGENESIS IN CHRONIC HCV-INFECTED PATIENTS. 2021 19 3907 42 LEUCOCYTIC DNA METHYLATION OF INTERLEUKIN-6 PROMOTER REDUCTION IN PRE-HYPERTENSIVE YOUNG ADULTS. BACKGROUND: PRE-HYPERTENSION IS ASSOCIATED WITH INCREASED RISK OF CARDIOVASCULAR DISEASE. CHRONIC INFLAMMATION PLAYS AN IMPORTANT ROLE IN THE PATHOPHYSIOLOGY OF ESSENTIAL HYPERTENSION, WITH EPIGENETIC DYSREGULATION INVOLVEMENT. NEVERTHELESS, THE ROLE OF DNA METHYLATION IN PREHYPERTENSIVE STATE IS UNKNOWN. THE AIM OF THIS STUDY WAS TO INVESTIGATE THE ASSOCIATION BETWEEN DNA METHYLATION LEVEL OF INTERLEUKIN-6 (IL-6) PROMOTER IN PRE-HYPERTENSIVE (PREHT) AND NORMOTENSIVE (NT) YOUNG ADULTS. METHODS: A TOTAL OF 80 NT AND 80 PREHT HEALTHY SUBJECTS AGED BETWEEN 18-45 YEARS WERE RECRUITED IN KUANTAN, PAHANG, MALAYSIA USING AN OBSERVATIONAL CROSS-SECTIONAL STUDY APPROACH. DNA METHYLATION LEVEL OF IL-6 PROMOTER IN PERIPHERAL LEUKOCYTES WERE MEASURED USING BISULPHITE CONVERSION AND METHYLIGHT ASSAY. RESULTS: THERE WAS NO SIGNIFICANT DIFFERENCE IN AGE BETWEEN NT AND PREHT (P = 0.655). THE MEAN BLOOD PRESSURE WAS 110(8)/73(5) MMHG IN NT AND 125(7)/82(5) MMHG IN PREHT SUBJECTS. THE IL-6 PROMOTER METHYLATION LEVEL WAS SIGNIFICANTLY LOWER IN PREHT COMPARED TO NT SUBJECTS (P < 0.001). CONCLUSION: THE CURRENT STUDY DEMONSTRATES THAT HYPOMETHYLATION OF IL-6 PROMOTER WAS ASSOCIATED WITH PRE-HYPERTENSION IN YOUNG ADULTS. THUS, IL-6 METHYLATION COULD BE USED AS AN EARLY INDICATOR FOR PREDICTING HYPERTENSION AND RELATED RISK OF CARDIOVASCULAR DISEASES IN PREHYPERTENSIVE SUBJECTS. GENE EXPRESSION AND LONGITUDINAL STUDIES ARE WARRANTED TO EXAMINE THE METHYLATION EFFECT ON IL-6 EXPRESSION OVER TIME. 2019 20 5621 35 SCREENING METHYLATION OF DNA REPAIR GENES IN THE ORAL MUCOSA OF CHRONIC SMOKERS. OBJECTIVE: THE AIM OF THIS STUDY WAS TO EVALUATE THE EPIGENETIC CHANGES IN THE PROCESS OF ORAL CARCINOGENESIS BY SCREENING THE METHYLATION OF REPAIR GENES IN CHRONIC SMOKERS. DESIGN: TWO GROUPS WERE FORMED: GROUP 1: 16 SMOKERS WITH CONSUMPTION OF 20 CIGARETTES/DAY FOR AT LEAST 10 YEARS; AND GROUP 2: 10 NON-SMOKING. EXFOLIATIVE CYTOLOGY OF THE TONGUE WAS PERFORMED, AND THE EXTRACTED DNA WAS TREATED BY ENZYMES. THE PCR ARRAY SYSTEM PERFORMED METHYLATION SCREENING TO EVALUATE 22 DNA REPAIR GENES, AND THE RESULTS WERE VALIDATED BY RT-QPCR FOR EACH GENE WITH METHYLATION LEVELS >/=10%. RESULTS: HIGHEST PERCENTAGES OF METHYLATION WERE OBSERVED FOR MLH3 AND XRCC1 GENES (11-20% METHYLATION) AND IN ONE CASE FOR MRE11A AND PMS2 (>50% METHYLATION). STATISTICAL ANALYSIS SHOWED SIGNIFICANT DIFFERENCES IN THE EXPRESSION OF THE GENES MRE11A (P = 0.0002), PMS2(P = 0.0068), XRCC1 (P = 0.0080) AND MLH3 (0.0057) BETWEEN THE TWO GROUPS. CONCLUSION: THE EFFECTS OF CHRONIC SMOKING ON ORAL MUCOSA LED TO THE METHYLATION OF GENES MRE11A PMS2, XRCC1 AND MLH3, BUT RESULTED IN A REDUCTION OF GENE EXPRESSION OF MRE11A AND PMS2, WHICH SHOWED >/=50% METHYLATION. THESE RESULTS PROVIDE EVIDENCE THAT SMOKING CAUSE METHYLATION AND REDUCED EXPRESSION OF REPAIR GENES. 2018