1 6355 145 THE ROLE OF HERPESVIRUS 6A AND 6B IN MULTIPLE SCLEROSIS AND EPILEPSY. HUMAN HERPESVIRUS 6A (HHV-6A) AND 6B (HHV-6B) ARE TWO CLOSELY RELATED VIRUSES THAT CAN INFECT CELLS OF THE CENTRAL NERVOUS SYSTEM (CNS). THE SIMILARITIES BETWEEN THESE VIRUSES HAVE MADE IT DIFFICULT TO SEPARATE THEM ON SEROLOGICAL LEVEL. THE BROAD TERM HHV-6 REMAINS WHEN REFERRING TO STUDIES WHERE THE TWO SPECIES WERE NOT DISTINGUISHED, AND AS SUCH, THE SEROPREVALENCE IS OVER 90% IN THE ADULT POPULATION. HHV-6B HAS BEEN DETECTED IN UP TO 100% OF INFANTS WITH THE PRIMARY INFECTION ROSEOLA INFANTUM, BUT LESS IS KNOWN ABOUT THE PRIMARY INFECTION OF HHV-6A. BOTH VIRUSES ARE NEUROTROPIC AND HAVE CAPACITY TO ESTABLISH LIFELONG LATENCY IN CELLS OF THE CENTRAL NERVOUS SYSTEM, WITH POTENTIAL TO REACTIVATE AND CAUSE COMPLICATIONS LATER IN LIFE. HHV-6A INFECTION HAS BEEN ASSOCIATED WITH AN INCREASED RISK OF MULTIPLE SCLEROSIS (MS), WHEREAS HHV-6B IS INDICATED TO BE INVOLVED IN PATHOGENESIS OF EPILEPSY. THESE TWO ASSOCIATIONS SHOW HOW NEUROLOGICAL DISEASES MIGHT BE CAUSED BY VIRAL INFECTIONS, BUT AS SUGGESTED HERE, THROUGH COMPLETELY DIFFERENT MOLECULAR MECHANISMS, IN AN AUTOIMMUNE DISEASE, SUCH AS MS, BY TRIGGERING AN OVERREACTION OF THE IMMUNE SYSTEM AND IN EPILEPSY BY HAMPERING INTERNAL CELLULAR FUNCTIONS WHEN THE IMMUNE SYSTEM FAILS TO ELIMINATE THE VIRUS. UNDERSTANDING THE VIRAL MECHANISMS OF PRIMARY INFECTION AND REACTIVATION AND THEIR SPECTRUM OF ASSOCIATED SYMPTOMS WILL AID OUR ABILITY TO DIAGNOSE, TREAT AND PREVENT THESE SEVERE AND CHRONIC DISEASES. THIS REVIEW EXPLORES THE ROLE OF HHV-6A AND HHV-6B SPECIFICALLY IN MS AND EPILEPSY, THE EVIDENCE TO DATE AND THE FUTURE DIRECTIONS OF THIS FIELD. 2020 2 2637 30 EPIGENOME-WIDE STUDY IDENTIFIES EPIGENETIC OUTLIERS IN NORMAL MUCOSA OF PATIENTS WITH COLORECTAL CANCER. NONGENETIC PREDISPOSITION TO COLORECTAL CANCER CONTINUES TO BE DIFFICULT TO MEASURE PRECISELY, HAMPERING EFFORTS IN TARGETED PREVENTION AND SCREENING. EPIGENETIC CHANGES IN THE NORMAL MUCOSA OF PATIENTS WITH COLORECTAL CANCER CAN SERVE AS A TOOL IN PREDICTING COLORECTAL CANCER OUTCOMES. WE IDENTIFIED EPIGENETIC CHANGES AFFECTING THE NORMAL MUCOSA OF PATIENTS WITH COLORECTAL CANCER. DNA METHYLATION PROFILING ON NORMAL COLON MUCOSA FROM 77 PATIENTS WITH COLORECTAL CANCER AND 68 CONTROLS IDENTIFIED A DISTINCT SUBGROUP OF NORMALLY-APPEARING MUCOSA WITH MARKEDLY DISRUPTED DNA METHYLATION AT A LARGE NUMBER OF CPGS, TERMED AS "OUTLIER METHYLATION PHENOTYPE" (OMP) AND ARE PRESENT IN 15 OF 77 PATIENTS WITH CANCER VERSUS 0 OF 68 CONTROLS (P < 0.001). SIMILAR FINDINGS WERE ALSO SEEN IN PUBLICLY AVAILABLE DATASETS. COMPARISON OF NORMAL COLON MUCOSA TRANSCRIPTION PROFILES OF PATIENTS WITH OMP CANCER WITH THOSE OF PATIENTS WITH NON-OMP CANCER INDICATES GENES WHOSE PROMOTERS ARE HYPERMETHYLATED IN THE OMP PATIENTS ARE ALSO TRANSCRIPTIONALLY DOWNREGULATED, AND THAT MANY OF THE GENES MOST AFFECTED ARE INVOLVED IN INTERACTIONS BETWEEN EPITHELIAL CELLS, THE MUCUS LAYER, AND THE MICROBIOME. ANALYSIS OF 16S RRNA PROFILES SUGGESTS THAT NORMAL COLON MUCOSA OF OMPS ARE ENRICHED IN BACTERIAL GENERA ASSOCIATED WITH COLORECTAL CANCER RISK, ADVANCED TUMOR STAGE, CHRONIC INTESTINAL INFLAMMATION, MALIGNANT TRANSFORMATION, NOSOCOMIAL INFECTIONS, AND KRAS MUTATIONS. IN CONCLUSION, OUR STUDY IDENTIFIES AN EPIGENETICALLY DISTINCT OMP GROUP IN THE NORMAL MUCOSA OF PATIENTS WITH COLORECTAL CANCER THAT IS CHARACTERIZED BY A DISRUPTED METHYLOME, ALTERED GENE EXPRESSION, AND MICROBIAL DYSBIOSIS. PROSPECTIVE STUDIES ARE NEEDED TO DETERMINE WHETHER OMP COULD SERVE AS A BIOMARKER FOR AN ELEVATED EPIGENETIC RISK FOR COLORECTAL CANCER DEVELOPMENT. PREVENTION RELEVANCE: OUR STUDY IDENTIFIES AN EPIGENETICALLY DISTINCT OMP GROUP IN THE NORMAL MUCOSA OF PATIENTS WITH COLORECTAL CANCER THAT IS CHARACTERIZED BY A DISRUPTED METHYLOME, ALTERED GENE EXPRESSION, AND MICROBIAL DYSBIOSIS. IDENTIFICATION OF OMPS IN HEALTHY CONTROLS AND PATIENTS WITH COLORECTAL CANCER WILL LEAD TO PREVENTION AND BETTER PROGNOSIS, RESPECTIVELY. 2022 3 1026 41 CIRCULATING MIRNAS EXPRESSION IN MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME. MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A COMPLEX MULTIFACTORIAL DISEASE THAT CAUSES INCREASING MORBIDITY WORLDWIDE, AND MANY INDIVIDUALS WITH ME/CFS SYMPTOMS REMAIN UNDIAGNOSED DUE TO THE LACK OF DIAGNOSTIC BIOMARKERS. ITS ETIOLOGY IS STILL UNKNOWN, BUT INCREASING EVIDENCE SUPPORTS A ROLE OF HERPESVIRUSES (INCLUDING HHV-6A AND HHV-6B) AS POTENTIAL TRIGGERS. INTERESTINGLY, THE INFECTION BY THESE VIRUSES HAS BEEN REPORTED TO IMPACT THE EXPRESSION OF MICRORNAS (MIRNAS), SHORT NON-CODING RNA SEQUENCES WHICH HAVE BEEN SUGGESTED TO BE EPIGENETIC FACTORS MODULATING ME/CFS PATHOGENIC MECHANISMS. NOTABLY, THE PRESENCE OF CIRCULATING MIRNAS IN PLASMA HAS RAISED THE POSSIBILITY TO USE THEM AS VALUABLE BIOMARKERS FOR DISTINGUISHING ME/CFS PATIENTS FROM HEALTHY CONTROLS. THUS, THIS STUDY AIMED AT DETERMINING THE ROLE OF EIGHT MIRNAS, WHICH WERE SELECTED FOR THEIR PREVIOUS ASSOCIATION WITH ME/CFS, AS POTENTIAL CIRCULATING BIOMARKERS OF THE DISEASE. THEIR PRESENCE WAS QUANTITATIVELY EVALUATED IN PLASMA FROM 40 ME/CFS PATIENTS AND 20 HEALTHY CONTROLS BY SPECIFIC TAQMAN ASSAYS, AND THE RESULTS SHOWED THAT SIX OUT OF THE EIGHT OF THE SELECTED MIRNAS WERE DIFFERENTLY EXPRESSED IN PATIENTS COMPARED TO CONTROLS; MORE SPECIFICALLY, FIVE MIRNAS WERE SIGNIFICANTLY UPREGULATED (MIR-127-3P, MIR-142-5P, MIR-143-3P, MIR-150-5P, AND MIR-448), AND ONE WAS DOWNMODULATED (MIR-140-5P). MIRNA LEVELS DIRECTLY CORRELATED WITH DISEASE SEVERITY, WHEREAS NO SIGNIFICANT CORRELATIONS WERE OBSERVED WITH THE PLASMA LEVELS OF SEVEN PRO-INFLAMMATORY CYTOKINES OR WITH THE PRESENCE/LOAD OF HHV-6A/6B GENOME, AS JUDGED BY SPECIFIC PCR AMPLIFICATION. THE RESULTS MAY OPEN THE WAY FOR FURTHER VALIDATION OF MIRNAS AS NEW POTENTIAL BIOMARKERS IN ME/CFS AND INCREASE THE KNOWLEDGE OF THE COMPLEX PATHWAYS INVOLVED IN THE ME/CFS DEVELOPMENT. 2023 4 5435 28 RELATIVE ROLE OF METHYLATOR AND TUMOR SUPPRESSOR PATHWAYS IN ULCERATIVE COLITIS-ASSOCIATED COLON CANCER. BACKGROUND: CHRONIC ULCERATIVE COLITIS (UC) IS ASSOCIATED WITH AN INCREASED COLORECTAL CANCER RISK WHICH MAY BE SECONDARY TO REPETITIVE MUCOSAL INJURY. BOTH EPIGENETIC METHYLATION AND THE CLASSIC ADENOMA-TO-CARCINOMA SEQUENCE HAVE BEEN IMPLICATED IN THIS MALIGNANT TRANSFORMATION, BUT THE UNDERLYING MOLECULAR MECHANISMS REMAIN POORLY DEFINED. THIS STUDY COMPARES THE MOLECULAR CHARACTERISTICS OF COLITIS-ASSOCIATED AND COMMON COLORECTAL CANCERS. METHODS: NINETEEN PATIENTS WITH COLORECTAL ADENOCARCINOMAS ARISING WITHIN UC WERE MATCHED FOR AGE AND CANCER SITE WITH 54 PATIENTS WITH SPORADIC ADENOCARCINOMAS. TUMOR TISSUE WAS EXAMINED FOR BRAF MUTATIONS, CPG ISLAND METHYLATOR PHENOTYPE (CIMP), AND MLH1 PROMOTER METHYLATION. MUTATIONS OF KRAS AND P53 WERE ASSESSED BY SEQUENCING. RESULTS: PATIENT DEMOGRAPHICS WERE SIMILAR FOR THE TWO GROUPS. CIMP WAS OBSERVED IN 22% OF SPORADIC COLORECTAL CANCERS AND IN 5% OF UC CANCERS (P = 0.162). RATES OF BRAF MUTATION (4% VS 5%, P = 1.0), MLH1 METHYLATION (9% VERSUS 5%, P = 0.682), AND KRAS MUTATIONS (24% VERSUS 32%, P = 0.552) WERE SIMILAR BETWEEN THE GROUPS. HOWEVER, COLITIS-ASSOCIATED COLORECTAL CANCERS WERE MORE LIKELY TO HAVE A P53 MUTATION COMPARED TO SPORADIC ADENOCARCINOMAS (95% VERSUS 53%, P = 0.001). THE DOMINANT MUTATION FOR COLITIS-ASSOCIATED CANCERS WAS A MUTATION IN CODON 4, REPRESENTING HALF OF THE MUTATIONS. FURTHERMORE, COLITIS-ASSOCIATED CANCERS HAD A HIGHER RATE OF MUTATION IN CODON 8 (48% VERSUS 6%, P < 0.001) THAN SPORADIC COUNTERPARTS. CONCLUSIONS: UNLIKE OTHER INFLAMMATORY GASTROINTESTINAL CANCERS, COLITIS-ASSOCIATED COLORECTAL CANCERS DO NOT PREFERENTIALLY ARISE VIA A METHYLATOR PATHWAY WHEN COMPARED TO SPORADIC COLORECTAL CANCERS. CHROMOSOMAL INSTABILITY REMAINS AN IMPORTANT ETIOLOGY, BUT WITH A UNIQUE P53 FREQUENCY AND MUTATION PATTERN. 2011 5 672 20 BRAF, KRAS AND HELICOBACTER PYLORI EPIGENETIC CHANGES-ASSOCIATED CHRONIC GASTRITIS IN EGYPTIAN PATIENTS WITH AND WITHOUT GASTRIC CANCER. WE AIMED TO STUDY MLH1 AND MGMT METHYLATION STATUS IN HELICOBACTER PYLORI-ASSOCIATED CHRONIC GASTRITIS IN EGYPTIAN PATIENTS WITH AND WITHOUT GASTRIC CANCER. 39 PATIENTS WERE INCLUDED IN OUR STUDY. THEY WERE DIVIDED INTO 2 GROUPS; PATIENTS WITHOUT (GROUP I) AND WITH GASTRIC ADENOCARCINOMA (GROUP II). PATIENTS WERE SUBJECTED TO CLINICAL EXAMINATION, ABDOMINAL ULTRASOUND AND UPPER ENDOSCOPY FOR GASTRIC BIOPSY. BIOPSIES WERE SUBJECTED TO UREASE TEST, HISTOLOGICAL EXAMINATION, AND DNA PURIFICATION. H. PYLORI, BRAF, KRAS, MLH1 AND MGMT METHYLATION WERE ASSESSED BY QUANTITATIVE PCR. DNA SEQUENCING WAS PERFORMED TO ASSESS BRAF AND KRAS GENES MUTATION. QPCR OF H. PYLORI WAS SIGNIFICANTLY HIGHER IN PATIENTS WITH ADENOCARCINOMA (GROUP II) THAN THOSE WITHOUT ADENOCARCINOMA (GROUP I); WITH A P < 0.001 AS WELL AS IN PATIENTS WITH AGE ABOVE 50 YEARS WITH A P VALUE = 0.008. BY APPLYING LOGISTIC REGRESSION ANALYSIS IT WAS REPORTED THAT THE H. PYLORI QPCR IS A SIGNIFICANT PREDICTOR TO THE ADENOCARCINOMA WITH OR = 1.025 (95 % CI: 1. 002-1.048), WITH SENSITIVITY OF 90 % AND SPECIFICITY OF 100 %. ADENOCARCINOMA PATIENTS HAD A SIGNIFICANTLY HIGHER MEAN AGE AND LEVELS OF H. PYLORI, BRAF, K-RAS, METHYLATED MGMT AND METHYLATED MLH1 THAN THOSE OF GASTRITIS PATIENTS. DNA SEQUENCE ANALYSIS OF BRAF (CODON 12) AND KRAS (CODON 600) HAD GENES MUTATION IN GASTRIC ADENOCARCINOMA VERSUS CHRONIC GASTRITIS. CONCLUSION: H. PYLORI MAY CAUSE EPIGENETIC CHANGES PREDISPOSING THE PATIENTS TO CANCER STOMACH. ESTIMATION OF H. PYLORI BY QPCR CAN BE A GOOD PREDICTOR TO ADENOCARCINOMA. BRAF AND KRAS GENES MUTATION WERE REVELED IN GASTRITIS AND ADENOCARCINOMA PATIENTS. 2016 6 1006 53 CHRONIC VIRAL INFECTION AND PRIMARY CENTRAL NERVOUS SYSTEM MALIGNANCY. PRIMARY CENTRAL NERVOUS SYSTEM (CNS) TUMORS CAUSE SIGNIFICANT MORBIDITY AND MORTALITY IN BOTH ADULTS AND CHILDREN. WHILE SOME OF THE GENETIC AND MOLECULAR MECHANISMS OF NEURO-ONCOGENESIS ARE KNOWN, MUCH LESS IS KNOWN ABOUT POSSIBLE EPIGENETIC CONTRIBUTIONS TO DISEASE PATHOPHYSIOLOGY. OVER THE LAST SEVERAL DECADES, CHRONIC VIRAL INFECTIONS HAVE BEEN ASSOCIATED WITH A NUMBER OF HUMAN MALIGNANCIES. IN PRIMARY CNS MALIGNANCIES, TWO FAMILIES OF VIRUSES, NAMELY POLYOMAVIRUS AND HERPESVIRUS, HAVE BEEN DETECTED WITH VARIED FREQUENCIES IN A NUMBER OF PEDIATRIC AND ADULT HISTOLOGICAL TUMOR SUBTYPES. HOWEVER, ESTABLISHING A LINK BETWEEN CHRONIC VIRAL INFECTION AND PRIMARY CNS MALIGNANCY HAS BEEN AN AREA OF CONSIDERABLE CONTROVERSY, DUE IN PART TO VARIATIONS IN DETECTION FREQUENCIES AND METHODOLOGIES USED AMONG RESEARCHERS. SINCE A LATENT VIRAL NEUROTROPISM CAN BE SEEN WITH A VARIETY OF VIRUSES AND A WIDESPREAD SEROPOSITIVITY EXISTS AMONG THE POPULATION, IT HAS BEEN DIFFICULT TO ESTABLISH AN ASSOCIATION BETWEEN VIRAL INFECTION AND CNS MALIGNANCY BASED ON EPIDEMIOLOGY ALONE. WHILE DIRECT EVIDENCE OF A ROLE OF VIRUSES IN NEURO-ONCOGENESIS IN HUMANS IS LACKING, A MORE PLAUSIBLE HYPOTHESIS OF NEURO-ONCOMODULATION HAS BEEN PROPOSED. THE OVERALL GOALS OF THIS REVIEW ARE TO SUMMARIZE THE MANY HUMAN INVESTIGATIONS THAT HAVE STUDIED VIRAL INFECTION IN PRIMARY CNS TUMORS, DISCUSS POTENTIAL NEURO-ONCOMODULATORY MECHANISMS OF VIRAL-ASSOCIATED CNS DISEASE AND PROPOSE FUTURE RESEARCH DIRECTIONS TO ESTABLISH A MORE FIRM ASSOCIATION BETWEEN CHRONIC VIRAL INFECTIONS AND PRIMARY CNS MALIGNANCIES. 2010 7 2439 23 EPIGENETIC SILENCING OF THE MLH1 PROMOTER IN RELATION TO THE DEVELOPMENT OF GASTRIC CANCER AND ITS USE AS A BIOMARKER FOR PATIENTS WITH MICROSATELLITE INSTABILITY: A SYSTEMATIC ANALYSIS. BACKGROUND/AIMS: HUMAN MUTL HOMOLOG 1 (MLH1) PROMOTER METHYLATION WAS REPORTED IN GASTRIC CANCER (GC). THIS STUDY DETERMINED THE CLINICOPATHOLOGICAL, PROGNOSTIC, AND DIAGNOSTIC EFFECTS OF MLH1 PROMOTER METHYLATION IN GC. METHODS: THE COMBINED ODDS RATIO (OR) OR HAZARD RATIO (HR) AND THEIR CORRESPONDING 95% CONFIDENCE INTERVALS (95% CI) WERE CALCULATED. THE POOLED SENSITIVITY, SPECIFICITY, AND AREA UNDER THE CURVE (AUC) WERE ANALYZED. RESULTS: A TOTAL OF 4654 GC PATIENTS AND 3669 NON-MALIGNANT CONTROLS WERE IDENTIFIED IN THIS SYSTEMATIC ANALYSIS. MLH1 PROMOTER METHYLATION WAS SIGNIFICANTLY HIGHER IN GC SAMPLES THAN IN GASTRIC ADENOMAS, CHRONIC GASTRITIS, ADJACENT TISSUES, NORMAL GASTRIC MUCOSA, AND NORMAL HEALTHY BLOOD SAMPLES, BUT IT EXHIBITED A SIMILAR FREQUENCY IN GC VS. INTESTINAL METAPLASIA AND DYSPLASIA SAMPLES. MLH1 PROMOTER METHYLATION CORRELATED WITH AGE AND MICROSATELLITE INSTABILITY (MSI), BUT IT WAS NOT ASSOCIATED WITH GENDER, H. PYLORI INFECTION, SMOKING, DRINKING BEHAVIORS, PATHOLOGICAL HISTOLOGY, TUMOR DIFFERENTIATION, CLINICAL STAGE, LYMPH NODE STATUS, DISTANT METASTASIS, OR OVERALL SURVIVAL OF GC. MLH1 PROMOTER METHYLATION EXHIBITED A POOR SENSITIVITY VALUE (< 0.5) IN PATIENTS WITH GC COMPARED WITH ADJACENT TISSUES, GASTRIC ADENOMAS, CHRONIC GASTRITIS, NORMAL GASTRIC MUCOSA, AND NORMAL HEALTHY BLOOD SAMPLES. THE POOLED SENSITIVITY, SPECIFICITY, AND AUC OF MLH1 PROMOTER METHYLATION IN GC WITH MSI VS. GC WITH MICROSATELLITE STABILITY (MSS) SAMPLES WERE 0.64, 0.96, AND 0.90, RESPECTIVELY. CONCLUSIONS: OUR RESULTS SUGGEST THAT THE DETECTION OF MLH1 PROMOTER METHYLATION MAY BE A POTENTIAL PROGNOSTIC BIOMARKER FOR GC PATIENTS WITH MSI. 2018 8 2856 34 FROM METHYLATION TO MYELINATION: EPIGENOMIC AND TRANSCRIPTOMIC PROFILING OF CHRONIC INACTIVE DEMYELINATED MULTIPLE SCLEROSIS LESIONS. IN THE PROGRESSIVE PHASE OF MULTIPLE SCLEROSIS (MS), THE HAMPERED DIFFERENTIATION CAPACITY OF OLIGODENDROCYTE PRECURSOR CELLS (OPCS) EVENTUALLY RESULTS IN REMYELINATION FAILURE. WE HAVE PREVIOUSLY SHOWN THAT DNA METHYLATION OF ID2/ID4 IS HIGHLY INVOLVED IN OPC DIFFERENTIATION AND REMYELINATION. IN THIS STUDY, WE TOOK AN UNBIASED APPROACH BY DETERMINING GENOME-WIDE DNA METHYLATION PATTERNS WITHIN CHRONICALLY DEMYELINATED MS LESIONS AND INVESTIGATED HOW CERTAIN EPIGENETIC SIGNATURES RELATE TO OPC DIFFERENTIATION CAPACITY. WE COMPARED GENOME-WIDE DNA METHYLATION AND TRANSCRIPTIONAL PROFILES BETWEEN CHRONICALLY DEMYELINATED MS LESIONS AND MATCHED NORMAL-APPEARING WHITE MATTER (NAWM), MAKING USE OF POST-MORTEM BRAIN TISSUE (N = 9/GROUP). DNA METHYLATION DIFFERENCES THAT INVERSELY CORRELATED WITH MRNA EXPRESSION OF THEIR CORRESPONDING GENES WERE VALIDATED FOR THEIR CELL-TYPE SPECIFICITY IN LASER-CAPTURED OPCS USING PYROSEQUENCING. THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM WAS USED TO EPIGENETICALLY EDIT HUMAN-IPSC-DERIVED OLIGODENDROCYTES TO ASSESS THE EFFECT ON CELLULAR DIFFERENTIATION. OUR DATA SHOW HYPERMETHYLATION OF CPGS WITHIN GENES THAT CLUSTER IN GENE ONTOLOGIES RELATED TO MYELINATION AND AXON ENSHEATHMENT. CELL TYPE-SPECIFIC VALIDATION INDICATES A REGION-DEPENDENT HYPERMETHYLATION OF MBP, ENCODING FOR MYELIN BASIC PROTEIN, IN OPCS OBTAINED FROM WHITE MATTER LESIONS COMPARED TO NAWM-DERIVED OPCS. BY ALTERING THE DNA METHYLATION STATE OF SPECIFIC CPGS WITHIN THE PROMOTOR REGION OF MBP, USING EPIGENETIC EDITING, WE SHOW THAT CELLULAR DIFFERENTIATION AND MYELINATION CAN BE BIDIRECTIONALLY MANIPULATED USING THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM IN VITRO. OUR DATA INDICATE THAT OPCS WITHIN CHRONICALLY DEMYELINATED MS LESIONS ACQUIRE AN INHIBITORY PHENOTYPE, WHICH TRANSLATES INTO HYPERMETHYLATION OF CRUCIAL MYELINATION-RELATED GENES. ALTERING THE EPIGENETIC STATUS OF MBP CAN RESTORE THE DIFFERENTIATION CAPACITY OF OPCS AND POSSIBLY BOOST (RE)MYELINATION. 2023 9 3413 26 HSA-MIR-29C AND HSA-MIR-135B DIFFERENTIAL EXPRESSION AS POTENTIAL BIOMARKER OF GASTRIC CARCINOGENESIS. AIM: TO INVESTIGATE THE EXPRESSION PROFILES OF HSA-MIR-29C AND HSA-MIR-135B IN GASTRIC MUCOSAL SAMPLES AND THEIR VALUES AS GASTRIC CARCINOGENESIS BIOMARKERS. METHODS: THE EXPRESSION LEVELS OF HSA-MIR-29C AND HSA-MIR-135B IN NORMAL GASTRIC MUCOSA, NON-ATROPHIC CHRONIC GASTRITIS, INTESTINAL METAPLASIA AND INTESTINAL-TYPE GASTRIC ADENOCARCINOMA WERE ANALYSED USING QUANTITATIVE REAL-TIME PCR. THE DIFFERENCE BETWEEN HSA-MIR-29C AND HSA-MIR-135B EXPRESSION PROFILES IN THE GROUPED SAMPLES WAS EVALUATED BY ANOVA AND STUDENT'S T-TEST TESTS. THE RESULTS WERE ADJUSTED FOR MULTIPLE TESTING BY USING BONFERRONI'S CORRECTION. P VALUES