1 2438 122 EPIGENETIC SILENCING OF THE CIRCADIAN CLOCK GENE CRY1 IS ASSOCIATED WITH AN INDOLENT CLINICAL COURSE IN CHRONIC LYMPHOCYTIC LEUKEMIA. DISRUPTION OF CIRCADIAN RHYTHM IS BELIEVED TO PLAY A CRITICAL ROLE IN CANCER DEVELOPMENT. CRYPTOCHROME 1 (CRY1) IS A CORE COMPONENT OF THE MAMMALIAN CIRCADIAN CLOCK AND WE HAVE PREVIOUSLY SHOWN ITS DEREGULATED EXPRESSION IN A SUBGROUP OF PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). USING REAL-TIME RT-PCR IN A COHORT OF 76 CLL PATIENTS AND 35 NORMAL BLOOD DONORS WE NOW DEMONSTRATE THAT DIFFERENTIAL CRY1 MRNA EXPRESSION IN HIGH-RISK (HR) CD38+/IMMUNOGLOBULIN VARIABLE HEAVY CHAIN GENE (IGVH) UNMUTATED PATIENTS AS COMPARED TO LOW-RISK (LR) CD38-/IGVH MUTATED PATIENTS CAN BE ATTRIBUTED TO DOWN-MODULATION OF CRY1 IN LR CLL CASES. ANALYSIS OF THE DNA METHYLATION PROFILE OF THE CRY1 PROMOTER IN A SUBGROUP OF 57 PATIENTS REVEALED THAT CRY1 EXPRESSION IN LR CLL CELLS IS SILENCED BY ABERRANT PROMOTER CPG ISLAND HYPERMETHYLATION. THE METHYLATION PATTERN OF THE CRY1 PROMOTER PROVED TO HAVE HIGH PROGNOSTIC IMPACT IN CLL WHERE ABERRANT PROMOTER METHYLATION PREDICTED A FAVOURABLE OUTCOME. CRY1 MRNA TRANSCRIPT LEVELS DID NOT CHANGE OVER TIME IN THE MAJORITY OF PATIENTS WHERE SEQUENTIAL SAMPLES WERE AVAILABLE FOR ANALYSIS. WE ALSO COMPARED THE CRY1 EXPRESSION IN CLL WITH OTHER LYMPHOID MALIGNANCIES AND OBSERVED EPIGENETIC SILENCING OF CRY1 IN A PATIENT WITH B CELL ACUTE LYMPHOBLASTIC LEUKEMIA (B-ALL). 2012 2 1473 35 DISTINCT PATTERNS OF GLOBAL PROMOTER METHYLATION IN EARLY STAGE CHRONIC LYMPHOCYTIC LEUKEMIA. GENOMIC AND EPIGENOMIC STUDIES OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) ARE RESHAPING OUR UNDERSTANDING OF THE DISEASE AND HAVE PROVIDED NEW PERSPECTIVES FOR A MORE INDIVIDUALIZED DIAGNOSIS AND NEW POTENTIAL THERAPEUTIC TARGETS. IN THIS STUDY, THE GLOBAL PROMOTER METHYLATION PROFILE WAS DETERMINED IN HIGHLY PURIFIED B-CELLS FROM 37 (BINET STAGE A) CLL PATIENTS, USING HIGH-RESOLUTION METHYLATION MICROARRAYS (27,578 CPG). OVERALL, THE METHYLATION PATTERN CORRELATED WITH THE MAJOR BIOLOGICAL (ZAP-70 AND CD38), AND MOLECULAR (IGHV MUTATION) MARKERS, DISTINGUISHING CLL CASES ACCORDING TO IGHV MUTATIONAL STATUS. CELL ADHESION MOLECULES WERE ENRICHED IN THE SIGNATURE OF UNMUTATED (UM) VERSUS MUTATED (M-) CLL. MOREOVER, IN M-CLL CPG HYPER-METHYLATION IN THREE GENES, INCLUDING SPG20, WAS SIGNIFICANTLY ANTI-CORRELATED WITH THE CORRESPONDING GENE EXPRESSION LEVEL. FINALLY, THE CORRELATION BETWEEN THE METHYLATION PATTERN AND CLINICAL PARAMETERS WAS INVESTIGATED. NOTABLY, OUT OF 42 METHYL-PROBES THAT WERE SIGNIFICANTLY ASSOCIATED WITH PROGRESSION FREE SURVIVAL (PFS), HYPER-METHYLATION OF SPG20 WAS ALSO POSITIVELY ASSOCIATED WITH PFS. THESE DATA SUPPORT THE NOTION THAT EPIGENETIC CHANGES HAVE CLINICAL IMPACT IN CLL AND MAY CONTRIBUTE TO THE IDENTIFICATION OF NOVEL CANDIDATE DISEASE-ASSOCIATED GENES POTENTIALLY USEFUL TO PREDICT THE CLINICAL OUTCOME OF EARLY STAGE CLL PATIENTS. 2014 3 3071 49 GENOME-WIDE DNA METHYLATION PROFILING INTEGRATED WITH GENE EXPRESSION PROFILING IDENTIFIES PAX9 AS A NOVEL PROGNOSTIC MARKER IN CHRONIC LYMPHOCYTIC LEUKEMIA. BACKGROUND: IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), EPIGENOMIC AND GENOMIC STUDIES HAVE EXPANDED THE EXISTING KNOWLEDGE ABOUT THE DISEASE BIOLOGY AND LED TO THE IDENTIFICATION OF POTENTIAL BIOMARKERS RELEVANT FOR IMPLEMENTATION OF PERSONALIZED MEDICINE. IN THIS STUDY, AN ATTEMPT HAS BEEN MADE TO EXAMINE AND INTEGRATE THE GLOBAL DNA METHYLATION CHANGES WITH GENE EXPRESSION PROFILE AND THEIR IMPACT ON CLINICAL OUTCOME IN EARLY STAGE CLL PATIENTS. RESULTS: THE INTEGRATION OF DNA METHYLATION PROFILE (N = 14) WITH THE GENE EXPRESSION PROFILE (N = 21) REVEALED 142 GENES AS HYPERMETHYLATED-DOWNREGULATED AND; 62 GENES AS HYPOMETHYLATED-UPREGULATED IN EARLY STAGE CLL PATIENTS COMPARED TO CD19+ B-CELLS FROM HEALTHY INDIVIDUALS. THE MRNA EXPRESSION LEVELS OF 17 GENES IDENTIFIED TO BE DIFFERENTIALLY METHYLATED AND/OR DIFFERENTIALLY EXPRESSED WAS FURTHER EXAMINED IN EARLY STAGE CLL PATIENTS (N = 93) BY QUANTITATIVE REAL TIME PCR (RQ-PCR). SIGNIFICANT DIFFERENCES WERE OBSERVED IN THE MRNA EXPRESSION OF MEIS1, PMEPA1, SOX7, SPRY1, CDK6, TBX2, AND SPRY2 GENES IN CLL CELLS AS COMPARED TO B-CELLS FROM HEALTHY INDIVIDUALS. THE ANALYSIS IN THE IGHV MUTATION BASED CATEGORIES (UNMUTATED = 39, MUTATED = 54) REVEALED SIGNIFICANTLY HIGHER MRNA EXPRESSION OF CRY1 AND PAX9 GENES IN THE IGHV UNMUTATED SUBGROUP (P < 0.001). THE RELATIVE RISK OF TREATMENT INITIATION WAS SIGNIFICANTLY HIGHER AMONG PATIENTS WITH HIGH EXPRESSION OF CRY1 (RR = 1.91, P = 0.005) OR PAX9 (RR = 1.87, P = 0.001). HIGH EXPRESSION OF CRY1 (HR: 3.53, P < 0.001) OR PAX9 (HR: 3.14, P < 0.001) GENE WAS SIGNIFICANTLY ASSOCIATED WITH SHORTER TIME TO FIRST TREATMENT. THE HIGH EXPRESSION OF PAX9 GENE (HR: 3.29, 95% CI 1.172-9.272, P = 0.016) WAS ALSO PREDICTIVE OF SHORTER OVERALL SURVIVAL IN CLL. CONCLUSIONS: THE DNA METHYLATION CHANGES ASSOCIATED WITH MRNA EXPRESSION OF CRY1 AND PAX9 GENES ALLOW RISK STRATIFICATION OF EARLY STAGE CLL PATIENTS. THIS COMPREHENSIVE ANALYSIS SUPPORTS THE CONCEPT THAT THE EPIGENETIC CHANGES ALONG WITH THE ALTERED EXPRESSION OF GENES HAVE THE POTENTIAL TO PREDICT CLINICAL OUTCOME IN EARLY STAGE CLL PATIENTS. 2017 4 1433 36 DIFFERENTIAL GENOME-WIDE ARRAY-BASED METHYLATION PROFILES IN PROGNOSTIC SUBSETS OF CHRONIC LYMPHOCYTIC LEUKEMIA. GLOBAL HYPOMETHYLATION AND REGIONAL HYPERMETHYLATION ARE WELL-KNOWN EPIGENETIC FEATURES OF CANCER; HOWEVER, IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), STUDIES ON GENOME-WIDE EPIGENETIC MODIFICATIONS ARE LIMITED. HERE, WE ANALYZED THE GLOBAL METHYLATION PROFILES IN CLL, BY APPLYING HIGH-RESOLUTION METHYLATION MICROARRAYS (27,578 CPG SITES) TO 23 CLL SAMPLES, BELONGING TO THE IMMUNOGLOBULIN HEAVY-CHAIN VARIABLE (IGHV) MUTATED (FAVORABLE) AND IGHV UNMUTATED/IGHV3-21 (POOR-PROGNOSTIC) SUBSETS. OVERALL, RESULTS DEMONSTRATED SIGNIFICANT DIFFERENCES IN METHYLATION PATTERNS BETWEEN THESE SUBGROUPS. SPECIFICALLY, IN IGHV UNMUTATED CLL, WE IDENTIFIED METHYLATION OF 7 KNOWN OR CANDIDATE TUMOR SUPPRESSOR GENES (EG, VHL, ABI3, AND IGSF4) AS WELL AS 8 UNMETHYLATED GENES INVOLVED IN CELL PROLIFERATION AND TUMOR PROGRESSION (EG, ADORA3 AND PRF1 ENHANCING THE NUCLEAR FACTOR-KAPPAB AND MITOGEN-ACTIVATED PROTEIN KINASE PATHWAYS, RESPECTIVELY). IN CONTRAST, THESE LATTER GENES WERE SILENCED BY METHYLATION IN IGHV MUTATED PATIENTS. THE ARRAY DATA WERE VALIDATED FOR SELECTED GENES USING METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION, QUANTITATIVE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN REACTION, AND BISULFITE SEQUENCING. FINALLY, THE SIGNIFICANCE OF DNA METHYLATION IN REGULATING GENE PROMOTERS WAS SHOWN BY REINDUCING 4 METHYLATED TUMOR SUPPRESSOR GENES (EG, VHL AND ABI3) IN IGHV UNMUTATED SAMPLES USING THE METHYL-INHIBITOR 5-AZA-2'-DEOXYCYTIDINE. TAKEN TOGETHER, OUR DATA FOR THE FIRST TIME REVEAL DIFFERENCES IN GLOBAL METHYLATION PROFILES BETWEEN PROGNOSTIC SUBSETS OF CLL, WHICH MAY UNFOLD EPIGENETIC SILENCING MECHANISMS INVOLVED IN CLL PATHOGENESIS. 2010 5 3896 42 LARGE-SCALE ANALYSIS OF DNA METHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA. AIMS: B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS A HETEROGENEOUS MALIGNANCY THAT CLINICALLY RANGES FROM INDOLENT TO RAPIDLY PROGRESSIVE. CLL, LIKE OTHER CANCERS, CAN BE AFFECTED BY EPIGENETIC ALTERATIONS. MATERIALS & METHODS: A MICROARRAY DISCOVERY-BASED STUDY WAS INITIATED TO DETERMINE DNA METHYLATION IN CLL CASES WITH A RANGE OF CD38 EXPRESSION (1-92%). RESULTS: MANY LOCI WERE EITHER METHYLATED OR UNMETHYLATED ACROSS ALL CD38 LEVELS, BUT DIFFERENTIAL METHYLATION WAS ALSO OBSERVED FOR SOME GENES. GENOMIC SEQUENCING OF DLEU7 CONFIRMED EXTENSIVE CYTOSINE METHYLATION PREFERENTIALLY IN PATIENT SAMPLES WITH LOW CD38 EXPRESSION, WHEREAS NRP2, SFRP2 AND ADAM12 WERE MORE COMMONLY METHYLATED IN THOSE WITH HIGH CD38 EXPRESSION. CONCLUSION: THIS STUDY DEMONSTRATES THAT CLL IS AFFECTED BY CPG ISLAND METHYLATION IN SOME GENES THAT SEGREGATE WITH CD38 EXPRESSION LEVELS, WHILE MOST OTHERS SHOW SIMILAR METHYLATION PATTERNS ACROSS ALL LEVELS. THE CPG ISLAND METHYLATION IN CERTAIN FUNCTIONAL GENE GROUPS AND PATHWAY-ASSOCIATED GENES THAT ARE KNOWN TO BE DEREGULATED IN CLL PROVIDES ADDITIONAL INSIGHTS INTO THE CLL METHYLOME AND EPIGENETIC CONTRIBUTION TO CELLULAR DYSFUNCTION. IT WILL NOW BE USEFUL TO INVESTIGATE THE EFFECTIVENESS OF EPIGENETIC THERAPEUTIC REVERSAL OF THESE ALTERATIONS TO DEVELOP EFFECTIVE TREATMENTS FOR THE DISEASE. 2009 6 2639 33 EPIGENOMIC ANALYSIS DETECTS WIDESPREAD GENE-BODY DNA HYPOMETHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA. WE HAVE EXTENSIVELY CHARACTERIZED THE DNA METHYLOMES OF 139 PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) WITH MUTATED OR UNMUTATED IGHV AND OF SEVERAL MATURE B-CELL SUBPOPULATIONS THROUGH THE USE OF WHOLE-GENOME BISULFITE SEQUENCING AND HIGH-DENSITY MICROARRAYS. THE TWO MOLECULAR SUBTYPES OF CLL HAVE DIFFERING DNA METHYLOMES THAT SEEM TO REPRESENT EPIGENETIC IMPRINTS FROM DISTINCT NORMAL B-CELL SUBPOPULATIONS. DNA HYPOMETHYLATION IN THE GENE BODY, TARGETING MOSTLY ENHANCER SITES, WAS THE MOST FREQUENT DIFFERENCE BETWEEN NAIVE AND MEMORY B CELLS AND BETWEEN THE TWO MOLECULAR SUBTYPES OF CLL AND NORMAL B CELLS. ALTHOUGH DNA METHYLATION AND GENE EXPRESSION WERE POORLY CORRELATED, WE IDENTIFIED GENE-BODY CPG DINUCLEOTIDES WHOSE METHYLATION WAS POSITIVELY OR NEGATIVELY ASSOCIATED WITH EXPRESSION. WE HAVE ALSO RECOGNIZED A DNA METHYLATION SIGNATURE THAT DISTINGUISHES NEW CLINICO-BIOLOGICAL SUBTYPES OF CLL. WE PROPOSE AN EPIGENOMIC SCENARIO IN WHICH DIFFERENTIAL METHYLATION IN THE GENE BODY MAY HAVE FUNCTIONAL AND CLINICAL IMPLICATIONS IN LEUKEMOGENESIS. 2012 7 27 32 A B-CELL EPIGENETIC SIGNATURE DEFINES THREE BIOLOGIC SUBGROUPS OF CHRONIC LYMPHOCYTIC LEUKEMIA WITH CLINICAL IMPACT. PROSPECTIVE IDENTIFICATION OF PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) DESTINED TO PROGRESS WOULD GREATLY FACILITATE THEIR CLINICAL MANAGEMENT. RECENTLY, WHOLE-GENOME DNA METHYLATION ANALYSES IDENTIFIED THREE CLINICOBIOLOGIC CLL SUBGROUPS WITH AN EPIGENETIC SIGNATURE RELATED TO DIFFERENT NORMAL B-CELL COUNTERPARTS. HERE, WE DEVELOPED A CLINICALLY APPLICABLE METHOD TO IDENTIFY THESE SUBGROUPS AND TO STUDY THEIR CLINICAL RELEVANCE. USING A SUPPORT VECTOR MACHINE APPROACH, WE BUILT A PREDICTION MODEL USING FIVE EPIGENETIC BIOMARKERS THAT WAS ABLE TO CLASSIFY CLL PATIENTS ACCURATELY INTO THE THREE SUBGROUPS, NAMELY NAIVE B-CELL-LIKE, INTERMEDIATE AND MEMORY B-CELL-LIKE CLL. DNA METHYLATION WAS QUANTIFIED BY HIGHLY REPRODUCIBLE BISULFITE PYROSEQUENCING ASSAYS IN TWO INDEPENDENT CLL SERIES. IN THE INITIAL SERIES (N=211), THE THREE SUBGROUPS SHOWED DIFFERENTIAL LEVELS OF IGHV (IMMUNOGLOBULIN HEAVY-CHAIN LOCUS) MUTATION (P<0.001) AND VH USAGE (P<0.03), AS WELL AS DIFFERENT CLINICAL FEATURES AND OUTCOME IN TERMS OF TIME TO FIRST TREATMENT (TTT) AND OVERALL SURVIVAL (P<0.001). A MULTIVARIATE COX MODEL SHOWED THAT EPIGENETIC CLASSIFICATION WAS THE STRONGEST PREDICTOR OF TTT (P<0.001) ALONG WITH BINET STAGE (P<0.001). THESE FINDINGS WERE CORROBORATED IN A VALIDATION SERIES (N=97). IN THIS STUDY, WE DEVELOPED A SIMPLE AND ROBUST METHOD USING EPIGENETIC BIOMARKERS TO CATEGORIZE CLLS INTO THREE SUBGROUPS WITH DIFFERENT CLINICOBIOLOGIC FEATURES AND OUTCOME. 2015 8 3062 38 GENOME-WIDE DNA METHYLATION ANALYSIS REVEALS NOVEL EPIGENETIC CHANGES IN CHRONIC LYMPHOCYTIC LEUKEMIA. WE CONDUCTED A GENOME-WIDE DNA METHYLATION ANALYSIS IN CD19 (+) B-CELLS FROM CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) PATIENTS AND NORMAL CONTROL SAMPLES USING REDUCED REPRESENTATION BISULFITE SEQUENCING (RRBS). THE METHYLATION STATUS OF 1.8-2.3 MILLION CPGS IN THE CLL GENOME WAS DETERMINED; ABOUT 45% OF THESE CPGS WERE LOCATED IN MORE THAN 23,000 CPG ISLANDS (CGIS). WHILE GLOBAL CPG METHYLATION WAS SIMILAR BETWEEN CLL AND NORMAL B-CELLS, 1764 GENE PROMOTERS WERE IDENTIFIED AS BEING DIFFERENTIALLY METHYLATED IN AT LEAST ONE CLL SAMPLE WHEN COMPARED WITH NORMAL B-CELL SAMPLES. NINETEEN PERCENT OF THE DIFFERENTIALLY METHYLATED GENES WERE INVOLVED IN TRANSCRIPTIONAL REGULATION. ABERRANT HYPERMETHYLATION WAS FOUND IN ALL HOX GENE CLUSTERS AND A SIGNIFICANT NUMBER OF WNT SIGNALING PATHWAY GENES. HYPOMETHYLATION OCCURRED MORE FREQUENTLY IN THE GENE BODY INCLUDING INTRONS, EXONS, AND 3'-UTRS IN CLL. THE NFATC1 P2 PROMOTER AND FIRST INTRON WAS FOUND TO BE HYPOMETHYLATED AND CORRELATED WITH UPREGULATION OF BOTH NFATC1 RNA AND PROTEIN EXPRESSION LEVELS IN CLL SUGGESTING THAT AN EPIGENETIC MECHANISM IS INVOLVED IN THE CONSTITUTIVE ACTIVATION OF NFAT ACTIVITY IN CLL CELLS. THIS COMPREHENSIVE DNA METHYLATION ANALYSIS WILL FURTHER OUR UNDERSTANDING OF THE EPIGENETIC CONTRIBUTION TO CELLULAR DYSFUNCTION IN CLL. 2012 9 3588 39 IMPACT OF TP53 GENE PROMOTER METHYLATION ON CHRONIC LYMPHOCYTIC LEUKEMIA PATHOGENESIS AND PROGRESSION. BACKGROUND: CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS A MALIGNANT LYMPHOID DISORDER THAT RESULTS FROM THE OVERGROWTH OF MATURE-LOOKING LYMPHOID CELLS IN THE BLOOD AND LYMPHATIC TISSUE. VARIOUS CLINICAL PRESENTATIONS HAVE BEEN ATTRIBUTED TO THE DISEASE AS A RESULT OF THE DIFFERENT UNDERLYING GENETIC AND EPIGENETIC ALTERATIONS. THE CURRENT STUDY HAS BEEN INITIATED TO STUDY THE ROLE OF AN EPIGENETIC ALTERATION AFFECTING THE PROMOTER OF THE TP53GENE ON CLL PATHOGENESIS AND PROGRESSION. METHODS: THE CURRENT STUDY INVOLVED 54 NEWLY DIAGNOSED PATIENTS PRESENTING WITH CLL AS WELL AS 30 NORMAL INDIVIDUALS AS CONTROLS. AFTER OBTAINING VERBAL CONSENT, DATA COLLECTION WAS DONE AND THE BLOOD COLLECTED FROM ALL ENROLLED INDIVIDUALS FOR HEMATOLOGICAL INVESTIGATIONS AS WELL AS FOR MOLECULAR CATEGORIZATION OF TP53 METHYLATION STATUS. METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION (MS-PCR) TECHNIQUE WAS USED TO DEFINE THE METHYLATION STATUS OF THE TP53 GENE PROMOTER THAT ENCOMPASSES DNA EXTRACTION, BISULFITE CONVERSION, CONVENTIONAL PCR AMPLIFICATION, RUNNING ON AGAROSE GEL AND DOCUMENTATION. FINALLY, STATISTICAL ANALYSIS WAS DONE TO ASSESS ANY CORRELATION OF THE TP53 EPIGENETIC ALTERATION TO THE DISEASE ETIOLOGY AND THE PROGRESSION. RESULTS: IN THE CURRENT STUDY, ALL CONTROLS AND 42 OF 54 PATIENTS SHOW UNMETHYLATED TP53 GENE PROMOTER; ON THE OTHER HAND, THE METHYLATED PROMOTER WAS DETECTED AMONG 12 PATIENTS WITH A P-VALUE OF 0.001. TP53 GENE PROMOTER METHYLATION SIGNIFICANTLY LINKED TO REDUCED PLATELET COUNT (P-VALUE OF 0.047) AND ADVANCED STAGE AT PRESENTATION (P-VALUE OF 0.076). NO SIGNIFICANT DIFFERENCES WERE SEEN AMONG BOTH METHYLATED AND UNMETHYLATED TP53 PROMOTERS IN RELATION TO THE AGE OF THE AFFECTED INDIVIDUALS, TOTAL WHITE BLOOD CELL COUNTS AND HEMOGLOBIN LEVEL OF THE AFFECTED INDIVIDUALS. CONCLUSION: THE CURRENT STUDY REVEALED A SIGNIFICANT CORRELATION OF TP53 GENE PROMOTER METHYLATION TO CHRONIC LYMPHOCYTIC LEUKEMIA PATHOGENESIS AND LOWER PLATELET COUNTS. 2019 10 2771 36 EXTENSIVE PROMOTER DNA HYPERMETHYLATION AND HYPOMETHYLATION IS ASSOCIATED WITH ABERRANT MICRORNA EXPRESSION IN CHRONIC LYMPHOCYTIC LEUKEMIA. DYSREGULATED MICRORNA (MIRNA) EXPRESSION CONTRIBUTES TO THE PATHOGENESIS OF HEMATOPOIETIC MALIGNANCIES, INCLUDING CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). HOWEVER, AN UNDERSTANDING OF THE MECHANISMS THAT CAUSE ABERRANT MIRNA TRANSCRIPTIONAL CONTROL IS LACKING. IN THIS STUDY, WE COMPREHENSIVELY INVESTIGATED THE ROLE AND EXTENT OF MIRNA EPIGENETIC REGULATION IN CLL. GENOME-WIDE PROFILING CONDUCTED ON 24 CLL AND 10 HEALTHY B CELL SAMPLES REVEALED GLOBAL DNA METHYLATION PATTERNS UPSTREAM OF MIRNA SEQUENCES THAT DISTINGUISHED MALIGNANT FROM HEALTHY CELLS AND IDENTIFIED PUTATIVE MIRNA PROMOTERS. INTEGRATION OF DNA METHYLATION AND MIRNA PROMOTER DATA LED TO THE IDENTIFICATION OF 128 RECURRENT MIRNA TARGETS FOR ABERRANT PROMOTER DNA METHYLATION. DNA HYPOMETHYLATION ACCOUNTED FOR MORE THAN 60% OF ALL ABERRANT PROMOTER-ASSOCIATED DNA METHYLATION IN CLL, AND PROMOTER DNA HYPOMETHYLATION WAS RESTRICTED TO WELL-DEFINED REGIONS. INDIVIDUAL HYPER- AND HYPOMETHYLATED PROMOTERS ALLOWED DISCRIMINATION OF CLL SAMPLES FROM HEALTHY CONTROLS. PROMOTER DNA METHYLATION PATTERNS WERE CONFIRMED IN AN INDEPENDENT PATIENT COHORT, WITH 11 MIRNAS CONSISTENTLY SHOWING AN INVERSE CORRELATION BETWEEN DNA METHYLATION STATUS AND EXPRESSION LEVEL. TOGETHER, OUR FINDINGS CHARACTERIZE THE ROLE OF EPIGENETIC CHANGES IN THE REGULATION OF MIRNA TRANSCRIPTION AND CREATE A REPOSITORY OF DISEASE-SPECIFIC PROMOTER REGIONS THAT MAY PROVIDE ADDITIONAL INSIGHTS INTO THE PATHOGENESIS OF CLL. 2012 11 15 42 450K-ARRAY ANALYSIS OF CHRONIC LYMPHOCYTIC LEUKEMIA CELLS REVEALS GLOBAL DNA METHYLATION TO BE RELATIVELY STABLE OVER TIME AND SIMILAR IN RESTING AND PROLIFERATIVE COMPARTMENTS. IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), THE MICROENVIRONMENT INFLUENCES GENE EXPRESSION PATTERNS; HOWEVER, KNOWLEDGE IS LIMITED REGARDING THE EXTENT TO WHICH METHYLATION CHANGES WITH TIME AND EXPOSURE TO SPECIFIC MICROENVIRONMENTS. USING HIGH-RESOLUTION 450K ARRAYS, WE PROVIDE THE MOST COMPREHENSIVE DNA METHYLATION STUDY OF CLL TO DATE, ANALYZING PAIRED DIAGNOSTIC/FOLLOW-UP SAMPLES FROM IGHV-MUTATED/UNTREATED AND IGHV-UNMUTATED/TREATED PATIENTS (N=36) AND PATIENT-MATCHED PERIPHERAL BLOOD AND LYMPH NODE SAMPLES (N=20). ON AN UNPRECEDENTED SCALE, WE REVEALED 2239 DIFFERENTIALLY METHYLATED CPG SITES BETWEEN IGHV-MUTATED AND UNMUTATED PATIENTS, WITH THE MAJORITY OF SITES POSITIONED OUTSIDE ANNOTATED CPG ISLANDS. INTRIGUINGLY, CLL PROGNOSTIC GENES (FOR EXAMPLE, CLLU1, LPL, ZAP70 AND NOTCH1), EPIGENETIC REGULATOR (FOR EXAMPLE, HDAC9, HDAC4 AND DNMT3B), B-CELL SIGNALING (FOR EXAMPLE, IBTK) AND NUMEROUS TGF-BETA AND NF-KAPPAB/TNF PATHWAY GENES WERE ALTERNATIVELY METHYLATED BETWEEN SUBGROUPS. CONTRARY, DNA METHYLATION OVER TIME WAS DEEMED RATHER STABLE WITH FEW RECURRENT CHANGES NOTED WITHIN SUBGROUPS. ALTHOUGH A LARGER NUMBER OF NON-RECURRENT CHANGES WERE IDENTIFIED AMONG IGHV-UNMUTATED RELATIVE TO MUTATED CASES OVER TIME, THESE EQUATED TO A LOW GLOBAL CHANGE. SIMILARLY, FEW CHANGES WERE IDENTIFIED BETWEEN COMPARTMENT CASES. ALTOGETHER, WE REVEAL CLL SUBGROUPS TO DISPLAY UNIQUE METHYLATION PROFILES AND UNVEIL METHYLATION AS RELATIVELY STABLE OVER TIME AND SIMILAR WITHIN DIFFERENT CLL COMPARTMENTS, IMPLYING ABERRANT METHYLATION AS AN EARLY LEUKEMOGENIC EVENT. 2013 12 18 31 5-AZACYTIDINE MODULATES CPG METHYLATION LEVELS OF EZH2 AND NOTCH1 IN MYELODYSPLASTIC SYNDROMES. PURPOSE: MOLECULAR MECHANISMS OF RESPONSE TO HYPOMETHYLATING AGENTS IN PATIENTS WITH MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) STILL REMAIN LARGELY UNKNOWN. THEREFORE, THE EFFECTS OF 5-AZACYTIDINE (AZA) ON CLONAL ARCHITECTURE AND DNA METHYLATION WERE INVESTIGATED IN THIS STUDY. METHODS: USING NEXT-GENERATION SEQUENCING (NGS), 30 MYELOID LEUKEMIA-ASSOCIATED GENES WERE ANALYZED IN 15 MDS/CMML PATIENTS WITH EXCELLENT RESPONSE TO AZA. EFFECTS ON METHYLATION LEVELS WERE ANALYZED BY QUANTITATIVE METHYLATION ANALYSIS USING PYROSEQUENCING FOR THE GLOBAL METHYLATION MARKER LINE-1 IN PATIENTS AND MYELOID CELL LINES. VARIOUS MYELOID CELL LINES AND A HEALTHY COHORT WERE SCREENED FOR METHYLATION LEVELS IN 23 GENES. SELECTED TARGETS WERE VERIFIED ON THE MDS/CMML COHORT. RESULTS: THE STUDY PRESENTED HERE SHOWED A STABLE VARIANT ALLELE FREQUENCY AND STABLE GLOBAL METHYLATION LEVELS IN RESPONDING PATIENTS. A SIGNIFICANT DEMETHYLATION OF EZH2 AND NOTCH1 WAS REVEALED IN PATIENTS WITH AZA RESPONSE. CONCLUSIONS: A RESPONSE TO AZA IS NOT ASSOCIATED WITH ERADICATION OF MALIGNANT CLONES, BUT RATHER WITH A STABILIZATION OF THE CLONAL ARCHITECTURE. WE SUGGEST CHANGES IN CPG METHYLATION LEVELS OF EZH2 AND NOTCH1 AS POTENTIAL TARGETS OF EPIGENETIC RESPONSE TO AZA TREATMENT WHICH MAY ALSO SERVE AS USEFUL BIOMARKERS AFTER CLINICAL EVALUATION. 2019 13 1424 30 DIFFERENTIAL DNA METHYLATION OF GENE PROMOTERS IN SMALL B-CELL LYMPHOMAS. IMPROVED CARE OF PATIENTS WITH SMALL B-CELL LYMPHOMAS (SBCLS) IS LIKELY TO RESULT FROM THE ONGOING DISCOVERY OF MOLECULAR MARKERS THAT BETTER DEFINE THESE MALIGNANT NEOPLASMS. WE IDENTIFIED MULTIPLE GENE LOCI WHOSE DNA METHYLATION PATTERNS DIFFERED BETWEEN 3 TYPES OF SBCL: B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA, MANTLE CELL LYMPHOMA, AND GRADES I AND II FOLLICULAR LYMPHOMA. THIS ANALYSIS WAS PERFORMED USING AN OLIGONUCLEOTIDE MICROARRAY THAT ALLOWED DETERMINATION OF THE DNA METHYLATION STATUS OF 156 LOCI IN 38 GENES. COMBINED BISULFITE RESTRICTION ANALYSIS AND METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION WERE USED TO VALIDATE THE DIFFERENTIAL METHYLATION OF 6 OF THESE GENES. BY USING NON-HODGKIN LYMPHOMA CELL LINES AS MODELS, THESE GENES WERE EXAMINED FURTHER FOR METHYLATION AND GENE EXPRESSION RELATIONSHIPS. THIS STUDY ILLUSTRATES NONRANDOM EPIGENETIC ALTERATIONS IN SBCLS THAT SEEM TO PREFERENTIALLY INVOLVE LYMPHOMAS OF GERMINAL CENTER DERIVATION. 2005 14 59 39 A GENOME-WIDE SCREEN IDENTIFIES FREQUENTLY METHYLATED GENES IN HAEMATOLOGICAL AND EPITHELIAL CANCERS. BACKGROUND: GENETIC AS WELL AS EPIGENETIC ALTERATIONS ARE A HALLMARK OF BOTH EPITHELIAL AND HAEMATOLOGICAL MALIGNANCIES. HIGH THROUGHPUT SCREENS ARE REQUIRED TO IDENTIFY EPIGENETIC MARKERS THAT CAN BE USEFUL FOR DIAGNOSTIC AND PROGNOSTIC PURPOSES ACROSS MALIGNANCIES. RESULTS: HERE WE REPORT FOR THE FIRST TIME THE USE OF THE MIRA ASSAY (METHYLATED CPG ISLAND RECOVERY ASSAY) IN COMBINATION WITH GENOME-WIDE CPG ISLAND ARRAYS TO IDENTIFY EPIGENETIC MOLECULAR MARKERS IN CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA (ALL) ON A GENOME-WIDE SCALE. WE IDENTIFIED 30 GENES DEMONSTRATING METHYLATION FREQUENCIES OF > OR =25% IN CHILDHOOD ALL, NINE GENES SHOWED SIGNIFICANTLY DIFFERENT METHYLATION FREQUENCIES IN B VS T-ALL. FOR MAJORITY OF THE GENES EXPRESSION COULD BE RESTORED IN METHYLATED LEUKEMIA LINES AFTER TREATMENT WITH 5-AZADC. FORTY-FOUR PERCENT OF THE GENES REPRESENT TARGETS OF THE POLYCOMB COMPLEX. IN CHRONIC MYELOID LEUKEMIA (CML) TWO OF THE GENES, (TFAP2A AND EBF2), DEMONSTRATED INCREASED METHYLATION IN BLAST CRISIS COMPARED TO CHRONIC PHASE (P < 0.05). FURTHERMORE HYPERMETHYLATION OF AN AUTOPHAGY RELATED GENE ATG16L2 WAS ASSOCIATED WITH POORER PROGNOSIS IN TERMS OF MOLECULAR RESPONSE TO IMATINIB TREATMENT. LASTLY WE DEMONSTRATED THAT TEN OF THESE GENES WERE ALSO FREQUENTLY METHYLATED IN COMMON EPITHELIAL CANCERS. CONCLUSION: IN SUMMARY WE HAVE IDENTIFIED A LARGE NUMBER OF GENES SHOWING FREQUENT METHYLATION IN CHILDHOOD ALL, METHYLATION STATUS OF TWO OF THESE GENES IS ASSOCIATED WITH ADVANCED DISEASE IN CML AND METHYLATION STATUS OF ANOTHER GENE IS ASSOCIATED WITH PROGNOSIS. IN ADDITION A SUBSET OF THESE GENES MAY ACT AS EPIGENETIC MARKERS ACROSS HEMATOLOGICAL MALIGNANCIES AS WELL AS COMMON EPITHELIAL CANCERS. 2010 15 3444 39 HYPERMETHYLATION OF E-CADHERIN IN LEUKEMIA. E-CADHERIN GENE IS OFTEN TERMED A "METASTASIS SUPPRESSOR" GENE BECAUSE THE E-CADHERIN PROTEIN CAN SUPPRESS TUMOR CELL INVASION AND METASTASIS. INACTIVATION OF THE E-CADHERIN GENE OCCURS IN UNDIFFERENTIATED SOLID TUMORS BY BOTH GENETIC AND EPIGENETIC MECHANISMS; HOWEVER, THE ROLE OF E-CADHERIN IN HEMATOLOGIC MALIGNANCIES IS ONLY NOW BEING RECOGNIZED. E-CADHERIN EXPRESSION IS ESSENTIAL FOR ERYTHROBLAST AND NORMOBLAST MATURATION, YET EXPRESSION IS REDUCED OR ABSENT IN LEUKEMIC BLAST CELLS. THIS STUDY EXAMINED THE MESSENGER RNA (MRNA) AND PROTEIN EXPRESSION OF THE E-CADHERIN GENE IN BONE MARROW AND BLOOD SAMPLES FROM NORMAL DONORS AND PATIENTS WITH LEUKEMIA. WE FOUND THAT ALL NORMAL DONOR SAMPLES EXPRESSED E-CADHERIN MRNA, WHEREAS BOTH SAMPLES OF ACUTE MYELOGENOUS LEUKEMIA AND CHRONIC LYMPHOCYTIC LEUKEMIA HAD A SIGNIFICANT REDUCTION OR ABSENCE OF EXPRESSION. HOWEVER, NORMAL BLAST COUNTERPARTS EXPRESSED ONLY A LOW LEVEL OF E-CADHERIN SURFACE PROTEIN. SODIUM BISULPHITE GENOMIC SEQUENCING WAS USED TO FULLY CHARACTERIZE THE METHYLATION PATTERNS OF THE CPG ISLAND ASSOCIATED WITH THE E-CADHERIN GENE PROMOTER IN THOSE SAMPLES WITH MATCHED DNA. ALL OF THE NORMAL CONTROL SAMPLES WERE ESSENTIALLY UNMETHYLATED; HOWEVER, 14 OF 18 (78%) OF THE LEUKEMIA SAMPLES HAD ABNORMAL HYPERMETHYLATION OF THE E-CADHERIN CPG ISLAND. IN FACT BOTH ALLELES OF THE E-CADHERIN GENE WERE OFTEN HYPERMETHYLATED. WE CONCLUDE THE E-CADHERIN GENE IS A COMMON TARGET FOR HYPERMETHYLATION IN HEMATOLOGIC MALIGNANCIES. 2000 16 1581 28 DNA METHYLATION PROFILES IN CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS TREATED WITH CHEMOIMMUNOTHERAPY. BACKGROUND: IN ORDER TO GAIN INSIGHT INTO THE CONTRIBUTION OF DNA METHYLATION TO DISEASE PROGRESSION OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), USING 450K ILLUMINA ARRAYS, WE DETERMINED THE DNA METHYLATION PROFILES IN PAIRED PRE-TREATMENT/RELAPSE SAMPLES FROM 34 CLL PATIENTS TREATED WITH CHEMOIMMUNOTHERAPY, MOSTLY (N = 31) WITH THE FLUDARABINE-CYCLOPHOSPHAMIDE-RITUXIMAB (FCR) REGIMEN. RESULTS: THE EXTENT OF IDENTIFIED CHANGES IN CLL CELLS VERSUS MEMORY B CELLS FROM HEALTHY DONORS WAS TERMED "EPIGENETIC BURDEN" (EB) WHEREAS THE NUMBER OF CHANGES BETWEEN THE PRE-TREATMENT VERSUS THE RELAPSE SAMPLE WAS TERMED "RELAPSE CHANGES" (RC). SIGNIFICANT (P < 0.05) ASSOCIATIONS WERE IDENTIFIED BETWEEN (I) HIGH EB AND SHORT TIME-TO-FIRST-TREATMENT (TTFT); AND, (II) FEW RCS AND SHORT TIME-TO-RELAPSE. BOTH THE EB AND THE RC CLUSTERED IN SPECIFIC GENOMIC REGIONS AND CHROMATIN STATES, INCLUDING REGULATORY REGIONS CONTAINING BINDING SITES OF TRANSCRIPTION FACTORS IMPLICATED IN B CELL AND CLL BIOLOGY. CONCLUSIONS: OVERALL, WE SHOW THAT DNA METHYLATION IN CLL FOLLOWS DIFFERENT DYNAMICS IN RESPONSE TO CHEMOIMMUNOTHERAPY. THESE EPIGENETIC ALTERATIONS WERE LINKED WITH SPECIFIC CLINICAL AND BIOLOGICAL FEATURES. 2019 17 2090 28 EPIGENETIC DYSREGULATION OF THE WNT SIGNALLING PATHWAY IN CHRONIC LYMPHOCYTIC LEUKAEMIA. BACKGROUND: WNT SIGNALLING HAS RECENTLY BEEN IMPLICATED IN THE PATHOGENESIS OF CANCER. METHODS: THIS STUDY INVESTIGATED THE ACTIVITY OF WNT SIGNALLING IN PERIPHERAL BLOOD CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) LYMPHOCYTES, AND THE METHYLATION STATUS OF SEVEN SOLUBLE WNT ANTAGONIST GENES, INCLUDING WIF1, DKK3, APC, SFRP1, SFRP2, SFRP4 AND SFRP5, BY USING METHYLATION-SPECIFIC PCR IN THE PERIPHERAL BLOOD CLL LYMPHOCYTES AND BONE MARROW SAMPLES OF PATIENTS WITH CLL AT DIAGNOSIS. RESULTS: IN THE PERIPHERAL BLOOD CLL LYMPHOCYTES, CONSTITUTIVE ACTIVATION OF WNT SIGNALLING WAS DETECTED, ASSOCIATED WITH HYPERMETHYLATION OF THE SOLUBLE WNT INHIBITOR GENES. IN THE DIAGNOSTIC CLL MARROW SAMPLES, METHYLATION OF THE SEVEN GENES WAS DETECTED IN UP TO 36.4% OF SAMPLES. MOREOVER, 23 (52.3%) PATIENTS HAD METHYLATION OF AT LEAST ONE OF THE SEVEN GENES, OF WHOM 14 (60.8%) HAD METHYLATION OF TWO OR MORE WNT INHIBITOR GENES. APART FROM AN ASSOCIATION OF ADVANCED AGE WITH DKK3 METHYLATION, THERE WAS NO ASSOCIATION OF GENE HYPERMETHYLATION WITH EITHER CLINICAL CHARACTERISTICS (INCLUDING AGE, GENDER, LYMPHOCYTE COUNT AT DIAGNOSIS, RAI STAGE AND POOR-RISK KARYOTYPE) OR SURVIVAL. CONCLUSION: WNT SIGNALLING IS CONSTITUTIVELY ACTIVATED IN CLL B LYMPHOCYTES IN ASSOCIATION WITH METHYLATION OF MULTIPLE SOLUBLE WNT ANTAGONIST GENES. METHYLATION OF THESE SOLUBLE WNT ANTAGONIST GENES, OCCASIONALLY MULTIPLE GENES, IN PRIMARY CLL MARROW SAMPLES SUGGESTS AN IMPORTANT ROLE IN CLL PATHOGENESIS. MOREOVER, THIS STUDY UNDERSCORED THE IMPORTANCE OF STUDYING METHYLATION OF A PANEL OF, BUT NOT INDIVIDUAL, GENES REGULATING A CELLULAR PATHWAY. 2008 18 2966 30 GENETIC AND EPIGENETIC PROFILING OF CLL DISEASE PROGRESSION REVEALS LIMITED SOMATIC EVOLUTION AND SUGGESTS A RELATIONSHIP TO MEMORY-CELL DEVELOPMENT. WE EXAMINED GENETIC AND EPIGENETIC CHANGES THAT OCCUR DURING DISEASE PROGRESSION FROM INDOLENT TO AGGRESSIVE FORMS OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) USING SERIAL SAMPLES FROM 27 PATIENTS. ANALYSIS OF DNA MUTATIONS GROUPED THE LEUKEMIA CASES INTO THREE CATEGORIES: EVOLVING (26%), EXPANDING (26%) AND STATIC (47%). THUS, APPROXIMATELY THREE-QUARTERS OF THE CLL CASES HAD LITTLE TO NO GENETIC SUBCLONAL EVOLUTION. HOWEVER, WE IDENTIFIED SIGNIFICANT RECURRENT DNA METHYLATION CHANGES DURING PROGRESSION AT 4752 CPGS ENRICHED FOR REGIONS NEAR POLYCOMB 2 REPRESSIVE COMPLEX (PRC2) TARGETS. PROGRESSION-ASSOCIATED CPGS NEAR THE PRC2 TARGETS UNDERGO METHYLATION CHANGES IN THE SAME DIRECTION DURING DISEASE PROGRESSION AS DURING NORMAL DEVELOPMENT FROM NAIVE TO MEMORY B CELLS. OUR STUDY SHOWS THAT CLL PROGRESSION DOES NOT TYPICALLY OCCUR VIA SUBCLONAL EVOLUTION, BUT THAT CERTAIN CPG SITES UNDERGO RECURRENT METHYLATION CHANGES. OUR RESULTS SUGGEST CLL PROGRESSION MAY INVOLVE DEVELOPMENTAL PROCESSES SHARED IN COMMON WITH THE GENERATION OF NORMAL MEMORY B CELLS. 2015 19 3098 32 GENOMIC DISRUPTION OF THE HISTONE METHYLTRANSFERASE SETD2 IN CHRONIC LYMPHOCYTIC LEUKAEMIA. HISTONE METHYLTRANSFERASES (HMTS) ARE IMPORTANT EPIGENETIC REGULATORS OF GENE TRANSCRIPTION AND ARE DISRUPTED AT THE GENOMIC LEVEL IN A SPECTRUM OF HUMAN TUMOURS INCLUDING HAEMATOLOGICAL MALIGNANCIES. USING HIGH-RESOLUTION SINGLE NUCLEOTIDE POLYMORPHISM (SNP) ARRAYS, WE IDENTIFIED RECURRENT DELETIONS OF THE SETD2 LOCUS IN 3% (8/261) OF CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) PATIENTS. FURTHER VALIDATION IN TWO INDEPENDENT COHORTS SHOWED THAT SETD2 DELETIONS WERE ASSOCIATED WITH LOSS OF TP53, GENOMIC COMPLEXITY AND CHROMOTHRIPSIS. WITH NEXT-GENERATION SEQUENCING WE DETECTED MUTATIONS OF SETD2 IN AN ADDITIONAL 3.8% OF PATIENTS (23/602). IN MOST CASES, SETD2 DELETIONS OR MUTATIONS WERE OFTEN OBSERVED AS A CLONAL EVENT AND ALWAYS AS A MONO-ALLELIC LESION, LEADING TO REDUCED MRNA EXPRESSION IN SETD2-DISRUPTED CASES. PATIENTS WITH SETD2 ABNORMALITIES AND WILD-TYPE TP53 AND ATM FROM FIVE CLINICAL TRIALS EMPLOYING CHEMOTHERAPY OR CHEMO-IMMUNOTHERAPY HAD REDUCED PROGRESSION-FREE AND OVERALL SURVIVAL COMPARED WITH CASES WILD TYPE FOR ALL THREE GENES. CONSISTENT WITH ITS POSTULATED ROLE AS A TUMOUR SUPPRESSOR, OUR DATA HIGHLIGHT SETD2 ABERRATION AS A RECURRENT, EARLY LOSS-OF-FUNCTION EVENT IN CLL PATHOBIOLOGY LINKED TO AGGRESSIVE DISEASE. 2016 20 349 36 ALTERED DNA METHYLATION PROFILES IN SF3B1 MUTATED CLL PATIENTS. MUTATIONS IN SPLICING FACTOR GENES HAVE A SEVERE IMPACT ON THE SURVIVAL OF CANCER PATIENTS. SPLICING FACTOR 3B SUBUNIT 1 (SF3B1) IS ONE OF THE MOST FREQUENTLY MUTATED GENES IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL); PATIENTS CARRYING THESE MUTATIONS HAVE A POOR PROGNOSIS. SINCE THE SPLICING MACHINERY AND THE EPIGENOME ARE CLOSELY INTERCONNECTED, WE INVESTIGATED WHETHER THESE ALTERATIONS MAY AFFECT THE EPIGENOMES OF CLL PATIENTS. WHILE AN OVERALL HYPOMETHYLATION DURING CLL CARCINOGENESIS HAS BEEN OBSERVED, THE INTERPLAY BETWEEN THE EPIGENETIC STAGE OF THE ORIGINATING B CELLS AND SF3B1 MUTATIONS, AND THE SUBSEQUENT EFFECT OF THE MUTATIONS ON METHYLATION ALTERATIONS IN CLL, HAVE NOT BEEN INVESTIGATED. WE PROFILED THE GENOME-WIDE DNA METHYLATION PATTERNS OF 27 CLL PATIENTS WITH AND WITHOUT SF3B1 MUTATIONS AND IDENTIFIED LOCAL DECREASES IN METHYLATION LEVELS IN SF3B1(MUT) CLL PATIENTS AT 67 GENOMIC REGIONS, MOSTLY IN PROXIMITY TO TELOMERIC REGIONS. THESE DIFFERENTIALLY METHYLATED REGIONS (DMRS) WERE ENRICHED IN GENE BODIES OF CANCER-RELATED SIGNALING GENES, E.G., NOTCH1, HTRA3, AND BCL9L. IN OUR STUDY, SF3B1 MUTATIONS EXCLUSIVELY EMERGED IN TWO OUT OF THREE EPIGENETIC STAGES OF THE ORIGINATING B CELLS. HOWEVER, NOT ALL THE DMRS COULD BE ASSOCIATED WITH THE METHYLATION PROGRAMMING OF B CELLS DURING DEVELOPMENT, SUGGESTING THAT MUTATIONS IN SF3B1 CAUSE ADDITIONAL EPIGENETIC ABERRATIONS DURING CARCINOGENESIS. 2021