1 4364 123 MIRNA DEREGULATION BY EPIGENETIC SILENCING DISRUPTS SUPPRESSION OF THE ONCOGENE PLAG1 IN CHRONIC LYMPHOCYTIC LEUKEMIA. MICRORNAS (MIRNA) PLAY A KEY ROLE IN CELLULAR REGULATION AND, IF DEREGULATED, IN THE DEVELOPMENT OF NEOPLASTIC DISORDERS INCLUDING CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). RNAS FROM PRIMARY CELLS OF 50 TREATMENT-NAIVE CLL PATIENTS AND PERIPHERAL B CELLS OF 14 HEALTHY DONORS WERE APPLIED TO MIRNA EXPRESSION PROFILING USING BEAD CHIP TECHNOLOGY. IN CLL CELLS, A SET OF 7 UP- AND 19 DOWN-REGULATED MIRNAS WAS IDENTIFIED. AMONG THE MIRNAS DOWN-REGULATED IN CLL CELLS, 6 OF 10 MIRNA PROMOTERS EXAMINED SHOWED GAIN OF METHYLATION COMPARED WITH NORMAL B-CELL CONTROLS. SUBSEQUENT TARGET PREDICTION OF DEREGULATED MIRNAS REVEALED A HIGHLY SIGNIFICANT BINDING PREDICTION AT THE 3' UNTRANSLATED REGION OF THE PLEOMORPHIC ADENOMA GENE 1 (PLAG1) ONCOGENE. LUCIFERASE REPORTER ASSAYS INCLUDING SITE-DIRECTED MUTAGENESIS OF BINDING SITES REVEALED A SIGNIFICANT REGULATION OF PLAG1 BY MIR-181A, MIR-181B, MIR-107, AND MIR-424. ALTHOUGH EXPRESSION OF PLAG1 MRNA WAS NOT AFFECTED, PLAG1 PROTEIN EXPRESSION WAS SHOWN TO BE SIGNIFICANTLY ELEVATED IN CLL CELLS COMPARED WITH THE LEVELS IN HEALTHY DONOR B CELLS. IN SUMMARY, WE COULD DEMONSTRATE DISRUPTION OF MIRNA-MEDIATED TRANSLATIONAL CONTROL, PARTLY DUE TO EPIGENETIC TRANSCRIPTIONAL SILENCING OF MIRNAS, WITH SUBSEQUENT OVEREXPRESSION OF THE ONCOGENIC TRANSCRIPTION FACTOR PLAG1 AS A PUTATIVE NOVEL MECHANISM OF CLL PATHOGENESIS. 2009 2 1227 46 CRITICAL ROLE OF MICRORNAS IN CHRONIC LYMPHOCYTIC LEUKEMIA: OVEREXPRESSION OF THE ONCOGENE PLAG1 BY DEREGULATED MIRNAS. MICRORNAS (MIRNAS) ARE SMALL, GENE ENCODED RNAS WHICH ARE ABLE TO INFLUENCE GENE EXPRESSION IN BINDING TO THE 3'UTR OF MRNAS. COMPARED TO HEALTHY TISSUES, THE GLOBAL EXPRESSION OF MIRNAS IN CANCEROUS TISSUE IS FREQUENTLY DOWN-REGULATED. LIKEWISE IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), DOWN-REGULATION OF SEVERAL MIRNAS HAS BEEN REPORTED. ANALYSIS OF MIRNA PROMOTERS FOR EPIGENETIC MODIFICATIONS REVEALED A STRONGER METHYLATION OF DOWN-REGULATED MIRNAS IN CLL. TO DATE, SEVERAL TARGET GENES AFFECTED BY DEREGULATED MIRNAS HAVE BEEN IDENTIFIED THAT HAVE IMPACT ON CLL PATHOGENESIS. THE BEST-DESCRIBED CONSEQUENCE OF MIRNA DEREGULATION IS FOR MIRNA-15/16 CLUSTER DELETION, WHICH IS FREQUENTLY DOWN-REGULATED IN A SUBGROUP OF PATIENTS WITH CLL CARRYING 13Q14 DELETION. SO FAR, MODELS FOR MIRNA DEREGULATION HAVE ADDRESSED JUST SINGLE MIRNAS. FOR ASSESSMENT OF COMPLETE MIRNA DEREGULATION, FURTHER EVALUATION OF THE RESULTS FROM MICROARRAY STUDIES IS NEEDED. PREVIOUSLY WE IDENTIFIED THE ONCOGENE PLAG1, WHOSE EXPRESSION IS AFFECTED BY VARIOUS MIRNAS DEREGULATED IN CLL. THE INVOLVEMENT OF MIRNAS IN PLAG1 EXPRESSION WAS SHOWN TO BE RELEVANT IN PLEOMORPHIC ADENOMAS OF THE SALIVARY GLAND, TOO. AS PLAG1 IS HIGHLY OVEREXPRESSED, AND ITS TARGET GENES APPEAR TO BE DEREGULATED IN CLL, E.G. BCL-2, PLAG1 IS A PUTATIVE NEW RELEVANT ONCOGENE INVOLVED IN THE PATHOGENESIS OF CLL. 2010 3 6813 21 [EPILEPSY-ASSOCIATED TUMORS OF THE CENTRAL NERVOUS SYSTEM: EPILEPSY SURGERY AND ONCOLOGICAL ASPECTS]. BACKGROUND: AMONG THE TUMORS ASSOCIATED WITH CHRONIC EPILEPSY, DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR AND GANGLIOGLIOMA ARE THE MOST COMMON BESIDES ANGIOCENTRIC GLIOMA, PLEOMORPHIC XANTHOASTROCYTOMA AND PILOCYTIC ASTROCYTOMA. THESE TUMORS ARE USUALLY CONSIDERED AS BEING BENIGN. OBJECTIVE: TO DETERMINE THE BEST CONSERVATIVE AND SURGICAL TREATMENT OF TUMORS ASSOCIATED WITH EPILEPSY. MATERIAL AND METHODS: THIS ARTICLE PRESENTS CASE REPORTS OF MALIGNANT TRANSFORMATION OF A DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR AND OF A TUMOR INITIALLY DIAGNOSED AS A GANGLIOGLIOMA BASED ON MAGNETIC RESONANCE IMAGING (MRI) CRITERIA. DESCRIPTION OF REFERENCES IN THE LITERATURE ON EPILEPSY SURGERY AND THE NEURO-ONCOLOGY OF EPILEPSY-ASSOCIATED TUMORS. RESULTS: IN THE CASE OF THE INITIALLY HISTOPATHOLOGICALLY DIAGNOSED DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR, A MALIGNANT TRANSFORMATION OCCURRED 5 YEARS AFTER INCOMPLETE RESECTION. THE DIFFERENTIATION FROM A GLIOBLASTOMA WAS POSSIBLE THROUGH THE ANALYSIS OF THE METHYLATION PROFILE. IN ANOTHER CASE A TUMOR ASSUMED TO BE A GANGLIOGLIOMA SHOWED AN INCREASE IN SIZE AFTER 6 YEARS. INITIAL HISTOPATHOLOGICAL RESULTS REVEALED A GLIOBLASTOMA. THE ANALYSIS OF THE METHYLATION PROFILE SUGGESTED THE DIAGNOSIS OF AN ANAPLASTIC PLEOMORPHIC XANTHOASTROCYTOMA AND AS A DIFFERENTIAL DIAGNOSIS AN ANAPLASTIC GANGLIOGLIOMA. TUMOR PROGRESS CORRELATED WITH THE WORSENING OF SEIZURES. CONCLUSION: RECENT STUDIES HAVE SHOWN THAT IN THE TREATMENT OF PREDOMINANTLY BENIGN EPILEPSY-ASSOCIATED TUMORS NEURO-ONCOLOGICAL ASPECTS SHOULD ALSO BE TAKEN INTO ACCOUNT IN ADDITION TO THE EPILEPTOLOGICAL CONSIDERATIONS. IN THE CASE OF MALIGNANT TRANSFORMATION EPIGENETIC SCREENING (METHYLATION PROFILES) CAN HELP TO CLASSIFY THE TUMOR ENTITY MORE PRECISELY. 2016 4 6793 35 [DOWN-REGULATION OF TRANSCRIPTION FACTOR PU.1 VIA ABNORMAL EPIGENETIC MODIFICATION IN CHRONIC MYELOID LEUKEMIA]. OBJECTIVE: TO INVESTIGATE THE UNDERLYING MECHANISM AND CLINICAL SIGNIFICANCE OF PU.1 DOWN-EXPRESSION IN CHRONIC MYELOID LEUKEMIA (CML) PATIENTS. METHODS: DIFFERENT METHYLATION STATUS OF PU.1 PROMOTER REGION CONTAINING 20 CPG ISLANDS IN NORMAL INDIVIDUALS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, COMPLETE CYTOGENETIC REMISSION PATIENTS AFTER IMATINIB TREATMENT, AND BLAST CRISIS BONE MARROW K562 CML CELLS WAS DETECTED BY BISULFITE SEQUENCING. SEMI-QUANTITATIVE PCR WAS USED TO DETECT THE PU.1 MRNA EXPRESSION IN NORMAL CONTROLS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, AND BLAST CRISIS BONE MARROW K562 CML CELLS. INDIRECT IMMUNE FLUORESCENCE AND WESTERN BLOT WERE USED TO ANALYZE THE EXPRTESSION OF PU.1 PROTEIN IN NORMAL INDIVIDUALS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, AND BLAST CRISIS BONE MARROW K562 CML CELLS. RESULTS: ABERRANT METHYLATION IN THE PROMOTER REGION OF TRANSCRIPTION FACTOR PU.1 WAS FOUND IN BOTH CML CHRONIC PHASE AND BLAST CRISIS PHASE BONE MARROW CELLS, AS WELL AS IN CML BLAST K562 CELLS. DOWN-EXPRESSION OF PU.1 MRNA AND PROTEIN LEVELS WAS FOUND IN ABOVE CELLS. NO METHYLATION IN THE PROMOTER REGION OF PU.1 WAS OBSERVED IN NORMAL INDIVIDUALS, AND THE PU.1 MRNA AND PROTEIN EXPRESSIONS WERE NOT REDUCED AT ALL. FURTHERMORE, HIGH METHYLATION STATUS OF BONE MARROW CELLS WAS EVEN OBSERVED IN THE CML PATIENTS WHO ACQUIRED COMPLETE CYTOGENETIC REMISSION. CONCLUSIONS: THE RESULTS OF OUR STUDY INDICATE THAT THE EPIGENETIC MODIFICATION OF PU.1 IN CML PATIENTS AND K562 CELL LINE MIGHT BE RESPONSIBLE FOR THE DOWN-EXPRESSION OF PU.1. THE DATA SUGGEST THAT ABERRANT METHYLATION OF PU.1 PLAYS A ROLE IN CML PATHOGENESIS, THEREFORE, IT MIGHT SERVE AS A USEFUL BIOMARKER AND POTENTIAL TARGET IN THERAPY FOR CHRONIC MYELOID LEUKEMIA. 2012 5 2845 34 FREQUENT EPIGENETIC INACTIVATION OF THE SLIT2 GENE IN CHRONIC AND ACUTE LYMPHOCYTIC LEUKEMIA. RECENTLY A MOUSE MODEL OF T/NATURAL KILLER ACUTE LYMPHOBLASTIC LEUKEMIA WAS USED TO ASSESS GLOBAL PROMOTER METHYLATION ACROSS THE MOUSE GENOME USING THE RESTRICTION LANDMARK GENOMIC SCANNING TECHNIQUE. ONE OF THE METHYLATED MOUSE GENES IDENTIFIED IN THIS WAY WAS SLIT2. THERE ARE THREE MAMMALIAN SLIT GENES (SLIT1, SLIT2, SLIT3), THAT BELONG TO A HIGHLY CONSERVED FAMILY OF AXON GUIDANCE MOLECULES. WE HAVE PREVIOUSLY DEMONSTRATED THAT SLIT2 IS FREQUENTLY INACTIVATED IN LUNG, BREAST, COLORECTAL AND GLIOMA TUMORS BY HYPERMETHYLATION OF A CPG ISLAND IN ITS PROMOTER REGION, WHILST INACTIVATING SOMATIC MUTATIONS ARE RARE. FURTHERMORE, WE DEMONSTRATED THAT SLIT2 ACTS AS A TUMOR SUPPRESSOR GENE IN BREAST AND COLORECTAL CANCER CELLS. IN THIS REPORT WE DETERMINED THE METHYLATION STATUS OF THE SLIT2 GENE IN LEUKEMIAS (CLL AND ALL). SLIT2 WAS METHYLATED IN ALL TEN LEUKEMIA CELL LINES ANALYZED (EIGHT COMPLETELY AND TWO PARTIALLY METHYLATED). SLIT2 EXPRESSION WAS RESTORED AFTER TREATING ALL LINES WITH 5-AZA-2DC. IN PRIMARY ALL AND CLL SAMPLES, SLIT2 WAS ALSO FREQUENTLY METHYLATED, 58% (30/52) B-ALL; 83% (10/12) T-ALL AND IN 80% (24/30) CLL. WHILST DNA FROM PERIPHERAL BLOOD AND BONE MARROW FROM HEALTHY CONTROL SAMPLES SHOWED NO SLIT2 METHYLATION. METHYLATION RESULTS IN LEUKEMIA CELL LINES AND ALL AND CLL PRIMARY SAMPLES WERE CONFIRMED BY DIRECT SEQUENCING OF BISULFITE MODIFIED DNA. OUR RESULTS DEMONSTRATE THAT METHYLATION OF THE SLIT2 5' CPG ISLAND IS CONSERVED BETWEEN MICE AND HUMANS, AND THEREFORE IS LIKELY TO BE OF FUNCTIONAL IMPORTANCE. 2009 6 2133 27 EPIGENETIC INACTIVATION OF THE MIR-34A IN HEMATOLOGICAL MALIGNANCIES. MIR-34A IS A TRANSCRIPTIONAL TARGET OF P53 AND IMPLICATED IN CARCINOGENESIS. WE STUDIED THE ROLE OF MIR-34A METHYLATION IN A PANEL OF HEMATOLOGICAL MALIGNANCIES INCLUDING ACUTE LEUKEMIA [ACUTE MYELOID LEUKEMIA (AML) AND ACUTE LYMPHOBLASTIC LEUKEMIA (ALL)], CHRONIC LEUKEMIA [CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) AND CHRONIC MYELOID LEUKEMIA (CML)], MULTIPLE MYELOMA (MM) AND NON-HODGKIN'S LYMPHOMA (NHL). THE METHYLATION STATUS OF MIR-34A PROMOTER WAS STUDIED IN 12 CELL LINES AND 188 DIAGNOSTIC SAMPLES BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION. MIR-34A PROMOTER WAS UNMETHYLATED IN NORMAL CONTROLS BUT METHYLATED IN 75% LYMPHOMA AND 37% MYELOMA CELL LINES. HYPOMETHYLATING TREATMENT LED TO RE-EXPRESSION OF PRI-MIR-34A TRANSCRIPT IN LYMPHOMA CELLS WITH HOMOZYGOUS MIR-34A METHYLATION. IN PRIMARY SAMPLES AT DIAGNOSIS, MIR-34A METHYLATION WAS DETECTED IN 4% CLL, 5.5% MM SAMPLES AND 18.8% OF NHL AT DIAGNOSIS BUT NONE OF ALL, AML AND CML (P = 0.011). IN MM PATIENTS WITH PAIRED SAMPLES, MIR-34A METHYLATION STATUS REMAINED UNCHANGED AT PROGRESSION. AMONGST LYMPHOID MALIGNANCIES, MIR-34A WAS PREFERENTIALLY METHYLATED IN NHL (P = 0.018), IN PARTICULAR NATURAL KILLER (NK)/T-CELL LYMPHOMA. IN CONCLUSION, AMONGST HEMATOLOGICAL MALIGNANCIES, MIR-34A METHYLATION IS PREFERENTIALLY HYPERMETHYLATED IN NHL, IN PARTICULAR NK/T-CELL LYMPHOMA, IN A TUMOR-SPECIFIC MANNER, THEREFORE THE ROLE OF MIR-34A IN LYMPHOMAGENESIS WARRANTS FURTHER STUDY. 2010 7 4601 40 NDRG2 MRNA LEVELS AND MIR-28-5P AND MIR-650 ACTIVITY IN CHRONIC LYMPHOCYTIC LEUKEMIA. BACKGROUND: NDRG2 IS IDENTIFIED AS A TUMOR SUPPRESSOR GENE IN MANY TUMORS, AND FUNCTIONS IN CELL PROLIFERATION, DIFFERENTIATION AND APOPTOSIS. RECENT DATA INDICATE THAT NDRG2 EXPRESSION IS UP-REGULATED BY TP53. MOREOVER, PROPOSED MECHANISMS OF NDRG2 INACTIVATION INCLUDE EPIGENETIC SILENCING OF THE NDRG2 PROMOTER AND DOWN-REGULATION BY MICRORNAS (MIRNAS). HOWEVER, FEW STUDIES HAVE EVER BEEN DONE ON THE ROLE OF NDRG2 AND THE NDRG2-REGULATING MIRNAS INTERFERENCE IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). METHODS: NDRG2 AND MICRORNAS MRNA LEVELS IN CLL SUBJECTS WERE ASSESSED BY QUANTITATIVE REAL-TIME POLYMERASE CHAIN REACTION (QRT-PCR). THE DUAL-LUCIFERASE REPORTER ASSAY WAS PERFORMED TO DETERMINE NDRG2-RELATED MIRNAS. LOW EXPRESSION OF MATURE EXOGENOUS MIRNAS IN CLL CELLS WAS ESTABLISHED BY TRANSIENT TRANSFECTION. NDRG2 PROTEIN LEVELS IN CLL CELLS WERE DETECTED BY WESTERN BLOT. IN ADDITION, FLOW CYTOMETRY WAS CONDUCTED TO EXAMINE THE APOPTOSIS OF CLL CELLS. RESULTS: LOWER EXPRESSION OF NDRG2 WAS FOUND IN THE B-CELLS FROM 102 CLL PATIENTS COMPARED THE 40 NORMAL SUBJECTS (P < 0.001). PATIENTS WITH ADVANCED BINET STAGE (P = 0.001), HIGH LACTATE DEHYDROGENASE (LDH) LEVEL (P = 0.036), UN-MUTATED IMMUNOGLOBULIN HEAVY CHAIN VARIABLE REGION GENE (IGHV) (P = 0.004) AND THOSE WITH P53 ABERRATIONS (P < 0.001) HAD A MARKEDLY LOWER LEVELS OF NDRG2 MRNA. THIS DECREASE WAS ASSOCIATED WITH BRIEFER TIME-TO-TREATMENT (P = 0.001) AND POORER SURVIVAL (P < 0.001). HIGH EXPRESSION OF MIR-28-5P AND MIR-650 WAS ASSOCIATED WITH BINET B/C STAGE (P = 0.044) AND IGHV UN-MUTATED (P = 0.011), AS WELL AS BINET B/C STAGE (P = 0.013) AND P53 ABERRATIONS (P = 0.037), RESPECTIVELY. INHIBITION OF MIR-28-5P OR MIR-650 COULD INDUCE MORE APOPTOSIS IN CLL CELLS WITH GERMLINE TP53. CONCLUSIONS: NDRG2 MRNA LEVELS MIGHT BE A USEFUL PROGNOSTIC VARIABLE FOR PATIENTS OF CLL AND UP-REGULATING NDRG2 TRANSCRIPTION MAY BE A THERAPY APPROACH IN CLL WITHOUT P53 ABERRATIONS. 2018 8 6390 21 THE ROLE OF THE GENETIC ABNORMALITIES, EPIGENETIC AND MICRORNA IN THE PROGNOSIS OF CHRONIC LYMPHOCYTIC LEUKEMIA. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS INCREASED PROLIFERATION OF B-CELLS WITH PERIPHERAL BLOOD AND BONE MARROW INVOLVEMENT, WHICH IS USUALLY OBSERVED IN OLDER PEOPLE. GENETIC MUTATIONS, EPIGENETIC CHANGES AND MIRS PLAY A ROLE IN CLL PATHOGENESIS. DEL 11Q, DEL L17Q, DEL 6Q, TRISOMY 12, P53 AND IGVH MUTATIONS ARE THE MOST IMPORTANT GENETIC CHANGES IN CLL. DELETION OF MIR-15A AND MIR-16A CAN INCREASE BCL2 GENE EXPRESSION, MIR-29 AND MIR-181 DELETIONS DECREASE THE EXPRESSION OF TCL1, AND MIR-146A DELETION PREVENTS TUMOR METASTASIS. EPIGENETIC CHANGES SUCH AS HYPO- AND HYPERMETHYLATION, UBIQUITINATION, HYPO- AND HYPERACETYLATION OF GENE PROMOTERS INVOLVED IN CLL PATHOGENESIS CAN ALSO PLAY A ROLE IN CLL. EXPRESSION OF CD38 AND ZAP70, PRESENCE OR ABSENCE OF MUTATION IN IGVH AND P53 MUTATION ARE AMONG THE FACTORS INVOLVED IN CLL PROGNOSIS. USE OF MONOCLONAL ANTIBODIES AGAINST SURFACE MARKERS OF B-CELLS LIKE ANTI-CD20 AS WELL AS TYROSINE KINASE INHIBITORS ARE THE MOST IMPORTANT THERAPEUTIC APPROACHES FOR CLL. 2018 9 2132 28 EPIGENETIC INACTIVATION OF THE MIR-124-1 IN HAEMATOLOGICAL MALIGNANCIES. MIR-124-1 IS A TUMOUR SUPPRESSOR MICRORNA (MIR). EPIGENETIC DEREGULATION OF MIRS IS IMPLICATED IN CARCINOGENESIS. PROMOTER DNA METHYLATION AND HISTONE MODIFICATION OF MIR-124-1 WAS STUDIED IN 5 NORMAL MARROW CONTROLS, 4 LYMPHOMA, 8 MULTIPLE MYELOMA (MM) CELL LINES, 230 DIAGNOSTIC PRIMARY SAMPLES OF ACUTE MYELOID LEUKAEMIA (AML), ACUTE LYMPHOBLASTIC LEUKAEMIA (ALL), CHRONIC MYELOID LEUKAEMIA (CML), CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL), MM, AND NON-HODGKIN'S LYMPHOMA (NHL), AND 53 MM SAMPLES AT STABLE DISEASE OR RELAPSE. PROMOTER OF MIR-124-1 WAS UNMETHYLATED IN NORMAL CONTROLS BUT HOMOZYGOUSLY METHYLATED IN 4 OF 4 LYMPHOMA AND 4 OF 8 MYELOMA CELL LINES. TREATMENT OF 5-AZA-2'-DEOXYCYTIDINE LED TO MIR-124-1 DEMETHYLATION AND RE-EXPRESSION OF MATURE MIR-124, WHICH ALSO ASSOCIATED WITH EMERGENCE OF EUCHROMATIC TRIMETHYL H3K4 AND CONSEQUENT DOWNREGULATION OF CDK6 IN MYELOMA CELLS HARBORING HOMOZYGOUS MIR-124-1 METHYLATION. IN PRIMARY SAMPLES AT DIAGNOSIS, MIR-124-1 METHYLATION WAS ABSENT IN CML BUT DETECTED IN 2% EACH OF MM AT DIAGNOSIS AND RELAPSE/PROGRESSION, 5% ALL, 15% AML, 14% CLL AND 58.1% OF NHL (P<0.001). AMONGST LYMPHOID MALIGNANCIES, MIR-124-1 WAS PREFERENTIALLY METHYLATED IN NHL THAN MM, CLL OR ALL. IN PRIMARY LYMPHOMA SAMPLES, MIR-124-1 WAS PREFERENTIALLY HYPERMETHYLATED IN B- OR NK/T-CELL LYMPHOMAS AND ASSOCIATED WITH REDUCED MIR-124 EXPRESSION. IN CONCLUSION, MIR-124-1 WAS HYPERMETHYLATED IN A TUMOUR-SPECIFIC MANNER, WITH A HETEROCHROMATIC HISTONE CONFIGURATION. HYPOMETHYLATION LED TO PARTIAL RESTORATION OF EUCHROMATIC HISTONE CODE AND MIR RE-EXPRESSION. INFREQUENT MIR-124-1 METHYLATION DETECTED IN DIAGNOSTIC AND RELAPSE MM SAMPLES SHOWED AN UNIMPORTANT ROLE IN MM PATHOGENESIS, DESPITE FREQUENT METHYLATION FOUND IN CELL LINES. AMONGST HAEMATOLOGICAL CANCERS, MIR-124-1 WAS MORE FREQUENTLY HYPERMETHYLATED IN NHL, AND HENCE WARRANTS FURTHER STUDY. 2011 10 2131 35 EPIGENETIC INACTIVATION OF THE HSA-MIR-203 IN HAEMATOLOGICAL MALIGNANCIES. MIR-203 IS A TUMOUR SUPPRESSOR MICRORNA (MIRNA). WE STUDIED THE METHYLATION OF HSA-MIR-203 IN 150 SAMPLES INCLUDING ACUTE MYELOID LEUKAEMIA (AML), ACUTE LYMPHOBLASTIC LEUKAEMIA (ALL), CHRONIC MYELOID LEUKAEMIA (CML), CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) AND NON-HODGKIN'S LYMPHOMA (NHL) BY METHYLATION-SPECIFIC PCR, AND MIRNA EXPRESSION BY STEM-LOOP RT-QPCR. HSA-MIR-203 PROMOTER WAS UNMETHYLATED IN NORMAL CONTROLS BUT HOMOZYGOUSLY METHYLATED IN TWO AML AND FOUR LYMPHOMA CELL LINES, IN WHICH 5-AZA-2'-DEOXYCYTIDINE TREATMENT LED TO PROMOTER DEMETHYLATION AND MIR-203 RE-EXPRESSION. RESTORATION OF MIR-203 EXPRESSION IN LYMPHOMA CELLS INHIBITED CELLULAR PROLIFERATION AND INCREASED CELL DEATH, SUGGESTING AN INHERENT TUMOUR SUPPRESSOR ACTIVITY. IN PRIMARY SAMPLES, HSA-MIR-203 METHYLATION WAS ABSENT IN CML BUT DETECTED IN 5.0% ALL, 10.0% AML, 42.0% CLL AND 38.8% OF NHL (INCLUDING SIX [60.0%] NATURAL KILLER-CELL, NINE [40.9%] B-CELL AND FOUR [23.5%] T CELL NHL). MOREOVER, HSA-MIR-203 METHYLATION WAS ASSOCIATED WITH HYPERMETHYLATION OF HSA-MIR-34A, -124A AND -196B IN NHL BUT NOT CLL. IN CLL, HSA-MIR-203 METHYLATION WAS ASSOCIATED WITH A HIGHER PRESENTING HB LEVEL (P = 0.033). THE PROJECTED 10 YEAR OVERALL SURVIVAL OF THE CLL PATIENTS WAS 58.2%, WHICH WAS IMPACTED BY RAI STAGE AND HIGH-RISK KARYOTYPES BUT NOT HSA-MIR-203 METHYLATION. HSA-MIR-203 WAS MORE FREQUENTLY METHYLATED IN LYMPHOID THAN MYELOID MALIGNANCIES (P = 0.002). IN CONCLUSION, MIR-203, A TUMOUR SUPPRESSOR GENE, WAS HYPERMETHYLATED IN A TUMOUR-SPECIFIC MANNER WITH GENE SILENCING. HSA-MIR-203 WAS MORE FREQUENTLY HYPERMETHYLATED IN LYMPHOID THAN MYELOID MALIGNANCIES. IN NHL, HSA-MIR-203 METHYLATION WAS ASSOCIATED WITH CONCOMITANT METHYLATION OF OTHER TUMOUR SUPPRESSOR MIRNAS. THE FREQUENT HSA-MIR-203 METHYLATION IN LYMPHOID MALIGNANCIES SUGGESTED A PATHOGENETIC ROLE OF HSA-MIR-203 METHYLATION. 2011 11 2126 35 EPIGENETIC INACTIVATION OF MIR-34B/C IN ADDITION TO MIR-34A AND DAPK1 IN CHRONIC LYMPHOCYTIC LEUKEMIA. BACKGROUND: TP53 MUTATION/DELETION IS UNCOMMON IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). WE POSTULATED THAT COMPONENTS OF TP53-CENTERED TUMOR SUPPRESSOR NETWORK, MIR-34B/C, IN ADDITION TO DAPK1 AND MIR-34A MIGHT BE INACTIVATED BY DNA HYPERMETHYLATION. MOREOVER, WE TESTED IF MIR-34B/C METHYLATION MIGHT CORRELATE WITH MIR-203 OR MIR-124-1 METHYLATION IN CLL. METHODS: MIR-34B/C, MIR-34A AND DAPK1 METHYLATION WAS STUDIED IN 11 NORMAL CONTROLS, 7 CLL CELL LINES, AND 78 DIAGNOSTIC CLL SAMPLES BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION. MEC-1 CELLS WERE TREATED WITH 5-AZA-2'-DEOXYCYTIDINE FOR REVERSAL OF METHYLATION-ASSOCIATED MIRNA SILENCING. TUMOR SUPPRESSOR PROPERTIES OF MIR-34B WERE DEMONSTRATED BY OVER-EXPRESSION OF PRECURSOR MIR-34B IN MEC-1 CELLS. RESULTS: MIR-34B/C PROMOTER WAS UNMETHYLATED IN NORMAL CONTROLS, BUT COMPLETELY METHYLATED IN 4 CLL CELL LINES. MIR-34B/C EXPRESSION WAS INVERSELY CORRELATED WITH MIR-34B/C METHYLATION. DIFFERENT MSP STATUSES OF MIR-34B/C, INCLUDING COMPLETE METHYLATION AND COMPLETE UNMETHYLATION, WERE VERIFIED BY QUANTITATIVE BISULFITE PYROSEQUENCING. 5-AZA-2'-DEOXYCYTIDINE TREATMENT RESULTED IN PROMOTER DEMETHYLATION AND MIR-34B RE-EXPRESSION IN MEC1 CELLS. MOREOVER, OVER-EXPRESSION OF MIR-34B RESULTED IN INHIBITION OF CELLULAR PROLIFERATION AND INCREASED CELL DEATH. IN PRIMARY CLL SAMPLES, MIR-34A, MIR-34B/C AND DAPK1 METHYLATION WAS DETECTED IN 2.6%, 17.9% AND 34.6% OF PATIENTS AT DIAGNOSIS RESPECTIVELY. FURTHERMORE, 39.7%, 3.8% AND 2.6% PATIENTS HAD METHYLATION OF ONE, TWO OR ALL THREE GENES RESPECTIVELY. OVERALL, 46.2% PATIENTS HAD METHYLATION OF AT LEAST ONE OF THESE THREE GENES. BESIDES, MIR-34B/C METHYLATION WAS ASSOCIATED WITH METHYLATION OF MIR-34A (P = 0.03) AND MIR-203 (P = 0.012) IN CLL. CONCLUSIONS: TAKEN TOGETHER, MIR-34B/C IS A TUMOR SUPPRESSOR MIRNA FREQUENTLY METHYLATED, AND HENCE SILENCED IN CLL. TOGETHER WITH DAPK1 METHYLATION, MIR-34B/C METHYLATION IS IMPLICATED IN THE DISRUPTION OF THE TP53-CENTERED TUMOR SUPPRESSOR NETWORK. MOREOVER, THE ASSOCIATION OF MIRNA METHYLATION WARRANTS FURTHER STUDY. 2014 12 2438 42 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 13 5730 32 SLIT2 PROMOTER HYPERMETHYLATION PREDICTS DISEASE PROGRESSION IN CHRONIC MYELOID LEUKEMIA. BACKGROUND: ABERRANT DNA METHYLATION PLAYS A CRUCIAL ROLE IN THE PROGRESSION OF MYELOID NEOPLASMS. PREVIOUSLY, OUR LITERATURE REPORTED THAT SLIT GUIDANCE LIGAND 2 (SLIT2) PROMOTER METHYLATION WAS ASSOCIATED WITH DISEASE PROGRESSION AND INDICATED A POOR PROGNOSIS IN PATIENTS WITH MYELODYSPLASTIC SYNDROME. HEREIN, WE FURTHER INVESTIGATED THE CLINICAL IMPLICATIONS AND ROLE OF SLIT2 PROMOTER METHYLATION IN PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML). METHODS: THE LEVEL OF SLIT2 PROMOTER METHYLATION WAS DETERMINED IN 104 CML PATIENTS, AND ITS CLINICAL SIGNIFICANCE WAS ANALYZED. MOREOVER, DEMETHYLATION STUDIES WERE PERFORMED IN K562 CELLS TO DETERMINE THE EPIGENETIC MECHANISM BY WHICH SLIT2 PROMOTER METHYLATION IS REGULATED IN CML. RESULTS: THE LEVEL OF SLIT2 PROMOTER METHYLATION WAS SIMILAR BETWEEN CML PATIENTS AND CONTROLS. HOWEVER, DEEPER ANALYSIS REVEALED THAT THE SLIT2 PROMOTER METHYLATION LEVEL IN THE ACCELERATED PHASE (AP) AND BLAST CRISIS (BC) WAS MARKEDLY HIGHER THAN THAT IN THE CHRONIC PHASE (CP) AND CONTROLS. ADDITIONALLY, A MARKED DIFFERENCE WAS IDENTIFIED BETWEEN THE SLIT2 PROMOTER HYPERMETHYLATED AND NON-HYPERMETHYLATED GROUPS AMONG CML PATIENTS GROUPED BY CLINICAL STAGE. THE FREQUENCY OF SLIT2 HYPERMETHYLATION WAS MARKEDLY INCREASED WITH THE PROGRESSION OF CLINICAL STAGE, THAT IS, IT WAS THE LOWEST IN CP SAMPLES (12/80, 15%), HIGHER IN AP SAMPLES (4/8, 50%) AND THE HIGHEST IN BC SAMPLES (11/16, 69%). IMPORTANTLY, THE LEVEL/DENSITY OF SLIT2 PROMOTER METHYLATION WAS SIGNIFICANTLY HIGHER IN THE ADVANCED STAGE THAN IN THE EARLY STAGE AMONG THE 6 TESTED PAIRED CML PATIENTS. EPIGENETICALLY, THE EXPRESSION OF THE SLIT2-EMBEDDED NON-CODING GENES SLIT2-IT1 AND MIR-218 EXPRESSION WAS DECREASED IN PATIENTS WITH CML. SLIT2 PROMOTER HYPERMETHYLATED CASES HAD A MARKEDLY LOWER SLIT2-IT1 EXPRESSION LEVEL THAN SLIT2 PROMOTER NON-HYPERMETHYLATED CASES. MOREOVER, SLIT2-IT1 AND MIR-218 EXPRESSION WAS REMARKABLY UPREGULATED IN A DOSE-DEPENDENT MANNER AFTER DEMETHYLATION TREATMENT OF K562 CELLS. CONCLUSIONS: HYPERMETHYLATION OF THE SLIT2 PROMOTER IS CORRELATED WITH DISEASE PROGRESSION IN CML. FURTHERMORE, SLIT2 PROMOTER METHYLATION MAY FUNCTION BY REGULATING THE EXPRESSION OF THE SLIT2-EMBEDDED NON-CODING GENES SLIT2-IT1 AND MIR-218 DURING CML PROGRESSION. 2022 14 5274 18 PROMOTER METHYLATION OF P16 AND EDNRB GENE IN LEUKEMIA PATIENTS IN TAIWAN. BOTH EPIGENETIC AND GENETIC ALTERNATIONS ARE INVOLVED IN CANCER FORMATION. IN THIS STUDY, WE HAVE IDENTIFIED THE METHYLATION FREQUENCY OF P16 AND ENDOTHELIN RECEPTOR TYPE B (EDNRB) OF 26 LEUKEMIA PATIENTS AND 8 RANDOMLY SELECTED NORMAL BLOOD DONORS IN TAIWAN. PROMOTER METHYLATION OF P16 WAS DETECTED IN 85% OF ACUTE LYMPHOCYTIC LEUKEMIA (ALL), 83% IN ACUTE MYELOID LEUKEMIA (AML) WHEREAS NO METHYLATION WAS DETECTED IN CHRONIC MYELOID LEUKEMIA (CML) IN BLAST CRISIS. HYPERMETHYLATION OF EDNRB WAS OBSERVED IN 92% OF ALL, 75% AML AND 100% IN CML IN BLAST CRISIS. NO ABERRANT METHYLATION OF P16 AND EDNRB WAS FOUND IN 8 NORMAL BLOOD DONORS. TAKEN TOGETHER, ABERRANT METHYLATION OF P16 AND EDNRB WAS HIGHLY PREVALENT IN LEUKEMIA PATIENTS IN TAIWAN. 2008 15 3347 31 HISTONE DEACETYLASES MEDIATE THE SILENCING OF MIR-15A, MIR-16, AND MIR-29B IN CHRONIC LYMPHOCYTIC LEUKEMIA. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) DEMONSTRATES A GLOBAL DOWN-REGULATION OF MIR-15A AND MIR-16 AND A SELECTIVE SILENCING OF THE RELATED MIR-29B IN AGGRESSIVE DISEASE. DELETIONS IN CHROMOSOME 13 [DEL(13Q14)] PARTIALLY ACCOUNT FOR THE LOSS OF EXPRESSION OF MIR-15A AND MIR-16, BUT THE MECHANISMS BY WHICH MIR-29B BECOMES SILENCED IS UNKNOWN. IN THE PRESENT STUDY, WE SHOW THAT THE HISTONE DEACETYLASES (HDACS) ARE OVEREXPRESSED IN CLL AND MEDIATE THE EPIGENETIC SILENCING OF MIR-15A, MIR-16, AND MIR-29B. HDAC INHIBITION TRIGGERED THE ACCUMULATION OF THE TRANSCRIPTIONALLY ACTIVATING CHROMATIN MODIFICATION H3K4ME2 AND RESTORED THE EXPRESSION OF MIR-15A, MIR-16, AND MIR-29B IN APPROXIMATELY 35% OF SAMPLES. ECTOPIC EXPRESSION OF MIR-15A AND MIR-16 AND HDAC INHIBITION-INDUCED EXPRESSION OF MIR-15A, MIR-16, OR MIR-29B IN PRIMARY CLL CELLS WAS ASSOCIATED WITH DECLINES IN THE LEVELS OF MCL-1, BUT NOT BCL-2, MITOCHONDRIAL DYSFUNCTION, AND INDUCTION OF CELL DEATH. THEREFORE, OUR RESULTS SHOW THAT HDACS ABERRANTLY SILENCE THE EXPRESSION OF THE CRITICAL TUMOR SUPPRESSORS MIR-15A, MIR-16, AND MIR-29B IN CLL. DEACETYLASE INHIBITION MAY BE A THERAPEUTIC STRATEGY THAT RESTORES THE EXPRESSION OF THESE MIRS TO ANTAGONIZE MCL-1, AN IMPORTANT SURVIVAL PROTEIN IN THESE CELLS. CONSEQUENTLY, CLL PATIENTS WHO EXHIBIT SUCH EPIGENETIC SILENCING MAY BENEFIT FROM HDAC INHIBITOR-BASED THERAPY. 2012 16 4361 39 MIR-96 ACTS AS A TUMOR SUPPRESSOR VIA TARGETING THE BCR-ABL1 ONCOGENE IN CHRONIC MYELOID LEUKEMIA BLASTIC TRANSFORMATION. MICRORNA-MEDIATED POSTTRANSCRIPTIONAL REGULATION IS AN IMPORTANT EPIGENETIC REGULATORY MECHANISM OF GENE EXPRESSION, AND ITS DYSREGULATION IS INVOLVED IN THE DEVELOPMENT AND PROGRESSION OF A VARIETY OF MALIGNANCIES, INCLUDING CHRONIC MYELOID LEUKEMIA (CML). THE BCR-ABL1 FUSION GENE IS NOT ONLY THE INITIATING FACTOR OF CML, BUT IT IS ALSO AN IMPORTANT DRIVING FACTOR FOR BLASTIC TRANSFORMATION. TYROSINE KINASE INHIBITORS (TKIS) TARGETING BCR-ABL1 TYROSINE KINASE ACTIVITY, REPRESENTED BY IMATINIB, ARE CURRENTLY THE FIRST-LINE TREATMENT FOR CML. HOWEVER, DUE TO PRIMARY RESISTANCE OR SECONDARY RESISTANCE CAUSED BY MUTATIONS IN THE BCR-ABL1 KINASE DOMAIN, TKIS CANNOT COMPLETELY PREVENT THE PROGRESSION OF CML; THUS, THE STUDY OF BCR-ABL1 GENE EXPRESSION REGULATION IS OF GREAT SIGNIFICANCE. IN THIS STUDY, BIOINFORMATICS ANALYSIS AND OUR RESULTS SHOWED THAT MIR-96 COULD DIRECTLY BIND TO THE 3'UTR REGION OF BCR-ABL1 TO REGULATE FUSION PROTEIN EXPRESSION, THEREBY REGULATING ITS DOWNSTREAM SIGNALING PATHWAY ACTIVITY. WE ALSO FOUND THAT MIR-96 WAS DOWNREGULATED DURING THE PROGRESSION FROM THE CHRONIC PHASE (CML-CP) TO THE BLAST CRISIS (CML-BC). DOWNREGULATION OF MIR-96 COULD PROMOTE THE PROLIFERATION AND PARTICIPATE IN THE CELL DIFFERENTIATION OF CML-BC CELLS. ADDITIONALLY, WE FOUND THAT THE NOVEL HISTONE DEACETYLASE DRUG CHIDAMIDE AND THE DNA METHYLTRANSFERASE INHIBITOR DECITABINE COULD RESTORE THE LOW EXPRESSION OF MIR-96 IN CML CELLS, AND THERE WERE TWO ABNORMAL HYPERMETHYLATED SITES IN THE PROMOTER REGION OF MIR-96 IN CML, SUGGESTING THAT ITS LOW EXPRESSION MIGHT BE AT LEAST PARTIALLY REGULATED BY EPIGENETIC MECHANISMS. IN ADDITION, RE-EXPRESSION OF MIR-96 COULD INCREASE THE SENSITIVITY OF CML-BC CELLS TO IMATINIB. THUS, MIR-96 FUNCTIONS AS A TUMOR SUPPRESSOR, AND RE-EXPRESSION OF THIS MICRORNA MIGHT HAVE THERAPEUTIC BENEFITS IN CML BLASTIC TRANSFORMATION. 2019 17 6238 37 THE MALIGNANCY SUPPRESSION ROLE OF MIR-23A BY TARGETING THE BCR/ABL ONCOGENE IN CHROMIC MYELOID LEUKEMIA. THE AIM OF THIS STUDY WAS TO INVESTIGATE THE ROLE AND MECHANISM OF MIR-23A IN THE REGULATION OF BCR/ABL AND TO PROVIDE A NEW PROGNOSTIC BIOMARKER FOR CHRONIC MYELOID LEUKEMIA (CML). THE EXPRESSION LEVELS OF MIR-23A AND BCR/ABL WERE ASSESSED IN 42 NEWLY DIAGNOSED CML PATIENTS, 37 CML PATIENTS IN FIRST COMPLETE REMISSION AND 25 HEALTHY CONTROLS. QUANTITATIVE REAL-TIME PCR, WESTERN BLOT ANALYSIS AND COLONY FORMATION ASSAY WERE USED TO EVALUATE CHANGES INDUCED BY OVEREXPRESSION OR INHIBITION OF MIR-23A OR BCR/ABL. MIR-23A MIMIC OR NEGATIVE CONTROL MIMIC WAS TRANSFECTED INTO A CML CELL LINE (K562) AND TWO LUNG CANCER CELL LINES (H157 AND SKMES1) USING LIPOFECTAMINE 2000, AND THE CELLS WERE USED FOR REAL-TIME REVERSE TRANSCRIPTION-PCR (RT-PCR) AND WESTERN BLOT ANALYSIS. WE FOUND THAT THE DOWNREGULATION OF MIR-23A EXPRESSION WAS A FREQUENT EVENT IN BOTH LEUKEMIA CELL LINES AND PRIMARY LEUKEMIC CELLS FROM PATIENTS WITH DE NOVO CML. THE MICROARRAY RESULTS SHOWED THAT MOST OF THE CML PATIENTS EXPRESSED HIGH LEVELS OF BCR/ABL AND LOW LEVELS OF MIR-23A. REAL-TIME RT-PCR AND WESTERN BLOT ANALYSIS SHOWED THAT THE BCR/ABL LEVELS IN MIR-23A-TRANSFECTED CELLS WERE LOWER THAN THOSE IN THE CONTROL GROUPS. ECTOPIC EXPRESSION OF MIR-23A IN K562 CELLS LED TO CELLULAR SENESCENCE. MOREOVER, WHEN K562 CELLS WERE TREATED WITH 5-AZA-2'-DEOXYCYTIDINE, A DNA METHYLATION INHIBITOR, BCR/ABL EXPRESSION WAS UPREGULATED, WHICH INDICATES EPIGENETIC SILENCING OF MIR-23A IN LEUKEMIC CELLS. BCR/ABL AND MIR-23A EXPRESSIONS WERE INVERSELY RELATED TO CML, AND BCR/ABL EXPRESSION WAS REGULATED BY MIR-23A IN LEUKEMIC CELLS. THE EPIGENETIC SILENCING OF MIR-23A LED TO DEREPRESSION OF BCR/ABL EXPRESSION, AND CONSEQUENTLY CONTRIBUTES TO CML DEVELOPMENT AND PROGRESSION. 2014 18 1211 39 CPG ISLAND METHYLATION AND EXPRESSION OF THE SECRETED FRIZZLED-RELATED PROTEIN GENE FAMILY IN CHRONIC LYMPHOCYTIC LEUKEMIA. B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS CHARACTERIZED BY A CLONAL ACCUMULATION OF MATURE NEOPLASTIC B CELLS INDICATING DISRUPTION OF APOPTOSIS. RESTRICTION LANDMARK GENOME SCANNING WAS DONE TO IDENTIFY NOVEL TARGET GENES SILENCED BY CPG ISLAND METHYLATION IN CLL. SECRETED FRIZZLED-RELATED PROTEIN 4 (SFRP4), A NEGATIVE REGULATOR OF THE WNT SIGNALING PATHWAY, WAS FOUND TO BE FREQUENTLY METHYLATED IN CLL SAMPLES. WNT SIGNALING HAS BEEN SHOWN TO CONTROL NORMAL APOPTOTIC BEHAVIOR AND IS REQUIRED FOR NORMAL B-CELL DEVELOPMENT WHEREAS ABERRANT ACTIVATION OF THIS PATHWAY HAS BEEN OBSERVED IN CLL. WE SHOW ABERRANT DNA METHYLATION AND SILENCING OF SFRP4, AS WELL AS OF ADDITIONAL SFRP FAMILY MEMBERS, IN PRIMARY CLL SAMPLES. INDUCTION OF THEIR EXPRESSION IN A DOSE-DEPENDENT MANNER FOLLOWING TREATMENT WITH A DEMETHYLATING AGENT, 5-AZA-2'-DEOXYCYTIDINE, WAS SHOWN. OF THE FIVE SFRP FAMILY MEMBERS STUDIED IN DETAIL, SFRP1 WAS HYPERMETHYLATED AND DOWN-REGULATED IN ALL CLL PATIENT SAMPLES STUDIED, SUGGESTING THAT THIS EPIGENETIC EVENT IS A CRITICAL STEP DURING LEUKEMOGENESIS. OUR RESULTS SUGGEST THAT SILENCING OF SFRPS BY CPG ISLAND METHYLATION IS ONE POSSIBLE MECHANISM CONTRIBUTING TO ABERRANT ACTIVATION OF WNT SIGNALING PATHWAY IN CLL. 2006 19 2081 34 EPIGENETIC DOWN-REGULATION OF BIM EXPRESSION IS ASSOCIATED WITH REDUCED OPTIMAL RESPONSES TO IMATINIB TREATMENT IN CHRONIC MYELOID LEUKAEMIA. BACKGROUND: EXPRESSION OF THE PRO-APOPTOTIC BCL-2-INTERACTING MEDIATOR (BIM) HAS RECENTLY BEEN IMPLICATED IN IMATINIB-INDUCED APOPTOSIS OF BCR-ABL1(+) CELLS. HOWEVER, THE MECHANISMS INVOLVED IN THE REGULATION OF BIM IN CML AND ITS ROLE IN THE CLINICAL SETTING HAVE NOT BEEN ESTABLISHED. DESIGN AND METHODS: WE ANALYSED THE MRNA EXPRESSION OF BIM IN 100 NEWLY DIAGNOSED PATIENTS WITH CML IN CHRONIC PHASE BY Q-RT-PCR AND THE PROTEIN LEVELS BY WESTERN BLOT ANALYSIS. METHYLATION STATUS WAS ANALYSED BY BISULPHITE GENOMIC SEQUENCING AND MSP. CML CELL LINES WERE TREATED WITH IMATINIB AND 5-AZA-2'-DEOXYCYTIDINE, AND WERE TRANSFECTED WITH TWO DIFFERENT SIRNAS AGAINST BIM AND CELL PROLIFERATION AND APOPTOSIS WERE ANALYSED. RESULTS: WE DEMONSTRATED THAT DOWN-REGULATION OF BIM EXPRESSION WAS PRESENT IN 36% OF THE PATIENTS AND WAS SIGNIFICANTLY ASSOCIATED WITH A LACK OF OPTIMAL RESPONSE TO IMATINIB AS INDICATED BY THE DECREASE IN CYTOGENETIC AND MOLECULAR RESPONSES AT 6, 12 AND 18 MONTHS IN COMPARISON WITH PATIENTS WITH NORMAL BIM EXPRESSION (P<0.05). EXPRESSION OF BIM WAS MEDIATED BY PROMOTER HYPERMETHYLATION AS DEMONSTRATED BY RESTORATION OF BIM EXPRESSION AFTER TREATMENT OF CML CELLS WITH 5-AZA-2'-DEOXYCYTIDINE. USING CML CELL LINES WITH LOW AND NORMAL EXPRESSION OF BIM WE FURTHER DEMONSTRATED THAT THE EXPRESSION OF BIM IS REQUIRED FOR IMATINIB-INDUCED CML APOPTOSIS. CONCLUSION: OUR DATA INDICATE THAT DOWN-REGULATION OF BIM IS EPIGENETICALLY CONTROLLED BY METHYLATION IN A PERCENTAGE OF CML PATIENTS AND HAS AN UNFAVOURABLE PROGNOSTIC IMPACT, AND THAT THE COMBINATION OF IMATINIB WITH A DE-METHYLATING AGENT MAY RESULT IN IMPROVED RESPONSES IN PATIENTS WITH DECREASED EXPRESSION OF BIM. 2009 20 2971 24 GENETIC AND EPIGENETIC SILENCING OF MICRORNA-203 ENHANCES ABL1 AND BCR-ABL1 ONCOGENE EXPRESSION. THE MAMMALIAN GENOME CONTAINS SEVERAL HUNDRED MICRORNAS THAT REGULATE GENE EXPRESSION THROUGH MODULATION OF TARGET MRNAS. HERE, WE REPORT A FRAGILE CHROMOSOMAL REGION LOST IN SPECIFIC HEMATOPOIETIC MALIGNANCIES. THIS 7 MB REGION ENCODES ABOUT 12% OF ALL GENOMIC MICRORNAS, INCLUDING MIR-203. THIS MICRORNA IS ADDITIONALLY HYPERMETHYLATED IN SEVERAL HEMATOPOIETIC TUMORS, INCLUDING CHRONIC MYELOGENOUS LEUKEMIAS AND SOME ACUTE LYMPHOBLASTIC LEUKEMIAS. A PUTATIVE MIR-203 TARGET, ABL1, IS SPECIFICALLY ACTIVATED IN THESE HEMATOPOIETIC MALIGNANCIES IN SOME CASES AS A BCR-ABL1 FUSION PROTEIN (PHILADELPHIA CHROMOSOME). RE-EXPRESSION OF MIR-203 REDUCES ABL1 AND BCR-ABL1 FUSION PROTEIN LEVELS AND INHIBITS TUMOR CELL PROLIFERATION IN AN ABL1-DEPENDENT MANNER. THUS, MIR-203 FUNCTIONS AS A TUMOR SUPPRESSOR, AND RE-EXPRESSION OF THIS MICRORNA MIGHT HAVE THERAPEUTIC BENEFITS IN SPECIFIC HEMATOPOIETIC MALIGNANCIES. 2008