1 574 111 BCR/ABL INCREASES EZH2 LEVELS WHICH REGULATES XIAP EXPRESSION VIA MIRNA-219 IN CHRONIC MYELOID LEUKEMIA CELLS. IN THIS STUDY, WE SHOWED THAT THE LEVELS OF EZH2 IN BONE MARROW MONONUCLEAR CELLS (BMMNCS) ISOLATED FROM INDIVIDUALS WITH CHRONIC MYELOID LEUKEMIA (CML) (N=12) WERE SIGNIFICANTLY GREATER THAN THOSE IN BMMNCS ISOLATED FROM HEALTHY VOLUNTEERS (N=6) AS WELL AS INDIVIDUALS WITH PHILADELPHIA CHROMOSOME-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS. LENTIVIRAL TRANSDUCTION OF THE BCR/ABL GENE IN BA/F3 CELLS INCREASED EZH2 LEVELS IN PARALLEL WITH PHOSPHORYLATION OF STAT5. NOTABLY, CHROMATIN IMMUNOPRECIPITATION ASSAYS SHOWED THAT STAT5A BOUND TO A PROMOTER REGION OF THE EZH2 GENE, RESULTING IN AN INCREASE IN THE TRANSCRIPTIONAL ACTIVITY OF EZH2 IN LEUKEMIA CELLS. IMPORTANTLY, DOWNREGULATION OF EZH2 BY SHORT HAIRPIN RNAS (SHRNAS) INHIBITED THE EXPRESSION OF XIAP AND INCREASED THE MIR-219 LEVELS ASSOCIATED WITH A DECREASE IN HYPERMETHYLATION OF MIR-219-1 CPG ISLANDS. MOREOVER, OVEREXPRESSION OF MIR-219 DECREASED THE LEVELS OF XIAP IN CML CELLS. SINCE THE 3'-UNTRANSLATED REGION (3'-UTR) OF XIAP CONTAINS MIR219-5P-COMPLEMENTARY BINDING SITE, MIR-219 MIGHT MODULATE THE EXPRESSION OF XIAP THROUGH BINDING OF MIR-219 ON THE 3'-UTR OF XIAP. TAKEN TOGETHER, BCR/ABL POSITIVELY REGULATES THE EXPRESSION OF EZH2 VIA STAT5 SIGNALING. EZH2 MODULATES EPIGENETIC CHANGES AT DNA METHYLATED REGIONS ENCODING MIR-219 AND DOWNREGULATES THE LEVEL OF MIR-219, RESULTING IN UPREGULATION OF XIAP. 2016 2 3725 31 INHIBITION OF GLYCOGEN SYNTHASE KINASE-3 ACTIVITY LEADS TO EPIGENETIC SILENCING OF NUCLEAR FACTOR KAPPAB TARGET GENES AND INDUCTION OF APOPTOSIS IN CHRONIC LYMPHOCYTIC LEUKEMIA B CELLS. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS COMMONLY DEFINED AS A DISEASE OF FAILED APOPTOSIS OF B CELLS AND REMAINS AN INCURABLE DISEASE. THE MECHANISM OF RESISTANCE TO APOPTOSIS IN CLL IS COMPLEX AND INFLUENCED BY NUMEROUS FACTORS, INCLUDING NUCLEAR FACTOR KAPPAB (NFKAPPAB)-MEDIATED EXPRESSION OF ANTIAPOPTOTIC MOLECULES. RECENT EVIDENCE INDICATES THAT GLYCOGEN SYNTHASE KINASE-3BETA (GSK-3BETA) POSITIVELY REGULATES NFKAPPAB-MEDIATED GENE TRANSCRIPTION AND CELL SURVIVAL. USING MALIGNANT B CELLS COLLECTED FROM PATIENTS WITH CLL, WE FIND THAT BOTH GSK-3BETA AND NFKAPPAB ACCUMULATE IN THE NUCLEUS OF CLL B CELLS, AND PHARMACOLOGIC INHIBITION OF GSK-3 RESULTS IN DECREASED EXPRESSION OF TWO NFKAPPAB TARGET GENES BCL-2 AND XIAP AND A SUBSEQUENT INCREASE IN CLL B-CELL APOPTOSIS EX VIVO. FURTHERMORE, WE OBSERVED THAT INHIBITION OF GSK-3 LEADS TO A DECREASE IN NFKAPPAB-MEDIATED GENE TRANSCRIPTION BUT DOES NOT AFFECT THE NUCLEAR ACCUMULATION OF NFKAPPAB IN CLL B CELLS. LAST, USING CHROMATIN IMMUNOPRECIPITATION, WE SHOW THAT GSK-3 INHIBITION ABROGATES NFKAPPAB BINDING TO ITS TARGET GENE PROMOTERS (XIAP, BCL-2), IN PART THROUGH EPIGENETIC MODIFICATION OF HISTONES. OUR RESULTS ESTABLISH THAT INHIBITION OF GSK-3 ABROGATES NFKAPPAB BINDING TO ITS TARGET GENE PROMOTERS THROUGH AN EPIGENETIC MECHANISM, ENHANCES APOPTOSIS IN CLL B CELLS EX VIVO AND IDENTIFIES GSK-3 AS A POTENTIAL THERAPEUTIC TARGET IN THE TREATMENT OF CLL. 2007 3 3475 31 IDENTIFICATION OF A STAT5 TARGET GENE, DPF3, PROVIDES NOVEL INSIGHTS IN CHRONIC LYMPHOCYTIC LEUKEMIA. STAT5 CONTROLS ESSENTIAL CELLULAR FUNCTIONS AND IS ENCODED BY TWO GENES, STAT5A AND STAT5B. TO PROVIDE INSIGHT TO THE MECHANISMS LINKING HEMATOLOGIC MALIGNANCY TO STAT5 ACTIVATION/REGULATION OF TARGET GENES, WE IDENTIFIED STAT5 TARGET GENES AND FOCUSED ON DPF3 GENE, WHICH ENCODES FOR AN EPIGENETIC FACTOR. DPF3 EXPRESSION WAS INDUCED UPON IL-3 STIMULATION IN BA/F3 CELLS, WHILE STRONG BINDING OF BOTH STAT5A AND STAT5B WAS DETECTED IN ITS PROMOTER. REDUCED EXPRESSION OF DPF3 WAS DETECTED IN BA/F3 CELLS WITH STAT5A AND STAT5B KNOCK-DOWN, SUGGESTING THAT THIS GENE IS POSITIVELY REGULATED BY STAT5, UPON IL-3 STIMULATION. FURTHERMORE, THIS GENE WAS SIGNIFICANTLY UP-REGULATED IN CLL PATIENTS, WHERE DPF3 GENE/PROTEIN UP-REGULATION AND STRONG STAT5 BINDING TO THE DPF3 PROMOTER, CORRELATED WITH INCREASED STAT5 ACTIVATION, MAINLY IN NON-MALIGNANT MYELOID CELLS (GRANULOCYTES). OUR FINDINGS PROVIDE INSIGHTS IN THE STAT5 DEPENDENT TRANSCRIPTIONAL REGULATION OF DPF3, AND DEMONSTRATE FOR THE FIRST TIME INCREASED STAT5 ACTIVATION IN GRANULOCYTES OF CLL PATIENTS. NOVEL ROUTES OF INVESTIGATION ARE OPENED TO FACILITATE THE UNDERSTANDING OF THE ROLE OF STAT5 ACTIVATION IN THE COMMUNICATION BETWEEN NON-MALIGNANT MYELOID AND MALIGNANT B-CELLS, AND THE FUNCTIONS OF STAT5 TARGET GENES NETWORKS IN CLL BIOLOGY. 2013 4 5940 27 TARGETING METHYLTRANSFERASE PRMT5 ELIMINATES LEUKEMIA STEM CELLS IN CHRONIC MYELOGENOUS LEUKEMIA. IMATINIB-INSENSITIVE LEUKEMIA STEM CELLS (LSCS) ARE BELIEVED TO BE RESPONSIBLE FOR RESISTANCE TO BCR-ABL TYROSINE KINASE INHIBITORS AND RELAPSE OF CHRONIC MYELOGENOUS LEUKEMIA (CML). IDENTIFYING THERAPEUTIC TARGETS TO ERADICATE CML LSCS MAY BE A STRATEGY TO CURE CML. IN THE PRESENT STUDY, WE DISCOVERED A POSITIVE FEEDBACK LOOP BETWEEN BCR-ABL AND PROTEIN ARGININE METHYLTRANSFERASE 5 (PRMT5) IN CML CELLS. OVEREXPRESSION OF PRMT5 WAS OBSERVED IN HUMAN CML LSCS. SILENCING PRMT5 WITH SHRNA OR BLOCKING PRMT5 METHYLTRANSFERASE ACTIVITY WITH THE SMALL-MOLECULE INHIBITOR PJ-68 REDUCED SURVIVAL, SERIAL REPLATING CAPACITY, AND LONG-TERM CULTURE-INITIATING CELLS (LTC-ICS) IN LSCS FROM CML PATIENTS. FURTHER, PRMT5 KNOCKDOWN OR PJ-68 TREATMENT DRAMATICALLY PROLONGED SURVIVAL IN A MURINE MODEL OF RETROVIRAL BCR-ABL-DRIVEN CML AND IMPAIRED THE IN VIVO SELF-RENEWAL CAPACITY OF TRANSPLANTED CML LSCS. PJ-68 ALSO INHIBITED LONG-TERM ENGRAFTMENT OF HUMAN CML CD34+ CELLS IN IMMUNODEFICIENT MICE. MOREOVER, INHIBITION OF PRMT5 ABROGATED THE WNT/BETA-CATENIN PATHWAY IN CML CD34+ CELLS BY DEPLETING DISHEVELLED HOMOLOG 3 (DVL3). THIS STUDY SUGGESTS THAT EPIGENETIC METHYLATION MODIFICATION ON HISTONE PROTEIN ARGININE RESIDUES IS A REGULATORY MECHANISM TO CONTROL SELF-RENEWAL OF LSCS AND INDICATES THAT PRMT5 MAY REPRESENT A POTENTIAL THERAPEUTIC TARGET AGAINST LSCS. 2016 5 5229 26 PRO-APOPTOTIC TP53 HOMOLOG TAP63 IS REPRESSED VIA EPIGENETIC SILENCING AND B-CELL RECEPTOR SIGNALLING IN CHRONIC LYMPHOCYTIC LEUKAEMIA. CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) IS AN ACCUMULATIVE DISORDER MARKED BY DEFICIENT APOPTOSIS. THE TP53 HOMOLOG TAP63 PROMOTES APOPTOSIS AND CHEMOSENSITIVITY IN SOLID TUMOURS AND ITS DEREGULATION MAY CONTRIBUTE TO CLL CELL SURVIVAL. WE FOUND THAT TAP63ALPHA WAS THE MOST PREVALENT TP63 ISOFORM IN CLL. COMPARED TO HEALTHY B CELLS, TAP63 MRNA WAS REPRESSED IN 55.7% OF CLL SAMPLES. TP63 PROMOTER METHYLATION WAS HIGH IN CLL AND INVERSELY CORRELATED WITH TP63 PROTEIN EXPRESSION IN B-CELL LYMPHOMA CELL LINES. SIRNA-MEDIATED KNOCKDOWN OF TP63 RESULTED IN PARTIAL PROTECTION FROM SPONTANEOUS APOPTOSIS ACCOMPANIED BY REDUCTIONS IN PMAIP1 (NOXA), BBC3 (PUMA), AND BAX MRNA IN CLL CELLS AND INCREASED PROLIFERATION OF RAJI LYMPHOMA CELLS. TAP63 MRNA LEVELS WERE HIGHER IN CLL WITH UNMUTATED IGHV. B-CELL RECEPTOR (BCR) ENGAGEMENT LED TO REPRESSION OF TP63 MRNA EXPRESSION IN MALIGNANT B CELLS, WHILE PHARMACOLOGICAL INHIBITION OF BCR SIGNALLING PREVENTED TP63 DOWNREGULATION. MIR21, KNOWN TO TARGET TAP63, CORRELATED INVERSELY WITH TAP63 EXPRESSION IN CLL, AND BCR-MEDIATED DOWNREGULATION OF TP63 WAS ACCOMPANIED BY MIR21 UPREGULATION IN MOST CLL SAMPLES. OUR DATA ILLUSTRATE THE PRO-APOPTOTIC FUNCTION OF TP63, PROVIDE INSIGHTS INTO THE MECHANISMS OF BCR-TARGETING AGENTS, AND ESTABLISH A RATIONALE FOR DESIGNING NOVEL APPROACHES TO INDUCE TP63 IN CLL AND B-CELL LYMPHOMA. 2013 6 2441 33 EPIGENETIC SILENCING OF TUMOR SUPPRESSOR MIR-3151 CONTRIBUTES TO CHINESE CHRONIC LYMPHOCYTIC LEUKEMIA BY CONSTITUTIVE ACTIVATION OF MADD/ERK AND PIK3R2/AKT SIGNALING PATHWAYS. WE HYPOTHESIZE THAT MIR-3151, LOCALIZED TO A GWAS-IDENTIFIED CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) RISK LOCUS (8Q22.3), IS A TUMOR SUPPRESSOR MIRNA SILENCED BY PROMOTER DNA METHYLATION IN CLL. THE PROMOTER OF MIR-3151 WAS METHYLATED IN 5/7 (71%) CLL CELL LINES, 30/98 (31%) DIAGNOSTIC PRIMARY SAMPLES, BUT NOT NORMAL CONTROLS. METHYLATION OF MIR-3151 CORRELATED INVERSELY WITH EXPRESSION. TREATMENT WITH 5-AZA-2'-DEOXYCYTIDINE LED TO PROMOTER DEMETHYLATION AND MIR-3151 RE-EXPRESSION. LUCIFERASE ASSAY CONFIRMED MAP-KINASE ACTIVATING DEATH DOMAIN (MADD) AND PHOSPHOINOSITIDE-3-KINASE, REGULATORY SUBUNIT 2 (PIK3R2) AS DIRECT TARGETS OF MIR-3151. MOREOVER, RESTORATION OF MIR-3151 RESULTED IN INHIBITION OF CELLULAR PROLIFERATION AND ENHANCED APOPTOSIS, REPRESSION OF MADD AND PIK3R2, DOWNREGULATION OF MEK/ERK AND PI3K/AKT SIGNALING, AND REPRESSION OF MCL1. LASTLY, MIR-3151 METHYLATION WAS SIGNIFICANTLY ASSOCIATED WITH METHYLATION OF MIR-203 AND MIR-34B/C IN PRIMARY CLL SAMPLES. THEREFORE, THIS STUDY SHOWED THAT MIR-3151 IS A TUMOR SUPPRESSIVE MIRNA FREQUENTLY HYPERMETHYLATED AND HENCE SILENCED IN CLL. MIR-3151 SILENCING BY DNA METHYLATION PROTECTED CLL CELLS FROM APOPTOSIS THROUGH OVER-EXPRESSION OF ITS DIRECT TARGETS MADD AND PIK3R2, HENCE CONSTITUTIVE ACTIVATION OF MEK/ERK AND PI3K/AKT SIGNALING RESPECTIVELY, AND CONSEQUENTLY OVER-EXPRESSION OF MCL1. 2015 7 10 30 14-3-3 LIGAND PREVENTS NUCLEAR IMPORT OF C-ABL PROTEIN IN CHRONIC MYELOID LEUKEMIA. HERE WE DEMONSTRATED THAT THE 'LOSS OF FUNCTION' OF NOT-REARRANGED C-ABL IN CHRONIC MYELOID LEUKEMIA (CML) IS PROMOTED BY ITS CYTOPLASMIC COMPARTMENTALIZATION BOUND TO 14-3-3 SIGMA SCAFFOLDING PROTEIN. IN PARTICULAR, CONSTITUTIVE TYROSINE KINASE (TK) ACTIVITY OF P210 BCR-ABL BLOCKS C-JUN N-TERMINAL KINASE (JNK) PHOSPHORYLATION LEADING TO 14-3-3 SIGMA PHOSPHORYLATION AT A CRITICAL RESIDUE (SER(186)) FOR C-ABL BINDING IN RESPONSE TO DNA DAMAGE. MOREOVER, IT IS ASSOCIATED WITH 14-3-3 SIGMA OVER-EXPRESSION ARISING FROM EPIGENETIC MECHANISMS (PROMOTER HYPER-ACETYLATION). ACCORDINGLY, P210 BCR-ABL TK INHIBITION BY THE TK INHIBITOR IMATINIB MESYLATE (IM) EVOKES MULTIPLE EVENTS, INCLUDING JNK PHOSPHORYLATION AT THR(183), P38 MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) PHOSPHORYLATION AT THR(180), C-ABL DE-PHOSPHORYLATION AT SER RESIDUES INVOLVED IN 14-3-3 BINDING AND REDUCTION OF 14-3-3 SIGMA EXPRESSION, THAT LET C-ABL RELEASE FROM 14-3-3 SIGMA AND NUCLEAR IMPORT, AND ADDRESS BCR-ABL-EXPRESSING CELLS TOWARDS APOPTOTIC DEATH. INFORMATIONAL SPECTRUM METHOD (ISM), A VIRTUAL SPECTROSCOPY METHOD FOR ANALYSIS OF PROTEIN INTERACTIONS BASED ON THEIR STRUCTURE, AND MATHEMATICAL FILTERING IN CROSS SPECTRUM (CS) ANALYSIS IDENTIFIED 14-3-3 SIGMA/C-ABL BINDING SITES. FURTHER INVESTIGATION ON CS PROFILES OF C-ABL- AND P210 BCR-ABL-CONTAINING COMPLEXES REVEALED THE MECHANISM LIKELY INVOLVED 14-3-3 PRECLUDED PHOSPHORYLATION IN CML CELLS. 2009 8 3982 46 LONG-TERM EXPOSURE OF LEUKEMIA CELLS TO MULTI-TARGETED TYROSINE KINASE INHIBITOR INDUCES ACTIVATIONS OF AKT, ERK AND STAT5 SIGNALING VIA EPIGENETIC SILENCING OF THE PTEN GENE. IMATINIB INDUCES COMPLETE MOLECULAR RESPONSE IN PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) AND CHRONIC EOSINOPHILIC LEUKEMIA (CEL). HOWEVER, DEVELOPMENT OF RESISTANCE TO IMATINIB HAS EMERGED AS AN IMPORTANT CLINICAL PROBLEM FOR MOLECULAR-TARGETED THERAPY IN CML AND CEL. IN THIS STUDY, WE HAVE ESTABLISHED THE IMATINIB-RESISTANT CEL EOL-1 SUB-LINES (DESIGNATED AS EOL-1R) BY CULTURING CELLS WITH INCREASING CONCENTRATIONS OF IMATINIB FOR 6 MONTHS. INTERESTINGLY, EOL-1R CELLS SHOWED EPIGENETIC SILENCING OF THE PHOSPHATASE AND TENSIN HOMOLOG DELETED ON CHROMOSOME TEN (PTEN) GENE. EXPOSURE OF EOL-1R CELLS TO IMATINIB FAILED TO DEPHOSPHORYLATE AKT, ERK AND STAT5, ALTHOUGH PDGFRALPHA WAS EFFECTIVELY INACTIVATED. THE FORCED EXPRESSION OF PTEN NEGATIVELY REGULATED THESE SIGNAL PATHWAYS AND SENSITIZED EOL-1R CELLS TO IMATINIB. NOTABLY, HYPERMETHYLATION OF THE PROMOTER REGION OF THE PTEN GENE IN ASSOCIATION WITH THE DOWNREGULATION OF THIS GENE'S TRANSCRIPTS WAS IDENTIFIED IN IMATINIB-RESISTANT LEUKEMIA CELLS ISOLATED FROM INDIVIDUALS WITH CEL, CML AND PHILADELPHIA-POSITIVE ACUTE LYMPHOBLASTIC LEUKEMIA. IN ADDITION, ANTI-EPIGENETIC AGENTS RESTORED PTEN EXPRESSION, RESULTING IN THE SENSITIZATION OF EOL-1R CELLS TO IMATINIB. TAKEN TOGETHER, EPIGENETIC SILENCE OF PTEN IS ONE OF THE MECHANISMS THAT CAUSE DRUG RESISTANCE IN INDIVIDUALS WITH LEUKEMIA AFTER EXPOSURE TO IMATINIB. ANTI-EPIGENETIC AGENTS MAY BE USEFUL FOR OVERCOMING DRUG RESISTANCE IN SUCH A CASE. 2010 9 2440 30 EPIGENETIC SILENCING OF TUMOR SUPPRESSOR LONG NON-CODING RNA BM742401 IN CHRONIC LYMPHOCYTIC LEUKEMIA. BM742401 IS A TUMOR SUPPRESSOR LNCRNA DOWNREGULATED IN GASTRIC CANCER. AS THE PROMOTER REGION AND THE ENTIRE TRANSCRIPT ARE EMBEDDED IN A CPG ISLAND, WE POSTULATED THAT BM742401 IS A TUMOR SUPPRESSOR LNCRNA INACTIVATED BY DNA METHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). THE PROMOTER OF BM742401 WAS UNMETHYLATED IN NORMAL CONTROLS INCLUDING THREE EACH OF NORMAL BONE MARROW, PERIPHERAL BLOOD BUFFY COATS, AND CD19-SORTED PERIPHERAL B-CELLS, BUT METHYLATED IN FOUR (57.1%) CLL CELL LINES. METHYLATION OF BM742401 CORRELATED INVERSELY WITH EXPRESSION. IN THE COMPLETELY METHYLATED WAC3CD5+ CLL CELLS, 5-AZA-2'-DEOXYCYTIDINE TREATMENT LED TO PROMOTER DEMETHYLATION AND RE-EXPRESSION OF BM742401 TRANSCRIPT. FUNCTIONALLY, STABLE OVEREXPRESSION OF BM742401 RESULTED IN INHIBITION OF CELLULAR PROLIFERATION AND ENHANCED APOPTOSIS THROUGH CASPASE-9-DEPENDENT INTRINSIC BUT NOT CASPASE-8-DEPENDENT EXTRINSIC APOPTOSIS PATHWAY, SUGGESTING A TUMOR SUPPRESSOR ROLE OF BM742401 IN CLL. IN PRIMARY CLL SAMPLES, METHYLATION OF BM742401 WAS DETECTED IN 43/98 (43.9%) OF PATIENTS. MOREOVER, AMONG CLL PATIENTS WITH STANDARD-RISK CYTOGENETIC ABERRATIONS, METHYLATION OF BM742401 CORRELATED WITH ADVANCED RAI STAGE (>/= STAGE 2)(P = 0.002). FURTHERMORE, BM742401 METHYLATION WAS ASSOCIATED WITH MIR-129-2 METHYLATION (P = 0.05). BM742401 IS A TUMOR SUPPRESSOR LNCRNA FREQUENTLY METHYLATED IN CLL. THE MECHANISM OF BM742401 AS A TUMOR SUPPRESSOR WARRANTS FURTHER STUDIES. 2016 10 1234 29 CRYPTOTANSHINONE SUPPRESSES KEY ONCO-PROLIFERATIVE AND DRUG-RESISTANT PATHWAYS OF CHRONIC MYELOID LEUKEMIA BY TARGETING STAT5 AND STAT3 PHOSPHORYLATION. C-MYC AND SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION (STAT) FAMILY PROTEINS HAVE BEEN PROPOSED TO BE IMPORTANT DOWNSTREAM GENES OF BCR-ABL, WHICH CHARACTERIZES MOST CASES OF CHRONIC MYELOID LEUKEMIA (CML). HERE, WE REPORT A C-MYC PATHWAY-TARGETED SCREENING OF SEVEN NATURAL ANTICANCER COMPOUNDS, IN WHICH WE IDENTIFIED CRYPTOTANSHINONE AS A HIGHLY PROMISING AGENT FOR CML THERAPY. CRYPTOTANSHINONE DEPLETES C-MYC IN CML BY REPRESSING THE PHOSPHORYLATION OF STAT5. DECREASED VIABILITY OF K562 CELLS CORRELATED WITH P-STAT5 SUPPRESSION. UNEXPECTEDLY, IMATINIB ACTIVATES RATHER THAN INHIBITS THE PHOSPHORYLATION OF STAT3 IN K562 CELLS. WE DEMONSTRATED THAT CRYPTOTANSHINONE, AS A DUAL INHIBITOR OF P-STAT5 AND P-STAT3, CAN EFFECTIVELY BLOCK IL-6-MEDIATED STAT3 ACTIVATION AND REVERSE BCR-ABL KINASE-INDEPENDENT DRUG RESISTANCE. MOREOVER, WE SHOWED THAT THE EPIGENETIC REBALANCE BETWEEN DECREASED BCR-ABL/STAT5/C-MYC AND ENHANCED STAT3/MULTI-DRUG RESISTANCE (MDR) PATHWAYS IS CHARACTERISTIC OF THE CANCER STEM CELL-LIKE PROPERTY OF K562/ADR. SIMULTANEOUSLY SUPPRESSING THESE TWO PATHWAYS USING CRYPTOTANSHINONE PROVES TO BE CRITICAL FOR THE MALIGNANT NETWORK REDRESS AND MDR REVERSAL OF K562/ADR. THESE STUDIES REVEAL THE DUAL FUNCTIONS OF CRYPTOTANSHINONE THAT SUPPRESS KEY ONCOGENIC PROLIFERATION AND DRUG-RESISTANT PATHWAYS IN CML CELLS BY TARGETING P-STAT5 AND P-STAT3, PROVIDING A NEW STRATEGY FOR CML THERAPY THAT TAKES ADVANTAGE OF NATURAL PRODUCTS. 2018 11 5319 34 PTEN IS FUNDAMENTAL FOR ELIMINATION OF LEUKEMIA STEM CELLS MEDIATED BY GSK126 TARGETING EZH2 IN CHRONIC MYELOGENOUS LEUKEMIA. PURPOSE: LEUKEMIA STEM CELLS (LSCS) ARE AN IMPORTANT SOURCE OF TYROSINE KINASE INHIBITOR RESISTANCE AND DISEASE RELAPSE IN PATIENTS WITH CHRONIC MYELOGENOUS LEUKEMIA (CML). TARGETING LSCS MAY BE AN ATTRACTIVE STRATEGY TO OVERRIDE THIS THORNY PROBLEM. GIVEN THAT EZH2 WAS OVEREXPRESSED IN PRIMARY CML CD34(+) CELLS, OUR PURPOSE IN THIS STUDY WAS TO EVALUATE THE EFFECTS OF TARGETING EZH2 ON CML LSCS AND CLARIFY ITS UNDERLYING MECHANISM.EXPERIMENTAL DESIGN: HUMAN PRIMARY CML CD34(+) CELLS AND RETROVIRALLY BCR-ABL-DRIVEN CML MOUSE MODELS WERE EMPLOYED TO EVALUATE THE EFFECTS OF SUPPRESSION OF EZH2 BY GSK126- OR EZH2-SPECIFIC SHRNA IN VITRO AND IN VIVO RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF TUMOR-SUPPRESSOR GENE PTEN IN CML CELLS WAS MEASURED BY CHROMATIN IMMUNOPRECIPITATION ASSAY.RESULTS: OUR RESULTS SHOWED THAT PHARMACOLOGIC INHIBITION OF EZH2 BY GSK126 NOT ONLY ELICITED APOPTOSIS AND RESTRICTED CELL GROWTH IN CML BULK LEUKEMIA CELLS, BUT ALSO DECREASED LSCS IN CML CD34(+) CELLS WHILE SPARING THOSE FROM NORMAL BONE MARROW CD34(+) CELLS. SUPPRESSION OF EZH2 BY GSK126 OR SPECIFIC SHRNA PROLONGED SURVIVAL OF CML MICE AND REDUCED THE NUMBER OF LSCS IN MICE. EZH2 KNOCKDOWN RESULTED IN ELEVATION OF PTEN AND LED TO IMPAIRED RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF PTEN GENE. THE EFFECT OF EZH2 KNOCKDOWN IN THE CML MICE WAS AT LEAST PARTIALLY REVERSED BY PTEN KNOCKDOWN.CONCLUSIONS: THESE FINDINGS IMPROVE THE UNDERSTANDING OF THE EPIGENETIC REGULATION OF STEMNESS IN CML LSCS AND WARRANT CLINICAL TRIAL OF GSK126 IN REFRACTORY PATIENTS WITH CML. CLIN CANCER RES; 24(1); 145-57. (C)2017 AACR. 2018 12 6028 28 THE BMI1 POLYCOMB PROTEIN REPRESSES CYCLIN G2-INDUCED AUTOPHAGY TO SUPPORT PROLIFERATION IN CHRONIC MYELOID LEUKEMIA CELLS. THE BMI1 POLYCOMB PROTEIN REGULATES SELF-RENEWAL, PROLIFERATION AND SURVIVAL OF CANCER-INITIATING CELLS ESSENTIALLY THROUGH EPIGENETIC REPRESSION OF THE CDKN2A TUMOR SUPPRESSOR LOCUS. WE DEMONSTRATE HERE FOR THE FIRST TIME THAT BMI1 ALSO PREVENTS AUTOPHAGY IN CHRONIC MYELOID LEUKEMIA (CML) CELL LINES, TO SUPPORT THEIR PROLIFERATION AND CLONOGENIC ACTIVITY. USING CHROMATIN IMMUNOPRECIPITATION, WE IDENTIFIED CCNG2/CYCLIN G2 (CCNG2) AS A DIRECT BMI1 TARGET. BMI1 DOWNREGULATION IN CD34+ CML CELLS BY PTC-209 PHARMACOLOGICAL TREATMENT OR SHBMI1 TRANSDUCTION TRIGGERED CCNG2 EXPRESSION AND DECREASED CLONOGENIC ACTIVITY. ALSO, ECTOPIC EXPRESSION OF CCNG2 IN CD34+ CML CELLS STRONGLY DECREASED THEIR CLONOGENICITY. CCNG2 WAS SHOWN TO ACT BY DISRUPTING THE PHOSPHATASE 2A COMPLEX, WHICH ACTIVATES A PKCZETA-AMPK-JNK-ERK PATHWAY THAT ENGAGES AUTOPHAGY. WE OBSERVED THAT BMI1 AND CCNG2 LEVELS EVOLVED INVERSELY DURING THE PROGRESSION OF CML TOWARDS AN ACUTE DEADLY PHASE, AND THEREFORE HYPOTHESIZED THAT BMI1 COULD SUPPORT ACUTE TRANSFORMATION OF CML THROUGH THE SILENCING OF A CCNG2-MEDIATED TUMOR-SUPPRESSIVE AUTOPHAGY RESPONSE. 2015 13 2887 29 GADD45A TRANSCRIPTIONAL INDUCTION ELICITED BY THE AURORA KINASE INHIBITOR MK-0457 IN BCR-ABL-EXPRESSING CELLS IS DRIVEN BY OCT-1 TRANSCRIPTION FACTOR. THE ADVANTAGE OF AURORA KINASE (AK) INHIBITORS IN CHRONIC MYELOID LEUKEMIA (CML) THERAPY MOSTLY ARISES FROM "OFF-TARGET" EFFECTS ON TYROSINE KINASE (TK) ACTIVITY OF WILD TYPE (WT) OR MUTATED BCR-ABL PROTEINS WHICH DRIVE THE DISEASE RESISTANCE TO IMATINIB (IM). WE PROVED THAT THE AK INHIBITOR MK-0457 INDUCES THE GROWTH ARREST DNA DAMAGE-INDUCIBLE (GADD) 45A THROUGH RECRUITMENT OF OCTAMER-BINDING (OCT)-1 TRANSCRIPTION FACTOR AT A CRITICAL PROMOTER REGION FOR GENE TRANSCRIPTION AND COVALENT MODIFICATIONS OF HISTONE H3 (LYSINE 14 ACETYLATION, LYSINE 9 DE-METHYLATION). SUCH EPIGENETIC CHROMATIN MODIFICATIONS MAY DEPICT A GENERAL MECHANISM PROMOTING THE RE-ACTIVATION OF TUMOR SUPPRESSOR GENES SILENCED BY BCR-ABL. 2012 14 6402 26 THE ROLES OF EPIGENETIC MODIFICATIONS OF PROAPOPTOTIC BID AND BIM GENES IN IMATINIB-RESISTANT CHRONIC MYELOID LEUKEMIA CELLS. IN CHRONIC MYELOID LEUKEMIA (CML), EPIGENETIC MODIFICATIONS SUCH AS PROMOTER HYPERMETHYLATION AND INACTIVE HISTONE MODIFICATION ARE KNOWN MECHANISMS OF DRUG RESISTANCE. IN OUR STUDY, WE INVESTIGATED THE ROLES OF PROMOTER HYPERMETHYLATION OF BIM AND BID GENES AND H3K27ME3 HISTONE MODIFICATION ON IMATINIB RESISTANCE. WE DETECTED HIGHER EXPRESSION LEVELS OF BIM AND BID GENES AND LOWER EXPRESSION LEVELS OF EZH2, EED2, SIRT1, AND SUZ12 GENES IN IMATINIB-RESISTANT K562/IMA-3 CELLS COMPARED TO IMATINIB-NON-RESISTANT K562 CELLS. WHILE WE DETERMINED THE EZH2 AND DNMT ENZYMES AS BOUNDED TO THE PROMOTER OF THE BIM GENE, WE DID NOT DETECT HYPERMETHYLATION OF THIS PROMOTER. WE ALSO FOUND THE H3K27ME3 HISTONE MODIFICATION PROMOTER OF BIM AND BID GENES IN BOTH CELL LINES. IN CONCLUSION, OUR RESULTS SUPPORT THE NOTION THAT DNA PROMOTER METHYLATION MAY BE FORMED INDEPENDENTLY FROM EZH2-H3K27ME3 AND PRO-APOPTOTIC BIM AND BID GENES ARE NOT METHYLLATED IN THE IMATINIB RESISTANCE OF CML CELLS. 2013 15 690 24 BRD4 DEGRADATION BLOCKS EXPRESSION OF MYC AND MULTIPLE FORMS OF STEM CELL RESISTANCE IN PH(+) CHRONIC MYELOID LEUKEMIA. IN MOST PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) CLONAL CELLS CAN BE KEPT UNDER CONTROL BY BCR::ABL1 TYROSINE KINASE INHIBITORS (TKI). HOWEVER, OVERT RESISTANCE OR INTOLERANCE AGAINST THESE TKI MAY OCCUR. WE IDENTIFIED THE EPIGENETIC READER BRD4 AND ITS DOWNSTREAM-EFFECTOR MYC AS GROWTH REGULATORS AND THERAPEUTIC TARGETS IN CML CELLS. BRD4 AND MYC WERE FOUND TO BE EXPRESSED IN PRIMARY CML CELLS, CD34(+) /CD38(-) LEUKEMIC STEM CELLS (LSC), AND IN THE CML CELL LINES KU812, K562, KCL22, AND KCL22(T315I) . THE BRD4-TARGETING DRUG JQ1 WAS FOUND TO SUPPRESS PROLIFERATION IN KU812 CELLS AND PRIMARY LEUKEMIC CELLS IN THE MAJORITY OF PATIENTS WITH CHRONIC PHASE CML. IN THE BLAST PHASE OF CML, JQ1 WAS LESS EFFECTIVE. HOWEVER, THE BRD4 DEGRADER DBET6 WAS FOUND TO BLOCK PROLIFERATION AND/OR SURVIVAL OF PRIMARY CML CELLS IN ALL PATIENTS TESTED, INCLUDING BLAST PHASE CML AND CML CELLS EXHIBITING THE T315I VARIANT OF BCR::ABL1. MOREOVER, DBET6 WAS FOUND TO BLOCK MYC EXPRESSION AND TO SYNERGIZE WITH BCR::ABL1 TKI IN INHIBITING THE PROLIFERATION IN THE JQ1-RESISTANT CELL LINE K562. FURTHERMORE, BRD4 DEGRADATION WAS FOUND TO OVERCOME OSTEOBLAST-INDUCED TKI RESISTANCE OF CML LSC IN A CO-CULTURE SYSTEM AND TO BLOCK INTERFERON-GAMMA-INDUCED UPREGULATION OF THE CHECKPOINT ANTIGEN PD-L1 IN LSC. FINALLY, DBET6 WAS FOUND TO SUPPRESS THE IN VITRO SURVIVAL OF CML LSC AND THEIR ENGRAFTMENT IN NSG MICE. TOGETHER, TARGETING OF BRD4 AND MYC THROUGH BET DEGRADATION SENSITIZES CML CELLS AGAINST BCR::ABL1 TKI AND IS A POTENT APPROACH TO OVERCOME MULTIPLE FORMS OF DRUG RESISTANCE IN CML LSC. 2022 16 2127 36 EPIGENETIC INACTIVATION OF MIR-9 FAMILY MICRORNAS IN CHRONIC LYMPHOCYTIC LEUKEMIA--IMPLICATIONS ON CONSTITUTIVE ACTIVATION OF NFKAPPAB PATHWAY. BACKGROUND: THE MIR-9 FAMILY MICRORNAS HAVE BEEN IDENTIFIED AS A TUMOR SUPPRESSOR MIRNA IN CANCERS. WE POSTULATED THAT MIR-9-1, MIR-9-2 AND MIR-9-3 MIGHT BE INACTIVATED BY DNA HYPERMETHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). METHODS: METHYLATION OF MIR-9-1, MIR-9-2 AND MIR-9-3 WAS STUDIED IN EIGHT NORMAL CONTROLS INCLUDING NORMAL BONE MARROW, BUFFY COAT, AND CD19-SORTED PERIPHERAL BLOOD B-CELLS FROM HEALTHY INDIVIDUALS, SEVEN CLL CELL LINES, AND SEVENTY-EIGHT DIAGNOSTIC CLL SAMPLES BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION. RESULTS: THE PROMOTERS OF MIR-9-3 AND MIR-9-1 WERE BOTH UNMETHYLATED IN NORMAL CONTROLS, BUT METHYLATED IN FIVE (71.4%) AND ONE OF SEVEN CLL CELL LINES RESPECTIVELY. HOWEVER, MIR-9-2 PROMOTER WAS METHYLATED IN NORMAL CONTROLS INCLUDING CD19 + VE B-CELLS, HENCE SUGGESTIVE OF A TISSUE-SPECIFIC BUT NOT TUMOR-SPECIFIC METHYLATION, AND THUS NOT FURTHER STUDIED. DIFFERENT MSP STATUSES OF MIR-9-3, INCLUDING COMPLETE METHYLATION, PARTIAL METHYLATION, AND COMPLETE UNMETHYLATION, WERE VERIFIED BY QUANTITATIVE BISULFITE METHYLATION ANALYSIS. 5-AZA-2'-DEOXYCYTIDINE TREATMENT RESULTED IN MIR-9-3 PROMOTER DEMETHYLATION AND RE-EXPRESSION OF PRI-MIR-9-3 IN I83-E95 AND WAC3CD5+ CELLS, WHICH WERE HOMOZYGOUSLY METHYLATED FOR MIR-9-3. MOREOVER, OVEREXPRESSION OF MIR-9 LED TO SUPPRESSED CELL PROLIFERATION AND ENHANCED APOPTOSIS TOGETHER WITH DOWNREGULATION OF NFKAPPAB1 IN I83-E95 CELLS, SUPPORTING A TUMOR SUPPRESSOR ROLE OF MIR-9-3 IN CLL. IN PRIMARY CLL SAMPLES, MIR-9-3 WAS DETECTED IN 17% AND MIR-9-1 METHYLATION IN NONE OF THE PATIENTS AT DIAGNOSIS. MOREOVER, MIR-9-3 METHYLATION WAS ASSOCIATED WITH ADVANCED RAI STAGE (>/= STAGE 2) (P = 0.04). CONCLUSIONS: OF THE MIR-9 FAMILY, MIR-9-3 IS A TUMOR SUPPRESSOR MIRNA RELATIVELY FREQUENTLY METHYLATED, AND HENCE SILENCED IN CLL; WHEREAS MIR-9-1 METHYLATION IS RARE IN CLL. THE ROLE OF MIR-9-3 METHYLATION IN THE CONSTITUTIVE ACTIVATION OF NFKAPPAB SIGNALING PATHWAY IN CLL WARRANTS FURTHER STUDY. 2013 17 3531 47 IMATINIB CAUSES EPIGENETIC ALTERATIONS OF PTEN GENE VIA UPREGULATION OF DNA METHYLTRANSFERASES AND POLYCOMB GROUP PROTEINS. WE HAVE RECENTLY REPORTED THE POSSIBLE IMATINIB-RESISTANT MECHANISM; LONG-TERM EXPOSURE OF LEUKEMIA CELLS TO IMATINIB DOWNREGULATED LEVELS OF PHOSPHATASE AND TENSIN HOMOLOG DELETED ON CHROMOSOME 10 (PTEN) VIA HYPERMETHYLATION OF ITS PROMOTER REGION (LEUKEMIA 2010; 24: 1631). THE PRESENT STUDY EXPLORED THE MOLECULAR MECHANISMS BY WHICH IMATINIB CAUSED METHYLATION ON THE PROMOTER REGION OF THIS TUMOR SUPPRESSOR GENE IN LEUKEMIA CELLS. REAL-TIME REVERSE TRANSCRIPTION PCR FOUND THAT LONG-TERM EXPOSURE OF CHRONIC EOSINOPHILIC LEUKEMIA EOL-1 CELLS EXPRESSING FIP1L1/PLATELET-DERIVED GROWTH FACTOR RECEPTOR-ALPHA TO IMATINIB INDUCED EXPRESSION OF DNA METHYLTRANSFERASE 3A (DNMT3A) AND HISTONE-METHYLTRANSFERASE ENHANCER OF ZESTE HOMOLOG 2 (EZH2), A FAMILY OF POLYCOMB GROUP, THEREBY INCREASING METHYLATION OF THE GENE. IMMUNOPRECIPITATION ASSAY FOUND THE INCREASED COMPLEX FORMATION OF DNMT3A AND EZH2 PROTEINS IN THESE CELLS. MOREOVER, CHROMATIN IMMUNOPRECIPITATION ASSAY SHOWED THAT AMOUNTS OF BOTH DNMT3A AND EZH2 PROTEINS BOUND AROUND THE PROMOTER REGION OF PTEN GENE WERE INCREASED IN EOL-1 CELLS AFTER EXPOSURE TO IMATINIB. FURTHERMORE, WE FOUND THAT LEVELS OF DNMT3A AND EZH2 WERE STRIKINGLY INCREASED IN LEUKEMIA CELLS ISOLATED FROM INDIVIDUALS WITH CHRONIC MYELOGENOUS LEUKEMIA (N=1) AND PHILADELPHIA CHROMOSOME-POSITIVE ACUTE LYMPHOBLASTIC LEUKEMIA (N=2), WHO RELAPSED AFTER TREATMENT WITH IMATINIB COMPARED WITH THOSE ISOLATED AT THEIR INITIAL PRESENTATION. TAKEN TOGETHER, IMATINIB COULD CAUSE DRUG-RESISTANCE VIA RECRUITMENT OF POLYCOMB GENE COMPLEX TO THE PROMOTER REGION OF THE PTEN AND DOWNREGULATION OF THIS GENE'S TRANSCRIPTS IN LEUKEMIA PATIENTS. 2011 18 5458 34 RESEARCH ON EPIGENETIC MECHANISM OF SFRP2 IN ADVANCED CHRONIC MYELOID LEUKEMIA. SECRETED FRIZZLED-RELATED PROTEIN 2 (SFRP2) HAS BEEN REPORTED TO ACT AS A TUMOR SUPPRESSORS. THIS STUDY AIMS TO DETECT THE BIOLOGICAL ROLE OF SFRP2 IN ADVANCED CHRONIC MYELOID LEUKEMIA (CML). IN THIS STUDY WE EXAMINED BONE MARROW SAMPLES FROM 45 CML PATIENTS AND 10 HEALTHY DONORS. K562 AND KCL22 CELLS WERE CULTURED AND TREATED WITH DEMETHYLATION DRUG AND HISTONE DEACETYLASE INHIBITOR (HDACI). KCL22 AND K562 CELLS WERE TRANSFECTED WITH LENTIVIRAL VECTOR (LV)-SFRP2, LV-CONTROL. THE CELLS WERE THEN SUBJECTED TO PROLIFERATION AND APOPTOSIS ASSAYS, REAL TIME POLYMERASE CHAIN REACTION (PCR), METHYLATION-SPECIFIC PCR (MSP), WESTERN BLOTTING, CO-IMMUNOPRECIPITATION (COIP) AND CHROMATIN IMMUNOPRECIPITATION (CHIP), WE FOUND THAT SFRP2 WAS DOWN-REGULATED IN THE ACCELERATED AND BLAST PHASE OF CML, WHEREAS, THE LEVELS OF WNT1, WNT3 AND WNT5A WERE UP-REGULATED IN THE ACCELERATED AND BLAST PHASE OF CML. OVEREXPRESSION SFRP2 INHIBITED PROLIFERATION, PROMOTED APOPTOSIS AND ACTIVATED THE WNT PATHWAY. COIP-MS RESULTS SHOWED THAT SFRP2 INTERACTED WITH WNT1 AND WNT5A. CHIP-SEQ RESULT INDICATED THAT THE PROMOTER OF H3K4ME3 AND H3K27ME3 WERE ABLE TO INTERACT WITH SFRP2. IN CONCLUSION, OUR FINDINGS DEMONSTRATED THE SFRP2 ACT AS A POTENTIAL THERAPEUTIC TARGET FOR ADVANCED CML. FURTHERMORE, OUR RESULTS SUPPORT THE USE OF DEMETHYLATION DRUGS AND HDACI AS A POTENTIAL CML TREATMENT STRATEGY. 2018 19 4729 30 NOTCH1 MUTATIONS ASSOCIATE WITH LOW CD20 LEVEL IN CHRONIC LYMPHOCYTIC LEUKEMIA: EVIDENCE FOR A NOTCH1 MUTATION-DRIVEN EPIGENETIC DYSREGULATION. IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), NOTCH1 MUTATIONS HAVE BEEN ASSOCIATED WITH CLINICAL RESISTANCE TO THE ANTI-CD20 RITUXIMAB, ALTHOUGH THE MECHANISMS BEHIND THIS PECULIAR BEHAVIOR REMAIN TO BE CLARIFIED. IN A WIDE CLL SERIES (N=692), WE DEMONSTRATED THAT CLL CELLS FROM NOTCH1-MUTATED CASES (87/692) WERE CHARACTERIZED BY LOWER CD20 EXPRESSION AND LOWER RELATIVE LYSIS INDUCED BY ANTI-CD20 EXPOSURE IN VITRO. CONSISTENTLY, CD20 EXPRESSION BY CLL CELLS WAS UPREGULATED IN VITRO BY GAMMA-SECRETASE INHIBITORS OR NOTCH1-SPECIFIC SMALL INTERFERING RNA AND THE STABLE TRANSFECTION OF A MUTATED (C.7541-7542DELCT) NOTCH1 INTRACELLULAR DOMAIN (NICD-MUT) INTO CLL-LIKE CELLS RESULTED IN A STRONG DOWNREGULATION OF BOTH CD20 PROTEIN AND TRANSCRIPT. BY USING THESE NICD-MUT TRANSFECTANTS, WE INVESTIGATED PROTEIN INTERACTIONS OF RBPJ, A TRANSCRIPTION FACTOR ACTING EITHER AS ACTIVATOR OR REPRESSOR OF NOTCH1 PATHWAY WHEN RESPECTIVELY BOUND TO NICD OR HISTONE DEACETYLASES (HDACS). COMPARED WITH CONTROLS, NICD-MUT TRANSFECTANTS HAD RBPJ PREFERENTIALLY COMPLEXED TO NICD AND SHOWED HIGHER LEVELS OF HDACS INTERACTING WITH THE PROMOTER OF THE CD20 GENE. FINALLY, TREATMENT WITH THE HDAC INHIBITOR VALPROIC ACID UPREGULATED CD20 IN BOTH NICD-MUT TRANSFECTANTS AND PRIMARY CLL CELLS. IN CONCLUSION, NOTCH1 MUTATIONS ARE ASSOCIATED WITH LOW CD20 LEVELS IN CLL AND ARE RESPONSIBLE FOR A DYSREGULATION OF HDAC-MEDIATED EPIGENETIC REPRESSION OF CD20 EXPRESSION. 2016 20 6134 22 THE EPIGENETICALLY-REGULATED MIR-34A TARGETING C-SRC SUPPRESSES RAF/MEK/ERK SIGNALING PATHWAY IN K-562 CELLS. PREVIOUS REPORTS SHOW THAT MIR-34A SUPPRESSED K-562 CELL PROLIFERATION AND CONTRIBUTED TO MEGAKARYOCYTIC DIFFERENTIATION OF K-562 CELLS. HERE, WE REPORTED THAT MIR-34A, A TUMOR SUPPRESSOR GENE, IS DOWN-REGULATED IN THE K-562 CELLS AND CHRONIC MYELOID LEUKEMIA (CML) PATIENTS DUE TO ABERRANT DNA HYPERMETHYLATION. C-SRC IS A TARGET OF MIR-34A. RESTORING MIR-34A EXPRESSION RESULTED IN DOWN-REGULATION OF C-SRC AND PHOSPHORYLATED (TYR416) C-SRC PROTEIN IN K-562 CELLS, WHICH CONSEQUENTLY TRIGGERED SUPPRESSION OF THE RAF/MEK/ERK SIGNALING PATHWAY TO DECREASE CELL PROLIFERATION. 2017