1 3982 124 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 2 5523 23 RISKS AND MECHANISMS OF ONCOLOGICAL DISEASE FOLLOWING STEM CELL TRANSPLANTATION. UNIQUE BIOLOGICAL PROPERTIES OF STEM CELLS MAKE THEM A PRECIOUS SOURCE OF CELL MATERIAL FOR TREATMENT OF A NUMBER OF PATHOLOGICAL CONDITIONS. AMONG ISSUES INHIBITING TRANSITION OF STEM CELL TECHNOLOGIES TO THE CLINICS, THE RISK OF ONCOLOGICAL COMPLICATIONS OF STEM CELL-BASED THERAPIES IS THE MOST CRITICAL. A MASSIVE AMOUNT OF CLINICAL AND EXPERIMENTAL DATA DEMONSTRATES THAT BOTH HEMATOLOGICAL (INCLUDING ACUTE AND CHRONIC MYELOID LEUKEMIA) AND NON-HEMATOLOGICAL (INCLUDING TERATOMA AND NON-TERATOMA TUMORS) MALIGNANCIES COULD ARISE FROM DONOR STEM CELLS OF DIFFERENT TYPES. A WIDE SPECTRUM OF MECHANISMS COULD UNDERLIE THE DEVELOPMENT OF ONCOLOGICAL DISEASE IN RECIPIENTS, INCLUDING: I) BLAST TRANSFORMATION OF PROLIFERATING DONOR STEM CELLS UNDER PERSISTENT ACTION OF CERTAIN FACTORS IN THE RECIPIENT, THUS CAUSING DE NOVO MALIGNANCIES; II) CONTAMINATION OF DONOR CELL MATERIAL WITH MALIGNANT CELLS; III) TRANSMISSION OF PARTICULAR VIRAL SUBTYPES WITH DONOR STEM CELLS, COMBINED WITH IMMUNOSUPPRESSION THERAPY EFFECTS; IV) UNCONTROLLABLE PROLIFERATION OF RESIDUAL UNDIFFERENTIATED STEM CELLS OF VARIOUS PLASTICITY; AND V) KARYOTYPIC INSTABILITY IN STEM CELLS FOLLOWING PROLONGED CULTURING/EXPANSION IN VITRO. POTENTIAL PREVENTIVE STRATEGIES ARE DIVERSE AND INCLUDE I) HIGH-THROUGHPUT CELL SORTING-BASED STRATEGIES; II) INTRODUCTION OF SUICIDE GENES INTO THE DONOR STEM CELL GENOME; III) APPLICATION OF APOPTOSIS-INDUCING EPIGENETIC FACTORS; AND SOME OTHER OPTIONS. 2010 3 3531 55 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 4 1824 24 EFFECTS OF ENVIRONMENTAL CONDITIONS ON NEPHRON NUMBER: MODELING MATERNAL DISEASE AND EPIGENETIC REGULATION IN RENAL DEVELOPMENT. A GROWING BODY OF EVIDENCE SUGGESTS THAT LOW NEPHRON NUMBERS AT BIRTH CAN INCREASE THE RISK OF CHRONIC KIDNEY DISEASE OR HYPERTENSION LATER IN LIFE. ENVIRONMENTAL STRESSORS, SUCH AS MATERNAL MALNUTRITION, MEDICATION AND SMOKING, CAN INFLUENCE RENAL SIZE AT BIRTH. USING METANEPHRIC ORGAN CULTURES TO MODEL SINGLE-VARIABLE ENVIRONMENTAL CONDITIONS, MODELS OF MATERNAL DISEASE WERE EVALUATED FOR PATTERNS OF DEVELOPMENTAL IMPAIRMENT. WHILE HYPERTHERMIA HAD LIMITED EFFECTS ON RENAL DEVELOPMENT, FETAL IRON DEFICIENCY WAS ASSOCIATED WITH SEVERE IMPAIRMENT OF RENAL GROWTH AND NEPHROGENESIS WITH AN ALL-PROXIMAL PHENOTYPE. CULTURING KIDNEY EXPLANTS UNDER HIGH GLUCOSE CONDITIONS LED TO CELLULAR AND TRANSCRIPTOMIC CHANGES RESEMBLING HUMAN DIABETIC NEPHROPATHY. SHORT-TERM HIGH GLUCOSE CULTURE CONDITIONS WERE SUFFICIENT FOR LONG-TERM ALTERATIONS IN DNA METHYLATION-ASSOCIATED EPIGENETIC MEMORY. FINALLY, THE ROLE OF EPIGENETIC MODIFIERS IN RENAL DEVELOPMENT WAS TESTED USING A SMALL COMPOUND LIBRARY. AMONG THE SELECTED EPIGENETIC INHIBITORS, VARIOUS COMPOUNDS ELICITED AN EFFECT ON RENAL GROWTH, SUCH AS HDAC (ENTINOSTAT, TH39), HISTONE DEMETHYLASE (DEFERASIROX, DEFEROXAMINE) AND HISTONE METHYLTRANSFERASE (CYPROHEPTADINE) INHIBITORS. THUS, METANEPHRIC ORGAN CULTURES PROVIDE A VALUABLE SYSTEM FOR STUDYING METABOLIC CONDITIONS AND A TOOL FOR SCREENING FOR EPIGENETIC MODIFIERS IN RENAL DEVELOPMENT. 2021 5 574 46 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 6 5319 38 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 7 32 46 A CASE OF TYROSINE KINASE INHIBITOR-RESISTANT CHRONIC MYELOID LEUKEMIA, CHRONIC PHASE WITH ASXL1 MUTATION. HEMATOLOGICAL MALIGNANCIES, INCLUDING CHRONIC MYELOID LEUKEMIA (CML), EXHIBIT ASXL1 MUTATIONS; HOWEVER, THE FUNCTION AND MOLECULAR MECHANISM OF THESE MUTATIONS REMAIN UNCLEAR. ASXL1 WAS ORIGINALLY IDENTIFIED AS TUMOR SUPPRESSOR GENE, IN WHICH LOSS OF FUNCTION CAUSES MYELODYSPLASTIC SYNDROME (MDS). ASXL1 MUTATIONS ARE COMMON AND ASSOCIATED WITH DISEASE PROGRESSION IN MYELOID MALIGNANCIES INCLUDING MDS, ACUTE MYELOID LEUKEMIA, AND SIMILARLY IN CML. IN MDS, ASXL1 MUTATIONS HAVE BEEN ASSOCIATED WITH POOR PROGNOSIS; HOWEVER, THE IMPACT OF ASXL1 MUTATIONS IN CML HAS NOT BEEN WELL DESCRIBED. A 31-YEAR-OLD MALE WAS DIAGNOSED AS CML-CHRONIC PHASE (CP). LABORATORY FINDINGS SHOWED A WHITE BLOOD CELL COUNT OF 187,200/MICROL, WITH ASYMPTOMATIC SPLENOMEGALY. BLAST COUNT WAS 5.0% IN PERIPHERAL BLOOD AND 7.3% IN BONE MARROW. THERE WAS NO ADDITIONAL CHROMOSOMAL ABNORMALITY EXCEPT FOR T(9;22)(Q34;Q11.2) BY CHROMOSOMAL ANALYSIS. AT ONSET, THE SOKAL SCORE WAS 1.4, INDICATING HIGH RISK. THE PATIENT RECEIVED TYROSINE KINASE INHIBITOR (TKI) THERAPY, COMPRISING NILOTINIB APPROXIMATELY 600 MG/DAY, BOSUTINIB APPROXIMATELY 600 MG/DAY, PONATINIB APPROXIMATELY 45 MG/DAY, AND DASATINIB APPROXIMATELY 100 MG/DAY. NEVERTHELESS, AFTER 1.5 YEARS OF CONTINUOUS TKI THERAPY, THE BEST OUTCOME WAS A HEMATOLOGICAL RESPONSE. ALTHOUGH ADDITIONAL CHROMOSOMAL ABERRATIONS AND ABL1 KINASE MUTATIONS WERE ANALYZED REPEATEDLY BEFORE AND DURING TKI THERAPY, KNOWN GENETIC ABNORMALITIES WERE NOT DETECTED. THEREAFTER, THE PATIENT UNDERWENT BONE MARROW TRANSPLANTATION FROM AN HLA 7/8 MATCHED UNRELATED DONOR (HLA-CW 1 LOCUS MISMATCH, GRAFT-VERSUS-HOST DIRECTION). THE PATIENT ACHIEVED NEUTROPHIL ENGRAFTMENT, 18 DAYS AFTER TRANSPLANTATION, LEADING TO COMPLETE REMISSION WITH AN UNDETECTABLE LEVEL OF BCR-ABL1 MRNA. THE PATIENT, HOWEVER, DIED FROM GRAFT-VERSUS-HOST DISEASE AND THROMBOTIC MICROANGIOPATHY AFTER 121 DAYS. GENE SEQUENCE ANALYSIS OF HIS CML CELL BEFORE STEM CELL TRANSPLANTATION REVEALED ASXL1 MUTATIONS. PHYSIOLOGICALLY, ASXL1 CONTRIBUTES TO EPIGENETIC REGULATION. IN THE CML-CP PATIENT IN THIS CASE REPORT, ASXL1 MUTATION CONFERRED RESISTANCE TO TKI THROUGH OBSCURE RESISTANCE MECHANISMS. EVEN THOUGH A MOLECULAR MECHANISM FOR TKI RESISTANCE IN ASXL1 MUTATION IN CML HAS REMAINED OBSCURE, EPIGENETIC MODULATION IS A PLAUSIBLE MODE OF CML DISEASE PROGRESSION. THE CLINICAL IMPACT INCLUDING PROGNOSIS OF ASXL1 FOR CML IS UNDERSCORED. AND THE TREATMENT STRATEGY OF CML WITH ASXL1 MUTATION HAS NOT BEEN ESTABLISHED. A DISCUSSION OF THIS CASE WAS EXPECTED TO FACILITATE TREATMENT OPTIONS. 2020 8 5940 36 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 9 139 35 ABERRANT DNA METHYLATION IS ASSOCIATED WITH DISEASE PROGRESSION, RESISTANCE TO IMATINIB AND SHORTENED SURVIVAL IN CHRONIC MYELOGENOUS LEUKEMIA. THE EPIGENETIC IMPACT OF DNA METHYLATION IN CHRONIC MYELOGENOUS LEUKEMIA (CML) IS NOT COMPLETELY UNDERSTOOD. TO ELUCIDATE ITS ROLE WE ANALYZED 120 PATIENTS WITH CML FOR METHYLATION OF PROMOTER-ASSOCIATED CPG ISLANDS OF 10 GENES. FIVE GENES WERE IDENTIFIED BY DNA METHYLATION SCREENING IN THE K562 CELL LINE AND 3 GENES IN PATIENTS WITH MYELOPROLIFERATIVE NEOPLASMS. THE CDKN2B GENE WAS SELECTED FOR ITS FREQUENT METHYLATION IN MYELOID MALIGNANCIES AND ABL1 AS THE TARGET OF BCR-ABL TRANSLOCATION. THIRTY PATIENTS WERE IMATINIB-NAIVE (MOSTLY TREATED BY INTERFERON-ALPHA BEFORE THE IMATINIB ERA), 30 WERE IMATINIB-RESPONSIVE, 50 WERE IMATINIB-RESISTANT, AND 10 WERE IMATINIB-INTOLERANT. WE QUANTIFIED DNA METHYLATION BY BISULFITE PYROSEQUENCING. THE AVERAGE NUMBER OF METHYLATED GENES WAS 4.5 PER PATIENT IN THE CHRONIC PHASE, INCREASING SIGNIFICANTLY TO 6.2 IN THE ACCELERATED AND 6.4 IN THE BLASTIC PHASE. HIGHER NUMBERS OF METHYLATED GENES WERE ALSO OBSERVED IN PATIENTS RESISTANT OR INTOLERANT TO IMATINIB. THESE PATIENTS ALSO SHOWED ALMOST EXCLUSIVE METHYLATION OF A PUTATIVE TRANSPORTER OSCP1. ABNORMAL METHYLATION OF A SRC SUPPRESSOR GENE PDLIM4 WAS ASSOCIATED WITH SHORTENED SURVIVAL INDEPENDENTLY OF CML STAGE AND IMATINIB RESPONSIVENESS. WE CONCLUDE THAT ABERRANT DNA METHYLATION IS ASSOCIATED WITH CML PROGRESSION AND THAT DNA METHYLATION COULD BE A MARKER ASSOCIATED WITH IMATINIB RESISTANCE. FINALLY, DNA METHYLATION OF PDLIM4 MAY HELP IDENTIFY A SUBSET OF CML PATIENTS THAT WOULD BENEFIT FROM TREATMENT WITH SRC/ABL INHIBITORS. 2011 10 3475 32 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 11 5924 32 TARGETING DNMT1 BY DEMETHYLATING AGENT OR-2100 INCREASES TYROSINE KINASE INHIBITORS-SENSITIVITY AND DEPLETES LEUKEMIC STEM CELLS IN CHRONIC MYELOID LEUKEMIA. ABL1 TYROSINE KINASE INHIBITORS (TKIS) DRAMATICALLY IMPROVE THE PROGNOSIS OF CHRONIC MYELOID LEUKEMIA (CML), BUT 10-20% OF PATIENTS ACHIEVE SUBOPTIMAL RESPONSES WITH LOW TKIS SENSITIVITY. FURTHERMORE, RESIDUAL LEUKEMIC STEM CELLS (LSCS) ARE INVOLVED IN THE MOLECULAR RELAPSE AFTER TKIS DISCONTINUATION. ABERRANT DNA HYPERMETHYLATION CONTRIBUTES TO LOW TKIS SENSITIVITY AND THE PERSISTENCE OF LSCS IN CML. DNMT1 IS A KEY REGULATOR OF HEMATOPOIETIC STEM CELLS, SUGGESTING THAT ABERRANT DNA HYPERMETHYLATION TARGETING DNMT1 REPRESENTS A POTENTIAL THERAPEUTIC TARGET FOR CML. WE INVESTIGATED THE EFFICACY OF OR-2100 (OR21), THE FIRST ORALLY AVAILABLE SINGLE-COMPOUND PRODRUG OF DECITABINE. OR21 EXHIBITED ANTI-TUMOR EFFECTS AS A MONOTHERAPY, AND IN COMBINATION THERAPY IT INCREASED TKI-INDUCED APOPTOSIS AND INDUCTION OF TUMOR SUPPRESSOR GENES INCLUDING PTPN6 ENCODING SHP-1 IN CML CELLS. OR21 IN COMBINATION WITH IMATINIB SIGNIFICANTLY SUPPRESSED TUMOR GROWTH IN A XENOTRANSPLANT MODEL. OR21 AND COMBINATION THERAPY DECREASED THE ABUNDANCE OF LSCS AND INHIBITED ENGRAFTMENT IN A BCR-ABL1-TRANSDUCED MOUSE MODEL. THESE RESULTS DEMONSTRATE THAT TARGETING DNMT1 USING OR21 EXERTS ANTI-TUMOR EFFECTS AND IMPAIRS LSCS IN CML. THEREFORE, COMBINATION TREATMENT OF TKIS AND OR21 REPRESENTS A PROMISING TREATMENT STRATEGY IN CML. 2022 12 4741 39 NOVEL HDAC INHIBITOR MAKV-8 AND IMATINIB SYNERGISTICALLY KILL CHRONIC MYELOID LEUKEMIA CELLS VIA INHIBITION OF BCR-ABL/MYC-SIGNALING: EFFECT ON IMATINIB RESISTANCE AND STEM CELLS. BACKGROUND: CHRONIC MYELOID LEUKEMIA (CML) PATHOGENESIS IS MAINLY DRIVEN BY THE ONCOGENIC BREAKPOINT CLUSTER REGION-ABELSON MURINE LEUKEMIA VIRAL ONCOGENE HOMOLOG 1 (BCR-ABL) FUSION PROTEIN. SINCE BCR-ABL DISPLAYS ABNORMAL CONSTITUTIVE TYROSINE KINASE ACTIVITY, THERAPIES USING TYROSINE KINASE INHIBITORS (TKIS) SUCH AS IMATINIB REPRESENT A MAJOR BREAKTHROUGH FOR THE OUTCOME OF CML PATIENTS. NEVERTHELESS, THE DEVELOPMENT OF TKI RESISTANCE AND THE PERSISTENCE OF LEUKEMIA STEM CELLS (LSCS) REMAIN BARRIERS TO CURE THE DISEASE, JUSTIFYING THE DEVELOPMENT OF NOVEL THERAPEUTIC APPROACHES. SINCE THE ACTIVITY OF HISTONE DEACETYLASE (HDAC) IS DEREGULATED IN NUMEROUS CANCERS INCLUDING CML, PAN-HDAC INHIBITORS MAY REPRESENT PROMISING THERAPEUTIC REGIMENS FOR THE TREATMENT OF CML CELLS IN COMBINATION WITH TKI. RESULTS: WE ASSESSED THE ANTI-LEUKEMIC ACTIVITY OF A NOVEL HYDROXAMATE-BASED PAN-HDAC INHIBITOR MAKV-8, WHICH COMPLIED WITH THE LIPINSKI'S "RULE OF FIVE," IN VARIOUS CML CELLS ALONE OR IN COMBINATION WITH IMATINIB. WE VALIDATED THE IN VITRO HDAC-INHIBITORY POTENTIAL OF MAKV-8 AND DEMONSTRATED EFFICIENT BINDING TO THE LIGAND-BINDING POCKET OF HDAC ISOENZYMES. IN CELLULO, MAKV-8 SIGNIFICANTLY INDUCED TARGET PROTEIN ACETYLATION, DISPLAYED CYTOSTATIC AND CYTOTOXIC PROPERTIES, AND TRIGGERED CONCOMITANT ER STRESS/PROTECTIVE AUTOPHAGY LEADING TO CANONICAL CASPASE-DEPENDENT APOPTOSIS. CONSIDERING THE SPECIFIC UPREGULATION OF SELECTED HDACS IN LSCS FROM CML PATIENTS, WE INVESTIGATED THE DIFFERENTIAL TOXICITY OF A CO-TREATMENT WITH MAKV-8 AND IMATINIB IN CML VERSUS HEALTHY CELLS. WE ALSO SHOWED THAT BECLIN-1 KNOCKDOWN PREVENTED MAKV-8-IMATINIB COMBINATION-INDUCED APOPTOSIS. MOREOVER, MAKV-8 AND IMATINIB CO-TREATMENT SYNERGISTICALLY REDUCED BCR-ABL-RELATED SIGNALING PATHWAYS INVOLVED IN CML CELL GROWTH AND SURVIVAL. SINCE OUR RESULTS SHOWED THAT LSCS FROM CML PATIENTS OVEREXPRESSED C-MYC, IMPORTANTLY MAKV-8-IMATINIB CO-TREATMENT REDUCED C-MYC LEVELS AND THE LSC POPULATION. IN VIVO, TUMOR GROWTH OF XENOGRAFTED K-562 CELLS IN ZEBRAFISH WAS COMPLETELY ABROGATED UPON COMBINED TREATMENT WITH MAKV-8 AND IMATINIB. CONCLUSIONS: COLLECTIVELY, THE PRESENT FINDINGS SHOW THAT COMBINATIONS HDAC INHIBITOR-IMATINIB ARE LIKELY TO OVERCOME DRUG RESISTANCE IN CML PATHOLOGY. 2020 13 3530 37 IMATINIB (ST1571) PROVIDES ONLY LIMITED SELECTIVITY FOR CML CELLS AND TREATMENT MIGHT BE COMPLICATED BY SILENT BCR-ABL GENES. VERY PROMISING RESULTS HAVE BEEN OBTAINED IN CLINICAL TRIALS ON CHRONIC-PHASE CHRONIC MYELOID LEUKEMIA (CP-CML) PATIENTS TREATED WITH IMATINIB MESYLATE (IM; GLEEVECR, STI571), A BCR-ABL TYROSINE KINASE INHIBITOR. HOWEVER, WE FOUND THAT IM CAUSED CONSIDERABLE INHIBITION OF NORMAL HEMATOPOIETIC PROGENITOR CELLS UPON TREATING CONTROL BONE MARROW (BM) CULTURES. IN VITRO IM TREATMENT GAVE A DECREASE IN THE YIELD AND SIZE OF COLONIES FROM BM OF UNTREATED CP-CML PATIENTS THAT WAS ONLY TWO TO THREE TIMES THAT FROM THE NORMAL SAMPLES. MOREOVER, ABOUT 30% OF MYELOID PROGENITORS (CFU-GM) FROM CML BM STILL FORMED COLONIES IN THE PRESENCE OF IM, MOST OF WHICH HAD BCR-ABL RNA. ABOUT HALF OF THESE TREATED COLONIES ALSO DISPLAYED METHYLATION OF THE INTERNAL ABL PA PROMOTER, A CML-SPECIFIC EPIGENETIC ALTERATION, WHICH WAS USED IN THIS STUDY AS A MARKER FOR BCR-ABL TRANSLOCATION-CONTAINING CELLS. HOWEVER, ~5-8% OF THE TREATED OR THE UNTREATED CML BM-DERIVED COLONIES HAD NO DETECTABLE BCR-ABL RNA BY TWO OR THREE ROUNDS OF RT-PCR DESPITE BEING POSITIVE FOR THE INTERNAL STANDARD RNA AND DISPLAYING HALLMARKS OF CML, EITHER T(9;22)(Q34;QL 1) OR ABL PA METHYLATION. OUR RESULTS INDICATE THAT IM IS ONLY PARTIALLY SPECIFIC FOR CML PROGENITOR CELLS COMPARED TO NORMAL HEMATOPOIETIC PROGENITOR CELLS AND SUGGEST THAT SOME CML CELLS MAY HAVE A SILENT BCR-ABL ONCOGENE THAT COULD INTERFERE WITH THERAPY. 2003 14 3352 36 HISTONE DEMETHYLASE RBP2 MEDIATES THE BLAST CRISIS OF CHRONIC MYELOID LEUKEMIA THROUGH AN RBP2/PTEN/BCR-ABL CASCADE. EPIGENETIC DISORDERS PLAY A KEY ROLE IN TUMORIGENESIS AND DEVELOPMENT, AMONG WHICH HISTONE METHYLATION ABNORMALITIES ARE COMMON. WHILE PATIENTS LIVING WITH CHRONIC MYELOID LEUKEMIA IN THE CHRONIC PHASE (CML-CP) HAVE A GOOD RESPONSE TO TKI, BLASTIC PHASE (CML-BP) PATIENTS DEMONSTRATE POOR EFFICACY AND HIGH FATALITY RATES. HOWEVER, WHILE THE MECHANISM OF BLAST CRISIS OF CHRONIC MYELOID LEUKEMIA REMAINS UNCLEAR, HIGH EXPRESSION AND ACTIVATION OF BCR-ABL ARE USUALLY RELATED TO CML BLAST CRISIS TRANSITION. WE FOUND THAT HISTONE H3 LYSINE 4 (H3K4) DEMETHYLASE RBP2 EXPRESSION IS NEGATIVELY CORRELATED WITH BCR-ABL EXPRESSION, WHICH SUGGESTS A REGULATORY LINK BETWEEN THESE TWO GENES. WE ALSO DISCOVERED THAT RBP2 MEDIATES THE DEPHOSPHORYLATION OF BCR-ABL BY DIRECTLY DOWNREGULATING PTEN EXPRESSION, DEPENDING ON HISTONE DEMETHYLASE ACTIVITY, WHILE PTEN TARGETS PROTEIN PHOSPHATASE ACTIVITY OF BCR-ABL, A PHOSPHATASE WHICH DIRECTLY DEPHOSPHORYLATES BCR-ABL. IN CLINICAL SPECIMENS, THE MRNA EXPRESSION OF RBP2 WAS FOUND TO BE POSITIVELY CORRELATED WITH THAT OF PTEN. THESE DATA SUGGEST THAT THE UNDER-EXPRESSION OF RBP2 PROMOTES BLAST CRISIS TRANSITION BY ACTIVATING AN RBP2/PTEN/BCR-ABL CASCADE. 2019 15 3409 39 HOXA4 GENE PROMOTER HYPERMETHYLATION AS AN EPIGENETIC MECHANISM MEDIATING RESISTANCE TO IMATINIB MESYLATE IN CHRONIC MYELOID LEUKEMIA PATIENTS. DEVELOPMENT OF RESISTANCE TO IMATINIB MESYLATE (IM) IN CHRONIC MYELOID LEUKEMIA (CML) PATIENTS HAS EMERGED AS A SIGNIFICANT CLINICAL PROBLEM. THE OBSERVATION THAT INCREASED EPIGENETIC SILENCING OF POTENTIAL TUMOR SUPPRESSOR GENES CORRELATES WITH DISEASE PROGRESSION IN SOME CML PATIENTS TREATED WITH IM SUGGESTS A RELATIONSHIP BETWEEN EPIGENETIC SILENCING AND RESISTANCE DEVELOPMENT. WE HYPOTHESIZE THAT PROMOTER HYPERMETHYLATION OF HOXA4 COULD BE AN EPIGENETIC MECHANISM MEDIATING IM RESISTANCE IN CML PATIENTS. THUS A STUDY WAS UNDERTAKEN TO INVESTIGATE THE PROMOTER HYPERMETHYLATION STATUS OF HOXA4 IN CML PATIENTS ON IM TREATMENT AND TO DETERMINE ITS ROLE IN MEDIATING RESISTANCE TO IM. GENOMIC DNA WAS EXTRACTED FROM PERIPHERAL BLOOD SAMPLES OF 95 CML PATIENTS (38 GOOD RESPONDERS AND 57 RESISTANT) AND 12 NORMAL CONTROLS. ALL SAMPLES WERE BISULFITE TREATED AND ANALYSED BY METHYLATION-SPECIFIC HIGH-RESOLUTION MELT ANALYSIS. COMPARED TO THE GOOD RESPONDERS, THE HOXA4 HYPERMETHYLATION LEVEL WAS SIGNIFICANTLY HIGHER (P = 0.002) IN IM-RESISTANT CML PATIENTS. ON COMPARING THE RISK, HOXA4 HYPERMETHYLATION WAS ASSOCIATED WITH A HIGHER RISK FOR IM RESISTANCE (OR 4.658; 95% CI, 1.673-12.971; P = 0.003). THUS, IT IS REASONABLE TO SUGGEST THAT PROMOTER HYPERMETHYLATION OF HOXA4 GENE COULD BE AN EPIGENETIC MECHANISM MEDIATING IM RESISTANCE IN CML PATIENTS. 2013 16 138 43 ABERRANT DNA METHYLATION AT HOXA4 AND HOXA5 GENES ARE ASSOCIATED WITH RESISTANCE TO IMATINIB MESYLATE AMONG CHRONIC MYELOID LEUKEMIA PATIENTS. BACKGROUND: IMATINIB MESYLATE IS A MOLECULARLY TARGETED TYROSINE KINASE INHIBITOR DRUG. IT IS EFFECTIVELY USED IN THE TREATMENT OF CHRONIC MYELOID LEUKEMIA (CML) PATIENTS. HOWEVER, DEVELOPMENT OF RESISTANCE TO IMATINIB MESYLATE AS A RESULT OF BCR-ABL DEPENDENT AND BCR-ABL INDEPENDENT MECHANISMS HAS EMERGED AS A DAUNTING PROBLEM IN THE MANAGEMENT OF CML PATIENTS. BETWEEN THESE MECHANISMS, BCR-ABL INDEPENDENT MECHANISMS ARE STILL NOT ROBUSTLY UNDERSTOOD. AIM: TO INVESTIGATE THE CORRELATION OF HOXA4 AND HOXA5 PROMOTER DNA HYPERMETHYLATION WITH IMATINIB RESISTANCE AMONG CML PATIENTS. METHODS AND RESULTS: SAMPLES FROM 175 PHILADELPHIA POSITIVE CML PATIENTS (83 GOOD RESPONSE AND 92 BCR-ABL NON-MUTATED IMATINIB RESISTANT PATIENTS) WERE SUBJECTED TO METHYLATION SPECIFIC HIGH RESOLUTION MELT ANALYSIS FOR METHYLATION LEVELS QUANTIFICATION OF THE HOXA4 AND HOXA5 PROMOTER REGIONS. RECEIVER OPERATING CHARACTERISTIC CURVE ANALYSIS WAS DONE TO ELUCIDATE THE OPTIMAL METHYLATION CUT-OFF POINT FOLLOWED BY MULTIPLE LOGISTIC REGRESSION ANALYSIS. LOG-RANK ANALYSIS WAS DONE TO MEASURE THE OVERALL SURVIVAL DIFFERENCE BETWEEN CML GROUPS. THE OPTIMAL METHYLATION CUT-OFF POINT WAS FOUND TO BE AT 62.5% FOR BOTH HOXA4 AND HOXA5. CHRONIC MYELOID LEUKEMIA PATIENTS WITH >/=63% HOXA4 AND HOXA5 METHYLATION LEVEL WERE SHOWN TO HAVE 3.78 AND 3.95 TIMES THE ODDS, RESPECTIVELY, TO ACQUIRE RESISTANCE TO IMATINIB. HOWEVER, OVERALL SURVIVAL OF CML PATIENTS THAT HAVE /= 63% METHYLATION LEVELS OF HOXA4 AND HOXA5 GENES WERE FOUND TO BE NOT SIGNIFICANT (P-VALUE = 0.126 FOR HOXA4; P-VALUE = 0.217 FOR HOXA5). CONCLUSION: HYPERMETHYLATION OF THE HOXA4 AND HOXA5 PROMOTER IS CORRELATED WITH IMATINIB RESISTANCE AND WITH FURTHER INVESTIGATION, IT COULD BE A POTENTIAL EPIGENETIC BIOMARKER IN SUPPLEMENT TO THE BCR-ABL GENE MUTATION IN PREDICTING IMATINIB TREATMENT RESPONSE AMONG CML PATIENTS BUT COULD NOT BE CONSIDERED AS A PROGNOSTIC MARKER. 2018 17 4560 21 MUTATIONS WITH EPIGENETIC EFFECTS IN MYELOPROLIFERATIVE NEOPLASMS AND RECENT PROGRESS IN TREATMENT: PROCEEDINGS FROM THE 5TH INTERNATIONAL POST-ASH SYMPOSIUM. IMMEDIATELY FOLLOWING THE 2010 ANNUAL AMERICAN SOCIETY OF HEMATOLOGY (ASH) MEETING, THE 5TH INTERNATIONAL POST-ASH SYMPOSIUM ON CHRONIC MYELOGENOUS LEUKEMIA AND BCR-ABL1-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS (MPNS) TOOK PLACE ON 7-8 DECEMBER 2010 IN ORLANDO, FLORIDA, USA. DURING THIS MEETING, THE MOST RECENT ADVANCES IN LABORATORY RESEARCH AND CLINICAL PRACTICE, INCLUDING THOSE THAT WERE PRESENTED AT THE 2010 ASH MEETING, WERE DISCUSSED AMONG RECOGNIZED AUTHORITIES IN THE FIELD. THE CURRENT PAPER SUMMARIZES THE PROCEEDINGS OF THIS MEETING IN BCR-ABL1-NEGATIVE MPN. WE PROVIDE A DETAILED OVERVIEW OF NEW MUTATIONS WITH PUTATIVE EPIGENETIC EFFECTS (TET ONCOGENE FAMILY MEMBER 2 (TET2), ADDITIONAL SEX COMB-LIKE 1 (ASXL1), ISOCITRATE DEHYDROGENASE (IDH) AND ENHANCER OF ZESTE HOMOLOG 2 (EZH2)) AND AN UPDATE ON TREATMENT WITH JANUS KINASE (JAK) INHIBITORS, POMALIDOMIDE, EVEROLIMUS, INTERFERON-ALPHA, MIDOSTAURIN AND CLADRIBINE. IN ADDITION, THE NEW 'DYNAMIC INTERNATIONAL PROGNOSTIC SCORING SYSTEM (DIPSS)-PLUS' PROGNOSTIC MODEL FOR PRIMARY MYELOFIBROSIS (PMF) AND THE CLINICAL RELEVANCE OF DISTINGUISHING ESSENTIAL THROMBOCYTHEMIA FROM PREFIBROTIC PMF ARE DISCUSSED. 2011 18 6793 34 [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 19 3158 37 GLYCOGEN SYNTHASE KINASE 3BETA MISSPLICING CONTRIBUTES TO LEUKEMIA STEM CELL GENERATION. RECENT EVIDENCE SUGGESTS THAT A RARE POPULATION OF SELF-RENEWING CANCER STEM CELLS (CSC) IS RESPONSIBLE FOR CANCER PROGRESSION AND THERAPEUTIC RESISTANCE. CHRONIC MYELOID LEUKEMIA (CML) REPRESENTS AN IMPORTANT PARADIGM FOR UNDERSTANDING THE GENETIC AND EPIGENETIC EVENTS INVOLVED IN CSC PRODUCTION. CML PROGRESSES FROM A CHRONIC PHASE (CP) IN HEMATOPOIETIC STEM CELLS (HSC) THAT HARBOR THE BCR-ABL TRANSLOCATION, TO BLAST CRISIS (BC), CHARACTERIZED BY ABERRANT ACTIVATION OF BETA-CATENIN WITHIN GRANULOCYTE-MACROPHAGE PROGENITORS (GMP). A MAJOR BARRIER TO PREDICTING AND INHIBITING BLAST CRISIS TRANSFORMATION HAS BEEN THE IDENTIFICATION OF MECHANISMS DRIVING BETA-CATENIN ACTIVATION. HERE WE SHOW THAT BC CML MYELOID PROGENITORS, IN PARTICULAR GMP, SERIALLY TRANSPLANT LEUKEMIA IN IMMUNOCOMPROMISED MICE AND THUS ARE ENRICHED FOR LEUKEMIA STEM CELLS (LSC). NOTABLY, CDNA SEQUENCING OF WNT/BETA-CATENIN PATHWAY REGULATORY GENES, INCLUDING ADENOMATOUS POLYPOSIS COLI, GSK3BETA, AXIN 1, BETA-CATENIN, LYMPHOID ENHANCER FACTOR-1, CYCLIN D1, AND C-MYC, REVEALED A NOVEL IN-FRAME SPLICE DELETION OF THE GSK3BETA KINASE DOMAIN IN THE GMP OF BC SAMPLES THAT WAS NOT DETECTABLE BY SEQUENCING IN BLASTS OR NORMAL PROGENITORS. MOREOVER, BC CML PROGENITORS WITH MISSPLICED GSK3BETA HAVE ENHANCED BETA-CATENIN EXPRESSION AS WELL AS SERIAL ENGRAFTMENT POTENTIAL WHILE REINTRODUCTION OF FULL-LENGTH GSK3BETA REDUCES BOTH IN VITRO REPLATING AND LEUKEMIC ENGRAFTMENT. WE PROPOSE THAT CP CML IS INITIATED BY BCR-ABL EXPRESSION IN AN HSC CLONE BUT THAT PROGRESSION TO BC MAY INCLUDE MISSPLICING OF GSK3BETA IN GMP LSC, ENABLING UNPHOSPHORYLATED BETA-CATENIN TO PARTICIPATE IN LSC SELF-RENEWAL. MISSPLICING OF GSK3BETA REPRESENTS A UNIQUE MECHANISM FOR THE EMERGENCE OF BC CML LSC AND MIGHT PROVIDE A NOVEL DIAGNOSTIC AND THERAPEUTIC TARGET. 2009 20 826 39 CHARACTERIZATION OF K562 CELLS: UNCOVERING NOVEL CHROMOSOMES, ASSESSING TRANSFERRIN RECEPTOR EXPRESSION, AND PROBING PHARMACOLOGICAL THERAPIES. HUMAN ERYTHROLEUKEMIC K562 CELLS REPRESENT THE PROTOTYPICAL CELL CULTURE MODEL OF CHRONIC MYELOID LEUKEMIA (CML). THE CELLS ARE PSEUDO-TRIPLOID AND POSITIVE FOR THE PHILADELPHIA CHROMOSOME. THEREFORE, K562 CELLS HAVE BEEN WIDELY USED FOR INVESTIGATING THE BCR/ABL1 ONCOGENE AND THE TYROSINE KINASE INHIBITOR, IMATINIB-MESYLATE. FURTHER, K562 CELLS OVEREXPRESS TRANSFERRIN RECEPTORS (TFR) AND HAVE BEEN USED AS A MODEL FOR TARGETING CYTOTOXIC THERAPIES, VIA RECEPTOR-MEDIATED ENDOCYTOSIS. HERE, WE HAVE CHARACTERIZED K562 CELLS FOCUSING ON THE KARYOTYPE OF CELLS IN PROLONGED CULTURE, REGULATION OF EXPRESSION OF TFR IN WILDTYPE (WT) AND DOXORUBICIN-RESISTANT CELLS, AND RESPONSES TO HISTONE DEACETYLASE INHIBITION (HDACI). KARYOTYPE ANALYSIS INDICATES NOVEL CHROMOSOMES AND GENE EXPRESSION ANALYSIS SUGGESTS A SHIFT OF CULTURED K562 CELLS AWAY FROM PATIENT-DERIVED LEUKEMIC CELLS. WE CONFIRM THE HIGH EXPRESSION OF TFR ON K562 CELLS USING IMMUNOFLUORESCENCE AND CELL-SURFACE RECEPTOR BINDING RADIOASSAYS. IMPORTANTLY, HIGH TFR EXPRESSION IS OBSERVED IN PATIENT-DERIVED CELLS, AND WE HIGHLIGHT THE PERSISTENT EXPRESSION OF TFR FOLLOWING DOXORUBICIN ACQUIRED RESISTANCE. EPIGENETIC ANALYSIS INDICATES THAT PERMISSIVE HISTONE ACETYLATION AND METHYLATION AT THE PROMOTER REGION REGULATES THE TRANSCRIPTION OF TFR IN K562 CELLS. FINALLY, WE SHOW RELATIVELY HIGH EXPRESSION OF HDAC ENZYMES IN K562 CELLS AND DEMONSTRATE THE CHEMOTOXIC EFFECTS OF HDACI, USING THE FDA-APPROVED HYDROXAMIC ACID, VORINOSTAT. TOGETHER WITH A DESCRIPTION OF MORPHOLOGY, INFRARED SPECTRAL ANALYSIS, AND EXAMINATION OF METABOLIC PROPERTIES, WE PROVIDE A COMPREHENSIVE CHARACTERIZATION OF K562 CELLS. OVERALL, K562 CELL CULTURE SYSTEMS REMAIN WIDELY USED FOR THE INVESTIGATION OF NOVEL THERAPEUTICS FOR CML, WHICH IS PARTICULARLY IMPORTANT IN CASES OF IMATINIB-MESYLATE RESISTANCE. 2023