1 5965 116 TEN-ELEVEN-TRANSLOCATION 2 (TET2) NEGATIVELY REGULATES HOMEOSTASIS AND DIFFERENTIATION OF HEMATOPOIETIC STEM CELLS IN MICE. THE TEN-ELEVEN-TRANSLOCATION 2 (TET2) GENE ENCODES A MEMBER OF TET FAMILY ENZYMES THAT ALTERS THE EPIGENETIC STATUS OF DNA BY OXIDIZING 5-METHYLCYTOSINE TO 5-HYDROXYMETHYLCYTOSINE (5HMC). SOMATIC LOSS-OF-FUNCTION MUTATIONS OF TET2 ARE FREQUENTLY OBSERVED IN PATIENTS WITH DIVERSE MYELOID MALIGNANCIES, INCLUDING MYELODYSPLASTIC SYNDROMES, MYELOPROLIFERATIVE NEOPLASMS, AND CHRONIC MYELOMONOCYTIC LEUKEMIA. BY ANALYZING MICE WITH TARGETED DISRUPTION OF THE TET2 CATALYTIC DOMAIN, WE SHOW HERE THAT TET2 IS A CRITICAL REGULATOR OF SELF-RENEWAL AND DIFFERENTIATION OF HEMATOPOIETIC STEM CELLS (HSCS). TET2 DEFICIENCY LED TO DECREASED GENOMIC LEVELS OF 5HMC AND AUGMENTED THE SIZE OF THE HEMATOPOIETIC STEM/PROGENITOR CELL POOL IN A CELL-AUTONOMOUS MANNER. IN COMPETITIVE TRANSPLANTATION ASSAYS, TET2-DEFICIENT HSCS WERE CAPABLE OF MULTILINEAGE RECONSTITUTION AND POSSESSED A COMPETITIVE ADVANTAGE OVER WILD-TYPE HSCS, RESULTING IN ENHANCED HEMATOPOIESIS INTO BOTH LYMPHOID AND MYELOID LINEAGES. IN VITRO, TET2 DEFICIENCY DELAYED HSC DIFFERENTIATION AND SKEWED DEVELOPMENT TOWARD THE MONOCYTE/MACROPHAGE LINEAGE. OUR DATA INDICATE THAT TET2 HAS A CRITICAL ROLE IN REGULATING THE EXPANSION AND FUNCTION OF HSCS, PRESUMABLY BY CONTROLLING 5HMC LEVELS AT GENES IMPORTANT FOR THE SELF-RENEWAL, PROLIFERATION, AND DIFFERENTIATION OF HSCS. 2011 2 5971 43 TET PROTEINS AND 5-METHYLCYTOSINE OXIDATION IN HEMATOLOGICAL CANCERS. DNA METHYLATION HAS PIVOTAL REGULATORY ROLES IN MAMMALIAN DEVELOPMENT, RETROTRANSPOSON SILENCING, GENOMIC IMPRINTING, AND X-CHROMOSOME INACTIVATION. CANCER CELLS DISPLAY HIGHLY DYSREGULATED DNA METHYLATION PROFILES CHARACTERIZED BY GLOBAL HYPOMETHYLATION IN CONJUNCTION WITH HYPERMETHYLATION OF PROMOTER CPG ISLANDS THAT PRESUMABLY LEAD TO GENOME INSTABILITY AND ABERRANT EXPRESSION OF TUMOR SUPPRESSOR GENES OR ONCOGENES. THE RECENT DISCOVERY OF TEN-ELEVEN-TRANSLOCATION (TET) FAMILY DIOXYGENASES THAT OXIDIZE 5MC TO 5-HYDROXYMETHYLCYTOSINE (5HMC), 5-FORMYLCYTOSINE (5FC), AND 5-CARBOXYLCYTOSINE (5CAC) IN DNA HAS LED TO PROFOUND PROGRESS IN UNDERSTANDING THE MECHANISM UNDERLYING DNA DEMETHYLATION. AMONG THE THREE TET GENES, TET2 RECURRENTLY UNDERGOES INACTIVATING MUTATIONS IN A WIDE RANGE OF MYELOID AND LYMPHOID MALIGNANCIES. TET2 FUNCTIONS AS A BONA FIDE TUMOR SUPPRESSOR PARTICULARLY IN THE PATHOGENESIS OF MYELOID MALIGNANCIES RESEMBLING CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND MYELODYSPLASTIC SYNDROMES (MDS) IN HUMAN. HERE WE REVIEW DIVERSE FUNCTIONS OF TET PROTEINS AND THE NOVEL EPIGENETIC MARKS THAT THEY GENERATE IN DNA METHYLATION/DEMETHYLATION DYNAMICS AND NORMAL AND MALIGNANT HEMATOPOIETIC DIFFERENTIATION. THE IMPACT OF TET2 INACTIVATION IN HEMATOPOIESIS AND VARIOUS MECHANISMS MODULATING THE EXPRESSION OR ACTIVITY OF TET PROTEINS ARE ALSO DISCUSSED. FURTHERMORE, WE ALSO PRESENT EVIDENCE THAT TET2 AND TET3 COLLABORATE TO SUPPRESS ABERRANT HEMATOPOIESIS AND HEMATOPOIETIC TRANSFORMATION. A DETAILED UNDERSTANDING OF THE NORMAL AND PATHOLOGICAL FUNCTIONS OF TET PROTEINS MAY PROVIDE NEW AVENUES TO DEVELOP NOVEL EPIGENETIC THERAPIES FOR TREATING HEMATOLOGICAL MALIGNANCIES. 2015 3 5985 38 TET2-MEDIATED CLONAL HEMATOPOIESIS ACCELERATES HEART FAILURE THROUGH A MECHANISM INVOLVING THE IL-1BETA/NLRP3 INFLAMMASOME. BACKGROUND: RECENT STUDIES HAVE SHOWN THAT HEMATOPOIETIC STEM CELLS CAN UNDERGO CLONAL EXPANSION SECONDARY TO SOMATIC MUTATIONS IN LEUKEMIA-RELATED GENES, THUS LEADING TO AN AGE-DEPENDENT ACCUMULATION OF MUTANT LEUKOCYTES IN THE BLOOD. THIS SOMATIC MUTATION-RELATED CLONAL HEMATOPOIESIS IS COMMON IN HEALTHY OLDER INDIVIDUALS, BUT IT HAS BEEN ASSOCIATED WITH AN INCREASED INCIDENCE OF FUTURE CARDIOVASCULAR DISEASE. THE EPIGENETIC REGULATOR TET2 IS FREQUENTLY MUTATED IN BLOOD CELLS OF INDIVIDUALS EXHIBITING CLONAL HEMATOPOIESIS. OBJECTIVES: THIS STUDY INVESTIGATED WHETHER TET2 MUTATIONS WITHIN HEMATOPOIETIC CELLS CAN CONTRIBUTE TO HEART FAILURE IN 2 MODELS OF CARDIAC INJURY. METHODS: HEART FAILURE WAS INDUCED IN MICE BY PRESSURE OVERLOAD, ACHIEVED BY TRANSVERSE AORTIC CONSTRICTION OR CHRONIC ISCHEMIA INDUCED BY THE PERMANENT LIGATION OF THE LEFT ANTERIOR DESCENDING ARTERY. COMPETITIVE BONE MARROW TRANSPLANTATION STRATEGIES WITH TET2-DEFICIENT CELLS WERE USED TO MIMIC TET2 MUTATION-DRIVEN CLONAL HEMATOPOIESIS. ALTERNATIVELY, TET2 WAS SPECIFICALLY ABLATED IN MYELOID CELLS USING CRE RECOMBINASE EXPRESSED FROM THE LYSM PROMOTER. RESULTS: IN BOTH EXPERIMENTAL HEART FAILURE MODELS, HEMATOPOIETIC OR MYELOID TET2 DEFICIENCY WORSENED CARDIAC REMODELING AND FUNCTION, IN PARALLEL WITH INCREASED INTERLEUKIN-1BETA (IL-1BETA) EXPRESSION. TREATMENT WITH A SELECTIVE NLRP3 INFLAMMASOME INHIBITOR PROTECTED AGAINST THE DEVELOPMENT OF HEART FAILURE AND ELIMINATED THE DIFFERENCES IN CARDIAC PARAMETERS BETWEEN TET2-DEFICIENT AND WILD-TYPE MICE. CONCLUSIONS: TET2 DEFICIENCY IN HEMATOPOIETIC CELLS IS ASSOCIATED WITH GREATER CARDIAC DYSFUNCTION IN MURINE MODELS OF HEART FAILURE AS A RESULT OF ELEVATED IL-1BETA SIGNALING. THESE DATA SUGGEST THAT INDIVIDUALS WITH TET2-MEDIATED CLONAL HEMATOPOIESIS MAY BE AT GREATER RISK OF DEVELOPING HEART FAILURE AND RESPOND BETTER TO IL-1BETA-NLRP3 INFLAMMASOME INHIBITION. 2018 4 1674 32 DRIVER MUTATIONS IN LEUKEMIA PROMOTE DISEASE PATHOGENESIS THROUGH A COMBINATION OF CELL-AUTONOMOUS AND NICHE MODULATION. STUDIES OF PATIENTS WITH ACUTE MYELOID LEUKEMIA (AML) HAVE LED TO THE IDENTIFICATION OF MUTATIONS THAT AFFECT DIFFERENT CELLULAR PATHWAYS. SOME OF THESE HAVE BEEN CLASSIFIED AS PRELEUKEMIC, AND A STEPWISE EVOLUTION PROGRAM WHEREBY CELLS ACQUIRE ADDITIONAL MUTATIONS HAS BEEN PROPOSED IN THE DEVELOPMENT OF AML. HOW THE TIMING OF ACQUISITION OF THESE MUTATIONS AND THEIR IMPACT ON TRANSFORMATION AND THE BONE MARROW (BM) MICROENVIRONMENT OCCURS HAS ONLY RECENTLY BEGUN TO BE INVESTIGATED. WE SHOW THAT CONSTITUTIVE AND EARLY LOSS OF THE EPIGENETIC REGULATOR, TET2, WHEN COMBINED WITH CONSTITUTIVE ACTIVATION OF FLT3, RESULTS IN TRANSFORMATION OF CHRONIC MYELOMONOCYTIC LEUKEMIA-LIKE OR MYELOPROLIFERATIVE NEOPLASM-LIKE PHENOTYPE TO AML, WHICH IS MORE PRONOUNCED IN DOUBLE-MUTANT MICE RELATIVE TO MICE CARRYING MUTATIONS IN SINGLE GENES. FURTHERMORE, WE SHOW THAT IN PRELEUKEMIC AND LEUKEMIC MICE THERE ARE ALTERATIONS IN THE BM NICHE AND SECRETED CYTOKINES, WHICH CREATES A PERMISSIVE ENVIRONMENT FOR THE GROWTH OF MUTATION-BEARING CELLS RELATIVE TO NORMAL CELLS. 2020 5 535 34 ASXL1 MUTATION CORRECTION BY CRISPR/CAS9 RESTORES GENE FUNCTION IN LEUKEMIA CELLS AND INCREASES SURVIVAL IN MOUSE XENOGRAFTS. RECURRENT SOMATIC MUTATIONS OF THE EPIGENETIC MODIFIER AND TUMOR SUPPRESSOR ASXL1 ARE COMMON IN MYELOID MALIGNANCIES, INCLUDING CHRONIC MYELOID LEUKEMIA (CML), AND ARE ASSOCIATED WITH POOR CLINICAL OUTCOME. CRISPR/CAS9 HAS RECENTLY EMERGED AS A POWERFUL AND VERSATILE GENOME EDITING TOOL FOR GENOME ENGINEERING IN VARIOUS SPECIES. WE HAVE USED THE CRISPR/CAS9 SYSTEM TO CORRECT THE ASXL1 HOMOZYGOUS NONSENSE MUTATION PRESENT IN THE CML CELL LINE KBM5, WHICH LACKS ASXL1 PROTEIN EXPRESSION. CRISPR/CAS9-MEDIATED ASXL1 HOMOZYGOUS CORRECTION RESULTED IN PROTEIN RE-EXPRESSION WITH RESTORED NORMAL FUNCTION, INCLUDING DOWN-REGULATION OF POLYCOMB REPRESSIVE COMPLEX 2 TARGET GENES. SIGNIFICANTLY REDUCED CELL GROWTH AND INCREASED MYELOID DIFFERENTIATION WERE OBSERVED IN ASXL1 MUTATION-CORRECTED CELLS, PROVIDING NEW INSIGHTS INTO THE ROLE OF ASXL1 IN HUMAN MYELOID CELL DIFFERENTIATION. MICE XENOGRAFTED WITH MUTATION-CORRECTED KBM5 CELLS SHOWED SIGNIFICANTLY LONGER SURVIVAL THAN UNCORRECTED XENOGRAFTS. THESE RESULTS SHOW THAT THE SOLE CORRECTION OF A DRIVER MUTATION IN LEUKEMIA CELLS INCREASES SURVIVAL IN VIVO IN MICE. THIS STUDY PROVIDES PROOF-OF-CONCEPT FOR DRIVER GENE MUTATION CORRECTION VIA CRISPR/CAS9 TECHNOLOGY IN HUMAN LEUKEMIA CELLS AND PRESENTS A STRATEGY TO ILLUMINATE THE IMPACT OF ONCOGENIC MUTATIONS ON CELLULAR FUNCTION AND SURVIVAL. 2015 6 5405 35 REGULATED EXPRESSION OF P210 BCR-ABL DURING EMBRYONIC STEM CELL DIFFERENTIATION STIMULATES MULTIPOTENTIAL PROGENITOR EXPANSION AND MYELOID CELL FATE. P210 BCR-ABL IS AN ACTIVATED TYROSINE KINASE ONCOGENE ENCODED BY THE PHILADELPHIA CHROMOSOME ASSOCIATED WITH HUMAN CHRONIC MYELOGENOUS LEUKEMIA (CML). THE DISEASE REPRESENTS A CLONAL DISORDER ARISING IN THE PLURIPOTENT HEMATOPOIETIC STEM CELL. DURING THE CHRONIC PHASE, PATIENTS PRESENT WITH A DRAMATIC EXPANSION OF MYELOID CELLS AND A MILD ANEMIA. RETROVIRAL GENE TRANSFER AND TRANSGENIC EXPRESSION IN RODENTS HAVE DEMONSTRATED THE ABILITY OF BCR-ABL TO INDUCE VARIOUS TYPES OF LEUKEMIA. HOWEVER, STUDY OF HUMAN CML OR RODENT MODELS HAS NOT DETERMINED THE DIRECT AND IMMEDIATE EFFECTS OF BCR-ABL ON HEMATOPOIETIC CELLS FROM THOSE REQUIRING SECONDARY GENETIC OR EPIGENETIC CHANGES SELECTED DURING THE PATHOGENIC PROCESS. WE UTILIZED TETRACYCLINE-REGULATED EXPRESSION OF BCR-ABL FROM A PROMOTER ENGINEERED FOR ROBUST EXPRESSION IN PRIMITIVE STEM CELLS THROUGH MULTILINEAGE BLOOD CELL DEVELOPMENT IN COMBINATION WITH THE IN VITRO DIFFERENTIATION OF EMBRYONAL STEM CELLS INTO HEMATOPOIETIC ELEMENTS. OUR RESULTS DEMONSTRATE THAT BCR-ABL EXPRESSION ALONE IS SUFFICIENT TO INCREASE THE NUMBER OF MULTIPOTENT AND MYELOID LINEAGE COMMITTED PROGENITORS IN A DOSE-DEPENDENT MANNER WHILE SUPPRESSING THE DEVELOPMENT OF COMMITTED ERYTHROID PROGENITORS. THESE EFFECTS ARE REVERSIBLE UPON EXTINGUISHING BCR-ABL EXPRESSION. THESE FINDINGS ARE CONSISTENT WITH BCR-ABL BEING THE SOLE GENETIC CHANGE NEEDED FOR THE ESTABLISHMENT OF THE CHRONIC PHASE OF CML AND PROVIDE A POWERFUL SYSTEM FOR THE ANALYSIS OF ANY GENETIC CHANGE THAT ALTERS CELL GROWTH AND LINEAGE CHOICES OF THE HEMATOPOIETIC STEM CELL. 2000 7 2111 34 EPIGENETIC FUNCTION OF TET FAMILY, 5-METHYLCYTOSINE, AND 5-HYDROXYMETHYLCYTOSINE IN HEMATOLOGIC MALIGNANCIES. DNA METHYLATION PLAYS SIGNIFICANT ROLES IN A VARIETY OF BIOLOGICAL AND PATHOLOGICAL PROCESSES INCLUDING MAMMALIAN DEVELOPMENT, GENOMIC IMPRINTING, RETROTRANSPOSON SILENCING, AND X-CHROMOSOME INACTIVATION. RECENT DISCOVERIES INDICATED THAT TEN-ELEVEN TRANSLOCATION (TET) FAMILY OF DIOXYGENASES CAN CONVERT 5-METHYLCYTOSINE (5-MC) INTO 5-HYDROXYMETHYLCYTOSINE (5-HMC). THE TET FAMILY INCLUDES THREE MEMBERS: TET1, TET2, AND TET3. WITH INCREASING EVIDENCE, MORE AND MORE BIOLOGICAL AND PATHOLOGICAL PROCESSES IN WHICH 5-HMC AND TET FAMILY SERVE UNPARALLELED BIOLOGICAL ROLES ARE NOTICED, FOR EXAMPLE, DNA DEMETHYLATION AND TRANSCRIPTIONAL REGULATION OF DIFFERENT TARGET GENES, WHICH ARE INVOLVED IN MANY HUMAN DISEASES, ESPECIALLY HEMATOLOGIC MALIGNANCIES, RESEMBLING CHRONIC MYELOMONOCYTIC LEUKEMIA, MYELODYSPLASTIC SYNDROMES, AND SO ON. IN THIS REVIEW, WE FOCUS ON THE DIVERSE FUNCTIONS OF TET FAMILY AND THE NOVEL EPIGENETIC MARKS, 5-MC AND 5-HMC, IN HEMATOLOGIC MALIGNANCIES. THIS REVIEW WILL PROVIDE VALUABLE INSIGHTS INTO THE POTENTIAL TARGETS OF HEMATOLOGIC MALIGNANCIES. FURTHER UNDERSTANDING OF THE NORMAL AND PATHOLOGICAL FUNCTIONS OF TET FAMILY MAY PROVIDE NEW METHODS TO DEVELOP NOVEL EPIGENETIC THERAPIES FOR TREATING HEMATOLOGIC MALIGNANCIES. 2019 8 4838 41 ONCOGENIC N-RAS AND TET2 HAPLOINSUFFICIENCY COLLABORATE TO DYSREGULATE HEMATOPOIETIC STEM AND PROGENITOR CELLS. CONCURRENT GENETIC LESIONS EXIST IN A MAJORITY OF PATIENTS WITH HEMATOLOGIC MALIGNANCIES. AMONG THESE, SOMATIC MUTATIONS THAT ACTIVATE RAS ONCOGENES AND INACTIVATE THE EPIGENETIC MODIFIER TEN-ELEVEN TRANSLOCATION 2 (TET2) FREQUENTLY CO-OCCUR IN HUMAN CHRONIC MYELOMONOCYTIC LEUKEMIAS (CMMLS) AND ACUTE MYELOID LEUKEMIAS, SUGGESTING A COOPERATIVITY IN MALIGNANT TRANSFORMATION. TO TEST THIS, WE APPLIED A CONDITIONAL MURINE MODEL THAT ENDOGENOUSLY EXPRESSED ONCOGENIC NRAS(G12D) AND MONOALLELIC LOSS OF TET2 AND EXPLORED THE COLLABORATIVE ROLE SPECIFICALLY WITHIN HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS) AT DISEASE INITIATION. WE DEMONSTRATE THAT THE 2 MUTATIONS COLLABORATED TO ACCELERATE A TRANSPLANTABLE CMML-LIKE DISEASE IN VIVO, WITH AN OVERALL SHORTENED SURVIVAL AND INCREASED DISEASE PENETRANCE COMPARED WITH SINGLE MUTANTS. AT PRELEUKEMIC STAGE, N-RAS(G12D) AND TET2 HAPLOINSUFFICIENCY TOGETHER INDUCED BALANCED HEMATOPOIETIC STEM CELL (HSC) PROLIFERATION AND ENHANCED COMPETITIVENESS. NRAS(G12D/+)/TET2(+/-) HSCS DISPLAYED INCREASED SELF-RENEWAL IN PRIMARY AND SECONDARY TRANSPLANTATIONS, WITH SIGNIFICANTLY HIGHER RECONSTITUTION THAN SINGLE MUTANTS. STRIKINGLY, THE 2 MUTATIONS TOGETHER CONFERRED LONG-TERM RECONSTITUTION AND SELF-RENEWAL POTENTIAL TO MULTIPOTENT PROGENITORS, A POOL OF CELLS THAT USUALLY HAVE LIMITED SELF-RENEWAL COMPARED WITH HSCS. MOREOVER, HSPCS FROM NRAS(G12D/+)/TET2(+/-) MICE DISPLAYED INCREASED CYTOKINE SENSITIVITY IN RESPONSE TO THROMBOPOIETIN. THEREFORE, OUR STUDIES ESTABLISH A NOVEL TRACTABLE CMML MODEL AND PROVIDE INSIGHTS INTO HOW DYSREGULATED SIGNALING PATHWAYS AND EPIGENETIC MODIFIERS COLLABORATE TO MODULATE HSPC FUNCTION AND PROMOTE LEUKEMOGENESIS. 2018 9 2781 33 EZH2 IN MYELOID MALIGNANCIES. OUR UNDERSTANDING OF THE SIGNIFICANCE OF EPIGENETIC DYSREGULATION IN THE PATHOGENESIS OF MYELOID MALIGNANCIES HAS GREATLY ADVANCED IN THE PAST DECADE. ENHANCER OF ZESTE HOMOLOG 2 (EZH2) IS THE CATALYTIC CORE COMPONENT OF THE POLYCOMB REPRESSIVE COMPLEX 2 (PRC2), WHICH IS RESPONSIBLE FOR GENE SILENCING THROUGH TRIMETHYLATION OF H3K27. EZH2 DYSREGULATION IS HIGHLY TUMORIGENIC AND HAS BEEN OBSERVED IN VARIOUS CANCERS, WITH EZH2 ACTING AS AN ONCOGENE OR A TUMOR-SUPPRESSOR DEPENDING ON CELLULAR CONTEXT. WHILE LOSS-OF-FUNCTION MUTATIONS OF EZH2 FREQUENTLY AFFECT PATIENTS WITH MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS, MYELODYSPLASTIC SYNDROME AND MYELOFIBROSIS, CASES OF CHRONIC MYELOID LEUKEMIA (CML) SEEM TO BE LARGELY CHARACTERIZED BY EZH2 OVEREXPRESSION. A VARIETY OF OTHER FACTORS FREQUENTLY ABERRANT IN MYELOID LEUKEMIA CAN AFFECT PRC2 FUNCTION AND DISEASE PATHOGENESIS, INCLUDING ADDITIONAL SEX COMBS LIKE 1 (ASXL1) AND SPLICING GENE MUTATIONS. AS THE GENETIC BACKGROUND OF MYELOID MALIGNANCIES IS LARGELY HETEROGENEOUS, IT IS NOT SURPRISING THAT EZH2 MUTATIONS ACT IN CONJUNCTION WITH OTHER ABERRATIONS. SINCE EZH2 MUTATIONS ARE CONSIDERED TO BE EARLY EVENTS IN DISEASE PATHOGENESIS, THEY ARE OF THERAPEUTIC INTEREST TO RESEARCHERS, THOUGH TARGETING OF EZH2 LOSS-OF-FUNCTION DOES PRESENT UNIQUE CHALLENGES. PRELIMINARY RESEARCH INDICATES THAT COMBINED TYROSINE KINASE INHIBITOR (TKI) AND EZH2 INHIBITOR THERAPY MAY PROVIDE A STRATEGY TO ELIMINATE THE RESIDUAL DISEASE BURDEN IN CML TO ALLOW PATIENTS TO REMAIN IN TREATMENT-FREE REMISSION. 2020 10 4876 30 OVEREXPRESSION OF ARGINASE 1 IS LINKED TO DNMT3A AND TET2 MUTATIONS IN LOWER-GRADE MYELODYSPLASTIC SYNDROMES AND CHRONIC MYELOMONOCYTIC LEUKEMIA. IMMUNE DYSREGULATION IS A COMMON FEATURE OF MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), PARTICULARLY IN EARLY STAGES. HOWEVER, THE GENETIC BASIS REMAINS POORLY UNDERSTOOD. WE RECENTLY REPORTED THAT MACROPHAGES FROM MICE DEFICIENT IN TET METHYLCYTOSINE DIOXYGENASE 2 (TET2), A MODEL OF MDS/CMML, ARE HYPERINFLAMMATORY AND HAVE INCREASED EXPRESSION OF ARGINASE 1 (ARG1). IN MACROPHAGES AND MYELOID DERIVED SUPPRESSOR CELLS (MDSCS) EXPRESSION OF ARG1 CONTRIBUTES TO T-CELL SUPPRESSION AND IMMUNE EVASION BY L-ARGININE DEPLETION, IN THE SETTING OF CHRONIC INFLAMMATION AND CANCER. SINCE HUMAN MDS AND CMML ARE DRIVEN BY TET2 MUTATIONS AND ASSOCIATED WITH CHRONIC INFLAMMATION, WE HYPOTHESIZED THAT ARGINASE ENZYMATIC ACTIVITY AND ARG1 EXPRESSION WOULD BE INCREASED IN HUMAN MDS/CMML BONE MARROW. ELEVATED ARGINASE ACTIVITY WAS OBSERVED IN BONE MARROW MONONUCLEAR CELLS OF MDS AND CMML PATIENTS WITH LOWER-GRADE FEATURES. IMMUNOHISTOCHEMICAL STUDIES CONFIRMED THAT MYELOMONOCYTIC CELLS OVEREXPRESS ARG1. ADDITIONALLY, MUTATIONS IN THE EPIGENETIC REGULATORS TET2 AND DNMT3A CORRESPONDED TO HIGH ARG1 EXPRESSION AND ACTIVITY. THESE FINDINGS SUGGEST ARG1 IS A BIOMARKER OF IMMUNE DYSREGULATION IN EARLY MDS AND CMML. RECENT MURINE FINDINGS HAVE IMPLICATED TET2 AND DNMT3A IN REGULATION OF INNATE IMMUNITY. OUR STUDY SUGGESTS SIMILAR CHANGES MAY BE DRIVEN BY HUMAN TET2 AND DNMT3A MUTATIONS. 2018 11 913 26 CHRONIC FLT3-ITD SIGNALING IN ACUTE MYELOID LEUKEMIA IS CONNECTED TO A SPECIFIC CHROMATIN SIGNATURE. ACUTE MYELOID LEUKEMIA (AML) IS CHARACTERIZED BY RECURRENT MUTATIONS THAT AFFECT THE EPIGENETIC REGULATORY MACHINERY AND SIGNALING MOLECULES, LEADING TO A BLOCK IN HEMATOPOIETIC DIFFERENTIATION. CONSTITUTIVE SIGNALING FROM MUTATED GROWTH FACTOR RECEPTORS IS A MAJOR DRIVER OF LEUKEMIC GROWTH, BUT HOW ABERRANT SIGNALING AFFECTS THE EPIGENOME IN AML IS LESS UNDERSTOOD. FURTHERMORE, AML CELLS UNDERGO EXTENSIVE CLONAL EVOLUTION, AND THE MUTATIONS IN SIGNALING GENES ARE OFTEN SECONDARY EVENTS. TO ELUCIDATE HOW CHRONIC GROWTH FACTOR SIGNALING ALTERS THE TRANSCRIPTIONAL NETWORK IN AML, WE PERFORMED A SYSTEM-WIDE MULTI-OMICS STUDY OF PRIMARY CELLS FROM PATIENTS SUFFERING FROM AML WITH INTERNAL TANDEM DUPLICATIONS IN THE FLT3 TRANSMEMBRANE DOMAIN (FLT3-ITD). THIS STRATEGY REVEALED COOPERATION BETWEEN THE MAP KINASE (MAPK) INDUCIBLE TRANSCRIPTION FACTOR AP-1 AND RUNX1 AS A MAJOR DRIVER OF A COMMON, FLT3-ITD-SPECIFIC GENE EXPRESSION AND CHROMATIN SIGNATURE, DEMONSTRATING A MAJOR IMPACT OF MAPK SIGNALING PATHWAYS IN SHAPING THE EPIGENOME OF FLT3-ITD AML. 2015 12 2237 36 EPIGENETIC MODIFIERS IN MYELOID MALIGNANCIES: THE ROLE OF HISTONE DEACETYLASE INHIBITORS. MYELOID HEMATOLOGICAL MALIGNANCIES ARE CLONAL BONE MARROW NEOPLASMS, COMPRISING OF ACUTE MYELOID LEUKEMIA (AML), THE MYELODYSPLASTIC SYNDROMES (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), THE MYELOPROLIFERATIVE NEOPLASMS (MPN) AND SYSTEMIC MASTOCYTOSIS (SM). THE FIELD OF EPIGENETIC REGULATION OF NORMAL AND MALIGNANT HEMATOPOIESIS IS RAPIDLY GROWING. IN RECENT YEARS, HETEROZYGOUS SOMATIC MUTATIONS IN GENES ENCODING EPIGENETIC REGULATORS HAVE BEEN FOUND IN ALL SUBTYPES OF MYELOID MALIGNANCIES, SUPPORTING THE RATIONALE FOR TREATMENT WITH EPIGENETIC MODIFIERS. HISTONE DEACETYLASE INHIBITORS (HDACI) ARE EPIGENETIC MODIFIERS THAT, IN VITRO, HAVE BEEN SHOWN TO INDUCE GROWTH ARREST, APOPTOTIC OR AUTOPHAGIC CELL DEATH, AND TERMINAL DIFFERENTIATION OF MYELOID TUMOR CELLS. THESE EFFECTS WERE OBSERVED BOTH AT THE BULK TUMOR LEVEL AND IN THE MOST IMMATURE CD34(+)38(-) CELL COMPARTMENTS CONTAINING THE LEUKEMIC STEM CELLS. THUS, THERE IS A STRONG RATIONALE SUPPORTING HDACI THERAPY IN MYELOID MALIGNANCIES. HOWEVER, DESPITE INITIAL PROMISING RESULTS IN PHASE I TRIALS, HDACI IN MONOTHERAPY AS WELL AS IN COMBINATION WITH OTHER DRUGS, HAVE FAILED TO IMPROVE RESPONSES OR SURVIVAL. THIS REVIEW PROVIDES AN OVERVIEW OF THE RATIONALE FOR HDACI IN MYELOID MALIGNANCIES, CLINICAL RESULTS AND SPECULATIONS ON WHY CLINICAL TRIALS HAVE THUS FAR NOT MET THE EXPECTATIONS, AND HOW THIS MAY BE IMPROVED IN THE FUTURE. 2018 13 3234 29 HEMATOPOIETIC AND CHRONIC MYELOID LEUKEMIA STEM CELLS: MULTI-STABILITY VERSUS LINEAGE RESTRICTION. THERE IS COMPELLING EVIDENCE TO SUPPORT THE VIEW THAT THE CELL-OF-ORIGIN FOR CHRONIC MYELOID LEUKEMIA IS A HEMATOPOIETIC STEM CELL. UNLIKE NORMAL HEMATOPOIETIC STEM CELLS, THE PROGENY OF THE LEUKEMIA STEM CELLS ARE PREDOMINANTLY NEUTROPHILS DURING THE DISEASE CHRONIC PHASE AND THERE IS A MILD ANEMIA. THE HALLMARK ONCOGENE FOR CHRONIC MYELOID LEUKEMIA IS THE BCR-ABLP210 FUSION GENE. VARIOUS STUDIES HAVE EXCLUDED A ROLE FOR BCR-ABLP210 EXPRESSION IN MAINTAINING THE POPULATION OF LEUKEMIA STEM CELLS. STUDIES OF BCR-ABLP210 EXPRESSION IN EMBRYONAL STEM CELLS THAT WERE DIFFERENTIATED INTO HEMATOPOIETIC STEM CELLS AND OF THE EXPRESSION IN TRANSGENIC MICE HAVE REVEALED THAT BCR-ABLP210 IS ABLE TO VEER HEMATOPOIETIC STEM AND PROGENITOR CELLS TOWARDS A MYELOID FATE. FOR THE TRANSGENIC MICE, GLOBAL CHANGES TO THE EPIGENETIC LANDSCAPE WERE OBSERVED. IN CHRONIC MYELOID LEUKEMIA, THE ABILITY OF THE LEUKEMIA STEM CELLS TO CHOOSE FROM THE MANY FATES THAT ARE AVAILABLE TO NORMAL HEMATOPOIETIC STEM CELLS APPEARS TO BE DEREGULATED BY BCR-ABLP210 AND CHANGES TO THE EPIGENOME ARE ALSO IMPORTANT. EVEN SO, WE STILL DO NOT HAVE A PRECISE PICTURE AS TO WHY NEUTROPHILS ARE ABUNDANTLY PRODUCED IN CHRONIC MYELOID LEUKEMIA. 2022 14 2911 39 GENE EXPRESSION PROFILING OF LOSS OF TET2 AND/OR JAK2V617F MUTANT HEMATOPOIETIC STEM CELLS FROM MOUSE MODELS OF MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLINICALLY CHARACTERIZED BY THE CHRONIC OVERPRODUCTION OF DIFFERENTIATED PERIPHERAL BLOOD CELLS AND THE GRADUAL EXPANSION OF MALIGNANT INTRAMEDULLARY/EXTRAMEDULLARY HEMATOPOIESIS. IN MPNS MUTATIONS IN JAK2 MPL OR CALR ARE DETECTED MUTUALLY EXCLUSIVE IN MORE THAN 90% OF CASES [1,2]. MUTATIONS IN THEM LEAD TO THE ABNORMAL ACTIVATION OF JAK/STAT SIGNALING AND THE AUTONOMOUS GROWTH OF DIFFERENTIATED CELLS THEREFORE THEY ARE CONSIDERED AS "DRIVER" GENE MUTATIONS. IN ADDITION TO THE ABOVE DRIVER GENE MUTATIONS MUTATIONS IN EPIGENETIC REGULATORS SUCH AS TET2 DNMT3A ASXL1 EZH2 OR IDH1/2 ARE DETECTED IN ABOUT 5%-30% OF CASES RESPECTIVELY [3]. MUTATIONS IN TET2 DNMT3A EZH2 OR IDH1/2 COMMONLY CONFER THE INCREASED SELF-RENEWAL CAPACITY ON NORMAL HEMATOPOIETIC STEM CELLS (HSCS) BUT THEY DO NOT LEAD TO THE AUTONOMOUS GROWTH OF DIFFERENTIATED CELLS AND ONLY EXHIBIT SUBTLE CLINICAL PHENOTYPES [4,6-8,5]. IT WAS UNCLEAR HOW MUTATIONS IN SUCH EPIGENETIC REGULATORS INFLUENCED ABNORMAL HSCS WITH DRIVER GENE MUTATIONS HOW THEY INFLUENCED THE DISEASE PHENOTYPE OR WHETHER A SINGLE DRIVER GENE MUTATION WAS SUFFICIENT FOR THE INITIATION OF HUMAN MPNS. THEREFORE WE FOCUSED ON JAK2V617F AND LOSS OF TET2-THE FORMER AS A REPRESENTATIVE OF DRIVER GENE MUTATIONS AND THE LATTER AS A REPRESENTATIVE OF MUTATIONS IN EPIGENETIC REGULATORS-AND EXAMINED THE INFLUENCE OF SINGLE OR DOUBLE MUTATIONS ON HSCS (LINEAGE(-)SCA-1(+)C-KIT(+) CELLS (LSKS)) BY FUNCTIONAL ANALYSES AND MICROARRAY WHOLE-GENOME EXPRESSION ANALYSES [9]. GENE EXPRESSION PROFILING SHOWED THAT THE HSC FINGERPRINT GENES [10] WAS STATISTICALLY EQUALLY ENRICHED IN TET2-KNOCKDOWN-LSKS BUT NEGATIVELY ENRICHED IN JAK2V617F-LSKS COMPARED TO THAT IN WILD-TYPE-LSKS. DOUBLE-MUTANT-LSKS SHOWED THE SAME TENDENCY AS JAK2V617F-LSKS IN TERMS OF THEIR HSC FINGERPRINT GENES BUT THE EXPRESSION OF INDIVIDUAL GENES DIFFERED BETWEEN THE TWO GROUPS. AMONG 245 HSC FINGERPRINT GENES 100 WERE MORE HIGHLY EXPRESSED IN DOUBLE-MUTANT-LSKS THAN IN JAK2V617F-LSKS. THESE ALTERED GENE EXPRESSIONS MIGHT PARTLY EXPLAIN THE MECHANISMS OF INITIATION AND PROGRESSION OF MPNS WHICH WAS OBSERVED IN THE FUNCTIONAL ANALYSES [9]. HERE WE DESCRIBE GENE EXPRESSION PROFILES DEPOSITED AT THE GENE EXPRESSION OMNIBUS (GEO) UNDER THE ACCESSION NUMBER GSE62302 INCLUDING EXPERIMENTAL METHODS AND QUALITY CONTROL ANALYSES. 2015 15 4530 33 MULTILAYER INTRACLONAL HETEROGENEITY IN CHRONIC MYELOMONOCYTIC LEUKEMIA. THE FUNCTIONAL DIVERSITY OF CELLS THAT COMPOSE MYELOID MALIGNANCIES, I.E., THE RESPECTIVE ROLES OF GENETIC AND EPIGENETIC HETEROGENEITY IN THIS DIVERSITY, REMAINS POORLY UNDERSTOOD. THIS QUESTION IS ADDRESSED IN CHRONIC MYELOMONOCYTIC LEUKEMIA, A MYELOID NEOPLASM IN WHICH CLINICAL DIVERSITY CONTRASTS WITH LIMITED GENETIC HETEROGENEITY. TO GENERATE INDUCED PLURIPOTENT STEM CELL CLONES, WE REPROGRAMMED CD34(+) CELLS COLLECTED FROM A PATIENT WITH A CHRONIC MYELOMONOCYTIC LEUKEMIA IN WHICH WHOLE EXOME SEQUENCING OF PERIPHERAL BLOOD MONOCYTE DNA HAD IDENTIFIED 12 GENE MUTATIONS, INCLUDING A MUTATION IN KDM6A AND TWO HETEROZYGOUS MUTATIONS IN TET2 IN THE FOUNDING CLONE AND A SECONDARY KRAS(G12D) MUTATION. CD34(+) CELLS FROM AN AGE-MATCHED HEALTHY DONOR WERE ALSO REPROGRAMMED. WE CAPTURED A PART OF THE GENETIC HETEROGENEITY OBSERVED IN THE PATIENT, I.E. WE ANALYZED FIVE CLONES WITH TWO GENETIC BACKGROUNDS, WITHOUT AND WITH THE KRAS(G12D) MUTATION. HEMATOPOIETIC DIFFERENTIATION OF THESE CLONES RECAPITULATED THE MAIN FEATURES OF THE PATIENT'S DISEASE, INCLUDING OVERPRODUCTION OF GRANULOMONOCYTES AND DYSMEGAKARYOPOIESIS. THESE ANALYSES ALSO DISCLOSED SIGNIFICANT DISCREPANCIES IN THE BEHAVIOR OF HEMATOPOIETIC CELLS DERIVED FROM INDUCED PLURIPOTENT STEM CELL CLONES WITH SIMILAR GENETIC BACKGROUND, CORRELATING WITH LIMITED EPIGENETIC CHANGES. THESE ANALYSES SUGGEST THAT, BEYOND THE CODING MUTATIONS, SEVERAL LEVELS OF INTRACLONAL HETEROGENEITY MAY PARTICIPATE IN THE YET UNEXPLAINED CLINICAL HETEROGENEITY OF THE DISEASE. 2020 16 5983 49 TET2 RESTRAINS INFLAMMATORY GENE EXPRESSION IN MACROPHAGES. TET METHYLCYTOSINE DIOXYGENASE 2 (TET2) IS ONE OF THE EARLIEST AND MOST FREQUENTLY MUTATED GENES IN CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP) AND MYELOID CANCERS, INCLUDING MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). TET2 CATALYZES THE OXIDATION OF 5-METHYLCYTOSINE TO 5-HYDROXYMETHYLCYTOSINE, LEADING TO DNA DEMETHYLATION, AND ALSO AFFECTS TRANSCRIPTION BY RECRUITING HISTONE MODIFIERS. INACTIVATING TET2 MUTATIONS CAUSE EPIGENETIC DYSREGULATION, CLONAL HEMATOPOIETIC STEM CELL (HSC) DOMINANCE, AND MONOCYTIC LINEAGE SKEWING. HERE, WE FOUND THAT TET2 WAS THE MOST HIGHLY EXPRESSED TET ENZYME IN MURINE MACROPHAGE (MPHI) DIFFERENTIATION. TET2 TRANSCRIPTION WAS FURTHER INDUCED BY LIPOPOLYSACCHARIDE (LPS), BUT NOT INTERLEUKIN (IL)-4, STIMULATION, POTENTIALLY IN A NUCLEAR FACTOR KAPPABETA-DEPENDENT MANNER. TET2 LOSS DID NOT AFFECT EARLY LPS GENE RESPONSES IN VITRO, BUT INCREASED IL-1B, IL-6, AND ARGINASE 1 (ARG1) MRNA EXPRESSION AT LATER STAGES OF STIMULATION IN BONE-MARROW-DERIVED MPHIS (BMMPHIS). TET2-DEFICIENT PERITONEAL MPHIS, HOWEVER, DEMONSTRATED PROFOUND, CONSTITUTIVE EXPRESSION OF LPS-INDUCED GENES ASSOCIATED WITH AN INFLAMMATORY STATE IN VIVO. IN CONTRAST, TET2 DEFICIENCY DID NOT AFFECT ALTERNATIVE MPHI GENE EXPRESSION SIGNIFICANTLY IN RESPONSE TO IL-4. THESE RESULTS SUGGESTED IMPAIRED RESOLUTION OF INFLAMMATION IN THE ABSENCE OF TET2 BOTH IN VITRO AND IN VIVO. FOR THE FIRST TIME, WE ALSO DETECTED TET2 MUTATIONS IN BMMPHIS FROM MDS AND CMML PATIENTS AND ASSAYED THEIR EFFECTS ON LPS RESPONSES, INCLUDING THEIR POTENTIAL INFLUENCE ON HUMAN IL-6 EXPRESSION. OUR RESULTS SHOW THAT TET2 RESTRAINS INFLAMMATION IN MURINE MPHIS AND MICE, RAISING THE POSSIBILITY THAT LOSS OF TET2 FUNCTION IN MPHIS MAY ALTER THE IMMUNE ENVIRONMENT IN THE LARGE ELDERLY POPULATION WITH TET2-MUTANT CHIP AND IN TET2-MUTANT MYELOID CANCER PATIENTS. 2017 17 390 32 AN INTEGRATIVE MODEL OF PATHWAY CONVERGENCE IN GENETICALLY HETEROGENEOUS BLAST CRISIS CHRONIC MYELOID LEUKEMIA. TARGETED THERAPIES AGAINST THE BCR-ABL1 KINASE HAVE REVOLUTIONIZED TREATMENT OF CHRONIC PHASE (CP) CHRONIC MYELOID LEUKEMIA (CML). IN CONTRAST, MANAGEMENT OF BLAST CRISIS (BC) CML REMAINS CHALLENGING BECAUSE BC CELLS ACQUIRE COMPLEX MOLECULAR ALTERATIONS THAT CONFER STEMNESS FEATURES TO PROGENITOR POPULATIONS AND RESISTANCE TO BCR-ABL1 TYROSINE KINASE INHIBITORS. COMPREHENSIVE MODELS OF BC TRANSFORMATION HAVE PROVED ELUSIVE BECAUSE OF THE RARITY AND GENETIC HETEROGENEITY OF BC, BUT ARE IMPORTANT FOR DEVELOPING BIOMARKERS PREDICTING BC PROGRESSION AND EFFECTIVE THERAPIES. TO BETTER UNDERSTAND BC, WE PERFORMED AN INTEGRATED MULTIOMICS ANALYSIS OF 74 CP AND BC SAMPLES USING WHOLE-GENOME AND EXOME SEQUENCING, TRANSCRIPTOME AND METHYLOME PROFILING, AND CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY HIGH-THROUGHPUT SEQUENCING. EMPLOYING PATHWAY-BASED ANALYSIS, WE FOUND THE BC GENOME WAS SIGNIFICANTLY ENRICHED FOR MUTATIONS AFFECTING COMPONENTS OF THE POLYCOMB REPRESSIVE COMPLEX (PRC) PATHWAY. WHILE TRANSCRIPTOMICALLY, BC PROGENITORS WERE ENRICHED AND DEPLETED FOR PRC1- AND PRC2-RELATED GENE SETS RESPECTIVELY. BY INTEGRATING OUR DATA SETS, WE DETERMINED THAT BC PROGENITORS UNDERGO PRC-DRIVEN EPIGENETIC REPROGRAMMING TOWARD A CONVERGENT TRANSCRIPTOMIC STATE. SPECIFICALLY, PRC2 DIRECTS BC DNA HYPERMETHYLATION, WHICH IN TURN SILENCES KEY GENES INVOLVED IN MYELOID DIFFERENTIATION AND TUMOR SUPPRESSOR FUNCTION VIA SO-CALLED EPIGENETIC SWITCHING, WHEREAS PRC1 REPRESSES AN OVERLAPPING AND DISTINCT SET OF GENES, INCLUDING NOVEL BC TUMOR SUPPRESSORS. ON THE BASIS OF THESE OBSERVATIONS, WE DEVELOPED AN INTEGRATED MODEL OF BC THAT FACILITATED THE IDENTIFICATION OF COMBINATORIAL THERAPIES CAPABLE OF REVERSING BC REPROGRAMMING (DECITABINE+PRC1 INHIBITORS), NOVEL PRC-SILENCED TUMOR SUPPRESSOR GENES (NR4A2), AND GENE EXPRESSION SIGNATURES PREDICTIVE OF DISEASE PROGRESSION AND DRUG RESISTANCE IN CP. 2020 18 144 29 ABERRANT DNA METHYLATION PROFILE OF CHRONIC AND TRANSFORMED CLASSIC PHILADELPHIA-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS. MOST DNA METHYLATION STUDIES IN CLASSIC PHILADELPHIA-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS HAVE BEEN PERFORMED ON A GENE-BY-GENE BASIS. THEREFORE, A MORE COMPREHENSIVE METHYLATION PROFILING IS NEEDED TO STUDY THE IMPLICATIONS OF THIS EPIGENETIC MARKER IN MYELOPROLIFERATIVE NEOPLASMS. HERE, WE HAVE ANALYZED 71 CHRONIC (24 POLYCYTHEMIA VERA, 23 ESSENTIAL THROMBOCYTHEMIA AND 24 PRIMARY MYELOFIBROSIS) AND 13 TRANSFORMED MYELOPROLIFERATIVE NEOPLASMS USING GENOME-WIDE DNA METHYLATION ARRAYS. THE THREE TYPES OF CHRONIC PHILADELPHIA-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS SHOWED A SIMILAR ABERRANT DNA METHYLATION PATTERN WHEN COMPARED TO CONTROL SAMPLES. DIFFERENTIALLY METHYLATED REGIONS WERE ENRICHED IN A GENE NETWORK CENTERED ON THE NF-KAPPAB PATHWAY, INDICATING THAT THEY MAY BE INVOLVED IN THE PATHOGENESIS OF THESE DISEASES. IN THE CASE OF TRANSFORMED MYELOPROLIFERATIVE NEOPLASMS, WE DETECTED AN INCREASED NUMBER OF DIFFERENTIALLY METHYLATED REGIONS WITH RESPECT TO CHRONIC MYELOPROLIFERATIVE NEOPLASMS. INTERESTINGLY, THESE GENES WERE ENRICHED IN A LIST OF DIFFERENTIALLY METHYLATED REGIONS IN PRIMARY ACUTE MYELOID LEUKEMIA AND IN A GENE NETWORK CENTERED AROUND THE IFN PATHWAY. OUR RESULTS SUGGEST THAT ALTERATIONS IN THE DNA METHYLATION LANDSCAPE PLAY AN IMPORTANT ROLE IN THE PATHOGENESIS AND LEUKEMIC TRANSFORMATION OF MYELOPROLIFERATIVE NEOPLASMS. THE THERAPEUTIC MODULATION OF EPIGENETICALLY-DEREGULATED PATHWAYS MAY ALLOW US TO DESIGN TARGETED THERAPIES FOR THESE PATIENTS. 2013 19 6773 27 [ADVANCES OF RESEARCH ON DEMETHYLATION THERAPY FOR HEMATOLOGIC MALIGNANCIES]. DNA METHYLATION IS AN IMPORTANT AND REVERSIBLE EPIGENETIC MODIFICATION WHICH REGULATES GENOMIC STABILITY. METHYLATION IS ESSENTIAL FOR MAMMALIAN DEVELOPMENT. GENERALLY, GENE EXPRESSION LEVEL AND DNA METHYLATION ARE NEGATIVE CORRELATION. TRANSCRIPTIONAL SILENCING VIA METHYLATION OF CPG ISLANDS IN THE PROMOTER IS IMPORTANT FOR CELL GROWTH AND DIFFERENTIATION AND PLAYS A KEY ROLE IN TUMORIGENESIS. DEMETHYLATION DRUG CAN MODIFY CHROMATIN AND RESTORE THE ABILITY OF ANTI-ONCOGENE. DEMETHYLATION THERAPY AS A NEW THERAPY MAY TREAT EFFICIENTLY HEMATOLOGICAL MALIGNANCIES WITH RESISTANCE AND RELAPSE. IN THIS REVIEW, DNA METHYLATION MECHANISM, RELATIONSHIP BETWEEN ABERRANT METHYLATION AND HEMATOLOGIC MALIGNANCIES, MECHANISM OF DEMETHYLATION THERAPY, THE ADVANCE OF RESEARCH ON THE DEMETHYLATION THERAPY OF HEMATOLOGICAL MALIGNANCIES, SUCH AS ACUTE AND CHRONIC LEUKEMIA, LYMPHOMA, MYELODYSPLASTIC SYNDROME WERE SUMMARIZED. 2009 20 825 33 CHARACTERIZATION OF FUNCTIONAL TRANSPOSABLE ELEMENT ENHANCERS IN ACUTE MYELOID LEUKEMIA. TRANSPOSABLE ELEMENTS (TES) HAVE BEEN SHOWN TO HAVE IMPORTANT GENE REGULATORY FUNCTIONS AND THEIR ALTERATION COULD LEAD TO DISEASE PHENOTYPES. ACUTE MYELOID LEUKEMIA (AML) DEVELOPS AS A CONSEQUENCE OF A SERIES OF GENETIC CHANGES IN HEMATOPOIETIC PRECURSOR CELLS, INCLUDING MUTATIONS IN EPIGENETIC FACTORS. HERE, WE SET OUT TO STUDY THE GENE REGULATORY ROLE OF TES IN AML. WE FIRST EXPLORED THE EPIGENETIC LANDSCAPE OF TES IN AML PATIENTS USING ATAC-SEQ DATA. WE SHOW THAT A LARGE NUMBER OF TES IN GENERAL, AND MORE SPECIFICALLY MAMMALIAN-WIDE INTERSPERSED REPEATS (MIRS), ARE MORE ENRICHED IN AML CELLS THAN IN NORMAL BLOOD CELLS. WE OBTAINED A SIMILAR FINDING WHEN ANALYZING HISTONE MODIFICATION DATA IN AML PATIENTS. GENE ONTOLOGY ENRICHMENT ANALYSIS SHOWED THAT GENES NEAR MIRS IN OPEN CHROMATIN REGIONS ARE INVOLVED IN LEUKEMOGENESIS. TO FUNCTIONALLY VALIDATE THEIR REGULATORY ROLE, WE SELECTED 19 MIR REGIONS IN AML CELLS, AND TESTED THEM FOR ENHANCER ACTIVITY IN AN AML CELL LINE (KASUMI-1) AND A CHRONIC MYELOID LEUKEMIA (CML) CELL LINE (K562); THE RESULTS REVEALED SEVERAL MIRS TO BE FUNCTIONAL ENHANCERS. TAKEN TOGETHER, OUR RESULTS SUGGEST THAT TES ARE POTENTIALLY INVOLVED IN MYELOID LEUKEMOGENESIS AND HIGHLIGHT THESE SEQUENCES AS POTENTIAL CANDIDATES HARBORING AML-ASSOCIATED VARIATION. 2020