1 5940 115 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 2 3644 24 INCREASED LEVELS OF ENDOGENOUS RETROVIRUSES TRIGGER FIBROINFLAMMATION AND PLAY A ROLE IN KIDNEY DISEASE DEVELOPMENT. INFLAMMATION IS A COMMON FEATURE OF ALL FORMS OF CHRONIC KIDNEY DISEASE; HOWEVER, THE UNDERLYING MECHANISM REMAINS POORLY UNDERSTOOD. EVOLUTIONARILY INHERITED ENDOGENOUS RETROVIRUSES (ERVS) HAVE THE POTENTIAL TO TRIGGER AN IMMUNE REACTION. COMPREHENSIVE RNA-SEQUENCING OF CONTROL AND DISEASED KIDNEYS FROM HUMAN AND MOUSE DISEASE MODELS INDICATED HIGHER EXPRESSION OF TRANSPOSABLE ELEMENTS (TES) AND ERVS IN DISEASED KIDNEYS. LOSS OF CYTOSINE METHYLATION CAUSING EPIGENETIC DEREPRESSION LIKELY CONTRIBUTES TO AN INCREASE IN ERV LEVELS. GENETIC DELETION/PHARMACOLOGICAL INHIBITION OF DNA METHYLTRANSFERASE 1 (DNMT1) INDUCES ERV EXPRESSION. IN CULTURED KIDNEY TUBULE CELLS, ERVS ELICIT THE ACTIVATION OF CYTOSOLIC NUCLEOTIDE SENSORS SUCH AS RIG-I, MDA5, AND STING. ERVS EXPRESSIONS IN KIDNEY TUBULES TRIGGER RIG-I/STING, AND CYTOKINE EXPRESSION, AND CORRELATE WITH THE PRESENCE OF IMMUNE CELLS. GENETIC DELETION OF RIG-I OR STING OR TREATMENT WITH REVERSE TRANSCRIPTASE INHIBITOR AMELIORATES KIDNEY FIBROINFLAMMATION. OUR DATA INDICATE AN IMPORTANT ROLE OF EPIGENETIC DEREPRESSION-INDUCED ERV ACTIVATION TRIGGERING RENAL FIBROINFLAMMATION. 2023 3 5861 53 SUPER-ENHANCER LANDSCAPE REVEALS LEUKEMIA STEM CELL RELIANCE ON X-BOX BINDING PROTEIN 1 AS A THERAPEUTIC VULNERABILITY. RELAPSE OF PATIENTS WITH CHRONIC MYELOGENOUS LEUKEMIA (CML) MAY OCCUR AT LEAST PARTIALLY BECAUSE LEUKEMIA STEM CELLS (LSCS) LACK SENSITIVITY TO TYROSINE KINASE INHIBITORS (TKIS) SUCH AS IMATINIB. THE PRECISE REGULATION OF LSC STEMNESS IS INCOMPLETELY UNDERSTOOD. GIVEN THAT TRAITS OF LSCS ARE SUBJECT TO EPIGENETIC REGULATION, WE HYPOTHESIZED THAT LSCS MIGHT BE DEPENDENT ON CONTINUOUS ACTIVE TRANSCRIPTION OF GENES ASSOCIATED WITH SUPER-ENHANCERS (SES), WHICH MIGHT, IN TURN, SUGGEST AN OPPORTUNITY FOR INTERVENTION. IN THIS STUDY, WE TESTED THIS HYPOTHESIS AND DELINEATED THE SE LANDSCAPE IN LSCS FROM PATIENTS WITH CML. DISRUPTION OF THE SE-ASSOCIATED GENE TRANSCRIPTION BY THZ1, A COVALENT CYCLIN-DEPENDENT KINASE 7 (CDK7) INHIBITOR, EFFICIENTLY ERADICATED LSCS IN RETROVIRAL BCR-ABL-DRIVEN CML MICE WHILE SPARING NORMAL HEMATOPOIETIC STEM CELLS. FURTHERMORE, WE FOUND THAT X-BOX BINDING PROTEIN 1 (XBP1), A SUBSTRATE OF MRNA-SPLICING ENDONUCLEASE IRE1ALPHA IN THE UNFOLDED PROTEIN RESPONSE PATHWAY, WAS AN SE-ASSOCIATED ONCOGENE IN LSCS. KNOCKDOWN OF XBP1 REDUCED SURVIVAL AND SELF-RENEWAL CAPACITY IN PRIMARY CML CD34(+) CELLS AND ERADICATED LSCS IN CML MICE. SELECTIVELY BLOCKING GENERATION OF THE SPLICED FORM OF XBP1 BY HEMATOPOIETIC CELL-SPECIFIC IRE1 CONDITIONAL KNOCKOUT SUPPRESSED THE PROGRESSION OF CML AND IMPAIRED THE LEUKEMOGENESIS OF LSCS IN CML MICE. OVERALL, WE IDENTIFIED AN EPIGENETIC TRANSCRIPTIONAL PROGRAM IN LSCS, ADDING TO EVIDENCE FOR THE THEORY OF "ONCOGENE ADDICTION" AND SUGGESTING A POTENTIAL TARGETING STRATEGY FOR CML. 2021 4 6523 27 TRANSCRIPTIONAL AND EPIGENETIC REGULATORY MECHANISMS AFFECTING HTLV-1 PROVIRUS. HUMAN T-CELL LEUKEMIA VIRUS TYPE 1 (HTLV-1) IS A RETROVIRUS ASSOCIATED WITH HUMAN DISEASES, SUCH AS ADULT T-CELL LEUKEMIA (ATL) AND HTLV-1-ASSOCIATED MYELOPATHY/TROPIC SPASTIC PARAPARESIS (HAM/TSP). AS A RETROVIRUS, ITS LIFE CYCLE INCLUDES A STEP WHERE HTLV-1 IS INTEGRATED INTO THE HOST GENOMIC DNA AND FORMS PROVIRAL DNA. IN THE CHRONIC PHASE OF THE INFECTION, HTLV?1 IS KNOWN TO PROLIFERATE AS A PROVIRUS VIA THE MITOTIC DIVISION OF THE INFECTED HOST CELLS. THERE ARE GENERALLY TENS OF THOUSANDS OF INFECTED CLONES WITHIN AN INFECTED INDIVIDUAL. THEY EXIST NOT ONLY IN PERIPHERAL BLOOD, BUT ALSO IN VARIOUS LYMPHOID ORGANS. VIRAL PROTEINS ENCODED IN HTLV-1 GENOME PLAY A ROLE IN THE PROLIFERATION AND SURVIVAL OF THE INFECTED CELLS. AS IS THE CASE WITH OTHER CHRONIC VIRAL INFECTIONS, HTLV-1 GENE EXPRESSION INDUCES THE ACTIVATION OF THE HOST IMMUNITY AGAINST THE VIRUS. THUS, THE TRANSCRIPTION FROM HTLV-1 PROVIRUS NEEDS TO BE CONTROLLED IN ORDER TO EVADE THE HOST IMMUNE SURVEILLANCE. THERE SHOULD BE A DYNAMIC AND COMPLEX REGULATION IN VIVO, WHERE AN EQUILIBRIUM BETWEEN VIRAL ANTIGEN EXPRESSION AND HOST IMMUNE SURVEILLANCE IS ACHIEVED. THE MECHANISMS REGULATING VIRAL GENE EXPRESSION FROM THE PROVIRUS ARE A KEY TO UNDERSTANDING THE PERSISTENT/LATENT INFECTION WITH HTLV-1 AND ITS PATHOGENESIS. IN THIS ARTICLE, WE WOULD LIKE TO REVIEW OUR CURRENT UNDERSTANDING ON THIS TOPIC. 2016 5 5319 53 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 6 1359 24 DEVELOPMENT REFRACTORINESS OF MLL-REARRANGED HUMAN B CELL ACUTE LEUKEMIAS TO REPROGRAMMING INTO PLURIPOTENCY. INDUCED PLURIPOTENT STEM CELLS (IPSCS) ARE A POWERFUL TOOL FOR DISEASE MODELING. THEY ARE ROUTINELY GENERATED FROM HEALTHY DONORS AND PATIENTS FROM MULTIPLE CELL TYPES AT DIFFERENT DEVELOPMENTAL STAGES. HOWEVER, REPROGRAMMING LEUKEMIAS IS AN EXTREMELY INEFFICIENT PROCESS. FEW STUDIES GENERATED IPSCS FROM PRIMARY CHRONIC MYELOID LEUKEMIAS, BUT IPSC GENERATION FROM ACUTE MYELOID OR LYMPHOID LEUKEMIAS (ALL) HAS NOT BEEN ACHIEVED. WE ATTEMPTED TO GENERATE IPSCS FROM DIFFERENT SUBTYPES OF B-ALL TO ADDRESS THE DEVELOPMENTAL IMPACT OF LEUKEMIC FUSION GENES. OKSM(L)-EXPRESSING MONO/POLYCISTRONIC-, RETROVIRAL/LENTIVIRAL/EPISOMAL-, AND SENDAI VIRUS VECTOR-BASED REPROGRAMMING STRATEGIES FAILED TO RENDER IPSCS IN VITRO AND IN VIVO. ADDITION OF TRANSCRIPTOMIC-EPIGENETIC REPROGRAMMING "BOOSTERS" ALSO FAILED TO GENERATE IPSCS FROM B CELL BLASTS AND B-ALL LINES, AND WHEN IPSCS EMERGED THEY LACKED LEUKEMIC FUSION GENES, DEMONSTRATING NON-LEUKEMIC MYELOID ORIGIN. CONVERSELY, MLL-AF4-OVEREXPRESSING HEMATOPOIETIC STEM CELLS/B PROGENITORS WERE SUCCESSFULLY REPROGRAMMED, INDICATING THAT B CELL ORIGIN AND LEUKEMIC FUSION GENE WERE NOT REPROGRAMMING BARRIERS. GLOBAL TRANSCRIPTOME/DNA METHYLOME PROFILING SUGGESTED A DEVELOPMENTAL/DIFFERENTIATION REFRACTORINESS OF MLL-REARRANGED B-ALL TO REPROGRAMMING INTO PLURIPOTENCY. 2016 7 3845 13 IS AGING A "RETRO"SPECTIVE EVENT? REACTIVATION OF ENDOGENOUS RETROVIRUSES (ERVS), THE RELICS OF ANCIENT INFECTIONS, HAS BEEN IMPLICATED IN A NUMBER OF DISEASE CONTEXTS. IN THIS ISSUE OF CELL, LIU ET AL. SHOW HOW REACTIVATION OF ERVS IN OLD AGE CAN INDUCE SENESCENCE. THIS AWAKENING OF ERVS IS ASSOCIATED WITH THEIR EPIGENETIC DEREPRESSION AND CONTRIBUTES TO AGE-ASSOCIATED CHRONIC INFLAMMATION. 2023 8 4569 27 MYELOID-SPECIFIC INACTIVATION OF P15INK4B RESULTS IN MONOCYTOSIS AND PREDISPOSITION TO MYELOID LEUKEMIA. INACTIVATION OF P15INK4B, AN INHIBITOR OF CYCLIN-DEPENDENT KINASES, THROUGH DNA METHYLATION IS ONE OF THE MOST COMMON EPIGENETIC ABNORMALITIES IN MYELOID LEUKEMIA. ALTHOUGH THIS SUGGESTS A KEY ROLE FOR THIS PROTEIN IN MYELOID DISEASE SUPPRESSION, EXPERIMENTAL EVIDENCE TO SUPPORT THIS HAS NOT BEEN REPORTED. TO ADDRESS WHETHER THIS EVENT IS CRITICAL FOR PREMALIGNANT MYELOID DISORDERS AND LEUKEMIA DEVELOPMENT, MICE WERE GENERATED THAT HAVE LOSS OF P15INK4B SPECIFICALLY IN MYELOID CELLS. THE P15INK4B(FL/FL)-LYSMCRE MICE DEVELOP NONREACTIVE MONOCYTOSIS IN THE PERIPHERAL BLOOD ACCOMPANIED BY INCREASED NUMBERS OF MYELOID AND MONOCYTIC CELLS IN THE BONE MARROW RESEMBLING THE MYELOPROLIFERATIVE FORM OF CHRONIC MYELOMONOCYTIC LEUKEMIA. SPONTANEOUS PROGRESSION FROM CHRONIC DISEASE TO ACUTE LEUKEMIA WAS NOT OBSERVED. NEVERTHELESS, MOL4070LTR RETROVIRUS INTEGRATIONS PROVIDED COOPERATIVE GENETIC MUTATIONS RESULTING IN A HIGH FREQUENCY OF MYELOID LEUKEMIA IN KNOCKOUT MICE. TWO COMMON RETROVIRUS INSERTION SITES NEAR C-MYB AND SOX4 GENES WERE IDENTIFIED, AND THEIR TRANSCRIPT UP-REGULATED IN LEUKEMIA, SUGGESTING A COLLABORATIVE ROLE OF THEIR PROTEIN PRODUCTS WITH P15INK4B-DEFICIENCY IN PROMOTING MALIGNANT DISEASE. THIS NEW ANIMAL MODEL DEMONSTRATES EXPERIMENTALLY THAT P15INK4B IS A TUMOR SUPPRESSOR FOR MYELOID LEUKEMIA, AND ITS LOSS MAY PLAY AN ACTIVE ROLE IN THE ESTABLISHMENT OF PRELEUKEMIC CONDITIONS. 2010 9 5924 38 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 10 3798 21 INTERPLAY BETWEEN ACTIVATION OF ENDOGENOUS RETROVIRUSES AND INFLAMMATION AS COMMON PATHOGENIC MECHANISM IN NEUROLOGICAL AND PSYCHIATRIC DISORDERS. HUMAN ENDOGENOUS RETROVIRUSES (ERVS) ARE ANCESTORIAL RETROVIRAL ELEMENTS THAT WERE INTEGRATED INTO OUR GENOME THROUGH GERMLINE INFECTIONS AND INSERTIONS DURING EVOLUTION. THEY HAVE REPEATEDLY BEEN IMPLICATED IN THE AETIOLOGY AND PATHOPHYSIOLOGY OF NUMEROUS HUMAN DISORDERS, PARTICULARLY IN THOSE THAT AFFECT THE CENTRAL NERVOUS SYSTEM. IN ADDITION TO THE KNOWN ASSOCIATION OF ERVS WITH MULTIPLE SCLEROSIS AND AMYOTROPHIC LATERAL SCLEROSIS, A GROWING NUMBER OF STUDIES LINKS THE INDUCTION AND EXPRESSION OF THESE RETROVIRAL ELEMENTS WITH THE ONSET AND SEVERITY OF NEURODEVELOPMENTAL AND PSYCHIATRIC DISORDERS. ALTHOUGH THESE DISORDERS DIFFER IN TERMS OF OVERALL DISEASE PATHOLOGY AND CAUSALITIES, A CERTAIN DEGREE OF (SUBCLINICAL) CHRONIC INFLAMMATION CAN BE IDENTIFIED IN ALL OF THEM. BASED ON THESE COMMONALITIES, WE DISCUSS THE BIDIRECTIONAL RELATIONSHIP BETWEEN ERV EXPRESSION AND INFLAMMATION AND HIGHLIGHT THAT NUMEROUS ENTRY POINTS TO THIS RECIPROCAL SEQUENCE OF EVENTS EXIST, INCLUDING INITIAL INFECTIONS WITH ERV-ACTIVATING PATHOGENS, EXPOSURE TO NON-INFECTIOUS INFLAMMATORY STIMULI, AND CONDITIONS IN WHICH EPIGENETIC SILENCING OF ERV ELEMENTS IS DISRUPTED. 2023 11 5405 34 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 12 1629 22 DNMT3A ARG882 MUTATION DRIVES CHRONIC MYELOMONOCYTIC LEUKEMIA THROUGH DISTURBING GENE EXPRESSION/DNA METHYLATION IN HEMATOPOIETIC CELLS. THE GENE ENCODING DNA METHYLTRANSFERASE 3A (DNMT3A) IS MUTATED IN APPROXIMATELY 20% OF ACUTE MYELOID LEUKEMIA CASES, WITH ARG882 (R882) AS THE HOTSPOT. HERE, WE ADDRESSED THE TRANSFORMATION ABILITY OF THE DNMT3A-ARG882HIS (R882H) MUTANT BY USING A RETROVIRAL TRANSDUCTION AND BONE MARROW TRANSPLANTATION (BMT) APPROACH AND FOUND THAT THE MUTANT GENE CAN INDUCE ABERRANT PROLIFERATION OF HEMATOPOIETIC STEM/PROGENITOR CELLS. AT 12 MO POST-BMT, ALL MICE DEVELOPED CHRONIC MYELOMONOCYTIC LEUKEMIA WITH THROMBOCYTOSIS. RNA MICROARRAY ANALYSIS REVEALED ABNORMAL EXPRESSIONS OF SOME HEMATOPOIESIS-RELATED GENES, AND THE DNA METHYLATION ASSAY IDENTIFIED CORRESPONDING CHANGES IN METHYLATION PATTERNS IN GENE BODY REGIONS. MOREOVER, DNMT3A-R882H INCREASED THE CDK1 PROTEIN LEVEL AND ENHANCED CELL-CYCLE ACTIVITY, THEREBY CONTRIBUTING TO LEUKEMOGENESIS. 2014 13 690 36 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 14 4760 33 NOVEL TREATMENTS OF ADULT T CELL LEUKEMIA LYMPHOMA. ADULT T CELL LEUKEMIA-LYMPHOMA (ATL) IS AN AGGRESSIVE MALIGNANCY SECONDARY TO CHRONIC INFECTION WITH THE HUMAN T CELL LEUKEMIA VIRUS TYPE I (HTLV-I) RETROVIRUS. ATL CARRIES A DISMAL PROGNOSIS. ATL CLASSIFIES INTO FOUR SUBTYPES (ACUTE, LYMPHOMA, CHRONIC, AND SMOLDERING) WHICH DISPLAY DIFFERENT CLINICAL FEATURES, PROGNOSIS AND RESPONSE TO THERAPY, HENCE REQUIRING DIFFERENT CLINICAL MANAGEMENT. SMOLDERING AND CHRONIC SUBTYPES RESPOND WELL TO ANTIRETROVIRAL THERAPY USING THE COMBINATION OF ZIDOVUDINE (AZT) AND INTERFERON-ALPHA (IFN) WITH A SIGNIFICANT PROLONGATION OF SURVIVAL. CONVERSELY, THE WATCH AND WAIT STRATEGY OR CHEMOTHERAPY FOR THESE INDOLENT SUBTYPES ALLIES WITH A POOR LONG-TERM OUTCOME. ACUTE ATL IS ASSOCIATED WITH CHEMO-RESISTANCE AND DISMAL PROGNOSIS. LYMPHOMA SUBTYPES RESPOND BETTER TO INTENSIVE CHEMOTHERAPY BUT SURVIVAL REMAINS POOR. ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION (HSCT) RESULTS IN LONG-TERM SURVIVAL IN ROUGHLY ONE THIRD OF TRANSPLANTED PATIENTS BUT ONLY A SMALL PERCENTAGE OF PATIENTS CAN MAKE IT TO TRANSPLANT. OVERALL, CURRENT TREATMENTS OF AGGRESSIVE ATL ARE NOT SATISFACTORY. PROGNOSIS OF REFRACTORY OR RELAPSED PATIENTS IS DISMAL WITH SOME ENCOURAGING RESULTS WHEN USING LENALIDOMIDE OR MOGAMULIZUMAB. TO OVERCOME RESISTANCE AND PREVENT RELAPSE, PRECLINICAL OR PILOT CLINICAL STUDIES USING TARGETED THERAPIES SUCH AS ARSENIC/IFN, MONOCLONAL ANTIBODIES, EPIGENETIC THERAPIES ARE PROMISING BUT WARRANT FURTHER CLINICAL INVESTIGATION. ANTI-ATL VACCINES INCLUDING TAX PEPTIDE-PULSED DENDRITIC CELLS, INDUCED TAX-SPECIFIC CTL RESPONSES IN ATL PATIENTS. FINALLY, BASED ON THE PROGRESS IN UNDERSTANDING THE PATHOPHYSIOLOGY OF ATL, AND THE RISK-ADAPTED TREATMENT APPROACHES TO DIFFERENT ATL SUBTYPES, TREATMENT STRATEGIES OF ATL SHOULD TAKE INTO ACCOUNT THE HOST IMMUNE RESPONSES AND THE HOST MICROENVIRONMENT INCLUDING HTLV-1 INFECTED NON-MALIGNANT CELLS. HEREIN, WE WILL PROVIDE A SUMMARY OF NOVEL TREATMENTS OF ATL IN VITRO, IN VIVO, AND IN EARLY CLINICAL TRIALS. 2020 15 3158 44 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 16 2402 43 EPIGENETIC REPROGRAMMING SENSITIZES CML STEM CELLS TO COMBINED EZH2 AND TYROSINE KINASE INHIBITION. A MAJOR OBSTACLE TO CURING CHRONIC MYELOID LEUKEMIA (CML) IS RESIDUAL DISEASE MAINTAINED BY TYROSINE KINASE INHIBITOR (TKI)-PERSISTENT LEUKEMIC STEM CELLS (LSC). THESE ARE BCR-ABL1 KINASE INDEPENDENT, REFRACTORY TO APOPTOSIS, AND SERVE AS A RESERVOIR TO DRIVE RELAPSE OR TKI RESISTANCE. WE DEMONSTRATE THAT POLYCOMB REPRESSIVE COMPLEX 2 IS MISREGULATED IN CHRONIC PHASE CML LSCS. THIS IS ASSOCIATED WITH EXTENSIVE REPROGRAMMING OF H3K27ME3 TARGETS IN LSCS, THUS SENSITIZING THEM TO APOPTOSIS UPON TREATMENT WITH AN EZH2-SPECIFIC INHIBITOR (EZH2I). EZH2I DOES NOT IMPAIR NORMAL HEMATOPOIETIC STEM CELL SURVIVAL. STRIKINGLY, TREATMENT OF PRIMARY CML CELLS WITH EITHER EZH2I OR TKI ALONE CAUSED SIGNIFICANT UPREGULATION OF H3K27ME3 TARGETS, AND COMBINED TREATMENT FURTHER POTENTIATED THESE EFFECTS AND RESULTED IN SIGNIFICANT LOSS OF LSCS COMPARED TO TKI ALONE, IN VITRO, AND IN LONG-TERM BONE MARROW MURINE XENOGRAFTS. OUR FINDINGS POINT TO A PROMISING EPIGENETIC-BASED THERAPEUTIC STRATEGY TO MORE EFFECTIVELY TARGET LSCS IN PATIENTS WITH CML RECEIVING TKIS. SIGNIFICANCE: IN CML, TKI-PERSISTENT LSCS REMAIN AN OBSTACLE TO CURE, AND APPROACHES TO ERADICATE THEM REMAIN A SIGNIFICANT UNMET CLINICAL NEED. WE DEMONSTRATE THAT EZH2 AND H3K27ME3 REPROGRAMMING IS IMPORTANT FOR LSC SURVIVAL, BUT RENDERS LSCS SENSITIVE TO THE COMBINED EFFECTS OF EZH2I AND TKI. THIS REPRESENTS A NOVEL APPROACH TO MORE EFFECTIVELY TARGET LSCS IN PATIENTS RECEIVING TKI TREATMENT. CANCER DISCOV; 6(11); 1248-57. (C)2016 AACR.SEE RELATED ARTICLE BY XIE ET AL., P. 1237THIS ARTICLE IS HIGHLIGHTED IN THE IN THIS ISSUE FEATURE, P. 1197. 2016 17 1901 26 ENGRAFTMENT OF CHRONIC MYELOMONOCYTIC LEUKEMIA CELLS IN IMMUNOCOMPROMISED MICE SUPPORTS DISEASE DEPENDENCY ON CYTOKINES. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL HEMATOPOIETIC STEM CELL DISORDER THAT TYPICALLY ASSOCIATES WITH MUTATIONS IN EPIGENETIC, SPLICING, AND SIGNALING GENES. GENETICALLY MODIFIED MOUSE MODELS ONLY PARTIALLY RECAPITULATE THE DISEASE PHENOTYPE, WHEREAS XENOTRANSPLANTATION OF CMML CELLS IN IMMUNOCOMPROMISED MICE HAS BEEN RARELY SUCCESSFUL SO FAR. HERE, CMML CD34(+) CELLS SORTED FROM PATIENT BONE MARROW (BM) OR PERIPHERAL BLOOD (PB) WERE INJECTED INTRAVENOUSLY INTO NSG (NOD/LTSZ-SCID IL2RGAMMANULL) MICE AND NSG MICE ENGINEERED TO EXPRESS HUMAN GRANULO-MONOCYTE COLONY-STIMULATING FACTOR, STEM CELL FACTOR, AND INTERLEUKIN-3 (NSGS MICE). FIFTEEN OUT OF 16 PATIENT SAMPLES (94%) SUCCESSFULLY ENGRAFTED INTO NSG OR NSGS OR BOTH MOUSE STRAINS. THE EXPANSION OF HUMAN CELLS, PREDOMINANT IN THE BM, WAS ALSO OBSERVED IN THE SPLEEN AND THE PB AND WAS GREATLY ENHANCED IN MICE PRODUCING THE 3 HUMAN CYTOKINES. GENE MUTATIONS IDENTIFIED IN ENGRAFTED CELLS WERE MOSTLY SIMILAR TO THOSE IDENTIFIED IN PATIENT CELLS BEFORE INJECTION. SUCCESSFUL SECONDARY ENGRAFTMENT WAS OBTAINED IN NSGS MICE IN 3 OUT OF 10 ATTEMPTS. THUS, PRIMARY CMML LEUKEMIC CELLS EXPAND MUCH BETTER IN NSGS COMPARED WITH NSG MICE WITH LIMITED EFFICACY OF SECONDARY TRANSPLANT. 2017 18 2971 19 GENETIC AND EPIGENETIC SILENCING OF MICRORNA-203 ENHANCES ABL1 AND BCR-ABL1 ONCOGENE EXPRESSION. THE MAMMALIAN GENOME CONTAINS SEVERAL HUNDRED MICRORNAS THAT REGULATE GENE EXPRESSION THROUGH MODULATION OF TARGET MRNAS. HERE, WE REPORT A FRAGILE CHROMOSOMAL REGION LOST IN SPECIFIC HEMATOPOIETIC MALIGNANCIES. THIS 7 MB REGION ENCODES ABOUT 12% OF ALL GENOMIC MICRORNAS, INCLUDING MIR-203. THIS MICRORNA IS ADDITIONALLY HYPERMETHYLATED IN SEVERAL HEMATOPOIETIC TUMORS, INCLUDING CHRONIC MYELOGENOUS LEUKEMIAS AND SOME ACUTE LYMPHOBLASTIC LEUKEMIAS. A PUTATIVE MIR-203 TARGET, ABL1, IS SPECIFICALLY ACTIVATED IN THESE HEMATOPOIETIC MALIGNANCIES IN SOME CASES AS A BCR-ABL1 FUSION PROTEIN (PHILADELPHIA CHROMOSOME). RE-EXPRESSION OF MIR-203 REDUCES ABL1 AND BCR-ABL1 FUSION PROTEIN LEVELS AND INHIBITS TUMOR CELL PROLIFERATION IN AN ABL1-DEPENDENT MANNER. THUS, MIR-203 FUNCTIONS AS A TUMOR SUPPRESSOR, AND RE-EXPRESSION OF THIS MICRORNA MIGHT HAVE THERAPEUTIC BENEFITS IN SPECIFIC HEMATOPOIETIC MALIGNANCIES. 2008 19 2242 27 EPIGENETIC MODULATION OF CD8(+) T CELL FUNCTION IN LENTIVIRUS INFECTIONS: A REVIEW. CD8(+) T CELLS ARE CRITICAL FOR CONTROLLING VIREMIA DURING HUMAN IMMUNODEFICIENCY VIRUS (HIV) INFECTION. THESE CELLS PRODUCE CYTOLYTIC FACTORS AND ANTIVIRAL CYTOKINES THAT ELIMINATE VIRALLY- INFECTED CELLS. DURING THE CHRONIC PHASE OF HIV INFECTION, CD8(+) T CELLS PROGRESSIVELY LOSE THEIR PROLIFERATIVE CAPACITY AND ANTIVIRAL FUNCTIONS. THESE DYSFUNCTIONAL CELLS ARE UNABLE TO CLEAR THE PRODUCTIVELY INFECTED AND REACTIVATED CELLS, REPRESENTING A ROADBLOCK IN HIV CURE. THEREFORE, MECHANISMS TO UNDERSTAND CD8(+) T CELL DYSFUNCTION AND STRATEGIES TO BOOST CD8(+) T CELL FUNCTION NEED TO BE INVESTIGATED. USING THE FELINE IMMUNODEFICIENCY VIRUS (FIV) MODEL FOR LENTIVIRAL PERSISTENCE, WE HAVE DEMONSTRATED THAT CD8(+) T CELLS EXHIBIT EPIGENETIC CHANGES SUCH AS DNA DEMETHYLATION DURING THE COURSE OF INFECTION AS COMPARED TO UNINFECTED CATS. WE HAVE ALSO DEMONSTRATED THAT LENTIVIRUS-ACTIVATED CD4(+)CD25(+) T REGULATORY CELLS INDUCE FORKHEAD BOX P3 (FOXP3) EXPRESSION IN VIRUS-SPECIFIC CD8(+) T CELL TARGETS, WHICH BINDS THE INTERLEUKIN (IL)-2, TUMOR NECROSIS FACTOR (TNF)-Α, AND INTERFERON (IFN)-Γ PROMOTERS IN THESE CD8(+) T CELLS. FINALLY, WE HAVE REPORTED THAT EPIGENETIC MODULATION REDUCES FOXP3 BINDING TO THESE PROMOTER REGIONS. THIS REVIEW COMPARES AND CONTRASTS OUR CURRENT UNDERSTANDING OF CD8(+) T CELL EPIGENETICS AND MECHANISMS OF LYMPHOCYTE SUPPRESSION DURING THE COURSE OF LENTIVIRAL INFECTION FOR TWO ANIMAL MODELS, FIV AND SIMIAN IMMUNODEFICIENCY VIRUS (SIV). 2018 20 5212 39 PRESERVATION OF QUIESCENT CHRONIC MYELOGENOUS LEUKEMIA STEM CELLS BY THE BONE MARROW MICROENVIRONMENT. THE MAJORITY OF LEUKEMIA PATIENTS ACHIEVING REMISSION ULTIMATELY RELAPSE. PERSISTENCE OF LEUKEMIA STEM CELLS (LSC) CAPABLE OF REGENERATING LEUKEMIA IS A MAJOR CAUSE OF RELAPSE. THERE IS A PRESSING NEED TO BETTER UNDERSTAND MECHANISMS OF LSC REGULATION AND THEIR RESISTANCE TO THERAPY IN ORDER TO IMPROVE OUTCOMES FOR LEUKEMIA. CHRONIC MYELOGENOUS LEUKEMIA (CML) IS A LETHAL MYELOPROLIFERATIVE DISORDER THAT THAT IS CAUSED BY HEMATOPOIETIC STEM CELL (HSC) TRANSFORMATION BY THE BCR-ABL TYROSINE KINASE. TREATMENT WITH TYROSINE KINASE INHIBITORS (TKI) HAS REVOLUTIONIZED CML TREATMENT, BUT FAILS TO ELIMINATE LSC RESPONSIBLE FOR PROPAGATING AND REGENERATING LEUKEMIA. THEREFORE, PATIENTS REQUIRE CONTINUED TREATMENT TO PREVENT RELAPSE. LEUKEMIC AND NORMAL STEM CELLS SHARE PROPERTIES OF QUIESCENCE AND SELF-RENEWAL, THAT ARE SUPPORTED BY BONE MARROW NICHES. PERSISTENCE OF LSC AFTER TKI TREATMENT IS RELATED TO TYROSINE KINASE INDEPENDENT MECHANISMS WHICH INCLUDE INTRINSIC PROPERTIES OF LSCS DETERMINED BY EPIGENETIC ALTERATIONS, ALTERED TRANSCRIPTIONAL REGULATORY NETWORKS OR MITOCHONDRIAL/METABOLIC CHANGES. IN ADDITION TO CELL INTRINSIC CHANGES, SIGNALS FROM THE BONE MARROW MICROENVIRONMENT (BMM) PLAY A CRITICAL ROLE IN PROTECTING LSC FROM TKI TREATMENT. EACH TYPE OF ALTERATION MAY OFFER POTENTIAL POINTS OF INTERVENTION FOR THERAPEUTIC TARGETING OF LSC. 2018