1 4533 135 MULTIPLE GENE KNOCKDOWN STRATEGIES FOR INVESTIGATING THE PROPERTIES OF HUMAN LEUKEMIA STEM CELLS AND EXPLORING NEW THERAPIES. THE PAST TWO DECADES HAVE WITNESSED SIGNIFICANT STRIDES IN LEUKEMIA THERAPIES THROUGH APPROVAL OF THERAPEUTIC INHIBITORS TARGETING ONCOGENE-DRIVING DYSREGULATED TYROSINE KINASE ACTIVITIES AND KEY EPIGENETIC AND APOPTOSIS REGULATORS. ALTHOUGH THESE DRUGS HAVE BROUGHT ABOUT COMPLETE REMISSION IN THE MAJORITY OF PATIENTS, MANY PATIENTS FACE RELAPSE OR HAVE REFRACTORY DISEASE. THE MAIN FACTOR CONTRIBUTING TO RELAPSE IS THE PRESENCE OF A SMALL SUBPOPULATION OF DORMANT DRUG-RESISTANT LEUKEMIA CELLS THAT POSSESS STEM CELL FEATURES (TERMED AS LEUKEMIA STEM CELLS OR LSCS). THUS, OVERCOMING DRUG RESISTANCE AND TARGETING LSCS REMAIN MAJOR CHALLENGES FOR CURATIVE TREATMENT OF HUMAN LEUKEMIA. CHRONIC MYELOID LEUKEMIA (CML) IS A GOOD EXAMPLE, WITH RARE, PROPAGATING LSCS AND DRUG-RESISTANT CELLS THAT CANNOT BE ERADICATED BY BCR-ABL-DIRECTED TYROSINE KINASE INHIBITOR (TKI) MONOTHERAPY AND THAT ARE RESPONSIBLE FOR DISEASE RELAPSE/PROGRESSION. THEREFORE, IT IS IMPERATIVE TO IDENTIFY KEY PLAYERS IN REGULATING BCR-ABL1-DEPENDENT AND INDEPENDENT DRUG-RESISTANCE MECHANISMS, AND THEIR KEY PATHWAYS, SO THAT CML LSCS CAN BE SELECTIVELY TARGETED OR SENSITIZED TO TKIS. HERE, WE DESCRIBE SEVERAL EASILY ADAPTABLE GENE KNOCKDOWN APPROACHES IN CD34(+) CML STEM/PROGENITOR CELLS THAT CAN BE USED TO INVESTIGATE THE BIOLOGICAL PROPERTIES OF LSCS AND MOLECULAR EFFECTS OF GENES OF INTEREST (GOI), WHICH CAN BE FURTHER EXPLORED AS THERAPEUTIC MODALITIES AGAINST LSCS IN THE CONTEXT OF HUMAN LEUKEMIA. 2022 2 5212 43 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 3 1469 31 DISTINCT EVOLUTIONARY PATHS IN CHRONIC LYMPHOCYTIC LEUKEMIA DURING RESISTANCE TO THE GRAFT-VERSUS-LEUKEMIA EFFECT. LEUKEMIC RELAPSE REMAINS A MAJOR BARRIER TO SUCCESSFUL ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION (ALLO-HSCT) FOR AGGRESSIVE HEMATOLOGIC MALIGNANCIES. THE BASIS FOR RELAPSE OF ADVANCED LYMPHOID MALIGNANCIES REMAINS INCOMPLETELY UNDERSTOOD AND MAY INVOLVE ESCAPE FROM THE GRAFT-VERSUS-LEUKEMIA (GVL) EFFECT. WE HYPOTHESIZED THAT FOR PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) TREATED WITH ALLO-HSCT, LEUKEMIC CELL-INTRINSIC FEATURES INFLUENCE TRANSPLANT OUTCOMES BY DIRECTING THE EVOLUTIONARY TRAJECTORIES OF CLL CELLS. INTEGRATED GENETIC, TRANSCRIPTOMIC, AND EPIGENETIC ANALYSES OF CLL CELLS FROM 10 PATIENTS REVEALED THAT THE CLINICAL KINETICS OF POST-HSCT RELAPSE ARE SHAPED BY DISTINCT MOLECULAR DYNAMICS. EARLY RELAPSES AFTER ALLO-HSCT EXHIBITED NOTABLE GENETIC STABILITY; SINGLE CLL CELL TRANSCRIPTIONAL ANALYSIS DEMONSTRATED A CELLULAR HETEROGENEITY THAT WAS STATIC OVER TIME. IN CONTRAST, CLL CELLS RELAPSING LATE AFTER ALLO-HSCT DISPLAYED NOTABLE GENETIC EVOLUTION AND EVIDENCE OF NEOANTIGEN DEPLETION, CONSISTENT WITH MARKED SINGLE-CELL TRANSCRIPTIONAL SHIFTS THAT WERE UNIQUE TO EACH PATIENT. WE OBSERVED A GREATER RATE OF EPIGENETIC CHANGE FOR LATE RELAPSES NOT SEEN IN EARLY RELAPSES OR RELAPSES AFTER CHEMOTHERAPY ALONE, SUGGESTING THAT THE SELECTION PRESSURES OF THE GVL BOTTLENECK ARE UNLIKE THOSE IMPOSED BY CHEMOTHERAPY. NO SELECTIVE ADVANTAGE FOR HUMAN LEUKOCYTE ANTIGEN (HLA) LOSS WAS OBSERVED, EVEN WHEN PRESENT IN PRETRANSPLANT SUBPOPULATIONS. GAIN OF STEM CELL MODULES WAS A COMMON SIGNATURE ASSOCIATED WITH LEUKEMIA RELAPSE REGARDLESS OF POSTTRANSPLANT RELAPSE KINETICS. THESE DATA ELUCIDATE THE BIOLOGICAL PATHWAYS THAT UNDERLIE GVL RESISTANCE AND POSTTRANSPLANT RELAPSE. 2020 4 953 41 CHRONIC MYELOID LEUKEMIA STEM CELLS. ALTHOUGH RARE, CHRONIC MYELOID LEUKEMIA (CML) REPRESENTS AN IMPORTANT PARADIGM FOR UNDERSTANDING THE MOLECULAR EVENTS LEADING TO MALIGNANT TRANSFORMATION OF PRIMITIVE HEMATOPOIETIC PROGENITORS. CML WAS THE FIRST CANCER TO BE ASSOCIATED WITH A DEFINED GENETIC ABNORMALITY, BCR-ABL, THAT IS NECESSARY AND SUFFICIENT FOR INITIATING CHRONIC PHASE DISEASE AS WELL AS THE FIRST CANCER TO BE TREATED WITH MOLECULAR TARGETED THERAPY. MALIGNANT PROGENITORS OR LEUKEMIA STEM CELLS (LSCS) EVOLVE AS A RESULT OF BOTH EPIGENETIC AND GENETIC EVENTS THAT ALTER HEMATOPOIETIC PROGENITOR DIFFERENTIATION, PROLIFERATION, SURVIVAL, AND SELF-RENEWAL. LSCS ARE RARE AND DIVIDE LESS FREQUENTLY, AND THUS, REPRESENT A RESERVOIR FOR RELAPSE AND RESISTANCE TO A MOLECULARLY TARGETED SINGLE AGENT. ON SUBVERTING DEVELOPMENTAL PROCESSES NORMALLY RESPONSIBLE FOR MAINTAINING ROBUST LIFE-LONG HEMATOPOIESIS, THE LSCS ARE ABLE TO EVADE THE MAJORITY OF CURRENT CANCER TREATMENTS THAT TARGET RAPIDLY DIVIDING CELLS. ENTHUSIASM FOR THE ENORMOUS SUCCESS OF TYROSINE KINASE INHIBITORS AT CONTROLLING THE CHRONIC PHASE DISEASE IS TEMPERED SOMEWHAT BY THE PERSISTENCE OF THE LSC POOL IN THE MAJORITY OF THE PATIENTS. COMBINED THERAPIES TARGETING ABERRANT PROPERTIES OF LSC MAY OBVIATE THERAPEUTIC RESISTANCE AND RELAPSE IN ADVANCED PHASE AND THERAPEUTICALLY RECALCITRANT CML. 2008 5 2402 49 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 6 952 37 CHRONIC MYELOID LEUKEMIA STEM CELL BIOLOGY. LEUKEMIA PROGRESSION AND RELAPSE IS FUELED BY LEUKEMIA STEM CELLS (LSC) THAT ARE RESISTANT TO CURRENT TREATMENTS. IN THE PROGRESSION OF CHRONIC MYELOID LEUKEMIA (CML), BLAST CRISIS PROGENITORS ARE CAPABLE OF ADOPTING MORE PRIMITIVE BUT DEREGULATED STEM CELL FEATURES WITH ACQUIRED RESISTANCE TO TARGETED THERAPIES. THIS IN TURN PROMOTES LSC BEHAVIOR CHARACTERIZED BY ABERRANT SELF-RENEWAL, DIFFERENTIATION, AND SURVIVAL CAPACITY. MULTIPLE REPORTS SUGGEST THAT CELL CYCLE ALTERATIONS, ACTIVATION OF CRITICAL SIGNALING PATHWAYS, ABERRANT MICROENVIRONMENTAL CUES FROM THE HEMATOPOIETIC NICHE, AND ABERRANT EPIGENETIC EVENTS AND DEREGULATION OF RNA PROCESSING MAY FACILITATE THE ENHANCED SURVIVAL AND MALIGNANT TRANSFORMATION OF CML PROGENITORS. HERE WE REVIEW THE MOLECULAR EVOLUTION OF CML LSC THAT PROMOTES CML PROGRESSION AND RELAPSE. RECENT ADVANCES IN THESE AREAS HAVE IDENTIFIED NOVEL TARGETS THAT REPRESENT IMPORTANT AVENUES FOR FUTURE THERAPEUTIC APPROACHES AIMED AT SELECTIVELY ERADICATING THE LSC POPULATION WHILE SPARING NORMAL HEMATOPOIETIC PROGENITORS IN PATIENTS SUFFERING FROM CHRONIC MYELOID MALIGNANCIES. 2012 7 5283 26 PROPHYLACTIC OR PREEMPTIVE LOW-DOSE AZACITIDINE AND DONOR LYMPHOCYTE INFUSION TO PREVENT DISEASE RELAPSE FOLLOWING ALLOGENEIC TRANSPLANTATION IN PATIENTS WITH HIGH-RISK ACUTE MYELOGENOUS LEUKEMIA OR MYELODYSPLASTIC SYNDROME. BECAUSE OF THE PERSISTENTLY HIGH RATES OF RELAPSE OF PATIENTS WITH HIGH-RISK ACUTE MYELOGENOUS LEUKEMIA (AML) AND MYELODYSPLASTIC SYNDROME (MDS) FOLLOWING ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION (ALLO-HSCT), POST-TRANSPLANTATION MAINTENANCE THERAPY HAS BEEN PROPOSED. WE PREVIOUSLY INITIATED A PHASE II TRIAL IN WHICH EPIGENETIC THERAPY WAS COMBINED WITH IMMUNOTHERAPY IN AN ATTEMPT TO REDUCE DISEASE RELAPSE. IN THAT STUDY, LOW-DOSE AZACITIDINE (AZA) AND ESCALATING DOSES OF DONOR LYMPHOCYTE INFUSION (DLI) WERE GIVEN AS POST-ALLO-HSCT MAINTENANCE TREATMENT. IN THE PRESENT STUDY, WE RETROSPECTIVELY ANALYZE A LARGER COHORT OF PATIENTS RECEIVING POST-TRANSPLANTATION MAINTENANCE THERAPY AND PROVIDE UPDATES ON SOME PATIENTS OF THE EARLIER STUDY. THE OBJECTIVES OF THE PRESENT STUDY WERE TO ANALYZE THE CUMULATIVE INCIDENCE OF RELAPSE (CIR), OVERALL SURVIVAL (OS), AND PROGRESSION-FREE SURVIVAL (PFS) AND THE INCIDENCE OF ACUTE AND CHRONIC GRAFT-VERSUS-HOST DISEASE (GVHD) OF PATIENTS WITH HIGH-RISK AML OR MDS RECEIVING POST-TRANSPLANTATION MAINTENANCE TREATMENT WITH AZA WITH OR WITHOUT DLI. WE RETROSPECTIVELY ANALYZED 77 PATIENTS (54 WITH AML, 23 WITH MDS) CONSIDERED AT HIGH RISK BASED ON EITHER THEIR GENOMIC OR CLINICAL STATUS AT TRANSPLANTATION. FOLLOWING ALLOGENEIC TRANSPLANTATION, THEY RECEIVED AT LEAST 1 CYCLE OF PROPHYLACTIC OR PREEMPTIVE LOW-DOSE AZA WITH OR WITHOUT ESCALATING DOSES OF DLI TO PREVENT DISEASE RELAPSE. ALMOST ONE-HALF OF THE PATIENTS (47%) WERE ABLE TO RECEIVE THE FULL 12 CYCLES OF SCHEDULED AZA, AND A MAJORITY (79%) RECEIVED AT LEAST 1 DLI. WITH A MEDIAN FOLLOW-UP OF 24 MONTHS, 19 PATIENTS (25%; 16 WITH AML, 3 WITH MDS) RELAPSED, AT A MEDIAN OF 9.8 MONTHS (RANGE, 4 TO 58.6 MONTHS), GIVING A 22% CIR AT 24 MONTHS. OS AND PFS AT 24 MONTHS WERE 70.8% AND 68.3%, RESPECTIVELY. THE CUMULATIVE INCIDENCES OF GRADE II-IV ACUTE GVHD AND CHRONIC GVHD WERE 27.4% AND 45%, RESPECTIVELY. ONLY A MINORITY OF PATIENTS (11%) REQUIRED DELAYED ADMINISTRATION OF AZA. THESE FINDINGS CONFIRM THAT AZA-DLI MAINTENANCE IS BOTH TOLERABLE AND EFFECTIVE IN REDUCING THE RISK OF POST-TRANSPLANTATION RELAPSE. 2021 8 6609 48 TYROSINE KINASE INHIBITORS IN PH+ CHRONIC MYELOID LEUKEMIA THERAPY: A REVIEW. CHRONIC MYELOID LEUKAEMIA (CML) IS A CLONAL MYELOPROLIFERATIVE HEMATOPOIETIC STEM CELL DISORDER. DEREGULATED BCRABL FUSION TYROSINE KINASE ACTIVITY IS THE MAIN CAUSE OF CML DISEASE PATHOGENESIS, MAKING BCRABL AN IDEAL TARGET FOR INHIBITION. CURRENT TYROSINE KINASE INHIBITORS (TKIS) DESIGNED TO INHIBIT BCRABL ONCOPROTEIN ACTIVITY, HAVE COMPLETELY TRANSFORMED THE PROGNOSIS OF CML. INTERRUPTION OF TKI TREATMENT LEADS TO MINIMAL RESIDUAL DISEASE RESIDE (MRD), THOUGHT TO RESIDE IN TKIINSENSITIVE LEUKAEMIA STEM CELLS WHICH REMAIN A POTENTIAL RESERVOIR FOR DISEASE RELAPSE. THIS HIGHLIGHTS THE NEED TO DEVELOP NEW THERAPEUTIC STRATEGIES FOR CML EITHER AS SMALL MOLECULE MASTER TKIS OR PHYTOPHARMACEUTICALS DERIVED FROM NATURE TO ACHIEVE CHRONIC MOLECULAR REMISSION. THIS REVIEW OUTLINES THE PAST, PRESENT AND FUTURE THERAPEUTIC APPROACHES FOR CML INCLUDING COVERAGE OF RELEVANT MECHANISMS, WHETHER ABL DEPENDENT OR INDEPENDENT, AND EPIGENETIC FACTORS RESPONSIBLE FOR DEVELOPING RESISTANCE AGAINST TKIS. APPEARANCE OF MUTANT CLONES ALONG THE COURSE OF THERAPY EITHER PREEXISTING OR INDUCED DUE TO THERAPY IS STILL A CHALLENGE FOR THE CLINICIAN. A PROPOSED INVITRO MODEL OF GENERATING COLONY FORMING UNITS FROM CML STEM CELLS DERIVED FROM DIAGNOSTIC SAMPLES SEEMS TO BE ACHIEVABLE IN THE ERA OF HIGH THROUGHPUT TECHNOLOGY WHICH CAN TAKE CARE OF SINGLE CELL GENOMIC PROFILING. 2016 9 6207 31 THE INHIBITION OF HISTONE DEACETYLASES REDUCES THE REINSTATEMENT OF COCAINE-SEEKING BEHAVIOR IN RATS. DRUG ADDICTION IS A CHRONIC BRAIN DISEASE CHARACTERIZED BY A PERSISTENT RISK OF RELAPSE, EVEN AFTER A LONG PERIOD OF ABSTINENCE. A CURRENT HYPOTHESIS STATES THAT RELAPSE RESULTS FROM LASTING NEUROADAPTATIONS THAT ARE INDUCED IN RESPONSE TO REPEATED DRUG ADMINISTRATION. THE ADAPTATIONS REQUIRE GENE EXPRESSION, SOME OF WHICH BEING UNDER THE CONTROL OF STABLE EPIGENETIC REGULATIONS. WE HAVE PREVIOUSLY DEMONSTRATED THAT PRETREATMENT WITH HISTONE DEACETYLASE (HDAC) INHIBITORS REDUCES THE COCAINE REINFORCING PROPERTIES AS WELL AS THE MOTIVATION OF RATS FOR COCAINE. WE SHOW HERE THAT THE SAME HDAC INHIBITORS, TRICHOSTATIN A AND PHENYLBUTYRATE, SIGNIFICANTLY REDUCED THE COCAINE-SEEKING BEHAVIOR INDUCED BY THE COMBINATION OF A COCAINE INJECTION TOGETHER WITH THE EXPOSURE TO A LIGHT CUE PREVIOUSLY ASSOCIATED WITH COCAINE TAKING. REINSTATEMENT OF DRUG-SEEKING BEHAVIOR WAS CARRIED OUT AFTER A 3-WEEK WITHDRAWAL PERIOD, WHICH CAME AFTER TEN DAILY SESSIONS OF COCAINE INTRAVENOUS SELF-ADMINISTRATION. OUR RESULTS SUGGEST THAT PHARMACOLOGICAL TREATMENT AIMED AT MODULATING EPIGENETIC REGULATION, AND PARTICULARLY TREATMENT THAT WOULD INHIBIT HDAC ACTIVITY, COULD REDUCE THE RISK OF RELAPSE, A MAJOR DRAWBACK IN THE TREATMENT OF DRUG ADDICTION. 2011 10 5535 25 ROLE OF BRD4 PHOSPHORYLATION IN THE NUCLEUS ACCUMBENS IN RELAPSE TO COCAINE-SEEKING BEHAVIOR IN MICE. COCAINE ADDICTION IS A CHRONIC RELAPSING BRAIN DISORDER CHARACTERIZED BY COMPULSIVE DRUG SEEKING. PRELIMINARY STUDY SUGGESTED THAT BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4), AN EPIGENETIC READER PROTEIN, PARTICIPATES IN COCAINE-INDUCED REWARD AND NEUROPLASTICITY. HOWEVER, THE EXACT ROLE OF BRD4 IN COCAINE ADDICTION, PARTICULARLY COCAINE RELAPSE, REMAINS ELUSIVE. IN THIS STUDY, WE FOUND THAT BRD4 PHOSPHORYLATION IN THE NUCLEUS ACCUMBENS (NAC) WAS CLOSELY RELATED TO THE MAINTENANCE OF COCAINE REINFORCEMENT AND RELAPSE IN DIFFERENT COCAINE EXPOSURE PARADIGMS. COCAINE SIGNIFICANTLY INCREASED THE BINDING OF PHOSPHORYLATED BRD4 (PBRD4) AT THE PROMOTER OF GRIA2 AND BDNF GENES IN THE NAC. (+)JQ1, A SELECTIVE BRD4 INHIBITOR, MARKEDLY REDUCED THE REINFORCEMENT AND REINSTATEMENT OF COCAINE-SEEKING BEHAVIORS, WHICH WAS ACCOMPANIED BY THE DECREASED EXPRESSIONS OF GRIA2 AND BDNF. FURTHERMORE, CHROMATIN IMMUNOPRECIPITATION ASSAY SHOWED THAT (+)JQ1 CLEARLY ATTENUATED COCAINE-ENHANCED BINDING OF PBRD4 AT THE PROMOTOR OF GRIA2 AND BDNF GENES. BLOCKADE OF CASEIN KINASE II SIGNIFICANTLY ATTENUATED BRD4 PHOSPHORYLATION AND COCAINE RELAPSE-LIKE BEHAVIORS, SUGGESTING THE IMPORTANT ROLE OF PBRD4 IN MODULATING COCAINE EFFECT. TOGETHER, OUR FINDINGS SUGGEST THAT BRD4 PHOSPHORYLATION IN THE NAC MODULATES MULTIPLE ADDICTION-RELATED BEHAVIORS OF COCAINE AND PARTICULARLY RELAPSE TO COCAINE-SEEKING BEHAVIORS. INHIBITION OF BRD4 ACTIVITY MAY BE A NOVEL TARGET AGAINST COCAINE ADDICTION AND RELAPSE. 2020 11 955 41 CHRONIC MYELOID LEUKEMIA: MECHANISMS OF BLASTIC TRANSFORMATION. THE BCR-ABL1 ONCOPROTEIN TRANSFORMS PLURIPOTENT HSCS AND INITIATES CHRONIC MYELOID LEUKEMIA (CML). PATIENTS WITH EARLY PHASE (ALSO KNOWN AS CHRONIC PHASE [CP]) DISEASE USUALLY RESPOND TO TREATMENT WITH ABL TYROSINE KINASE INHIBITORS (TKIS), ALTHOUGH SOME PATIENTS WHO RESPOND INITIALLY LATER BECOME RESISTANT. IN MOST PATIENTS, TKIS REDUCE THE LEUKEMIA CELL LOAD SUBSTANTIALLY, BUT THE CELLS FROM WHICH THE LEUKEMIA CELLS ARE DERIVED DURING CP (SO-CALLED LEUKEMIA STEM CELLS [LSCS]) ARE INTRINSICALLY INSENSITIVE TO TKIS AND SURVIVE LONG TERM. LSCS OR THEIR PROGENY CAN ACQUIRE ADDITIONAL GENETIC AND/OR EPIGENETIC CHANGES THAT CAUSE THE LEUKEMIA TO TRANSFORM FROM CP TO A MORE ADVANCED PHASE, WHICH HAS BEEN SUBCLASSIFIED AS EITHER ACCELERATED PHASE OR BLASTIC PHASE DISEASE. THE LATTER RESPONDS POORLY TO TREATMENT AND IS USUALLY FATAL. HERE, WE DISCUSS WHAT IS KNOWN ABOUT THE MOLECULAR MECHANISMS LEADING TO BLASTIC TRANSFORMATION OF CML AND PROPOSE SOME NOVEL THERAPEUTIC APPROACHES. 2010 12 2259 35 EPIGENETIC PRIMING IN DRUG ADDICTION. DRUG ADDICTION IS A CHRONIC RELAPSING BRAIN DISORDER THAT IS CHARACTERIZED BY COMPULSIVE DRUG SEEKING AND CONTINUED USE DESPITE NEGATIVE OUTCOMES. CURRENT PHARMACOLOGICAL THERAPIES TARGET NEURONAL RECEPTORS OR TRANSPORTERS UPON WHICH DRUGS OF ABUSE ACT INITIALLY, YET THESE TREATMENTS REMAIN INEFFECTIVE FOR MOST INDIVIDUALS AND DO NOT PREVENT DISEASE RELAPSE AFTER ABSTINENCE. DRUGS OF ABUSE, IN ADDITION TO THEIR ACUTE EFFECTS, CAUSE PERSISTENT PLASTICITY AFTER REPEATED USE, INVOLVING DYSREGULATED GENE EXPRESSION IN THE BRAIN'S REWARD REGIONS, WHICH ARE THOUGHT TO MEDIATE THE PERSISTENT BEHAVIORAL ABNORMALITIES THAT CHARACTERIZE ADDICTION. EMERGING EVIDENCE IMPLICATES EPIGENETIC PRIMING AS A KEY MECHANISM THAT UNDERLIES THE LONG-LASTING ALTERATIONS IN NEURONAL GENE REGULATION, WHICH CAN REMAIN LATENT UNTIL TRIGGERED BY RE-EXPOSURE TO DRUG-ASSOCIATED STIMULI OR THE DRUG ITSELF. THUS, TO EFFECTIVELY TREAT DRUG ADDICTION, WE MUST IDENTIFY THE PRECISE EPIGENETIC MECHANISMS THAT ESTABLISH AND PRESERVE THE DRUG-INDUCED PATHOLOGY OF THE BRAIN REWARD CIRCUITRY. 2018 13 5940 42 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 14 1091 29 COGNITIVE ENHANCERS AS A TREATMENT FOR HEROIN RELAPSE AND ADDICTION. HEROIN ADDICTION IS A DISORDER THAT STEMS FROM MALADAPTIVE PLASTICITY WITHIN NEURAL CIRCUITS AND PRODUCES BROAD COGNITIVE DEFICITS. DESPITE CONSIDERABLE ADVANCES IN PSYCHOTHERAPY AND PHARMACOTHERAPY FOR HEROIN RELAPSE AND ADDICTION, EFFECTIVE TREATMENTS FOR HEROIN USE DISORDER ARE STILL LACKING. INCREASING PRECLINICAL EVIDENCE INDICATES THAT HEROIN SEEKING BEHAVIOR IS PERSISTENT AFTER WITHDRAWAL, WHILE COGNITIVE DYSFUNCTIONS ASSOCIATED WITH CHRONIC HEROIN USE ARE AN IMPORTANT CONTRIBUTING FACTOR TO RISK OF HEROIN RELAPSE AND ADDICTION. COGNITIVE ENHANCERS MAY BE USED TO STIMULATE TREATMENT SUCCESS AND ENHANCE TREATMENT EFFICACY. THE PURPOSE OF THIS REVIEW IS TO OUTLINE THE LITERATURE THAT DEMONSTRATES THE COGNITIVE DEFICITS DURING THE DEVELOPMENT OF HEROIN ADDICTION AND WITHDRAWAL PROCESS, AND SEVERAL FACTORS THAT UNDERLINE THE EFFICACY OF COGNITIVE ENHANCERS FOR HEROIN USE DISORDERS. THE REVIEW, THEN, EXAMINES THE POTENTIAL USE AND PHARMACOLOGICAL MECHANISMS OF COGNITIVE ENHANCERS THAT ACT ON CHOLINERGIC, GLUTAMATERGIC, DOPAMINERGIC OR ADRENERGIC PATHWAYS. IT ALSO EXAMINES THE EFFECTS OF COMPOUNDS THAT ALTER CREB SIGNALING AND EPIGENETIC MECHANISMS IN ANIMAL MODEL OF HEROIN RELAPSE. THE CURRENT BODY OF RESEARCH REVEALS THE NEW INSIGHTS INTO THE PHARMACOLOGICAL MECHANISMS UNDERLYING HEROIN ADDICTION AND HOLDS A SIGNIFICANT PROMISE FOR COGNITIVE ENHANCERS AS AN IMPROVED APPROACH TO TREAT HEROIN USE DISORDER IN A MORE EFFICIENT AND PERSISTENT WAY. 2019 15 5319 41 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 16 791 37 CELLULAR AND MOLECULAR NETWORKS IN CHRONIC MYELOID LEUKEMIA: THE LEUKEMIC STEM, PROGENITOR AND STROMAL CELL INTERPLAY. THE USE OF IMATINIB, SECOND AND THIRD GENERATION ABL TYROSINE KINASE INHIBITORS (TKI) (I.E. DASATINIB, NILOTINIB, BOSUTINIB AND PONATINIB) MADE CML A CLINICALLY MANAGEABLE AND, IN A SMALL PERCENTAGE OF CASES, A CURED DISEASE. TKI THERAPY ALSO TURNED CML BLASTIC TRANSFORMATION INTO A RARE EVENT; HOWEVER, DISEASE PROGRESSION STILL OCCURS IN THOSE PATIENTS WHO ARE REFRACTORY, NOT COMPLIANT WITH TKI THERAPY OR DEVELOP RESISTANCE TO MULTIPLE TKIS. IN THE PAST FEW YEARS, IT BECAME CLEAR THAT THE BCRABL1 ONCOGENE DOES NOT OPERATE ALONE TO DRIVE DISEASE EMERGENCE, MAINTENANCE AND PROGRESSION. INDEED, IT SEEMS THAT BONE MARROW (BM) MICROENVIRONMENT-GENERATED SIGNALS AND CELL AUTONOMOUS BCRABL1 KINASE-INDEPENDENT GENETIC AND EPIGENETIC ALTERATIONS ALL CONTRIBUTE TO: I. PERSISTENCE OF A QUIESCENT LEUKEMIC STEM CELL (LSC) RESERVOIR, II. INNATE OR ACQUIRED RESISTANCE TO TKIS, AND III. PROGRESSION INTO THE FATAL BLAST CRISIS STAGE. HEREIN, WE REVIEW THE INTRICATE LEUKEMIC NETWORK IN WHICH ABERRANT, BUT FINELY TUNED, SURVIVAL, MITOGENIC AND SELF-RENEWAL SIGNALS ARE GENERATED BY LEUKEMIC PROGENITORS, STROMAL CELLS, IMMUNE CELLS AND METABOLIC MICROENVIRONMENTAL CONDITIONS (E.G. HYPOXIA) TO PROMOTE LSC MAINTENANCE AND BLASTIC TRANSFORMATION. 2017 17 1882 32 EMERGING TREATMENTS IN ACUTE MYELOID LEUKAEMIA. ACUTE MYELOID LEUKAEMIA (AML) IS THE MOST COMMON FORM OF LEUKAEMIA IN YOUNG ADULTS. ALTHOUGH 75-85% OF PATIENTS WILL ACHIEVE COMPLETE REMISSION AFTER INDUCTION CHEMOTHERAPY, THE LONG-TERM SURVIVAL IS STILL < 50% AT 5 YEARS. CHEMOTHERAPY HAS INCREASED IN INTENSITY IN RECENT YEARS AND IS PERCEIVED TO HAVE REACHED THE LIMIT OF TOXICITY. ALLOGENEIC BONE MARROW TRANSPLANTATION, WHICH IS UNDOUBTEDLY THE MOST EFFECTIVE WAY TO PREVENT RELAPSE, MAY NOT ADD SUBSTANTIAL SURVIVAL BENEFITS. SEVERAL NEW PHARMACOLOGICAL APPROACHES TO THE TREATMENT OF AML ARE NOW BECOMING AVAILABLE, WITH VARIOUS MOLECULAR TARGETS IDENTIFIED, INCLUDING THE FARNESYLATION OF RAS FAMILY PROTEINS AND TYROSINE KINASES INVOLVED IN SIGNAL TRANSDUCTION AND EPIGENETIC METHYLATION. MORE SELECTIVE DELIVERY OF CHEMOTHERAPEUTIC AGENTS IS ALSO FEASIBLE USING HUMANISED MONOCLONAL ANTIBODIES, WITH THE INTRIGUING POSSIBILITY OF INCREASING TREATMENT DELIVERY WITHOUT INCREASING THE TOXICITY. HOWEVER, DESPITE THE PROGRESS IN THE RATIONAL DESIGN OF DRUGS IN DISORDERS SUCH AS CHRONIC MYELOID LEUKAEMIA, AML LACKS A SINGLE SPECIFIC PATHOGNOMIC GENETIC EVENT TO ACT AS A DRUG TARGET. THIS REVIEW DISCUSSES THE DRUGS PRESENTLY UNDER INVESTIGATION IN PHASE II OR PHASE III TRIALS IN AML. 2004 18 1685 46 DRUGGABLE BIOCHEMICAL PATHWAYS AND POTENTIAL THERAPEUTIC ALTERNATIVES TO TARGET LEUKEMIC STEM CELLS AND ELIMINATE THE RESIDUAL DISEASE IN CHRONIC MYELOID LEUKEMIA. CHRONIC MYELOID LEUKEMIA (CML) IS A DISEASE ARISING IN STEM CELLS EXPRESSING THE BCR-ABL ONCOGENIC TYROSINE KINASE THAT TRANSFORMS ONE HEMATOPOIETIC STEM/PROGENITOR CELL INTO A LEUKEMIC STEM CELL (LSC) AT THE ORIGIN OF DIFFERENTIATED AND PROLIFERATING LEUKEMIC CELLS IN THE BONE MARROW (BM). CML-LSCS ARE RECOGNIZED AS BEING RESPONSIBLE FOR RESISTANCES AND RELAPSES THAT OCCUR DESPITE THE ADVENT OF BCR-ABL-TARGETING THERAPIES WITH TYROSINE KINASE INHIBITORS (TKIS). LSCS SHARE A LOT OF FUNCTIONAL PROPERTIES WITH HEMATOPOIETIC STEM CELLS (HSCS) ALTHOUGH SOME PHENOTYPICAL AND FUNCTIONAL DIFFERENCES HAVE BEEN DESCRIBED DURING THE LAST TWO DECADES. SUBVERTED MECHANISMS AFFECTING EPIGENETIC PROCESSES, APOPTOSIS, AUTOPHAGY AND MORE RECENTLY METABOLISM AND IMMUNOLOGY IN THE BONE MARROW MICROENVIRONMENT (BMM) HAVE BEEN REPORTED. THE AIM OF THIS REVIEW IS TO BRING TOGETHER THE MODIFICATIONS AND MOLECULAR MECHANISMS THAT ARE KNOWN TO ACCOUNT FOR TKI RESISTANCE IN PRIMARY CML-LSCS AND TO FOCUS ON THE POTENTIAL SOLUTIONS THAT CAN CIRCUMVENT THESE RESISTANCES, IN PARTICULAR THOSE THAT HAVE BEEN, OR WILL BE TESTED IN CLINICAL TRIALS. 2019 19 570 46 BCR-ABL INDEPENDENT MECHANISMS OF RESISTANCE IN CHRONIC MYELOID LEUKEMIA. NOT ALL CHRONIC MYELOID LEUKEMIA (CML) PATIENTS ARE CURED WITH TYROSINE KINASE INHIBITORS (TKIS), AND A PROPORTION OF THEM DEVELOP RESISTANCE. RECENTLY, CONTINUOUS BCR-ABL GENE EXPRESSION HAS BEEN FOUND IN RESISTANT CELLS WITH UNDETECTABLE BCR-ABL PROTEIN EXPRESSION, INDICATING THAT RESISTANCE MAY OCCUR THROUGH KINASE INDEPENDENT MECHANISMS, MAINLY DUE TO THE PERSISTENCE OF LEUKEMIA STEM CELLS (LSCS). LSCS RESIDE IN THE BONE MARROW NICHE IN A QUIESCENT STATE, AND ARE CHARACTERIZED BY A HIGH HETEROGENEITY IN GENETIC, EPIGENETIC, AND TRANSCRIPTIONAL MECHANISMS. NEW APPROACHES BASED ON SINGLE CELL GENOMICS HAVE OFFERED THE OPPORTUNITY TO IDENTIFY DISTINCT SUBPOPULATIONS OF LSCS AT DIAGNOSIS AND DURING TREATMENT. IN THE ONE HAND, TKIS ARE NOT ABLE TO EFFICIENTLY KILL CML-LSCS, BUT THEY MAY BE RESPONSIBLE FOR THE MODIFICATION OF SOME LSCS CHARACTERISTICS, THUS CONTRIBUTING TO HETEROGENEITY WITHIN THE TUMOR. IN THE OTHER HAND, THE BONE MARROW NICHE IS RESPONSIBLE FOR THE INTERACTIONS BETWEEN SURROUNDING STROMAL CELLS AND LSCS, RESULTING IN THE GENERATION OF SPECIFIC SIGNALS WHICH COULD FAVOR LSCS CELL CYCLE ARREST AND ALLOW THEM TO PERSIST DURING TREATMENT WITH TKIS. ADDITIONALLY, LSCS MAY THEMSELVES ALTER THE NICHE BY EXPRESSING VARIOUS COSTIMULATORY MOLECULES AND SECRETING SUPPRESSIVE CYTOKINES, ABLE TO TARGET METABOLIC PATHWAYS, CREATE AN ANTI-APOPTOTIC ENVIRONMENT, AND ALTER IMMUNE SYSTEM FUNCTIONS. ACCORDINGLY, THE PRODUCTION OF AN IMMUNOSUPPRESSANT MILIEU MAY FACILITATE TUMOR ESCAPE FROM IMMUNE SURVEILLANCE AND INDUCE CHEMO-RESISTANCE. IN THIS REVIEW WE WILL FOCUS ON BCR-ABL-INDEPENDENT MECHANISMS, ANALYZING ESPECIALLY THOSE WITH A POTENTIAL CLINICAL IMPACT IN THE MANAGEMENT OF CML PATIENTS. 2019 20 4436 32 MOLECULAR EVOLUTION OF CHRONIC MYELOID LEUKAEMIA. CHRONIC MYELOID LEUKAEMIA (CML) IS A CLONAL DISORDER OF THE PLURIPOTENT HAEMATOPOIETIC STEM CELL. THE TYPICAL TRIPHASIC COURSE OF CML STARTS WITH THE PREMALIGNANT CHRONIC PHASE INITIATED BY BCR-ABL HYBRID ONCOGENE FORMATION. SECONDARY GENETIC AND EPIGENETIC ABERRATIONS ACCOMPANY THE PROGRESSION TO THE ACCELERATED PHASE AND FATAL BLASTIC CRISIS. PROPERLY TIMED BONE MARROW TRANSPLANTATION IN ELIGIBLE PATIENTS CAN RESULT IN DURABLE REMISSIONS OR CURE. BOTH OF THESE STATES ARE OFTEN ACCOMPANIED BY A LONG-TERM PERSISTENCE OF QUIESCENT LEUKAEMIC CELLS. ACCORDINGLY, A "FUNCTIONAL CURE" (I.E. TUMOUR DORMANCY INDUCTION), RATHER THAN COMPLETE ERADICATION OF THE MALIGNANT CELLS, IS AN ADEQUATE THERAPEUTICAL GOAL. THE LEVEL OF THE RESIDUAL BCR-ABL-POSITIVE CLONES SHOULD BE MONITORED AND SALVAGE TREATMENT INITIATED WHENEVER THESE QUIESCENT LEUKAEMIC CELLS EXIT THEIR DORMANT STATE. 2001