1 2985 140 GENETIC DIVERSITY FOR NITROGEN USE EFFICIENCY IN ARABIDOPSIS THALIANA. THE PLASTICITY OF PLANT GROWTH RESPONSE TO DIFFERING NITRATE AVAILABILITY RENDERS THE IDENTIFICATION OF BIOMARKERS DIFFICULT, BUT ALLOWS ACCESS TO GENETIC FACTORS AS TOOLS TO MODULATE ROOT SYSTEMS TO A WIDE RANGE OF SOIL CONDITIONS. NITROGEN AVAILABILITY IS A MAJOR DETERMINANT OF CROP YIELD. WHILE THE APPLICATION OF FERTILISER SUBSTANTIALLY INCREASES THE YIELD ON POOR SOILS, IT ALSO CAUSES NITRATE POLLUTION OF WATER RESOURCES AND HIGH COSTS FOR FARMERS. INCREASING NITROGEN USE EFFICIENCY IN CROP PLANTS IS A NECESSARY STEP TO IMPLEMENT LOW-INPUT AGRICULTURAL SYSTEMS. WE EXPLOITED THE GENETIC DIVERSITY PRESENT IN THE WORLDWIDE ARABIDOPSIS THALIANA POPULATION TO STUDY ADAPTIVE GROWTH PATTERNS AND CHANGES IN GENE EXPRESSION ASSOCIATED WITH CHRONIC LOW NITRATE STRESS, TO IDENTIFY BIOMARKERS ASSOCIATED WITH GOOD PLANT PERFORMANCE UNDER LOW NITRATE AVAILABILITY. ARABIDOPSIS ACCESSIONS WERE GROWN ON AGAR PLATES WITH LIMITED AND SUFFICIENT SUPPLY OF NITRATE TO MEASURE ROOT SYSTEM ARCHITECTURE AS WELL AS SHOOT AND ROOT FRESH WEIGHT. DIFFERENTIAL GENE EXPRESSION WAS DETERMINED USING AFFYMETRIX ATH1 ARRAYS. WE SHOW THAT THE RESPONSE TO DIFFERING NITRATE AVAILABILITY IS HIGHLY VARIABLE IN ARABIDOPSIS ACCESSIONS. ANALYSES OF VEGETATIVE SHOOT GROWTH AND ROOT SYSTEM ARCHITECTURE IDENTIFIED ACCESSION-SPECIFIC REACTION MODES TO COPE WITH LIMITED NITRATE AVAILABILITY. TRANSCRIPTION AND EPIGENETIC FACTORS WERE IDENTIFIED AS IMPORTANT PLAYERS IN THE ADAPTION TO LIMITED NITROGEN IN A GLOBAL GENE EXPRESSION ANALYSIS. FIVE NITRATE-RESPONSIVE GENES EMERGED AS POSSIBLE BIOMARKERS FOR NUE IN ARABIDOPSIS. THE PLASTICITY OF PLANT GROWTH IN RESPONSE TO DIFFERING NITRATE AVAILABILITY IN THE SUBSTRATE RENDERS THE IDENTIFICATION OF MORPHOLOGICAL AND MOLECULAR FEATURES AS BIOMARKERS DIFFICULT, BUT AT THE SAME TIME ALLOWS ACCESS TO A MULTITUDE OF GENETIC FACTORS WHICH CAN BE USED AS TOOLS TO MODULATE AND ADJUST ROOT SYSTEMS TO A WIDE RANGE OF SOIL CONDITIONS. 2019 2 5242 25 PROGESTERONE RESISTANCE IN ENDOMETRIOSIS: ORIGINS, CONSEQUENCES AND INTERVENTIONS. ENDOMETRIOSIS IS A COMMON CAUSE OF PELVIC PAIN AND AFFECTS UP TO 10% OF WOMEN OF REPRODUCTIVE AGE. ABERRANT PROGESTERONE SIGNALING IN THE ENDOMETRIUM PLAYS A SIGNIFICANT ROLE IN IMPAIRED DECIDUALIZATION AND ESTABLISHMENT OF ECTOPIC ENDOMETRIAL IMPLANTS. EUTOPIC ENDOMETRIAL CELLS FROM WOMEN WITH ENDOMETRIOSIS FAIL TO DOWNREGULATE GENES NEEDED FOR DECIDUALIZATION, SUCH AS THOSE INVOLVED IN CELL CYCLE REGULATION, LEADING TO UNBRIDLED PROLIFERATION. SEVERAL CAUSES OF PROGESTERONE RESISTANCE IN THE ENDOMETRIUM HAVE BEEN POSTULATED, INCLUDING CONGENITAL "PRECONDITIONING", WHEREBY THE IN UTERO ENVIRONMENT RENDERS INFANTS SUSCEPTIBLE TO NEONATAL UTERINE BLEEDING AND ENDOMETRIOSIS. PROGESTERONE ACTION IS CRUCIAL TO DECREASING INFLAMMATION IN THE ENDOMETRIUM, AND DEVIANT PROGESTERONE SIGNALING RESULTS IN A PROINFLAMMATORY PHENOTYPE. CONVERSELY, CHRONIC INFLAMMATION CAN INDUCE A PROGESTERONE-RESISTANT STATE. REPETITIVE RETROGRADE ENDOMETRIAL SHEDDING BEGETS CHRONIC PERITONEAL INFLAMMATION, WHICH FURTHER EXACERBATES PROGESTERONE RESISTANCE. GENETIC CAUSES OF PROGESTERONE RESISTANCE INCLUDE PROGESTERONE RECEPTOR GENE POLYMORPHISMS, ALTERED MICRORNA EXPRESSION, AND EPIGENETIC MODIFICATIONS TO PROGESTERONE RECEPTORS AND THEIR TARGETS. ENVIRONMENTAL TOXINS SUCH AS DIOXIN PLAY A POSSIBLE ROLE IN THE GENESIS OF ENDOMETRIOSIS BY PERMITTING AN INFLAMMATORY MILIEU. A CONSEQUENCE OF IMPAIRED PROGESTERONE ACTION IS THAT HORMONAL THERAPY IS RENDERED INEFFECTIVE FOR A SUBSET OF WOMEN WITH ENDOMETRIOSIS. SYNTHETIC PROGESTINS, SUCH AS DIENOGEST, MAY OVERCOME THIS PHENOMENON BY INCREASING PROGESTERONE RECEPTOR EXPRESSION AND DECREASING PROINFLAMMATORY CYTOKINES. OTHER MODALITIES INCLUDE HIGH DOSE DEPOT FORMULATIONS OF PROGESTINS, MEDICATED INTRAUTERINE DEVICES AND THE LIKELY ADVENT OF ORAL GNRH ANTAGONISTS. UNEARTHING ROOT CAUSES OF PROGESTERONE INACTION IN ENDOMETRIOSIS WILL AID IN THE DEVELOPMENT OF NOVEL THERAPEUTICS GEARED TOWARD PREVENTION AND TREATMENT. 2017 3 3097 30 GENOMIC DEREGULATION OF PRMT5 SUPPORTS GROWTH AND STRESS TOLERANCE IN CHRONIC LYMPHOCYTIC LEUKEMIA. PATIENTS SUFFERING FROM CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) DISPLAY HIGHLY DIVERSE CLINICAL COURSES RANGING FROM INDOLENT CASES TO AGGRESSIVE DISEASE, WITH GENETIC AND EPIGENETIC FEATURES RESEMBLING THIS DIVERSITY. HERE, WE DEVELOPED A COMPREHENSIVE APPROACH COMBINING A VARIETY OF MOLECULAR AND CLINICAL DATA TO PINPOINT TRANSLOCATION EVENTS DISRUPTING LONG-RANGE CHROMATIN INTERACTIONS AND CAUSING CANCER-RELEVANT TRANSCRIPTIONAL DEREGULATION. THEREBY, WE DISCOVERED A B CELL SPECIFIC CIS-REGULATORY ELEMENT RESTRICTING THE EXPRESSION OF GENES IN THE ASSOCIATED LOCUS, INCLUDING PRMT5 AND DAD1, TWO FACTORS WITH ONCOGENIC POTENTIAL. EXPERIMENTAL PRMT5 INHIBITION IDENTIFIED TRANSCRIPTIONAL PROGRAMS SIMILAR TO THOSE IN PATIENTS WITH DIFFERENCES IN PRMT5 ABUNDANCE, ESPECIALLY MYC-DRIVEN AND STRESS RESPONSE PATHWAYS. IN TURN, SUCH INHIBITION IMPAIRS FACTORS INVOLVED IN DNA REPAIR, SENSITIZING CELLS FOR APOPTOSIS. MOREOVER, WE SHOW THAT ARTIFICIAL DELETION OF THE REGULATORY ELEMENT FROM ITS ENDOGENOUS CONTEXT RESULTED IN UPREGULATION OF CORRESPONDING GENES, INCLUDING PRMT5. FURTHERMORE, SUCH DISRUPTION RENDERS PRMT5 TRANSCRIPTION VULNERABLE TO ADDITIONAL STIMULI AND SUBSEQUENTLY ALTERS THE EXPRESSION OF DOWNSTREAM PRMT5 TARGETS. THESE STUDIES PROVIDE A MECHANISM OF PRMT5 DEREGULATION IN CLL AND THE MOLECULAR DEPENDENCIES IDENTIFIED MIGHT HAVE THERAPEUTIC IMPLEMENTATIONS. 2020 4 2402 19 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 5 6695 21 VARIANT GENE EXPRESSION AND ANTIGENIC VARIATION BY MALARIA PARASITES. MALARIA IS A SIGNIFICANT THREAT THROUGHOUT THE DEVELOPING WORLD. AMONG THE MOST FASCINATING ASPECTS OF THE PROTOZOAN PARASITES RESPONSIBLE FOR THIS DISEASE ARE THE METHODS THEY EMPLOY TO AVOID THE IMMUNE SYSTEM AND PERPETUATE CHRONIC INFECTIONS. KEY AMONG THESE IS ANTIGENIC VARIATION: BY SYSTEMATICALLY ALTERING ANTIGENS THAT ARE DISPLAYED TO THE HOST'S IMMUNE SYSTEM, THE PARASITE RENDERS THE ADAPTIVE IMMUNE RESPONSE INEFFECTIVE. FOR PLASMODIUM FALCIPARUM, THE SPECIES RESPONSIBLE FOR THE MOST SEVERE FORM OF HUMAN MALARIA, THIS PROCESS INVOLVES A COMPLICATED MOLECULAR MECHANISM THAT RESULTS IN CONTINUOUSLY CHANGING PATTERNS OF VARIANT-ANTIGEN-ENCODING GENE EXPRESSION. ALTHOUGH MANY FEATURES OF THIS PROCESS REMAIN OBSCURE, SIGNIFICANT PROGRESS HAS BEEN MADE IN RECENT YEARS TO DECIPHER VARIOUS MOLECULAR ASPECTS OF THE REGULATORY CASCADE THAT CAUSES CHRONIC INFECTION. 2017 6 3276 25 HEPATOCYTE GROWTH CONTROL BY SOCS1 AND SOCS3. THE EXTRAORDINARY CAPACITY OF THE LIVER TO REGENERATE FOLLOWING INJURY IS DEPENDENT ON COORDINATED AND REGULATED ACTIONS OF CYTOKINES AND GROWTH FACTORS. WHEREAS HEPATOCYTE GROWTH FACTOR (HGF) AND EPIDERMAL GROWTH FACTOR (EGF) ARE DIRECT MITOGENS TO HEPATOCYTES, INFLAMMATORY CYTOKINES SUCH AS TNFALPHA AND IL-6 ALSO PLAY ESSENTIAL ROLES IN THE LIVER REGENERATION PROCESS. THESE CYTOKINES AND GROWTH FACTORS ACTIVATE DIFFERENT SIGNALING PATHWAYS IN A SEQUENTIAL MANNER TO ELICIT HEPATOCYTE PROLIFERATION. THE KINETICS AND MAGNITUDE OF THESE HEPATOCYTE-ACTIVATING STIMULI ARE TIGHTLY REGULATED TO ENSURE RESTORATION OF A FUNCTIONAL LIVER MASS WITHOUT CAUSING UNCONTROLLED CELL PROLIFERATION. HEPATOCYTE PROLIFERATION CAN BECOME DEREGULATED UNDER CONDITIONS OF CHRONIC INFLAMMATION, LEADING TO ACCUMULATION OF GENETIC ABERRATIONS AND EVENTUAL NEOPLASTIC TRANSFORMATION. AMONG THE CONTROL MECHANISMS THAT REGULATE HEPATOCYTE PROLIFERATION, NEGATIVE FEEDBACK INHIBITION BY THE 'SUPPRESSOR OF CYTOKINE SIGNALING (SOCS)' FAMILY PROTEINS SOCS1 AND SOCS3 PLAY CRUCIAL ROLES IN ATTENUATING CYTOKINE AND GROWTH FACTOR SIGNALING. LOSS OF SOCS1 OR SOCS3 IN THE MOUSE LIVER INCREASES THE RATE OF LIVER REGENERATION AND RENDERS HEPATOCYTES SUSCEPTIBLE TO NEOPLASTIC TRANSFORMATION. THE FREQUENT EPIGENETIC REPRESSION OF THE SOCS1 AND SOCS3 GENES IN HEPATOCELLULAR CARCINOMA HAS STIMULATED RESEARCH IN UNDERSTANDING THE GROWTH REGULATORY MECHANISMS OF SOCS1 AND SOCS3 IN HEPATOCYTES. WHEREAS SOCS3 IS IMPLICATED IN REGULATING JAK-STAT SIGNALING INDUCED BY IL-6 AND ATTENUATING EGFR SIGNALING, SOCS1 IS CRUCIAL FOR THE REGULATION OF HGF SIGNALING. THESE TWO PROTEINS ALSO MODULE THE FUNCTIONS OF CERTAIN KEY PROTEINS THAT CONTROL THE CELL CYCLE. IN THIS REVIEW, WE DISCUSS THE CURRENT UNDERSTANDING OF THE FUNCTIONS OF SOCS1 AND SOCS3 IN CONTROLLING HEPATOCYTE PROLIFERATION, AND ITS IMPLICATIONS TO LIVER HEALTH AND DISEASE. 2019 7 3619 22 IN VIVO ACUTE ON CHRONIC ETHANOL EFFECTS IN LIVER: A MOUSE MODEL EXHIBITING EXACERBATED INJURY, ALTERED METABOLIC AND EPIGENETIC RESPONSES. CHRONIC ALCOHOLICS WHO ALSO BINGE DRINK (I.E., ACUTE ON CHRONIC) ARE PRONE TO AN EXACERBATED LIVER INJURY BUT ITS MECHANISM IS NOT UNDERSTOOD. WE THEREFORE INVESTIGATED THE IN VIVO EFFECTS OF CHRONIC AND BINGE ETHANOL INGESTION AND COMPARED TO CHRONIC ETHANOL FOLLOWED BY THREE REPEAT BINGE ETHANOL ON THE LIVER OF MALE C57/BL6 MICE FED ETHANOL IN LIQUID DIET (4%) FOR FOUR WEEKS FOLLOWED BY BINGE ETHANOL (INTRAGASTRIC ADMINISTRATION, 3.5 G/KG BODY WEIGHT, THREE DOSES, 12H APART). CHRONIC FOLLOWED BY BINGE ETHANOL EXACERBATED FAT ACCUMULATION, NECROSIS, DECREASE IN HEPATIC SAM AND SAM:SAH RATIO, INCREASE IN ADENOSINE LEVELS, AND ELEVATED CYP2E1 LEVELS. HISTONE H3 LYSINE ACETYLATION (H3ACK9), DUALLY MODIFIED PHOSPHOACETYLATED HISTONE H3 (H3ACK9/PS10), AND PHOSPHORYLATED H2AX INCREASED AFTER BINGE WHEREAS PHOSPHORYLATION OF HISTONE H3 SER 10 (H3S10) AND H3 SER 28 (H3S28) INCREASED AFTER CHRONIC ETHANOL-BINGE. HISTONE H3 LYSINE 4 AND 9 DIMETHYLATION INCREASED WITH A MARKED DIMETHYLATION IN H3K9 IN CHRONIC ETHANOL BINGE GROUP. TRIMETHYLATED HISTONE H3 LEVELS DID NOT CHANGE. NUCLEAR LEVELS OF HISTONE ACETYL TRANSFERASE GCN5 AND HISTONE DEACETYLASE HDAC3 WERE ELEVATED WHEREAS PHOSPHO-CREB DECREASED IN A DISTINCTIVE MANNER. TAKEN TOGETHER, ACUTE ON CHRONIC ETHANOL INGESTION CAUSED AMPLIFICATION OF LIVER INJURY AND ELICITED CHARACTERISTIC PROFILES OF HISTONE MODIFICATIONS, METABOLIC ALTERATIONS, AND CHANGES IN NUCLEAR PROTEIN LEVELS. THESE FINDINGS DEMONSTRATE THAT CHRONIC ETHANOL EXPOSURE RENDERS LIVER MORE SUSCEPTIBLE TO REPEAT ACUTE/BINGE ETHANOL INDUCED ACCELERATION OF ALCOHOLIC LIVER DISEASE. 2015 8 2687 32 EVIDENCE OF EPIGENETIC ALTERATIONS IN THROMBOSIS AND COAGULATION: A SYSTEMATIC REVIEW. THROMBOSIS IN THE CONTEXT OF CARDIOVASCULAR DISEASE (CVD) AFFECTS MAINLY THE BLOOD VESSELS SUPPLYING THE HEART, BRAIN AND PERIPHERIES AND IT IS THE LEADING CAUSE OF DEATH WORLDWIDE. THE PATHOPHYSIOLOGICAL THROMBOTIC MECHANISMS ARE LARGELY UNKNOWN. HERITABILITY CONTRIBUTES TO A 30% OF THE INCIDENCE OF CVD. THE REMAINING VARIATION CAN BE EXPLAINED BY LIFE STYLE FACTORS SUCH AS SMOKING, DIETARY AND EXERCISE HABITS, ENVIRONMENTAL EXPOSURE TO TOXINS, AND DRUG USAGE AND OTHER COMORBIDITIES. EPIGENETIC VARIATION CAN BE ACQUIRED OR INHERITED AND CONSTITUTES AN INTERACTION BETWEEN GENES AND THE ENVIRONMENT. EPIGENETICS HAVE BEEN IMPLICATED IN ATHEROSCLEROSIS, ISCHEMIA/REPERFUSION DAMAGE AND THE CARDIOVASCULAR RESPONSE TO HYPOXIA. EPIGENETIC REGULATORS OF GENE EXPRESSION ARE MAINLY THE METHYLATION OF CPG ISLANDS, HISTONE POST TRANSLATIONAL MODIFICATIONS (PTMS) AND MICRORNAS (MIRNAS). THESE EPIGENETIC REGULATORS CONTROL GENE EXPRESSION EITHER THROUGH ACTIVATION OR SILENCING. EPIGENETIC CONTROL IS MOSTLY DYNAMIC AND CAN POTENTIALLY BE MANIPULATED TO PREVENT OR REVERSE THE UNCONTROLLED EXPRESSION OF GENES, A TRAIT THAT RENDERS THEM PUTATIVE THERAPEUTIC TARGETS. IN THE CURRENT REVIEW, WE SYSTEMATICALLY STUDIED AND PRESENT AVAILABLE DATA ON EPIGENETIC ALTERATIONS IMPLICATED IN THROMBOSIS DERIVED FROM HUMAN STUDIES. EVIDENCE OF EPIGENETIC ALTERATIONS IS OBSERVED IN SEVERAL THROMBOTIC DISEASES SUCH AS CORONARY ARTERY DISEASE AND CEREBROVASCULAR DISEASE, PREECLAMPSIA AND ANTIPHOSPHOLIPID SYNDROME. DIFFERENTIAL CPG METHYLATION AND SPECIFIC HISTONE PTMS THAT CONTROL TRANSCRIPTION OF PROTHROMBOTIC AND PROINFLAMMATORY GENES HAVE ALSO BEEN ASSOCIATED WITH PREDISPOSING FACTORS OF THROMBOSIS AND CVD, SUCH US SMOKING, AIR POLLUTION, HYPERTRIGLYCERIDEMIA, OCCUPATIONAL EXPOSURE TO PARTICULATE MATTER AND COMORBIDITIES INCLUDING CANCER, CHRONIC OBSTRUCTIVE PULMONARY DISEASE AND CHRONIC KIDNEY DISEASE. THESE CLINICAL OBSERVATIONS ARE FURTHER SUPPORTED BY IN VITRO EXPERIMENTS AND INDICATE THAT EPIGENETIC REGULATION AFFECTS THE PATHOPHYSIOLOGY OF THROMBOTIC DISORDERS WITH POTENTIAL DIAGNOSTIC OR THERAPEUTIC UTILITY. 2019 9 4129 22 MECHANISMS OF ENDOMETRIAL PROGESTERONE RESISTANCE. THROUGHOUT THE REPRODUCTIVE YEARS, THE RISE AND FALL IN OVARIAN HORMONES ELICIT IN THE ENDOMETRIUM WAVES OF CELL PROLIFERATION, DIFFERENTIATION, RECRUITMENT OF INFLAMMATORY CELLS, APOPTOSIS, TISSUE BREAKDOWN AND REGENERATION. THE ACTIVATED PROGESTERONE RECEPTOR, A MEMBER OF THE SUPERFAMILY OF LIGAND-DEPENDENT TRANSCRIPTION FACTORS, IS THE MASTER REGULATOR OF THIS INTENSE TISSUE REMODELLING PROCESS IN THE UTERUS. ITS ACTIVITY IS TIGHTLY REGULATED BY INTERACTION WITH CELL-SPECIFIC TRANSCRIPTION FACTORS AND COREGULATORS AS WELL AS BY SPECIFIC POSTTRANSLATIONAL MODIFICATIONS THAT RESPOND DYNAMICALLY TO A VARIETY OF ENVIRONMENTAL AND INFLAMMATORY SIGNALS. ENDOMETRIOSIS, A CHRONIC INFLAMMATORY DISORDER, DISRUPTS COORDINATED PROGESTERONE RESPONSES THROUGHOUT THE REPRODUCTIVE TRACT, INCLUDING IN THE ENDOMETRIUM. THIS PHENOMENON IS INCREASINGLY REFERRED TO AS 'PROGESTERONE RESISTANCE'. EMERGING EVIDENCE SUGGESTS THAT PROGESTERONE RESISTANCE IN ENDOMETRIOSIS IS NOT JUST A CONSEQUENCE OF PERTURBED PROGESTERONE SIGNAL TRANSDUCTION CAUSED BY CHRONIC INFLAMMATION BUT ASSOCIATED WITH EPIGENETIC CHROMATIN CHANGES THAT DETERMINE THE INTRINSIC RESPONSIVENESS OF ENDOMETRIAL CELLS TO DIFFERENTIATION CUES. 2012 10 3856 23 ISCHAEMIA REPERFUSION INJURY: MECHANISMS OF PROGRESSION TO CHRONIC GRAFT DYSFUNCTION. THE INCREASING USE OF EXTENDED CRITERIA ORGANS TO MEET THE DEMAND FOR KIDNEY TRANSPLANTATION RAISES AN IMPORTANT QUESTION OF HOW THE SEVERITY OF EARLY ISCHAEMIC INJURY INFLUENCES LONG-TERM OUTCOMES. SIGNIFICANT ACUTE ISCHAEMIC KIDNEY INJURY IS ASSOCIATED WITH DELAYED GRAFT FUNCTION, INCREASED IMMUNE-ASSOCIATED EVENTS AND, ULTIMATELY, EARLIER DETERIORATION OF GRAFT FUNCTION. A COMPREHENSIVE UNDERSTANDING OF IMMEDIATE MOLECULAR EVENTS THAT ENSUE POST-ISCHAEMIA AND THEIR POTENTIAL LONG-TERM CONSEQUENCES ARE KEY TO THE DISCOVERY OF NOVEL THERAPEUTIC TARGETS. ACUTE ISCHAEMIC INJURY PRIMARILY AFFECTS TUBULAR STRUCTURE AND FUNCTION. DEPENDING ON THE SEVERITY AND PERSISTENCE OF THE INSULT, THIS MAY RESOLVE COMPLETELY, LEADING TO RESTORATION OF NORMAL FUNCTION, OR BE SUSTAINED, RESULTING IN PERSISTENT RENAL IMPAIRMENT AND PROGRESSIVE FUNCTIONAL LOSS. LONG-TERM EFFECTS OF ACUTE RENAL ISCHAEMIA ARE MEDIATED BY SEVERAL MECHANISMS INCLUDING HYPOXIA, HIF-1 ACTIVATION, ENDOTHELIAL DYSFUNCTION LEADING TO VASCULAR RAREFACTION, SUSTAINED PRO-INFLAMMATORY STIMULI INVOLVING INNATE AND ADAPTIVE IMMUNE RESPONSES, FAILURE OF TUBULAR CELLS TO RECOVER AND EPIGENETIC CHANGES. THIS REVIEW DESCRIBES THE BIOLOGICAL RELEVANCE AND INTERACTION OF THESE MECHANISMS BASED ON CURRENTLY AVAILABLE EVIDENCE. 2019 11 4003 19 LOSS OF PRMT7 REPROGRAMS GLYCINE METABOLISM TO SELECTIVELY ERADICATE LEUKEMIA STEM CELLS IN CML. OUR GROUP HAS REPORTED PREVIOUSLY ON THE ROLE OF VARIOUS MEMBERS OF THE PROTEIN ARGININE METHYLTRANSFERASE (PRMT) FAMILY, WHICH ARE INVOLVED IN EPIGENETIC REGULATION, IN THE PROGRESSION OF LEUKEMIA. HERE, WE EXPLORED THE ROLE OF PRMT7, GIVEN ITS UNIQUE FUNCTION WITHIN THE PRMT FAMILY, IN THE MAINTENANCE OF LEUKEMIA STEM CELLS (LSCS) IN CHRONIC MYELOID LEUKEMIA (CML). GENETIC LOSS OF PRMT7, AND THE DEVELOPMENT AND TESTING OF A SMALL-MOLECULE SPECIFIC INHIBITOR OF PRMT7, SHOWED THAT TARGETING PRMT7 DELAYED LEUKEMIA DEVELOPMENT AND IMPAIRED SELF-RENEWAL OF LSCS IN A CML MOUSE MODEL AND IN PRIMARY CML CD34(+) CELLS FROM HUMANS WITHOUT AFFECTING NORMAL HEMATOPOIESIS. MECHANISTICALLY, LOSS OF PRMT7 RESULTED IN REDUCED EXPRESSIONS OF GLYCINE DECARBOXYLASE, LEADING TO THE REPROGRAMING OF GLYCINE METABOLISM TO GENERATE METHYLGLYOXAL, WHICH IS DETRIMENTAL TO LSCS. THESE FINDINGS LINK HISTONE ARGININE METHYLATION WITH GLYCINE METABOLISM, WHILE SUGGESTING PRMT7 AS A POTENTIAL THERAPEUTIC TARGET FOR THE ERADICATION OF LSCS IN CML. 2022 12 5488 18 REVERSING HEPATOCELLULAR CARCINOMA PROGRESSION BY USING NETWORKED BIOLOGICAL THERAPIES. THE LIVER IS DISTINGUISHED FROM OTHER TISSUES BY (A) ITS DETOXIFYING FUNCTION, (B) ITS RESISTANCE TO APOPTOSIS, AND (C) ITS REGENERATIVE RESPONSE TO DAMAGE. HEPATOCELLULAR CARCINOMA ARISES WHEN CHRONIC INSULTS, SUCH AS HEPATITIS OR IRON OVERLOAD, CONSTITUTIVELY ACTIVATE THIS REGENERATIVE PROGRAM. HERE, WE PROPOSE THAT THE PROLIFERATIVE RESPONSE OF THE LIVER TO DAMAGE UNDERLIES THE RESISTANCE OF HEPATOCELLULAR CARCINOMA TO CYTOTOXIC THERAPY, AND THAT HEPATOCELLULAR CARCINOMA GROWTH SHOULD THEREFORE BE MORE READILY CONTROLLED BY USING A NETWORKED COMBINATION OF NONCYTOTOXIC INTERVENTIONS TO INTERRUPT THE DAMAGE-INDUCIBLE REGENERATIVE PATHWAY. TO THIS END, HEPATOCELLULAR CARCINOMA BOASTS A WEALTH OF POTENTIAL DRUG TARGETS, INCLUDING VIRAL REPLICATION, THE ANTIAPOPTOTIC IMMUNOSUPPRESSANT ALPHA-FETOPROTEIN, HEPATIC IRON OVERLOAD, INFLAMMATORY SIGNALING, EXTRACELLULAR PROTEASES, AND GROWTH FACTORS. BY BLOCKING THESE POSITIVE FEEDBACK LOOPS IN PARALLEL, AND SO RETURNING THE HOST ENVIRONMENT TO A MORE NORMAL STATE, EPIGENETIC REPRESSION OF TUMOR-SUPPRESSOR GENE FUNCTION MAY BE REVERSED AND TUMOR DORMANCY RESTORED. NONCYTOTOXIC MANEUVERS THAT SHORT CIRCUIT DAMAGE RESISTANCE LOOPS MAY THUS REPRESENT AN INDIRECT FORM OF GENE THERAPY MERITING INCORPORATION INTO HEPATOCELLULAR CARCINOMA CLINICAL TRIALS. 2007 13 3702 23 INFLAMMATORY SIGNALING PATHWAYS IN PRELEUKEMIC AND LEUKEMIC STEM CELLS. HEMATOPOIETIC STEM CELLS (HSCS) ARE A RARE SUBSET OF BONE MARROW CELLS THAT USUALLY EXIST IN A QUIESCENT STATE, ONLY ENTERING THE CELL CYCLE TO REPLENISH THE BLOOD COMPARTMENT, THEREBY LIMITING THE POTENTIAL FOR ERRORS IN REPLICATION. INFLAMMATORY SIGNALS THAT ARE RELEASED IN RESPONSE TO ENVIRONMENTAL STRESSORS, SUCH AS INFECTION, TRIGGER ACTIVE CYCLING OF HSCS. THESE INFLAMMATORY SIGNALS CAN ALSO DIRECTLY INDUCE HSCS TO RELEASE CYTOKINES INTO THE BONE MARROW ENVIRONMENT, PROMOTING MYELOID DIFFERENTIATION. AFTER STRESS MYELOPOIESIS IS TRIGGERED, HSCS REQUIRE INTRACELLULAR SIGNALING PROGRAMS TO DEACTIVATE THIS RESPONSE AND RETURN TO STEADY STATE. PROLONGED OR EXCESSIVE EXPOSURE TO INFLAMMATORY CYTOKINES, SUCH AS IN PROLONGED INFECTION OR IN CHRONIC RHEUMATOLOGIC CONDITIONS, CAN LEAD TO CONTINUED HSC CYCLING AND EVENTUAL HSC LOSS. THIS PROMOTES BONE MARROW FAILURE, AND CAN PRECIPITATE PRELEUKEMIC STATES OR LEUKEMIA THROUGH THE ACQUISITION OF GENETIC AND EPIGENETIC CHANGES IN HSCS. THIS CAN OCCUR THROUGH THE INITIATION OF CLONAL HEMATOPOIESIS, FOLLOWED BY THE EMERGENCE PRELEUKEMIC STEM CELLS (PRE-LSCS). IN THIS REVIEW, WE DESCRIBE THE ROLES OF MULTIPLE INFLAMMATORY SIGNALING PATHWAYS IN THE GENERATION OF PRE-LSCS AND IN PROGRESSION TO MYELODYSPLASTIC SYNDROME (MDS), MYELOPROLIFERATIVE NEOPLASMS, AND ACUTE MYELOID LEUKEMIA (AML). IN AML, ACTIVATION OF SOME INFLAMMATORY SIGNALING PATHWAYS CAN PROMOTE THE CYCLING AND DIFFERENTIATION OF LSCS, AND THIS CAN BE EXPLOITED THERAPEUTICALLY. WE ALSO DISCUSS THE THERAPEUTIC POTENTIAL OF MODULATING INFLAMMATORY SIGNALING FOR THE TREATMENT OF MYELOID MALIGNANCIES. 2017 14 2968 25 GENETIC AND EPIGENETIC REGULATION OF PD-1 EXPRESSION. THE INHIBITORY IMMUNE RECEPTOR PROGRAMMED CELL DEATH-1 (PD-1) IS INTRICATELY REGULATED. IN T CELLS, PD-1 IS EXPRESSED IN RESPONSE TO MOST IMMUNE CHALLENGES, BUT IT IS RAPIDLY DOWNREGULATED IN ACUTE SETTINGS, ALLOWING FOR NORMAL IMMUNE RESPONSES. ON CHRONICALLY STIMULATED AG-SPECIFIC T CELLS, PD-1 EXPRESSION REMAINS HIGH, LEADING TO AN IMPAIRED RESPONSE TO STIMULI. AB BLOCKADE OF PD-1 INTERACTIONS DURING CHRONIC AG SETTINGS PARTIALLY RESTORES IMMUNE FUNCTION AND IS NOW USED CLINICALLY TO TREAT A VARIETY OF DEVASTATING CANCERS. UNDERSTANDING THE REGULATION OF PD-1 EXPRESSION MAY BE USEFUL FOR DEVELOPING NOVEL IMMUNE-BASED THERAPIES. IN THIS REVIEW, THE MOLECULAR MECHANISMS THAT DRIVE DYNAMIC PD-1 EXPRESSION DURING ACUTE AND CHRONIC ANTIGENIC STIMULI ARE DISCUSSED. AN ARRAY OF CIS-DNA ELEMENTS, TRANSCRIPTION FACTORS, AND EPIGENETIC COMPONENTS, INCLUDING DNA METHYLATION AND HISTONE MODIFICATIONS, CONTROL PD-1 EXPRESSION. THE INTERPLAY BETWEEN THESE REGULATORS FINE-TUNES PD-1 EXPRESSION IN DIFFERENT INFLAMMATORY ENVIRONMENTS AND ACROSS NUMEROUS CELL TYPES TO MODULATE IMMUNE RESPONSES. 2016 15 5589 23 ROLE OF SIRT1 IN THE GROWTH AND REGULATION OF NORMAL HEMATOPOIETIC AND LEUKEMIA STEM CELLS. PURPOSE OF REVIEW: RECENT STUDIES HAVE ENHANCED OUR UNDERSTANDING OF THE ROLE OF THE SIRT1 DEACETYLASE IN REGULATION OF NORMAL HEMATOPOIETIC STEM CELLS (HSCS) AND LEUKEMIA STEM CELLS (LSCS), AND ITS IMPORTANCE IN REGULATING AUTOPHAGY AND EPIGENETIC REPROGRAMMING IN RESPONSE TO METABOLIC ALTERATIONS. RECENT FINDINGS: STUDIES EMPLOYING CONDITIONAL DELETION MOUSE MODELS INDICATE AN IMPORTANT ROLE OF SIRT1 IN MAINTENANCE OF ADULT HSCS UNDER CONDITIONS OF STRESS. SIRT1 IS SIGNIFICANTLY OVEREXPRESSED IN LSC POPULATIONS FROM ACUTE MYELOID LEUKEMIA (AML) PATIENTS WITH THE FLT3-ITD MUTATION, AND MAINTAINS THEIR SURVIVAL, GROWTH AND DRUG RESISTANCE, AS PREVIOUSLY DESCRIBED FOR CHRONIC MYELOGENOUS LEUKEMIA (CML). SIRT1 CAN ALSO ENHANCE LEUKEMIA EVOLUTION AND DRUG RESISTANCE BY PROMOTING GENETIC INSTABILITY. RECENT STUDIES INDICATE AN IMPORTANT ROLE OF SIRT1 IN REGULATING AUTOPHAGY IN RESPONSE TO OXIDATIVE STRESS AND NUTRIENT REQUIREMENTS, AND HAVE ELUCIDATED COMPLEX MECHANISMS BY WHICH SIRT1 REGULATES EPIGENETIC REPROGRAMMING OF STEM CELLS. SUMMARY: SIRT1 INHIBITION HOLDS PROMISE AS A NOVEL APPROACH FOR ABLATION OF LSCS IN CHRONIC PHASE CML OR FLT3-ITD-ASSOCIATED AML. ADDITIONAL STUDIES TO UNDERSTAND THE ROLE OF SIRT1 IN LINKING METABOLIC ALTERATIONS TO GENOMIC STABILITY, AUTOPHAGY AND EPIGENETIC REPROGRAMMING OF STEM CELLS ARE WARRANTED. 2015 16 5212 19 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 17 2141 28 EPIGENETIC INTERVENTIONS FOR EPILEPTOGENESIS: A NEW FRONTIER FOR CURING EPILEPSY. THIS ARTICLE HIGHLIGHTS THE EMERGING THERAPEUTIC POTENTIAL OF SPECIFIC EPIGENETIC MODULATORS AS PROMISING ANTIEPILEPTOGENIC OR DISEASE-MODIFYING AGENTS FOR CURING EPILEPSY. CURRENTLY, THERE IS AN UNMET NEED FOR ANTIEPILEPTOGENIC AGENTS THAT TRULY PREVENT THE DEVELOPMENT OF EPILEPSY IN PEOPLE AT RISK. THERE IS STRONG EVIDENCE THAT EPIGENETIC SIGNALING, WHICH EXERTS HIGH FIDELITY REGULATION OF GENE EXPRESSION, PLAYS A CRUCIAL ROLE IN THE PATHOPHYSIOLOGY OF EPILEPTOGENESIS AND CHRONIC EPILEPSY. THESE MODIFICATIONS ARE NOT HARD-WIRED INTO THE GENOME AND ARE CONSTANTLY REPROGRAMMED BY ENVIRONMENTAL INFLUENCES. THE POTENTIAL EPIGENETIC MECHANISMS, INCLUDING HISTONE MODIFICATIONS, DNA METHYLATION, MICRORNA-BASED TRANSCRIPTIONAL CONTROL, AND BROMODOMAIN READING ACTIVITY, CAN DRASTICALLY ALTER THE NEURONAL GENE EXPRESSION PROFILE BY EXERTING THEIR SUMMATIVE EFFECTS IN A COORDINATED FASHION. SUCH AN EPIGENETIC INTERVENTION APPEARS MORE RATIONAL STRATEGY FOR PREVENTING EPILEPSY BECAUSE IT TARGETS THE PRIMARY PATHWAY THAT INITIALLY TRIGGERS THE NUMEROUS DOWNSTREAM CELLULAR AND MOLECULAR EVENTS MEDIATING EPILEPTOGENESIS. AMONG CURRENTLY APPROVED EPIGENETIC DRUGS, THE MAJORITY ARE ANTICANCER DRUGS WITH WELL-ESTABLISHED PROFILES IN CLINICAL TRIALS AND PRACTICE. EVIDENCE FROM PRECLINICAL STUDIES SUPPORTS THE PREMISE THAT THESE DRUGS MAY BE APPLIED TO A WIDE RANGE OF BRAIN DISORDERS. TARGETING HISTONE DEACETYLATION BY INHIBITING HISTONE DEACETYLASE ENZYMES APPEARS TO BE ONE PROMISING EPIGENETIC THERAPY SINCE CERTAIN INHIBITORS HAVE BEEN SHOWN TO PREVENT EPILEPTOGENESIS IN ANIMAL MODELS. HOWEVER, DEVELOPING NEURONAL SPECIFIC EPIGENETIC MODULATORS REQUIRES RATIONAL, PATHOPHYSIOLOGY-BASED OPTIMIZATION TO EFFICIENTLY INTERCEPT THE UPSTREAM PATHWAYS IN EPILEPTOGENESIS. OVERALL, EPIGENETIC AGENTS HAVE BEEN WELL POSITIONED AS NEW FRONTIER TOOLS TOWARDS THE NATIONAL GOAL OF CURING EPILEPSY. 2017 18 6521 22 TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF PD-1 EXPRESSION. PROGRAMMED CELL DEATH-1 (PD-1) IS A CO-INHIBITORY RECEPTOR THAT PLAYS IMPORTANT ROLES IN REGULATING T CELL IMMUNITY AND PERIPHERAL TOLERANCE. PD-1 SIGNALING PREVENTS T CELLS FROM OVERACTIVATION DURING ACUTE INFECTIONS, BUT IT MAINTAINS T CELL EXHAUSTION DURING CHRONIC INFECTIONS. TUMOR CELLS CAN EXPLOIT THE PD-1 SIGNALING PATHWAY TO EVADE ANTITUMOR IMMUNE RESPONSES. THE PD-1 SIGNALING PATHWAY IS ALSO ESSENTIAL FOR MAINTAINING PERIPHERAL TOLERANCE AND PREVENTION OF AUTOIMMUNITY. PD-1 EXPRESSION IS STRICTLY AND DIFFERENTIALLY REGULATED BY DIVERSE MECHANISMS IN IMMUNE CELLS. IT IS ACTIVATED AND REPRESSED BY DISTINCT TRANSCRIPTION FACTORS IN DIFFERENT CIRCUMSTANCES. MOREOVER, EPIGENETIC MECHANISMS ARE ALSO INVOLVED IN REGULATING PD-1 EXPRESSION. IN THIS REVIEW, WE SUMMARIZE THE KNOWLEDGE OF THE TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF PD-1 EXPRESSION DURING DIFFERENT IMMUNE RESPONSES. 2021 19 1711 26 DYSFUNCTIONAL STATE OF T CELLS OR EXHAUSTION DURING CHRONIC VIRAL INFECTIONS AND COVID-19: A REVIEW. CORONAVIRUS DISEASE 2019 (COVID-19) CONTINUOUSLY AFFECTING THE LIVES OF MILLIONS OF PEOPLE. THE VIRUS IS SPREAD THROUGH THE RESPIRATORY ROUTE TO AN UNINFECTED PERSON, CAUSING MILD-TO-MODERATE RESPIRATORY DISEASE-LIKE SYMPTOMS THAT SOMETIMES PROGRESS TO SEVERE FORM AND CAN BE FATAL. WHEN THE HOST IS INFECTED WITH THE VIRUS, BOTH INNATE AND ADAPTIVE IMMUNITY COMES INTO PLAY. THE EFFECTOR T CELLS ACT AS THE MASTER PLAYER OF ADAPTIVE IMMUNE RESPONSE IN ERADICATING THE VIRUS FROM THE SYSTEM. BUT DURING CANCER AND CHRONIC VIRAL INFECTIONS, THE FATE OF AN EFFECTOR T CELL IS ALTERED, AND THE T CELL MAY ENTERS A STATE OF EXHAUSTION, WHICH IS MARKED BY LOSS OF EFFECTOR FUNCTION, DEPLETED PROLIFERATIVE CAPACITY AND CYTOTOXIC EFFECT ACCOMPLISHED BY AN INCREASED EXPRESSION OF NUMEROUS INHIBITORY RECEPTORS SUCH AS PROGRAMMED CELL DEATH PROTEIN 1 (PD-1), LYMPHOCYTE-ACTIVATION PROTEIN 3 (LAG-3), AND CYTOTOXIC T LYMPHOCYTE-ASSOCIATED ANTIGEN 4 (CTLA-4) ON THEIR SURFACE. VARIOUS OTHER TRANSCRIPTIONAL AND EPIGENETIC CHANGES TAKE PLACE INSIDE THE T CELL WHEN IT ENTERS INTO AN EXHAUSTED STATE. LATEST STUDIES POINT TOWARD THE INDUCTION OF AN ABNORMAL IMMUNE RESPONSE SUCH AS LYMPHOPENIA, CYTOKINE STORM, AND T CELL EXHAUSTION DURING SARS-COV-2 (SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS 2) INFECTION. THIS REVIEW SHEDS LIGHT ON THE DYSFUNCTIONAL STATE OF T CELLS DURING CHRONIC VIRAL INFECTION AND COVID-19. UNDERSTANDING THE CAUSE AND THE EFFECT OF T CELL EXHAUSTION OBSERVED DURING COVID-19 MAY HELP RESOLVE NEW THERAPEUTIC POTENTIALS FOR TREATING CHRONIC INFECTIONS AND OTHER DISEASES. 2022 20 570 28 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