1 821 117 CHARACTERIZATION OF ACETYLATION OF HISTONE H3 AT LYSINE 9 IN THE TRIGEMINAL GANGLION OF A RAT TRIGEMINAL NEURALGIA MODEL. TRIGEMINAL NEURALGIA (TN) IS A CHRONIC NEUROPATHIC PAIN DISORDER CHARACTERIZED BY SPONTANEOUS AND ELICITED PAROXYSMS OF ELECTRIC-SHOCK-LIKE OR STABBING PAIN IN A REGION OF THE FACE. THE EPIGENETIC REGULATION OF TN IS STILL OBSCURE. IN CURRENT STUDY, A RAT TN MODEL SUBJECT TO CARBAMAZEPINE (CBZ) TREATMENT WAS ESTABLISHED, AND TRANSCRIPTOME- AND GENOME-SCALE PROFILING OF H3K9AC AND HDAC3 WAS PERFORMED BY RNA-SEQ AND CHIP-SEQ. WE OBSERVED THAT H3K9AC LEVELS IN THE TRIGEMINAL GANGLION WERE LOWER IN THE TN RATS COMPARED WITH THOSE IN THE CONTROL, AND CBZ TREATMENT LED TO RECOVERY OF H3K9AC LEVELS. FURTHER, WE FOUND THAT HDAC3 WAS OVERACTIVATED, WHICH INTERFERED WITH H3K9 ACETYLATION DUE TO HIGHER PHOSPHORYLATION IN TN COMPARED WITH THAT IN THE CONTROL. FINALLY, THE PHOSPHOKINASE LEUCINE-RICH REPEAT KINASE 2 (LRRK2) WAS DEMONSTRATED TO CONTRIBUTE TO HDAC3 ACTIVITY VIA THE MAPK SIGNALING PATHWAY. TAKEN TOGETHER, WE IDENTIFIED A REGULATORY MECHANISM IN WHICH THE PHOSPHATE GROUPS TRANSFERRED FROM ACTIVATED ERK AND LRRK2 TO HDAC3 CAUSED GENOME-SCALE DEACETYLATION AT H3K9 AND RESULTED IN THE SILENCING OF A LARGE NUMBER OF GENES IN TN. THE KINASES OR IMPORTANT ENZYMES WITHIN THIS REGULATORY AXIS MAY REPRESENT IMPORTANT TARGETS FOR TN THERAPY AND PREVENTION. 2022 2 1019 26 CIRCRNA-MIRNA CROSS-TALK IN THE TRANSITION FROM PAROXYSMAL TO PERMANENT ATRIAL FIBRILLATION. BACKGROUND: ATRIAL FIBRILLATION (AF) IS THE MOST PREVALENT CARDIAC ARRHYTHMIA IN WESTERN COUNTRIES. THE FACTORS GOVERNING THE PROGRESSION OF AF TO A PERMANENT CHRONIC CONDITION ARE STILL NOT WELL CHARACTERIZED. AMONG EPIGENETIC FACTORS, NON-CODING RNAS (NCRNAS) SUCH AS MIRNAS AND LNCRNAS HAVE BEEN RECENTLY DESCRIBED AS IMPORTANT PLAYERS INVOLVED IN THE AF PROGRESSION. WE HYPOTHESIZE ABOUT THE EXISTENCE OF ADDITIONAL REGULATORY LAYERS IN AF INVOLVING AN INTRICATE CROSS-TALK BETWEEN DIFFERENT NCRNA SPECIES, NAMELY MIRNAS AND CIRCRNAS FOR THE ESTABLISHMENT OF A CHRONIC AF CONDITION. METHODS AND RESULTS: WE HAVE PERFORMED AN UNBIASED STUDY ANALYZING THE EXPRESSION PROFILE FOR MIRNAS AND CIRCRNAS IN LEFT-ATRIAL BIOPSIES FROM PATIENTS WITH PAROXYSMAL AND PERMANENT AF BY RNA-SEQ. THE TRANSITION FROM PAROXYSMAL TO PERMANENT AF IS CHARACTERIZED BY A PATTERN OF DOWN-REGULATED MIRNAS, CONCOMITANT TO THE APPEARANCE OF SPECIFIC CIRCRNA SPECIES. THE ANALYSIS OF THE SPONGING ACTIVITIES OF THE CIRCRNAS EXCLUSIVELY EXPRESSED IN PERMANENT AF SAMPLES, ALLOWED US TO DETERMINE THAT THEY COULD BE RESPONSIBLE FOR THE DOWNREGULATION OF SPECIFIC MIRNAS IN ESTABLISHMENT OF A PERMANENT AF CONDITION. CONCLUSION: SPONGING ACTIVITY OF CIRCRNAS SEQUESTERING SPECIFIC MIRNAS IS AN IMPORTANT FACTOR TO BE CONSIDERED FOR THE DETERMINATION OF THE MOLECULAR MECHANISMS INVOLVED IN AF PROGRESSION. 2019 3 1078 24 CLONAL NON-MALIGNANT HEMATOLOGICAL DISORDERS: UNRAVELING MOLECULAR PATHOGENIC MECHANISMS TO DEVELOP NOVEL TARGETED THERAPEUTICS. CLONAL NON-MALIGNANT HEMATOLOGICAL DISORDERS ARE A HETEROGENEOUS GROUP OF DISEASES THAT ARE PARTICULARLY CHALLENGING FOR HEMATOLOGISTS. INDEED, MOST OBVIOUS AND FREQUENT HEMATOLOGICAL DISEASES INCLUDE A BROAD SPECTRUM OF MALIGNANCIES, SUCH AS LEUKEMIAS, LYMPHOMAS, MYELOMA, AND OTHER MYELOPROLIFERATIVE OR LYMPHOPROLIFERATIVE DISORDERS. IN RECENT YEARS, ALL THESE DISEASES HAVE BEEN CATEGORIZED BY THE WHO ACCORDING TO A NOVEL CLASSIFICATION OF MYELOID AND LYMPHOID MALIGNANCIES, WHICH TAKES IN ACCOUNT THE OUTSTANDING PROGRESS IN OUR UNDERSTANDING OF MOLECULAR DEFECTS UNDERLYING HEMATOLOGICAL MALIGNANCIES. REGARDLESS OF A NUMBER OF NOVEL TECHNOLOGIES, HEMATOLOGISTS CONTINUE TO DEAL DAILY WITH CONDITIONS WHERE A CLEAR DIAGNOSIS OF A MALIGNANCY IS MISSING: THIS IS THE CASE OF SEVERAL CLONAL HEMATOLOGICAL DISORDERS, WHICH ARE CONSIDERED BONA FIDE NON-MALIGNANT. SOME MYELODYSPLASTIC SYNDROMES, CHRONIC T AND NK DISORDERS OF GRANULAR LYMPHOCYTES, MYELOFIBROSIS, MONOCLONAL GAMMOPATHIES, MONOCLONAL B-CEL LYMPHOCYTOSIS, MASTOCYTOSIS AND PAROXYSMAL NOCTURNAL HEMOGLOBINURIA ARE PARADIGMATIC EXAMPLES OF HOW CLONAL DISORDERS ARE CLEARLY DIFFERENT FROM CANCERS, EVEN IF THEY MAY SHARE WITH HEMATOLOGICAL MALIGNANCIES SIMILAR MOLECULAR, GENETIC, EPIGENETIC AND IMMUNOLOGICAL PROCESSES. INDEED, IT IS NOT ENTIRELY CLEAR WHETHER IN INDIVIDUAL CONDITIONS SUCH PATHOGENIC MECHANISMS MAY REPRESENT INITIAL STEP(S) OF MALIGNANT TRANSFORMATION, MAKING A BRIDGE BETWEEN THESE CLONAL NON-MALIGNANT DISORDERS AND TYPICAL HEMATOLOGICAL CANCERS. SOME OF THESE NON-MALIGNANT DISORDERS IMPLY SPECIFIC PATHOGENIC MECHANISMS AND/OR CLINICAL COURSE, AND SO THEY HAVE BEEN DEFINITELY ESTABLISHED WITH THEIR OWN BIOLOGICAL AND CLINICAL IDENTITY. HOWEVER, THE OBVIOUS QUESTION WHETHER SOME OF THESE CLONAL NON-MALIGNANT HEMATOLOGICAL DISEASES FORM SOME A KIND OF DISEASE-CONTINUUM WITH THEIR CORRESPONDING MALIGNANT COUNTERPART IS STILL TO BE ANSWERED. 2014 4 3542 37 IMMUNOHISTOCHEMICAL ANALYSIS OF HISTONE H3 ACETYLATION IN THE TRIGEMINAL ROOT ENTRY ZONE IN AN ANIMAL MODEL OF TRIGEMINAL NEURALGIA. OBJECTIVE: THE TRIGEMINAL ROOT ENTRY ZONE (TREZ) IS A TRANSITIONAL ZONE BETWEEN THE CENTRAL NERVOUS SYSTEM (CNS) AND PERIPHERAL NERVOUS SYSTEM (PNS), ADJACENT TO THE BRAINSTEM. MICROVASCULAR COMPRESSION OF THE TREZ HAS BEEN CONSIDERED TO BE THE PRIMARY ETIOLOGY IN MOST CASES OF TRIGEMINAL NEURALGIA (TN), BUT WHETHER EPIGENETIC REGULATION IS INVOLVED IN THE PATHOGENESIS OF TN IS STILL UNCLEAR. THEREFORE, THIS STUDY WAS DESIGNED TO INVESTIGATE THE EPIGENETIC REGULATION OF HISTONE H3 ACETYLATION IN THE TREZ IN AN ANIMAL MODEL OF TN. METHODS: AN ANIMAL MODEL OF TN WAS ESTABLISHED, AND ADULT MALE SPRAGUE-DAWLEY RATS WERE RANDOMLY ASSIGNED TO A TN GROUP WITH TRIGEMINAL NERVE ROOT COMPRESSION, SHAM OPERATION GROUP, TN+HDACI GROUP (TN PLUS SELECTIVE HISTONE DEACETYLASE INHIBITOR INJECTION INTO THE TREZ), OR TN+VEH GROUP (TN PLUS VEHICLE INJECTION INTO THE TREZ). TO MEASURE THE LENGTH OF THE CENTRAL PORTION OF THE TREZ FROM THE JUNCTION OF THE TRIGEMINAL NERVE ROOT ENTERING THE PONS TO THE INTERFACE OF THE DOME-SHAPED CNS-PNS TRANSITIONAL ZONE, IMMUNOFLUORESCENT STAINING OF GLIA AND GLIAL NUCLEI WAS PERFORMED USING GLIAL FIBRILLARY ACIDIC PROTEIN (GFAP) ANTIBODY AND DAPI, RESPECTIVELY. TO INVESTIGATE THE ACETYLATION OF HISTONE H3 WITHIN THE TREZ IN A TN ANIMAL MODEL GROUP AND A SHAM OPERATION GROUP, LOCALIZATION OF HISTONE H3K9, H3K18, AND H3K27 ACETYLATION WAS EXAMINED VIA IMMUNOHISTOCHEMICAL STAINING METHODS. RESULTS: MEASUREMENTS OF THE CNS-PNS TRANSITIONAL ZONE IN THE TREZ REVEALED THAT THE AVERAGE LENGTH FROM THE JUNCTION OF THE TRIGEMINAL NERVE ROOT CONNECTING THE PONS TO THE GLIAL FRINGE OF THE TREZ IN THE TN GROUP WAS LONGER THAN THAT IN THE SHAM OPERATION GROUP (P < 0.05) AND THAT THE INTERFACE GRADUALLY MIGRATED DISTALLY. CELLS THAT STAINED POSITIVE FOR ACETYLATED HISTONE H3K9, H3K18, AND H3K27 WERE DISTRIBUTED AROUND BOTH SIDES OF THE BORDER OF THE CNS-PNS JUNCTION IN THE TREZ. THE RATIO OF IMMUNOREACTIVE H3K9-, H3K18- AND H3K27-POSITIVE CELLS IN THE TN GROUP WAS OBVIOUSLY HIGHER THAN THAT IN THE SHAM OPERATION GROUP ON POSTOPERATIVE DAYS 7, 14, 21, AND 28 (P < 0.05). CONCLUSIONS: THESE RESULTS SUGGESTED THAT CHRONIC COMPRESSION OF THE TRIGEMINAL NERVE ROOT MAY BE INVOLVED IN THE PATHOGENESIS OF TN IN AN ANIMAL MODEL BY INFLUENCING THE PLASTICITY OF THE CNS-PNS TRANSITIONAL ZONE AND THE LEVEL OF HISTONE ACETYLATION IN THE TREZ. 2018 5 5462 17 RESEARCH PROGRESS ON EPIGENETICS OF SMALL B-CELL LYMPHOMA. SMALL B-CELL LYMPHOMA IS THE CLASSIFICATION OF B-CELL CHRONIC LYMPHOPROLIFERATIVE DISORDERS THAT INCLUDE CHRONIC LYMPHOCYTIC LEUKAEMIA/SMALL LYMPHOCYTIC LYMPHOMA, FOLLICULAR LYMPHOMA, MANTLE CELL LYMPHOMA, MARGINAL ZONE LYMPHOMA, LYMPHOPLASMACYTIC LYMPHOMA/WALDENSTROM MACROGLOBULINEMIA. THE CLINICAL PRESENTATION IS SOMEWHAT HETEROGENEOUS, AND ITS OCCURRENCE AND DEVELOPMENT MECHANISMS ARE NOT YET PRECISE AND MAY INVOLVE EPIGENETIC CHANGES. EPIGENETIC ALTERATIONS MAINLY INCLUDE DNA METHYLATION, HISTONE MODIFICATION, AND NON-CODING RNA, WHICH ARE ESSENTIAL FOR GENETIC DETECTION, EARLY DIAGNOSIS, AND ASSESSMENT OF TREATMENT RESISTANCE IN SMALL B-CELL LYMPHOMA. AS CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA HAS ALREADY BEEN REPORTED IN THE LITERATURE, THIS ARTICLE FOCUSES ON SMALL B-CELL LYMPHOMAS SUCH AS FOLLICULAR LYMPHOMA, MANTLE CELL LYMPHOMA, MARGINAL ZONE LYMPHOMA, AND WALDENSTROM MACROGLOBULINEMIA. IT DISCUSSES RECENT DEVELOPMENTS IN EPIGENETIC RESEARCH TO DIAGNOSE AND TREAT THIS GROUP OF LYMPHOMAS. THIS REVIEW PROVIDES NEW IDEAS FOR THE TREATMENT AND PROGNOSIS ASSESSMENT OF SMALL B-CELL LYMPHOMA BY EXPLORING THE CONNECTION BETWEEN SMALL B-CELL LYMPHOMA AND EPIGENETICS. 2022 6 964 22 CHRONIC MYELOPROLIFERATIVE DISEASES WITH AND WITHOUT THE PH CHROMOSOME: SOME UNRESOLVED ISSUES. PH-POSITIVE CHRONIC MYELOID LEUKEMIA (CML) AND PH-NEGATIVE CHRONIC MYELOPROLIFERATIVE DISEASES (MPDS), CHARACTERIZED IN MANY CASES BY THE PRESENCE OF THE JAK2(V617F) MUTATION, HAVE MANY FEATURES IN COMMON AND YET ALSO SHOW FUNDAMENTAL DIFFERENCES. IN THIS REVIEW, WE POSE FIVE DISCRETE AND RELATED QUESTIONS RELEVANT TO BOTH CATEGORIES OF HEMATOLOGICAL MALIGNANCY, NAMELY: WHAT ARE THE MECHANISMS THAT UNDERLIE DISEASE PROGRESSION FROM A RELATIVELY BENIGN OR CHRONIC PHASE? BY WHAT THERAPEUTIC METHODS MIGHT ONE TARGET RESIDUAL LEUKEMIA STEM CELLS IN CML? IS JAK2(V617F) THE ORIGINAL MOLECULAR EVENT IN MPD? WHAT EPIGENETIC EVENTS MUST HAVE A ROLE IN DICTATING DISEASE PHENOTYPE IN MPDS? AND FINALLY, WILL THE BENEFITS CONFERRED BY CURRENT OR FUTURE JAK2(V617F) INHIBITORS EQUAL OR EVEN SURPASS THE CLINICAL SUCCESS THAT HAS RESULTED FROM THE USE OF TYROSINE KINASE INHIBITORS IN CML? THESE AND OTHERS QUESTIONS MUST BE ADDRESSED AND IN SOME CASES SHOULD BE ANSWERED IN THE FORESEEABLE FUTURE. 2009 7 791 20 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 8 5512 18 RICHTER SYNDROME IN CHRONIC LYMPHOCYTIC LEUKEMIA: UPDATES ON BIOLOGY, CLINICAL FEATURES AND THERAPY. RICHTER SYNDROME (RS) OR RICHTER TRANSFORMATION IS THE DEVELOPMENT OF SECONDARY AGGRESSIVE LYMPHOMA IN THE SETTING OF UNDERLYING CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA (CLL/SLL). MOST FREQUENTLY CLL TRANSFORMS INTO DIFFUSE LARGE B-CELL LYMPHOMA (DLBCL) (90%) AND RARELY (10%) INTO HODGKIN LYMPHOMA, TERMED HODGKIN VARIANT OF RICHTER SYNDROME (HVRS). RS IS GENERALLY CHARACTERIZED BY AN AGGRESSIVE CLINICAL COURSE AND POOR PROGNOSIS. IN RECENT YEARS, MAJOR ADVANCES HAVE BEEN MADE IN UNDERSTANDING GENETIC EVENTS WHICH RELATE TO THE PROGRESSION OF CLL OR TRANSFORMATION INTO RS. BETTER UNDERSTANDING OF THE MOLECULAR PATHWAYS HAS REVEALED THAT RS IS NOT A SINGLE HOMOGENEOUS ENTITY. THE MAJORITY OF CASES ARE CLONALLY RELATED TO THE ORIGINAL CLL CLONE, WHILE A MINORITY DEVELOP FROM AN UNRELATED CLONE. THIS REVIEW SUMMARIZES NEW DATA RELATING TO THE MOLECULAR BIOLOGY AND THE GENETIC/EPIGENETIC CHANGES OCCURRING DURING RICHTER TRANSFORMATION, AND ALSO CONSIDERS THE CLINICAL FEATURES AND THERAPY FOR BOTH DLBCL-RS AND HODGKIN VARIANT-RS. 2015 9 955 18 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 10 3902 24 LEARNING FROM THE FAILURES OF DRUG DISCOVERY IN B-CELL NON-HODGKIN LYMPHOMAS AND PERSPECTIVES FOR THE FUTURE: CHRONIC LYMPHOCYTIC LEUKEMIA AND DIFFUSE LARGE B-CELL LYMPHOMA AS TWO ENDS OF A SPECTRUM IN DRUG DEVELOPMENT. DESPITE SUBSTANTIAL RECENT ADVANCES, THERE IS STILL AN UNMET NEED FOR BETTER THERAPIES IN B-CELL NON HODGKIN LYMPHOMAS (B-NHL), ESPECIALLY IN RELAPSED OR REFRACTORY DISEASE. MANY NOVEL TARGETED DRUGS HAVE BEEN DEVELOPED BASED ON A BETTER MOLECULAR UNDERSTANDING OF B-NHL. AREAS COVERED: THIS ARTICLE FOCUSES ON CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) AS A REPRESENTATIVE FOR INDOLENT LYMPHOMAS AND PARADIGMATIC FOR THE TREMENDOUS PROGRESS IN TREATING B-NHL ON THE ONE HAND AND DIFFUSE LARGE B-CELL LYMPHOMA (DLBCL) AS A REPRESENTATIVE FOR AGGRESSIVE LYMPHOMAS AND PARADIGMATIC FOR MANY UNSOLVED PROBLEMS IN LYMPHOMA TREATMENT OR THE OTHER HAND. WE HIGHLIGHT SALIENT POINTS IN CURRENT THERAPIES TARGETING GENETIC, EPIGENETIC, IMMUNOLOGICAL AND MICROENVIRONMENTAL ALTERATIONS. POSSIBLE REASONS FOR DRUG FAILURE IN CLINICAL TRIALS LIKE TUMOR HETEROGENEITY, CLONAL EVOLUTION AND DRUG RESISTANCE MECHANISMS ARE DISCUSSED. BASED THEREON, SOME PERSPECTIVES FOR FURTHER DRUG DISCOVERY ARE GIVEN. EXPERT OPINION: IN VIEW OF THE PATHOGENETIC COMPLEXITY OF LYMPHOMAS, THERAPIES TARGETING EXCLUSIVELY A SINGLE ALTERATION MAY FAIL BECAUSE RESISTANCE MECHANISMS ARE PRESENT EITHER INITIALLY OR EVOLVE DURING TREATMENT. THEREFORE, FUTURE THERAPIES IN B-NHL MAY HAVE TO TARGET THE GREATEST POSSIBLE NUMBER OF GENETIC, IMMUNOLOGICAL OR EPIGENETIC ALTERATIONS STILL ALLOWING TOLERABILITY AND TO MONITOR THESE ALTERATIONS DURING THERAPY. 2017 11 6040 20 THE CHRONIC MYELOPROLIFERATIVE DISORDERS: CLONALITY AND CLINICAL HETEROGENEITY. THE CHRONIC MYELOPROLIFERATIVE DISORDERS (MPD), POLYCYTHEMIA VERA (PV), CHRONIC IDIOPATHIC MYELOFIBROSIS (IMF), ESSENTIAL THROMBOCYTOSIS (ET), AND CHRONIC MYELOGENOUS LEUKEMIA (CML), ARE THOUGHT TO BE CLONAL DISORDERS ARISING IN A MULTIPOTENT HEMATOPOIETIC PROGENITOR CELL. HOWEVER, ESTABLISHING THE DIAGNOSIS OF AN MPD OTHER THAN CML IS PROBLEMATIC DUE TO A LACK OF CLINICALLY APPLICABLE CLONAL MARKERS. FURTHERMORE, IN SOME PATIENTS, IN WHOM A CLASSICAL MPD PHENOTYPE IS PRESENT, THE HEMATOPOIETIC STEM CELLS APPEAR TO BE POLYCLONAL, SUGGESTING THAT THE CHRONIC MPD OTHER THAN CML MAY ACTUALLY BE A GENETICALLY HETEROGENEOUS GROUP OF DISORDERS. FURTHERMORE, SINCE THE ABERRANT CLONE IS BELIEVED TO ARISE FROM A MULTIPOTENT HEMATOPOIETIC STEM CELL, THE NON-CML CHRONIC MPD-ET, PV, AND IMF-COULD BE RELATED. ADDITIONAL UNRESOLVED ISSUES REGARDING THE MPD INCLUDE: IDENTIFICATION OF THE MULTIPOTENT HEMATOPOIETIC PROGENITOR CELL INVOLVED, THE MOLECULAR BASIS FOR THE CLINICAL HETEROGENEITY AMONGST THE INDIVIDUAL MPD, THE CLINICAL SIGNIFICANCE OF CLONALITY IN NON-CML MPD, AND RECONCILIATION OF THERAPY WITH THE CLONAL AND CLINICAL HETEROGENEITY OF THESE DISORDERS. DETERMINATION OF CLONALITY HAS LARGELY BEEN CARRIED OUT USING X CHROMOSOME-LINKED POLYMORPHISMS, BUT SUCH STUDIES ARE LIMITED TO WOMEN AND WITH INCREASING PATIENT AGE ARE COMPROMISED BY SKEWING OF ALLELIC EXPRESSION IN BOTH NEUTROPHILS AND T LYMPHOCYTES, MAKING THE RESULTS DIFFICULT TO INTERPRET. X CHROMOSOME-LINKED POLYMORPHISM STUDIES HAVE INDICATED THAT IN PV THE TARGET STEM CELL IS ONE THAT GIVES RISE TO BOTH LYMPHOID AND MYELOID PROGENITORS. RECENTLY, TWO EPIGENETIC MARKERS HAVE BEEN IDENTIFIED IN THE MPD: IMPAIRED EXPRESSION OF THE THROMBOPOIETIN RECEPTOR, MPL, IN PLATELETS AND MEGAKARYOCYTES, AND OVEREXPRESSION IN NEUTROPHILS OF THE MRNA OF A GENE DESIGNATED POLYCYTHEMIA RUBRA VERA-1 (PRV-1). THE ROLE OF THESE EPIGENETIC ABNORMALITIES IN THE DIAGNOSIS OF THE MPD REMAINS TO BE ESTABLISHED. CURRENTLY, GIVEN THE UNRESOLVED ISSUES WITH RESPECT TO THE CLINICAL AND CLONAL HETEROGENEITY OF THE MPD, TREATMENT NEEDS TO BE TAILORED INDIVIDUALLY IN PATIENTS WITH AN MPD. 2004 12 6609 25 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 13 4442 20 MOLECULAR GENETICS OF MDS/MPN OVERLAP SYNDROMES. THE MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) ARE A HETEROGENOUS GROUP OF MYELOID MALIGNANCIES HALLMARKED BY CLINICOPATHOLOGIC FEATURES THAT OVERLAP WITH MYELODYSPLASTIC SYNDROMES AND MYELOPROLIFERATIVE NEOPLASMS. FORMALLY RECOGNIZED BY THE WORLD HEALTH ORGANIZATION, THIS GROUP INCLUDES THE ENTITIES CHRONIC MYELOMONOCYTIC LEUKEMIA, JUVENILE MYELOMONOCYTIC LEUKEMIA, ATYPICAL CHRONIC MYELOID LEUKEMIA, MDS/MPN WITH RING SIDEROBLASTS AND THROMBOCYTOSIS AND MDS/MPN, UNCLASSIFIABLE. ADVANCEMENTS IN NEXT GENERATION SEQUENCING HAVE BEGUN TO UNRAVEL THE MOLECULAR UNDERPINNINGS OF THESE DISEASES, IDENTIFYING AN ARRAY OF RECURRENTLY MUTATED GENES INVOLVED IN EPIGENETIC REGULATION, RNA SPLICING, TRANSCRIPTION, AND CELL SIGNALING. DESPITE MOLECULAR OVERLAP WITH OTHER MYELOID MALIGNANCIES, EACH ENTITY DISPLAYS A UNIQUE SPECTRUM OF SOMATIC MUTATIONS SUPPORTING THEIR UNIQUE PATHOBIOLOGY AND CLINICAL FEATURES. IMPORTANTLY, MOLECULAR PROFILING IS BECOMING AN INTEGRAL TOOL UTILIZED IN ROUTINE CLINICAL PRACTICE. THIS REVIEW SUMMARIZES OUR CURRENT UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF OVERLAP SYNDROMES AND DETAILS THE IMPACT OF SOMATIC MUTATIONS IN DIAGNOSTIC, PROGNOSTIC, AND THERAPEUTIC DECISION-MAKING. 2020 14 5212 25 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 15 954 22 CHRONIC MYELOID LEUKEMIA: CURRENT PERSPECTIVES. CHRONIC MYELOID LEUKEMIA (CML), CHARACTERIZED BY THE T(9;22) AND BCR/ABL1 FUSION, IS A DISEASE MODEL FOR STUDYING THE MECHANISMS OF GENETIC ABNORMALITIES IN LEUKEMOGENESIS. THE DETECTION OF THE T(9;22), CHARACTERIZATION OF THE BCR/ABL FUSION, AND THE DISCOVERY OF IMATINIB HAVE ELEGANTLY REFLECTED THE SUCCESS OF OUR RESEARCH EFFORTS IN CML. HOWEVER, GENOMIC INSTABILITIES THAT LEAD TO THE FORMATION OF THE BCR/ ABL1 FUSION ARE NOT FULLY UNDERSTOOD. IT IS IMPORTANT TO UNDERSTAND HOW VARIOUS GENES THAT ARE INVOLVED IN REGULATING THE SIGNALING PATHWAY AND EPIGENETIC DEREGULATION COOPERATE WITH THE BCR/ABL1 FUSION IN THE INITIATION AND PROGRESSION OF CML. 2011 16 6618 24 UNDERSTANDING AND MONITORING CHRONIC MYELOID LEUKEMIA BLAST CRISIS: HOW TO BETTER MANAGE PATIENTS. CHRONIC MYELOID LEUKEMIA (CML) IS TRIGGERED PRIMARILY BY THE T(9;22) (Q34.13; Q11.23) TRANSLOCATION. THIS RECIPROCAL CHROMOSOMAL TRANSLOCATION LEADS TO THE FORMATION OF THE BCR-ABL FUSION GENE. PATIENTS IN THE CHRONIC PHASE (CP) EXPERIENCE A GOOD CURATIVE EFFECT WITH TYROSINE KINASE INHIBITORS. HOWEVER, CASES ARE TREATMENT REFRACTORY, WITH A DISMAL PROGNOSIS, WHEN THE DISEASE HAS PROGRESSED TO THE ACCELERATED PHASE (AP) OR BLAST PHASE (BP). UNTIL NOW, FEW REPORTS HAVE PROVIDED A COMPREHENSIVE DESCRIPTION OF THE MECHANISMS INVOLVED AT DIFFERENT MOLECULAR LEVELS. INDEED, THE UNDERLYING PATHOGENESIS OF CML EVOLUTION COMPRISES GENETIC ABERRATIONS, CHROMOSOMAL TRANSLOCATIONS (EXCEPT FOR THE PHILADELPHIA CHROMOSOME), TELOMERE BIOLOGY, AND EPIGENETIC ANOMALIES. HEREIN, WE PROVIDE KNOWLEDGE OF THE BIOLOGY RESPONSIBLE FOR BLAST TRANSFORMATION OF CML AT SEVERAL LEVELS, SUCH AS GENETICS, TELOMERE BIOLOGY, AND EPIGENETIC ANOMALIES. BECAUSE OF THE LIMITED TREATMENT OPTIONS AVAILABLE AND POOR OUTCOMES, ONLY THE THERAPEUTIC RESPONSE IS MONITORED REGULARLY, WHICH INVOLVES BCR-ABL TRANSCRIPT LEVEL ASSESSMENT AND IMMUNOLOGIC SURVEILLANCE, WITH THE OPTIMAL TREATMENT STRATEGY FOR PATIENTS IN CP ADAPTED TO EVALUATE DISEASE RECURRENCE OR PROGRESSION. OVERALL, SELECTING OPTIMAL TREATMENT ENDPOINTS TO PREDICT SURVIVAL AND SUCCESSFUL TFR IMPROVES THE QUALITY OF LIFE OF PATIENTS. THUS, IDENTIFYING RISK FACTORS AND DEVELOPING RISK-ADAPTED THERAPEUTIC OPTIONS MAY CONTRIBUTE TO A BETTER OUTCOME FOR ADVANCED-PHASE PATIENTS. 2021 17 5782 18 SPLICING ANOMALIES IN MYELOPROLIFERATIVE NEOPLASMS: PAVING THE WAY FOR NEW THERAPEUTIC VENUES. SINCE THE DISCOVERY OF SPLICEOSOME MUTATIONS IN MYELOID MALIGNANCIES, ABNORMAL PRE-MRNA SPLICING, WHICH HAS BEEN WELL STUDIED IN VARIOUS CANCERS, HAS ATTRACTED NOVEL INTEREST IN HEMATOLOGY. HOWEVER, DESPITE THE COMMON OCCURRENCE OF SPLICEOSOME MUTATIONS IN MYELO-PROLIFERATIVE NEOPLASMS (MPN), NOT MUCH IS KNOWN REGARDING THE CHARACTERIZATION AND MECHANISMS OF SPLICING ANOMALIES IN MPN. IN THIS ARTICLE, WE REVIEW THE CURRENT SCIENTIFIC LITERATURE REGARDING "SPLICING AND MYELOPROLIFERATIVE NEOPLASMS". WE FIRST ANALYSE THE CLINICAL SERIES REPORTING SPLICEOSOME MUTATIONS IN MPN AND THEIR CLINICAL CORRELATES. WE THEN PRESENT THE CURRENT KNOWLEDGE ABOUT MOLECULAR MECHANISMS BY WHICH THESE MUTATIONS PARTICIPATE IN THE PATHOGENESIS OF MPN OR OTHER MYELOID MALIGNANCIES. BESIDE SPLICEOSOME MUTATIONS, SPLICING ANOMALIES HAVE BEEN DESCRIBED IN MYELOPROLIFERATIVE NEOPLASMS, AS WELL AS IN ACUTE MYELOID LEUKEMIAS, A DREADFUL COMPLICATION OF THESE CHRONIC DISEASES. BASED ON SPLICING ANOMALIES REPORTED IN CHRONIC MYELOGENOUS LEUKEMIA AS WELL AS IN ACUTE LEUKEMIA, AND THE MECHANISMS PRESIDING SPLICING DEREGULATION, WE PROPOSE THAT ABNORMAL SPLICING PLAYS A MAJOR ROLE IN THE EVOLUTION OF MYELOPROLIFERATIVE NEOPLASMS AND MAY BE THE TARGET OF SPECIFIC THERAPEUTIC STRATEGIES. 2020 18 4485 28 MOLECULAR SIMILARITY BETWEEN MYELODYSPLASTIC FORM OF CHRONIC MYELOMONOCYTIC LEUKEMIA AND REFRACTORY ANEMIA WITH RING SIDEROBLASTS. CHRONIC MYELOMONOCYTIC LEUKEMIA IS SIMILAR TO BUT A SEPARATE ENTITY FROM BOTH MYELOPROLIFERATIVE NEOPLASMS AND MYELODYSPLASTIC SYNDROMES, AND SHOWS EITHER MYELOPROLIFERATIVE OR MYELODYSPLASTIC FEATURES. WE ASK WHETHER THIS DISTINCTION MAY HAVE A MOLECULAR BASIS. WE ESTABLISHED THE GENE EXPRESSION PROFILES OF 39 SAMPLES OF CHRONIC MYELOMONOCYTIC LEUKEMIA (INCLUDING 12 CD34-POSITIVE) AND 32 CD34-POSITIVE SAMPLES OF MYELODYSPLASTIC SYNDROMES BY USING AFFYMETRIX MICROARRAYS, AND STUDIED THE STATUS OF 18 GENES BY SANGER SEQUENCING AND ARRAY-COMPARATIVE GENOMIC HYBRIDIZATION IN 53 SAMPLES. ANALYSIS OF 12 MRNAS FROM CHRONIC MYELOMONOCYTIC LEUKEMIA ESTABLISHED A GENE EXPRESSION SIGNATURE OF 122 PROBE SETS DIFFERENTIALLY EXPRESSED BETWEEN PROLIFERATIVE AND DYSPLASTIC CASES OF CHRONIC MYELOMONOCYTIC LEUKEMIA. AS COMPARED TO PROLIFERATIVE CASES, DYSPLASTIC CASES OVER-EXPRESSED GENES INVOLVED IN RED BLOOD CELL BIOLOGY. WHEN APPLIED TO 32 MYELODYSPLASTIC SYNDROMES, THIS GENE EXPRESSION SIGNATURE WAS ABLE TO DISCRIMINATE REFRACTORY ANEMIAS WITH RING SIDEROBLASTS FROM REFRACTORY ANEMIAS WITH EXCESS OF BLASTS. BY COMPARING MRNAS FROM THESE TWO FORMS OF MYELODYSPLASTIC SYNDROMES WE DERIVED A SECOND GENE EXPRESSION SIGNATURE. THIS SIGNATURE SEPARATED THE MYELODYSPLASTIC AND MYELOPROLIFERATIVE FORMS OF CHRONIC MYELOMONOCYTIC LEUKEMIAS. THESE RESULTS WERE VALIDATED USING TWO INDEPENDENT GENE EXPRESSION DATA SETS. WE FOUND THAT MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS ARE CHARACTERIZED BY MUTATIONS IN TRANSCRIPTION/EPIGENETIC REGULATORS (ASXL1, RUNX1, TET2) AND SPLICING GENES (SRSF2) AND THE ABSENCE OF MUTATIONS IN SIGNALING GENES. MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS AND REFRACTORY ANEMIAS WITH RING SIDEROBLASTS SHARE A COMMON EXPRESSION PROGRAM SUGGESTING THEY ARE PART OF A CONTINUUM, WHICH IS NOT TOTALLY EXPLAINED BY THEIR SIMILAR BUT NOT, HOWEVER, IDENTICAL MUTATION SPECTRUM. 2013 19 4533 26 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 20 543 35 ATRIAL FIBRILLATION IS ASSOCIATED WITH HYPERMETHYLATION IN HUMAN LEFT ATRIUM, AND TREATMENT WITH DECITABINE REDUCES ATRIAL TACHYARRHYTHMIAS IN SPONTANEOUSLY HYPERTENSIVE RATS. ATRIAL FIBRILLATION (AF) IS THE MOST COMMON CARDIAC ARRHYTHMIA. AS THE MOLECULAR MECHANISMS UNDERLYING THE PATHOLOGY ARE LARGELY UNKNOWN, THIS CARDIAC ARRHYTHMIA REMAINS DIFFICULT TO TREAT. TO IDENTIFY SPECIFIC MOLECULAR ACTORS INVOLVED IN AF, WE HAVE PERFORMED A TRANSCRIPTOMIC ANALYSIS ON LEFT ATRIUM (LA) FROM PATIENTS WITH VALVULAR HEART DISEASE WITH OR WITHOUT AF. WE SHOWED THAT 1627 GENES HAD ALTERED BASAL EXPRESSION LEVEL IN LA TISSUE OF AF PATIENTS COMPARED WITH THE CONTROL GROUP. THE SIGNIFICANTLY ENRICHED GENE ONTOLOGY BIOLOGICAL PROCESS "ANATOMICAL STRUCTURE MORPHOGENESIS" CONTAINED THE HIGHEST NUMBER OF GENES IN LINE WITH CHANGES IN STRUCTURE THAT OCCUR WHEN THE HUMAN HEART REMODELS FOLLOWING AF DEVELOPMENT (IE, LA DILATATION AND INTERSTITIAL FIBROSIS). WE THEN FOCUSED THE STUDY ON PITX2 (PAIRED-LIKE HOMEODOMAIN 2), BEING THE MOST ALTERED TRANSCRIPTION FACTOR IN LA FROM AF PATIENTS AND FROM WHICH COMPELLING EVIDENCE HAVE INDICATED THAT ITS REDUCED EXPRESSION CAN BE CONSIDERED AS A MARKER FOR THE DISEASE. IN ADDITION, ITS EXPRESSION WAS INVERSELY CORRELATED WITH LA SIZE. WE DEMONSTRATED THAT AF IS ASSOCIATED WITH PITX2 PROMOTER HYPERMETHYLATION BOTH IN HUMANS AND ARRHYTHMIC AGING SPONTANEOUSLY HYPERTENSIVE RATS. CHRONIC ADMINISTRATION OF A DNA METHYLATION INHIBITOR (IE, 5-AZA-2'-DEOXYCITIDINE) IMPROVED ECG ARRHYTHMIC PROFILES AND SUPEROXIDE DISMUTASE ACTIVITIES AND REDUCED FIBROSIS IN THE LEFT VENTRICLE OF SPONTANEOUSLY HYPERTENSIVE RATS. TAKEN TOGETHER, THESE DATA SUPPORT THE NOTION THAT AF IS ASSOCIATED WITH EPIGENETIC CHANGES IN LA AND PROVIDE A PROOF-OF-CONCEPT THAT HYPOMETHYLATING AGENTS HAVE TO BE CONSIDERED IN THE TREATMENT OF ATRIAL ARRHYTHMIAS. 2017