1 5455 111 RESCUE OF A PRIMARY MYELOFIBROSIS MODEL BY RETINOID-ANTAGONIST THERAPY. MOLECULAR TARGETING OF THE TWO RECEPTOR INTERACTION DOMAINS OF THE EPIGENETIC REPRESSOR SILENCING MEDIATOR OF RETINOID AND THYROID HORMONE RECEPTORS (SMRT(MRID)) PRODUCED A TRANSPLANTABLE SKELETAL SYNDROME THAT REDUCED RADIAL BONE GROWTH, INCREASED NUMBERS OF BONE-RESORBING PERIOSTEAL OSTEOCLASTS, AND INCREASED BONE FRACTURE RISK. FURTHERMORE, SMRT(MRID) MICE DEVELOP SPONTANEOUS PRIMARY MYELOFIBROSIS, A CHRONIC, USUALLY IDIOPATHIC DISORDER CHARACTERIZED BY PROGRESSIVE BONE MARROW FIBROSIS. FREQUENTLY LINKED TO POLYCYTHEMIA VERA AND CHRONIC MYELOID LEUKEMIA, MYELOFIBROSIS DISPLAYS HIGH PATIENT MORBIDITY AND MORTALITY, AND CURRENT TREATMENT IS MOSTLY PALLIATIVE. TO DECIPHER THE ETIOLOGY OF THIS DISEASE, WE IDENTIFIED THE THROMBOPOIETIN (TPO) GENE AS A TARGET OF THE SMRT-RETINOIC ACID RECEPTOR SIGNALING PATHWAY IN BONE MARROW STROMAL CELLS. CHRONIC INDUCTION OF TPO IN SMRT(MRID) MICE RESULTS IN UP-REGULATION OF TGF-BETA AND PDGF IN MEGAKARYOCYTES, UNCONTROLLED PROLIFERATION OF BONE MARROW RETICULAR CELLS, AND FIBROSIS OF THE MARROW COMPARTMENT. OF THERAPEUTIC RELEVANCE, WE SHOW THAT THIS SYNDROME CAN BE RESCUED BY RETINOID ANTAGONISTS, DEMONSTRATING THAT THE PHYSICAL INTERFACE BETWEEN SMRT AND RETINOIC ACID RECEPTOR CAN BE A POTENTIAL THERAPEUTIC TARGET TO BLOCK PRIMARY MYELOFIBROSIS DISEASE PROGRESSION. 2013 2 4837 22 ONCOGENIC GENE EXPRESSION AND EPIGENETIC REMODELING OF CIS-REGULATORY ELEMENTS IN ASXL1-MUTANT CHRONIC MYELOMONOCYTIC LEUKEMIA. MYELOID NEOPLASMS ARE CLONAL HEMATOPOIETIC STEM CELL DISORDERS DRIVEN BY THE SEQUENTIAL ACQUISITION OF RECURRENT GENETIC LESIONS. TRUNCATING MUTATIONS IN THE CHROMATIN REMODELER ASXL1 (ASXL1(MT)) ARE ASSOCIATED WITH A HIGH-RISK DISEASE PHENOTYPE WITH INCREASED PROLIFERATION, EPIGENETIC THERAPEUTIC RESISTANCE, AND POOR SURVIVAL OUTCOMES. WE PERFORMED A MULTI-OMICS INTERROGATION TO DEFINE GENE EXPRESSION AND CHROMATIN REMODELING ASSOCIATED WITH ASXL1(MT) IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). ASXL1(MT) ARE ASSOCIATED WITH A LOSS OF REPRESSIVE HISTONE METHYLATION AND INCREASE IN PERMISSIVE HISTONE METHYLATION AND ACETYLATION IN PROMOTER REGIONS. ASXL1(MT) ARE FURTHER ASSOCIATED WITH DE NOVO ACCESSIBILITY OF DISTAL ENHANCERS BINDING ETS TRANSCRIPTION FACTORS, TARGETING IMPORTANT LEUKEMOGENIC DRIVER GENES. CHROMATIN REMODELING OF PROMOTERS AND ENHANCERS IS STRONGLY ASSOCIATED WITH GENE EXPRESSION AND HETEROGENOUS AMONG OVEREXPRESSED GENES. THESE RESULTS PROVIDE A COMPREHENSIVE MAP OF THE TRANSCRIPTOME AND CHROMATIN LANDSCAPE OF ASXL1(MT) CMML, FORMING AN IMPORTANT FRAMEWORK FOR THE DEVELOPMENT OF NOVEL THERAPEUTIC STRATEGIES TARGETING ONCOGENIC CIS INTERACTIONS. 2022 3 1260 25 CURRENT VIEWS ON THE INTERPLAY BETWEEN TYROSINE KINASES AND PHOSPHATASES IN CHRONIC MYELOID LEUKEMIA. CHRONIC MYELOID LEUKEMIA (CML) IS A MYELOPROLIFERATIVE DISORDER CHARACTERIZED BY BCR-ABL1 ONCOGENE EXPRESSION. THIS DYSREGULATED PROTEIN-TYROSINE KINASE (PTK) IS KNOWN AS THE PRINCIPAL DRIVER OF THE DISEASE AND IS TARGETED BY TYROSINE KINASE INHIBITORS (TKIS). EXTENSIVE DOCUMENTATION HAS ELUCIDATED HOW THE TRANSFORMATION OF MALIGNANT CELLS IS CHARACTERIZED BY MULTIPLE GENETIC/EPIGENETIC CHANGES LEADING TO THE LOSS OF TUMOR-SUPPRESSOR GENES FUNCTION OR PROTO-ONCOGENES EXPRESSION. THE IMPAIRMENT OF ADEQUATE LEVELS OF SUBSTRATES PHOSPHORYLATION, THUS AFFECTING THE BALANCE PTKS AND PROTEIN PHOSPHATASES (PPS), REPRESENTS A WELL-ESTABLISHED CELLULAR MECHANISM TO ESCAPE FROM SELF-LIMITING SIGNALS. IN THIS REVIEW, WE FOCUS OUR ATTENTION ON THE CHARACTERIZATION OF AND INTERACTIONS BETWEEN PTKS AND PPS, EMPHASIZING THEIR BIOLOGICAL ROLES IN DISEASE EXPANSION, THE REGULATION OF LSCS AND TKI RESISTANCE. WE DECIDED TO SEPARATE THOSE PPS THAT HAVE BEEN VALIDATED IN PRIMARY CELL MODELS OR LEUKEMIA MOUSE MODELS FROM THOSE WHOSE STUDIES HAVE BEEN PERFORMED ONLY IN CELL LINES (AND, THUS, REQUIRE VALIDATION), AS THERE MAY BE DIFFERENCES IN THE MANNER THAT THE ASSOCIATED PATHWAYS ARE MODIFIED UNDER THESE TWO CONDITIONS. THIS REVIEW SUMMARIZES THE ROLES OF DIVERSE PPS, WITH HOPE THAT BETTER KNOWLEDGE OF THE INTERPLAY AMONG PHOSPHATASES AND KINASES WILL EVENTUALLY RESULT IN A BETTER UNDERSTANDING OF THIS DISEASE AND CONTRIBUTE TO ITS ERADICATION. 2021 4 102 23 A REGULATORY ROLE FOR CHD2 IN MYELOPOIESIS. THE TRANSCRIPTIONAL PROGRAM THAT DICTATES HAEMATOPOIETIC CELL FATE AND DIFFERENTIATION REQUIRES AN EPIGENETIC REGULATORY AND MEMORY FUNCTION, PROVIDED BY A NETWORK OF EPIGENETIC FACTORS THAT REGULATE DNA METHYLATION, POST-TRANSLATIONAL HISTONE MODIFICATIONS AND CHROMATIN STRUCTURE. DISTURBED EPIGENETIC REGULATION CAUSES PERTURBATIONS IN THE BLOOD CELL DIFFERENTIATION PROGRAM THAT RESULTS IN VARIOUS TYPES OF HAEMATOPOIETIC DISORDERS. THUS, ACCURATE EPIGENETIC REGULATION IS ESSENTIAL FOR FUNCTIONAL HAEMATOPOIESIS. IN THIS STUDY, WE USED A CRISPR-CAS9 SCREENING APPROACH TO IDENTIFY NEW EPIGENETIC REGULATORS IN MYELOID DIFFERENTIATION. WE DESIGNED A CHROMATIN-UMI CRISPR GUIDE LIBRARY TARGETING 1092 EPIGENETIC REGULATORS. PHORBOL 12-MYRISTATE 13-ACETATE (PMA) TREATMENT OF THE CHRONIC MYELOID LEUKAEMIA CELL LINE K-562 WAS USED AS A MEGAKARYOCYTIC MYELOID DIFFERENTIATION MODEL. BOTH PREVIOUSLY DESCRIBED DEVELOPMENTAL EPIGENETIC REGULATORS AND NOVEL FACTORS WERE IDENTIFIED IN OUR SCREEN. IN THIS STUDY, WE VALIDATED AND CHARACTERIZED A ROLE FOR THE CHROMATIN REMODELLER CHD2 IN MYELOID PROLIFERATION AND MEGAKARYOCYTIC DIFFERENTIATION. 2020 5 5249 31 PROGRAMMED CELL DEATH-1 PATHWAY INHIBITION IN MYELOID MALIGNANCIES: IMPLICATIONS FOR MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLONAL HEMATOPOIETIC DISEASES THAT BELONG TO THE SPECTRUM OF MYELOID MALIGNANCIES (MYMS), WHICH ALSO INCLUDE MYELODYSPLASTIC SYNDROMES (MDS), ACUTE MYELOID LEUKEMIA (AML), AND CHRONIC MYELOGENOUS LEUKEMIA (CML). WHILE HEMATOPOIETIC STEM CELL TRANSPLANTATION (HSCT) IS A POTENTIALLY CURATIVE THERAPEUTIC APPROACH TO MANY MYMS, THE ASSOCIATED MORBIDITY AND MORTALITY HAVE NECESSITATED THE DEVELOPMENT OF NON-HSCT THERAPEUTICS FOR SYMPTOM MANAGEMENT AND DISEASE COURSE MODIFICATION. IMMUNE CHECKPOINT INHIBITION, IN PARTICULAR ALONG THE PROGRAMMED CELL DEATH PROTEIN 1 (PD-1)/B7-H1 (PD-L1) AXIS, IS AN ESTABLISHED STRATEGY IN SOLID TUMORS WITH POTENTIAL AS AN ADJUNCTIVE THERAPY IN HEMATOLOGIC MALIGNANCIES. SEMINAL STUDIES SUGGEST THAT THE PRO-INFLAMMATORY MICROENVIRONMENT OF MYMS CAN SUPPRESS T LYMPHOCYTE-MEDIATED IMMUNITY VIA PD-1 SIGNALING AND THAT RESPONSE TO MAINSTAY EPIGENETIC THERAPIES FOR MYMS MAY BE GOVERNED BY PD-1 GENE REGULATION. ALTHOUGH THE ROLE OF PD-1 SIGNALING IN MPN PATHOGENESIS AND PROGRESSION IS AS YET UNCLEAR, RESEARCH IN MPN PATIENTS HAS REVEALED EXPANSION OF MYELOID-DERIVED SUPPRESSOR CELLS (MDSCS), WHICH MAY EFFECT HOST IMMUNE TOLERANCE OF TUMOR VIA TEMPORALLY AND SPATIALLY SPECIFIC ACTIVATION OF PD-1/PD-L1 SIGNALING. THE CURRENT UNDERSTANDING OF IMMUNE DYSFUNCTION IN MPNS AND ANALOGOUS MYMS OFFERS A COMPELLING RATIONALE TO STUDY PD-1/PD-L1 INHIBITION IN PATIENTS AS A NOVEL TREATMENT OPTION. 2017 6 5688 24 SILENCING EFFECTS OF MUTANT RAS SIGNALLING ON TRANSCRIPTOMES. MUTATED GENES OF THE RAS FAMILY ENCODING SMALL GTP-BINDING PROTEINS DRIVE NUMEROUS CANCERS, INCLUDING PANCREATIC, COLON AND LUNG TUMORS. BESIDES THE NUMEROUS EFFECTS OF MUTANT RAS GENE EXPRESSION ON ABERRANT PROLIFERATION, TRANSFORMED PHENOTYPES, METABOLISM, AND THERAPY RESISTANCE, THE MOST STRIKING CONSEQUENCES OF CHRONIC RAS ACTIVATION ARE CHANGES OF THE GENETIC PROGRAM. BY PERFORMING SYSTEMATIC GENE EXPRESSION STUDIES IN CELLULAR MODELS THAT ALLOW COMPARISONS OF PRE-NEOPLASTIC WITH RAS-TRANSFORMED CELLS, WE AND OTHERS HAVE ESTIMATED THAT 7 PERCENT OR MORE OF ALL TRANSCRIPTS ARE ALTERED IN CONJUNCTION WITH THE EXPRESSION OF THE ONCOGENE. IN THIS CONTEXT, THE NUMBER OF UP-REGULATED TRANSCRIPTS APPROXIMATES THAT OF DOWN-REGULATED TRANSCRIPTS. WHILE UP-REGULATED TRANSCRIPTION FACTORS SUCH AS MYC, FOSL1, AND HMGA2 HAVE BEEN IDENTIFIED AND CHARACTERIZED AS RAS-RESPONSIVE DRIVERS OF THE ALTERED TRANSCRIPTOME, THE SUPPRESSED FACTORS HAVE BEEN LESS WELL STUDIED AS POTENTIAL REGULATORS OF THE GENETIC PROGRAM AND TRANSFORMED PHENOTYPE IN THE BREADTH OF THEIR OCCURRENCE. WE THEREFORE HAVE COLLECTED INFORMATION ON DOWNREGULATED RAS-RESPONSIVE FACTORS AND DISCUSS THEIR POTENTIAL ROLE AS TUMOR SUPPRESSORS THAT ARE LIKELY TO ANTAGONIZE ACTIVE CANCER DRIVERS. TO BETTER UNDERSTAND THE ACTIVE MECHANISMS THAT ENTAIL ANTI-RAS FUNCTION AND THOSE THAT LEAD TO LOSS OF TUMOR SUPPRESSOR ACTIVITY, WE FOCUS ON THE TUMOR SUPPRESSOR HREV107 (ALIAS PLAAT3 [PHOSPHOLIPASE A AND ACYLTRANSFERASE 3], PLA2G16 [PHOSPHOLIPASE A2, GROUP XVI] AND HRASLS3 [HRAS-LIKE SUPPRESSOR 3]). INACTIVATING HREV107 MUTATIONS IN TUMORS ARE EXTREMELY RARE, HENCE EPIGENETIC CAUSES MODULATED BY THE RAS PATHWAY ARE LIKELY TO LEAD TO DOWN-REGULATION AND LOSS OF FUNCTION. 2023 7 5101 29 POLYCOMB FACTOR PHF19 CONTROLS CELL GROWTH AND DIFFERENTIATION TOWARD ERYTHROID PATHWAY IN CHRONIC MYELOID LEUKEMIA CELLS. POLYCOMB GROUP (PCG) OF PROTEINS ARE A GROUP OF HIGHLY CONSERVED EPIGENETIC REGULATORS INVOLVED IN MANY BIOLOGICAL FUNCTIONS, SUCH AS EMBRYONIC DEVELOPMENT, CELL PROLIFERATION, AND ADULT STEM CELL DETERMINATION. PHD FINGER PROTEIN 19 (PHF19) IS AN ASSOCIATED FACTOR OF POLYCOMB REPRESSOR COMPLEX 2 (PRC2), OFTEN UPREGULATED IN HUMAN CANCERS. IN PARTICULAR, MYELOID LEUKEMIA CELL LINES SHOW INCREASED LEVELS OF PHF19, YET LITTLE IS KNOWN ABOUT ITS FUNCTION. HERE, WE HAVE CHARACTERIZED THE ROLE OF PHF19 IN MYELOID LEUKEMIA CELLS. WE DEMONSTRATED THAT PHF19 DEPLETION DECREASES CELL PROLIFERATION AND PROMOTES CHRONIC MYELOID LEUKEMIA (CML) DIFFERENTIATION. MECHANISTICALLY, WE HAVE SHOWN HOW PHF19 REGULATES THE PROLIFERATION OF CML THROUGH A DIRECT REGULATION OF THE CELL CYCLE INHIBITOR P21. FURTHERMORE, WE OBSERVED THAT MTF2, A PHF19 HOMOLOG, PARTIALLY COMPENSATES FOR PHF19 DEPLETION IN A SUBSET OF TARGET GENES, INSTRUCTING SPECIFIC ERYTHROID DIFFERENTIATION. TAKEN TOGETHER, OUR RESULTS SHOW THAT PHF19 IS A KEY TRANSCRIPTIONAL REGULATOR FOR CELL FATE DETERMINATION AND COULD BE A POTENTIAL THERAPEUTIC TARGET FOR MYELOID LEUKEMIA TREATMENT. 2021 8 1902 23 ENHANCED EXPRESSION OF THE NUCLEAR ENVELOPE LAP2 TRANSCRIPTIONAL REPRESSORS IN NORMAL AND MALIGNANT ACTIVATED LYMPHOCYTES. EXTENSIVE RESEARCH IN RECENT YEARS HAS BROADENED THE FUNCTIONS OF NUCLEAR ENVELOPE PROTEINS BEYOND SIMPLY STABILIZING THE NUCLEUS ARCHITECTURE. PARTICULARLY, INTEGRAL NUCLEAR MEMBRANE PROTEINS, SUCH AS THE ALTERNATIVE SPLICED ISOFORMS OF LAMINA-ASSOCIATED POLYPEPTIDE 2 (LAP2), HAVE BEEN SHOWN TO BE IMPORTANT FOR THE INITIATION OF REPLICATION AND REPRESSION OF TRANSCRIPTION. THE LATTER IS REGULATED BY EPIGENETIC CHANGES, INDUCED BY THE BINDING OF LAP2BETA TO HISTONE DEACETYLASE-3 (HDAC3), RESULTING IN HISTONE H4 DEACETYLATION. INVOLVEMENT OF NUCLEAR ENVELOPE PROTEINS IN PATHOLOGICAL PROLIFERATIVE CONDITIONS, MAINLY THOSE INVOLVING ABNORMAL RECRUITMENT AND ACTIVATION OF HDACS, IS STILL UNKNOWN. IN THIS PAPER, WE SHOW THAT VARIOUS NUCLEAR ENVELOPE PROTEINS ARE HIGHLY EXPRESSED IN NORMAL AND MALIGNANT ACTIVATED LYMPHOCYTES. SPECIFICALLY, RAPIDLY REPLICATING CELLS OF VARIOUS HEMATOLOGICAL MALIGNANCIES HIGHLY EXPRESS LAP2BETA, WHILE SLOWLY PROLIFERATING MALIGNANT CELLS OF CHRONIC MALIGNANT HEMATOLOGICAL DISEASES DO NOT. TAKING TOGETHER THE ELEVATED EXPRESSION OF LAP2BETA IN HIGHLY PROLIFERATIVE MALIGNANT CELLS WITH ITS KNOWN ABILITY TO MODIFY HISTONES THROUGH BINDING WITH HDAC3 RAISES THE POSSIBILITY OF ITS ROLE IN HEMATOLOGICAL MALIGNANCIES INVOLVING ABERRANT ACTIVITY OF HDAC3. BASED ON OUR PRESENTED RESULTS, WE BELIEVE THAT THE LAP2-HDAC REGULATORY PATHWAY SHOULD BE STUDIED AS A NEW TARGET FOR RATIONAL THERAPY. 2007 9 5433 16 REL/NF-KAPPA B/I KAPPA B SIGNAL TRANSDUCTION IN THE GENERATION AND TREATMENT OF HUMAN CANCER. THE REL/NF-KAPPA B FAMILY IS A GROUP OF STRUCTURALLY-RELATED, TIGHTLY-REGULATED TRANSCRIPTION FACTORS THAT CONTROL THE EXPRESSION OF A MULTITUDE OF GENES INVOLVED IN KEY CELLULAR AND ORGANISMAL PROCESSES. THE REL/NF-KAPPA B SIGNAL TRANSDUCTION PATHWAY IS MISREGULATED IN A VARIETY OF HUMAN CANCERS, ESPECIALLY ONES OF LYMPHOID CELL ORIGIN, DUE EITHER TO GENETIC CHANGES (SUCH AS CHROMOSOMAL REARRANGEMENTS, AMPLIFICATIONS, AND MUTATIONS) OR TO CHRONIC ACTIVATION OF THE PATHWAY BY EPIGENETIC MECHANISMS. CONSTITUTIVE ACTIVATION OF THE REL/NF-KAPPA B PATHWAY CAN CONTRIBUTE TO THE ONCOGENIC STATE IN SEVERAL WAYS, FOR EXAMPLE, BY DRIVING PROLIFERATION, BY ENHANCING CELL SURVIVAL, OR BY PROMOTING ANGIOGENESIS OR METASTASIS. IN MANY CASES, INHIBITION OF REL/NF-KAPPA B ACTIVITY REVERSES ALL OR PART OF THE MALIGNANT STATE. THUS, THE REL/NF-KAPPA B PATHWAY HAS RECEIVED MUCH ATTENTION AS A FOCAL POINT FOR CLINICAL INTERVENTION. 2002 10 6584 23 TRIGGERING RECEPTORS EXPRESSED ON MYELOID CELLS 1 : OUR NEW PARTNER IN HUMAN ONCOLOGY? INFLAMMATION IS RECOGNIZED AS ONE OF THE HALLMARKS OF CANCER. INDEED, STRONG EVIDENCE INDICATES THAT CHRONIC INFLAMMATION PLAYS A MAJOR ROLE IN ONCOGENESIS, PROMOTING GENOME INSTABILITY, EPIGENETIC ALTERATIONS, PROLIFERATION AND DISSEMINATION OF CANCER CELLS. MONONUCLEAR PHAGOCYTES (MPS) HAVE BEEN IDENTIFIED AS KEY CONTRIBUTORS OF THE INFLAMMATORY INFILTRATE IN SEVERAL SOLID HUMAN NEOPLASIA, PROMOTING ANGIOGENESIS AND CANCER PROGRESSION. ONE OF THE MOST DESCRIBED AMPLIFIERS OF MPS PRO-INFLAMMATORY INNATE IMMUNE RESPONSE IS THE TRIGGERING RECEPTORS EXPRESSED ON MYELOID CELLS 1 (TREM-1). GROWING EVIDENCE SUGGESTS TREM-1 INVOLVEMENT IN ONCOGENESIS THROUGH CANCER RELATED INFLAMMATION AND THE SURROUNDING TUMOR MICROENVIRONMENT. IN HUMAN ONCOLOGY, HIGH LEVELS OF TREM-1 AND/OR ITS SOLUBLE FORM HAVE BEEN ASSOCIATED WITH POORER SURVIVAL DATA IN SEVERAL SOLID MALIGNANCIES, ESPECIALLY IN HEPATOCELLULAR CARCINOMA AND LUNG CANCER. TREM-1 SHOULD BE CONSIDERED AS A POTENTIAL BIOMARKER IN HUMAN ONCOLOGY AND COULD BE USED AS A NEW THERAPEUTIC TARGET OF INTEREST IN HUMAN ONCOLOGY (TREM-1 INHIBITORS, TREM-1 AGONISTS). MORE CLINICAL STUDIES ARE URGENTLY NEEDED TO CONFIRM TREM-1 (AND TREM FAMILY) ROLES IN THE PROGNOSIS AND THE TREATMENT OF HUMAN SOLID CANCERS. 2022 11 2462 28 EPIGENETIC THERAPY OF MYELODYSPLASTIC SYNDROMES CONNECTS TO CELLULAR DIFFERENTIATION INDEPENDENTLY OF ENDOGENOUS RETROELEMENT DEREPRESSION. BACKGROUND: MYELODYSPLASTIC SYNDROMES (MDS) AND ACUTE MYELOID LEUKAEMIA (AML) ARE CHARACTERISED BY ABNORMAL EPIGENETIC REPRESSION AND DIFFERENTIATION OF BONE MARROW HAEMATOPOIETIC STEM CELLS (HSCS). DRUGS THAT REVERSE EPIGENETIC REPRESSION, SUCH AS 5-AZACYTIDINE (5-AZA), INDUCE HAEMATOLOGICAL IMPROVEMENT IN HALF OF TREATED PATIENTS. ALTHOUGH THE MECHANISMS UNDERLYING THERAPY SUCCESS ARE NOT YET CLEAR, INDUCTION OF ENDOGENOUS RETROELEMENTS (ERES) HAS BEEN HYPOTHESISED. METHODS: USING RNA SEQUENCING (RNA-SEQ), WE COMPARED THE TRANSCRIPTION OF ERES IN BONE MARROW HSCS FROM A NEW COHORT OF MDS AND CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML) PATIENTS BEFORE AND AFTER 5-AZA TREATMENT WITH HSCS FROM HEALTHY DONORS AND AML PATIENTS. WE FURTHER EXAMINED ERE TRANSCRIPTION USING THE MOST COMPREHENSIVE ANNOTATION OF ERE-OVERLAPPING TRANSCRIPTS EXPRESSED IN HSCS, GENERATED HERE BY DE NOVO TRANSCRIPT ASSEMBLY AND SUPPORTED BY FULL-LENGTH RNA-SEQ. RESULTS: CONSISTENT WITH PRIOR REPORTS, WE FOUND THAT TREATMENT WITH 5-AZA INCREASED THE REPRESENTATION OF ERE-DERIVED RNA-SEQ READS IN THE TRANSCRIPTOME. HOWEVER, SUCH INCREASES WERE COMPARABLE BETWEEN TREATMENT RESPONSES AND FAILURES. THE EXTENDED VIEW OF HSC TRANSCRIPTIONAL DIVERSITY OFFERED BY DE NOVO TRANSCRIPT ASSEMBLY ARGUED AGAINST 5-AZA-RESPONSIVE ERES AS DETERMINANTS OF THE OUTCOME OF THERAPY. INSTEAD, IT UNCOVERED PRE-TREATMENT EXPRESSION AND ALTERNATIVE SPLICING OF DEVELOPMENTALLY REGULATED GENE TRANSCRIPTS AS PREDICTORS OF THE RESPONSE OF MDS AND CMML PATIENTS TO 5-AZA TREATMENT. CONCLUSIONS: OUR STUDY IDENTIFIES THE DEVELOPMENTALLY REGULATED TRANSCRIPTIONAL SIGNATURES OF PROTEIN-CODING AND NON-CODING GENES, RATHER THAN ERES, AS CORRELATES OF A FAVOURABLE RESPONSE OF MDS AND CMML PATIENTS TO 5-AZA TREATMENT AND OFFERS NOVEL CANDIDATES FOR FURTHER EVALUATION. 2019 12 5691 35 SILENCING OF HDAC6 AS A THERAPEUTIC TARGET IN CHRONIC LYMPHOCYTIC LEUKEMIA. ALTHOUGH THE TREATMENT PARADIGM FOR CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS RAPIDLY CHANGING, THE DISEASE REMAINS INCURABLE, EXCEPT WITH ALLOGENEIC BONE MARROW TRANSPLANTATION, AND RESISTANCE, RELAPSED DISEASE, AND PARTIAL RESPONSES PERSIST AS SIGNIFICANT CHALLENGES. RECENT STUDIES HAVE UNCOVERED ROLES FOR EPIGENETIC MODIFICATION IN THE REGULATION OF MECHANISMS CONTRIBUTING TO MALIGNANT PROGRESSION OF CLL B CELLS. HOWEVER, THE EXTENT TO WHICH EPIGENETIC MODIFIERS CAN BE TARGETED FOR THERAPEUTIC BENEFIT IN CLL PATIENTS REMAINS POORLY EXPLORED. WE REPORT FOR THE FIRST TIME THAT EXPRESSION OF EPIGENETIC MODIFIER HISTONE DEACETYLASE 6 (HDAC6) IS UPREGULATED IN CLL PATIENT SAMPLES, CELL LINES, AND EUTCL1 TRANSGENIC MOUSE MODELS COMPARED WITH HDAC6 IN NORMAL CONTROLS. GENETIC SILENCING OF HDAC6 CONFERRED SURVIVAL BENEFIT IN EUTCL1 MICE. ADMINISTRATION OF ISOFORM-SPECIFIC HDAC6 INHIBITOR ACY738 IN THE EUTCL1 AGING AND ADOPTIVE TRANSFER MODELS DETERRED PROLIFERATION OF CLL B CELLS, DELAYED DISEASE ONSET VIA DISRUPTION OF B-CELL RECEPTOR SIGNALING, AND SENSITIZED CLL B CELLS TO APOPTOSIS. FURTHERMORE, COADMINISTRATION OF ACY738 AND IBRUTINIB DISPLAYED SYNERGISTIC CELL KILL AGAINST CLL CELL LINES AND IMPROVED OVERALL SURVIVAL COMPARED WITH EITHER SINGLE AGENT IN VIVO. THESE RESULTS DEMONSTRATE FOR THE FIRST TIME THE THERAPEUTIC EFFICACY OF SELECTIVE HDAC6 INHIBITION IN PRECLINICAL CLL MODELS AND SUGGEST A RATIONALE FOR THE CLINICAL DEVELOPMENT OF HDAC6 INHIBITORS FOR CLL TREATMENT, EITHER ALONE OR IN COMBINATION WITH BRUTON TYROSINE KINASE INHIBITION. 2018 13 409 19 ANALYSIS OF GENES ENCODING EPIGENETIC REGULATORS IN MYELOPROLIFERATIVE NEOPLASMS: COEXISTENCE OF A NOVEL SETBP1 MUTATION IN A PATIENT WITH A P.V617F JAK2 POSITIVE MYELOFIBROSIS. IN RECENT YEARS IT HAS BEEN SHOWN THAT THE CAUSES OF CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE MORE COMPLEX THAN A SIMPLE SIGNALING ABERRATION AND MANY OTHER MUTATED GENES AFFECTING DIFFERENT CELL PROCESSES HAVE BEEN DESCRIBED. FOR INSTANCE, MUTATIONS IN GENES ENCODING EPIGENETIC REGULATORS ARE MORE FREQUENT THAN EXPECTED. ONE OF THE LATEST GENES DESCRIBED AS MUTATED IS SET BINDING PROTEIN 1 (SETBP1). IN SILICO TOOLS HAVE REVEALED THAT THERE ARE SEVERAL HUMAN SETBP1 PARALOGOUS TO NUCLEAR RECEPTOR BINDING SET DOMAIN PROTEIN 1 (NSD1), NSD2 AND NSD3, FOR EXAMPLE, WHICH ARE ALSO INVOLVED IN THE DEVELOPMENT OF OTHER HEMATOLOGICAL MALIGNANCIES. THEREFORE, THE PRESENT STUDY ANALYZED THE MUTATIONAL STATUS OF NSD1, NSD2, NSD3 AND SETBP1 IN BCR-ABL1 NEGATIVE MPNS WITH OR WITHOUT JANUS KINASE 2 (JAK2) P.V617F MUTATION. THE PRESENT STUDY REVEALED THAT THE NSD GENES ARE NOT FREQUENTLY MUTATED IN MPNS. HOWEVER, A NOVEL SETBP1 MUTATION WAS IDENTIFIED IN A PATIENT WITH P.V617F JAK2 POSITIVE PRIMARY MYELOFIBROSIS. THESE RESULTS PROVIDE FURTHER INSIGHT INTO THE GENETIC COMPLEXITY OF MPNS. 2019 14 5785 23 SPONTANEOUS NEOPLASTIC TRANSFORMATION OF WB-F344 RAT LIVER EPITHELIAL CELLS. SEVERAL STUDIES HAVE SHOWN THAT CULTURED RAT LIVER EPITHELIAL CELLS TRANSFORM SPONTANEOUSLY AFTER CHRONIC MAINTENANCE IN A CONFLUENT STATE IN VITRO. IN THE PRESENT STUDY, MULTIPLE INDEPENDENT LINEAGES OF LOW-PASSAGE WB-F344 RAT LIVER EPITHELIAL STEM-LIKE CELLS WERE INITIATED AND SUBJECTED IN PARALLEL TO SELECTION FOR SPONTANEOUS TRANSFORMATION TO DETERMINE WHETHER SPONTANEOUS ACQUISITION OF TUMORIGENICITY WAS THE RESULT OF EVENTS (GENETIC OR EPIGENETIC) THAT OCCURRED INDEPENDENTLY AND STOCHASTICALLY, OR REFLECTED THE EXPRESSION OF A PRE-EXISTING ALTERATION WITHIN THE PARENTAL WB-F344 CELL LINE. TEMPORAL ANALYSIS OF THE SPONTANEOUS ACQUISITION OF TUMORIGENICITY BY WB-F344 CELLS DEMONSTRATED LINEAGE-SPECIFIC DIFFERENCES IN THE TIME OF FIRST EXPRESSION OF THE TUMORIGENIC PHENOTYPE, FREQUENCIES AND LATENCIES OF TUMOR FORMATION, AND TUMOR DIFFERENTIATIONS. ALTHOUGH SPONTANEOUSLY TRANSFORMED WB-F344 CELLS PRODUCED DIVERSE TUMOR TYPES (INCLUDING HEPATOCELLULAR CARCINOMAS, CHOLANGIOCARCINOMAS, HEPATOBLASTOMAS, AND OSTEOGENIC SARCOMAS), INDIVIDUAL LINEAGES YIELDED TUMORS WITH CONSISTENT AND SPECIFIC PATTERNS OF DIFFERENTIATION. THESE RESULTS PROVIDE SUBSTANTIAL EVIDENCE THAT THE STOCHASTIC ACCUMULATION OF INDEPENDENT TRANSFORMING EVENTS DURING THE SELECTION REGIMEN IN VITRO WERE RESPONSIBLE FOR SPONTANEOUS NEOPLASTIC TRANSFORMATION OF WB-F344 CELLS. FURTHERMORE, CELL LINEAGE COMMITMENT TO A SPECIFIC DIFFERENTIATION PROGRAM WAS STABLE WITH TIME IN CULTURE AND WITH SITE OF TRANSPLANTATION. THIS IS THE FIRST REPORT OF A COHORT OF RELATED, BUT INDEPENDENT, RAT LIVER EPITHELIAL CELL LINES THAT COLLECTIVELY PRODUCE A SPECTRUM OF TUMOR TYPES BUT INDIVIDUALLY REPRODUCE A SPECIFIC TUMOR TYPE. THESE CELL LINES WILL PROVIDE VALUABLE REAGENTS FOR INVESTIGATION OF THE MOLECULAR MECHANISMS INVOLVED IN THE DIFFERENTIATION OF HEPATIC STEM-LIKE CELLS AND FOR EXAMINATION OF POTENTIAL CAUSAL RELATIONSHIPS IN SPONTANEOUSLY TRANSFORMED RAT LIVER EPITHELIAL CELL LINES BETWEEN MOLECULAR/CELLULAR ALTERATIONS AND THE ABILITY TO PRODUCE TUMORS IN SYNGENEIC ANIMALS. 1998 15 4388 32 MLL2/KMT2D AND MLL3/KMT2C EXPRESSION CORRELATES WITH DISEASE PROGRESSION AND RESPONSE TO IMATINIB MESYLATE IN CHRONIC MYELOID LEUKEMIA. BACKGROUND: CHRONIC MYELOID LEUKEMIA (CML) IS A CLONAL MYELOPROLIFERATIVE NEOPLASM WHOSE PATHOGENESIS IS LINKED TO THE PHILADELPHIA CHROMOSOME PRESENCE THAT GENERATES THE BCR-ABL1 FUSION ONCOGENE. TYROSINE KINASE INHIBITORS (TKI) SUCH AS IMATINIB MESYLATE (IM) DRAMATICALLY IMPROVED THE TREATMENT EFFICIENCY AND SURVIVAL OF CML PATIENTS BY TARGETING BCR-ABL TYROSINE KINASE. THE DISEASE SHOWS THREE DISTINCT CLINICAL-LABORATORY STAGES: CHRONIC PHASE, ACCELERATED PHASE AND BLAST CRISIS. ALTHOUGH PATIENTS IN THE CHRONIC PHASE RESPOND WELL TO TREATMENT, PATIENTS IN THE ACCELERATED PHASE OR BLAST CRISIS USUALLY SHOW THERAPY RESISTANCE AND CML RELAPSE. IT IS CRUCIAL, THEREFORE, TO IDENTIFY BIOMARKERS TO PREDICT CML GENETIC EVOLUTION AND RESISTANCE TO TKI THERAPY, CONSIDERING NOT ONLY THE EFFECTS OF GENETIC ABERRATIONS BUT ALSO THE ROLE OF EPIGENETIC ALTERATIONS DURING THE DISEASE. ALTHOUGH DYSREGULATIONS IN EPIGENETIC MODULATORS SUCH AS HISTONE METHYLTRASNFERASES HAVE ALREADY BEEN DESCRIBED FOR SOME HEMATOLOGIC MALIGNANCIES, TO DATE VERY LIMITED DATA IS AVAILABLE FOR CML, ESPECIALLY WHEN CONSIDERING THE LYSINE METHYLTRANSFERASE MLL2/KMT2D AND MLL3/KMT2C. METHODS: HERE WE INVESTIGATED THE EXPRESSION PROFILE OF BOTH GENES IN CML PATIENTS IN DIFFERENT STAGES OF THE DISEASE, IN PATIENTS SHOWING DIFFERENT RESPONSES TO THERAPY WITH IM AND IN NON-NEOPLASTIC CONTROL SAMPLES. IMATINIB SENSITIVE AND RESISTANT CML CELL LINES WERE ALSO USED TO INVESTIGATE WHETHER TREATMENT WITH OTHER TYROSINE KINASE INHIBITORS INTERFERED IN THEIR EXPRESSION. RESULTS: IN PATIENTS, BOTH METHYLTRANSFERASES WERE EITHER UPREGULATED OR WITH BASAL EXPRESSION LEVEL DURING THE CHRONIC PHASE COMPARED TO CONTROLS. INTERESTINGLY, MLL3/KMT2C AND SPECIALLY MLL2/KMT2D LEVELS DECREASED DURING DISEASE PROGRESSION CORRELATING WITH DISTINCT CLINICAL STAGES. FURTHERMORE, MLL2/KMT2D WAS DECREASED IN PATIENTS RESISTANT TO IM TREATMENT. A RESCUE IN THE EXPRESSION OF BOTH MLL GENES WAS OBSERVED IN KCL22S, A CML CELL LINE SENSITIVE TO IM, AFTER TREATMENT WITH DASATINIB OR NILOTINIB WHICH WAS ASSOCIATED WITH A HIGHER RATE OF APOPTOSIS, AN ENHANCED EXPRESSION OF P21 (CDKN1A) AND A CONCOMITANT DECREASE IN THE EXPRESSION OF CDK2, CDK4 AND CYCLIN B1 (CCNB1) IN COMPARISON TO UNTREATED KCL22S CONTROL OR IM RESISTANT KCL22R CELL LINE, WHICH SUGGESTS INVOLVEMENT OF P53 REGULATED PATHWAY. CONCLUSION: OUR RESULTS ESTABLISHED A NEW ASSOCIATION BETWEEN MLL2/KMT2D AND MLL3/KMT2C GENES WITH CML AND SUGGEST THAT MLL2/KMT2D IS ASSOCIATED WITH DISEASE EVOLUTION AND MAY BE A POTENTIAL MARKER TO PREDICT THE DEVELOPMENT OF THERAPY RESISTANCE. 2018 16 5982 29 TET2 REGULATES IMMUNE TOLERANCE IN CHRONICALLY ACTIVATED MAST CELLS. MUTATION OF THE TET2 DNA-HYDROXYMETHYLASE HAS BEEN ASSOCIATED WITH A NUMBER OF IMMUNE PATHOLOGIES. THE DISPARITY IN PHENOTYPE AND CLINICAL PRESENTATION AMONG THESE PATHOLOGIES LEADS TO QUESTIONS REGARDING THE ROLE OF TET2 MUTATION IN PROMOTING DISEASE EVOLUTION IN DIFFERENT IMMUNE CELL TYPES. HERE WE SHOW THAT, IN PRIMARY MAST CELLS, TET2 EXPRESSION IS INDUCED IN RESPONSE TO CHRONIC AND ACUTE ACTIVATION SIGNALS. IN TET2-DEFICIENT MAST CELLS, CHRONIC ACTIVATION VIA THE ONCOGENIC KITD816V ALLELE ASSOCIATED WITH MASTOCYTOSIS, SELECTS FOR A SPECIFIC EPIGENETIC SIGNATURE CHARACTERIZED BY HYPERMETHYLATED DNA REGIONS (HMR) AT IMMUNE RESPONSE GENES. H3K27AC AND TRANSCRIPTION FACTOR BINDING IS CONSISTENT WITH PRIMING OR MORE OPEN CHROMATIN AT BOTH HMR AND NON-HMR IN PROXIMITY TO IMMUNE GENES IN THESE CELLS, AND THIS SIGNATURE COINCIDES WITH INCREASED PATHOLOGICAL INFLAMMATION SIGNALS. HMR ARE ALSO ASSOCIATED WITH A SUBSET OF IMMUNE GENES THAT ARE DIRECT TARGETS OF TET2 AND REPRESSED IN TET2-DEFICIENT CELLS. REPRESSION OF THESE GENES RESULTS IN IMMUNE TOLERANCE TO ACUTE STIMULATION THAT CAN BE RESCUED WITH VITAMIN C TREATMENT OR REITERATED WITH A TET INHIBITOR. OVERALL, OUR DATA SUPPORT A MODEL WHERE TET2 PLAYS A DIRECT ROLE IN PREVENTING IMMUNE TOLERANCE IN CHRONICALLY ACTIVATED MAST CELLS, SUPPORTING TET2 AS A VIABLE TARGET TO REPROGRAM THE INNATE IMMUNE RESPONSE FOR INNOVATIVE THERAPIES. 2022 17 3641 34 INCREASED GENE EXPRESSION OF HISTONE DEACETYLASES IN PATIENTS WITH PHILADELPHIA-NEGATIVE CHRONIC MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATION, MYELOACCUMULATION (DECREASED APOPTOSIS), INFLAMMATION, BONE MARROW FIBROSIS AND ANGIOGENESIS ARE CARDINAL FEATURES OF THE PHILADELPHIA-NEGATIVE CHRONIC MYELOPROLIFERATIVE NEOPLASMS: ESSENTIAL THROMBOCYTHEMIA (ET), POLYCYTHEMIA VERA (PV) AND PRIMARY MYELOFIBROSIS (PMF). HISTONE DEACETYLASES (HDACS) HAVE A CRITICAL ROLE IN MODULATING GENE EXPRESSION AND, ACCORDINGLY, IN THE CONTROL OF CELL PATHOBIOLOGY AND CANCER DEVELOPMENT. HDAC INHIBITION HAS BEEN SHOWN TO INHIBIT TUMOR GROWTH (IMPAIRED MYELOPROLIFERATION), TO MODULATE THE BALANCE BETWEEN PRO- AND ANTIAPOPTOTIC PROTEINS IN FAVOR OF APOPTOSIS (ENHANCED APOPTOSIS) AND ALSO TO INHIBIT ANGIOGENESIS. RECENTLY, ENHANCED HDAC ENZYME ACTIVITY HAS BEEN FOUND IN CD34+CELLS FROM PATIENTS WITH PMF, ENZYME ACTIVITY LEVELS HIGHLY EXCEEDING THOSE RECORDED IN OTHER CHRONIC MYELOPROLIFERATIVE NEOPLASMS (CMPNS). THE RAISED LEVELS CORRELATED TO THE DEGREE OF SPLENOMEGALY, SUGGESTING THAT HDAC MIGHT BE RECRUITED AS ET OR PV PROGRESSES INTO MYELOFIBROSIS OR PMF PROGRESSES INTO A MORE ADVANCED STAGE. ACCORDINGLY, HDAC INHIBITION IS AN OBVIOUS NOVEL THERAPEUTIC APPROACH IN THESE NEOPLASMS. USING GLOBAL GENE EXPRESSION PROFILING OF WHOLE BLOOD FROM PATIENTS WITH CMPNS, WE HAVE FOUND A PRONOUNCED DEREGULATION OF HDAC GENES, INVOLVING SIGNIFICANT UP-REGULATION OF THE HDAC GENES 9 AND 11, WITH THE HIGHEST EXPRESSION LEVELS BEING FOUND IN PATIENTS WITH ET (HDAC9 AND 11), PMF (HDAC9) AND CMPNS (BOTH HDAC9 AND HDAC11). FURTHERMORE, WE HAVE IDENTIFIED THAT THE HDAC6 GENE IS PROGRESSIVELY EXPRESSED IN PATIENTS WITH ET, PV AND PMF, REFLECTING A STEADY ACCUMULATION OF ABNORMALLY EXPRESSED HDAC6 DURING DISEASE EVOLUTION. OUR RESULTS LEND FURTHER SUPPORT TO HDACS AS IMPORTANT EPIGENETIC TARGETS IN THE FUTURE TREATMENT OF PATIENTS WITH CMPNS. SINCE THE HIGHEST EXPRESSION LEVELS OF HDAC GENES WERE RECORDED IN ET, IN PMF AND IN THE ENTIRE CMPN GROUP, THEIR DOWN-REGULATION BY HDAC INHIBITORS MIGHT BE ASSOCIATED WITH DECREASED DISEASE ACTIVITY, INCLUDING REDUCTION OF SPLENOMEGALY. 2012 18 6421 24 THE THERAPEUTIC PROPERTIES OF RESMINOSTAT FOR HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) IS THE MOST COMMON FORM OF PRIMARY LIVER CANCER WITH INCREASES IN NEW CASES BEING REPORTED ANNUALLY. HISTOPATHOLOGISTS HAVE IDENTIFIED HEPATIC STEATOSIS AS A CHARACTERISTIC OF A BROAD RANGE OF CHRONIC LIVER DISEASES THAT ARE ASSOCIATED WITH THE ONSET AND DEVELOPMENT OF HCC. IN THIS CONTEXT, EPIGENETIC MODIFICATIONS MAY SERVE AS PRECANCEROUS FACTORS PREDISPOSING NORMAL CELLS TO THE INITIATION OF CARCINOGENESIS. THIS STUDY DEMONSTRATED THAT HEPATIC TUMORIGENESIS AND DIFFERENTIATED ADIPOCYTES MAY MODULATE BOTH GLOBAL HISTONE DEACETYLASE (HDAC) EXPRESSION AND SPECIFIC CLASS I HDAC GENES IN THE TUMOUR MICROENVIRONMENT. THE NOVEL CLASS I HDAC INHIBITOR RESMINOSTAT WAS SHOWN TO REDUCE THE PROLIFERATION OF HCC CELLS ALONG WITH ITS SPECIFICITY IN TARGETING CLASS I HDACS AND ONCOGENES. THE COMBINED EFFECT OF RESMINOSTAT WITH SEVERAL PHARMACEUTICAL AGENTS SUCH AS SORAFENIB, CISPLATIN AND DOXORUBICIN WAS ALSO DEMONSTRATED. THE INHIBITION OF HEAT SHOCK PROTEIN 90 (HSP90) HAS BEEN DEMONSTRATED AS A POTENTIAL THERAPEUTIC OPTION FOR HCC. IN LINE WITH THIS, THE SPECIFIC HSP90 INHIBITOR 17-(ALLYLAMINO)-17-DEMETHOXYGELDANAMYCIN (17-AAG) WAS SELECTED AND IT WAS FOUND THAT THE COMBINATION OF RESMINOSTAT AND 17-AAG MAY PROVIDE A "SMART" CLINICAL STRATEGY FOR HCC PATIENTS BY TARGETING CELLULAR COMMUNICATION WITHIN THE TUMOUR MICROENVIRONMENT. THIS STUDY PROVIDES AN INSIGHT INTO THE USE OF RESMINOSTAT AS AN EPIGENETIC BASED THERAPEUTIC FOR HCC ALONG WITH OTHER PHARMACEUTICAL OPTIONS, IN PARTICULAR BY TARGETING THE CELL-TO-CELL COMMUNICATION THAT OCCURS BETWEEN HEPATOMA AND ADIPOCYTES. 2018 19 4558 20 MUTATIONS IN THE NF-KAPPAB SIGNALING PATHWAY: IMPLICATIONS FOR HUMAN DISEASE. THE NUCLEAR FACTOR-KAPPA B (NF-KAPPAB) SIGNALING PATHWAY IS A MULTI-COMPONENT PATHWAY THAT REGULATES THE EXPRESSION OF HUNDREDS OF GENES THAT ARE INVOLVED IN DIVERSE AND KEY CELLULAR AND ORGANISMAL PROCESSES, INCLUDING CELL PROLIFERATION, CELL SURVIVAL, THE CELLULAR STRESS RESPONSE, INNATE IMMUNITY AND INFLAMMATION. NOT SURPRISINGLY, MIS-REGULATION OF THE NF-KAPPAB PATHWAY, EITHER BY MUTATION OR EPIGENETIC MECHANISMS, IS INVOLVED IN MANY HUMAN AND ANIMAL DISEASES, ESPECIALLY ONES ASSOCIATED WITH CHRONIC INFLAMMATION, IMMUNODEFICIENCY OR CANCER. THIS REVIEW DESCRIBES HUMAN DISEASES IN WHICH MUTATIONS IN THE COMPONENTS OF THE CORE NF-KAPPAB SIGNALING PATHWAY HAVE BEEN IMPLICATED AND DISCUSSES THE MOLECULAR MECHANISMS BY WHICH THESE ALTERATIONS IN NF-KAPPAB SIGNALING ARE LIKELY TO CONTRIBUTE TO THE DISEASE PATHOLOGY. THESE MUTATIONS CAN BE GERMLINE OR SOMATIC AND INCLUDE GENE AMPLIFICATION (E.G., REL), POINT MUTATIONS AND DELETIONS (REL, NFKB2, IKBA, CYLD, NEMO) AND CHROMOSOMAL TRANSLOCATIONS (BCL-3). IN ADDITION, HUMAN GENETIC DISEASES ARE BRIEFLY DESCRIBED WHEREIN MUTATIONS AFFECT PROTEIN MODIFIERS OR TRANSDUCERS OF NF-KAPPAB SIGNALING OR DISRUPT NF-KAPPAB-BINDING SITES IN PROMOTERS/ENHANCERS. 2006 20 4002 23 LOSS OF P120 CATENIN AND LINKS TO MITOTIC ALTERATIONS, INFLAMMATION, AND SKIN CANCER. TUMOR FORMATION INVOLVES EPIGENETIC MODIFICATIONS AND MICROENVIRONMENTAL CHANGES AS WELL AS CUMULATIVE GENETIC ALTERATIONS ENCOMPASSING SOMATIC MUTATIONS, LOSS OF HETEROZYGOSITY, AND ANEUPLOIDY. HERE, WE SHOW THAT CONDITIONAL TARGETING OF P120 CATENIN IN MICE LEADS TO PROGRESSIVE DEVELOPMENT OF SKIN NEOPLASIAS ASSOCIATED WITH INTRINSIC NF-KAPPAB ACTIVATION. WE FIND THAT, SIMILARLY, SQUAMOUS CELL CARCINOMAS IN HUMANS DISPLAY ALTERED P120 AND ACTIVATED NF-KAPPAB. WE SHOW THAT EPIDERMAL HYPERPROLIFERATION ARISING FROM P120 LOSS CAN BE ABROGATED BY IKAPPAB KINASE 2 INHIBITORS. ALTHOUGH THIS UNDERSCORES THE IMPORTANCE OF THIS PATHWAY, THE ROLE OF NF-KAPPAB IN HYPERPROLIFERATION APPEARS ROOTED IN ITS IMPACT ON EPIDERMAL MICROENVIRONMENT BECAUSE AS P120-NULL KERATINOCYTES DISPLAY A GROWTH-ARRESTED PHENOTYPE IN CULTURE. WE TRACE THIS TO A MITOTIC DEFECT, RESULTING IN UNSTABLE, BINUCLEATED CELLS IN VITRO AND IN VIVO. WE SHOW THAT THE ABNORMAL MITOSES CAN BE AMELIORATED BY INHIBITING RHOA, THE ACTIVITY OF WHICH IS ABNORMALLY HIGH. CONVERSELY, WE CAN ELICIT SUCH MITOTIC DEFECTS IN CONTROL KERATINOCYTES BY ELEVATING RHOA ACTIVITY. THE ABILITY OF P120 DEFICIENCY TO ELICIT MITOTIC ALTERATIONS AND CHRONIC INFLAMMATORY RESPONSES, THAT TOGETHER MAY FACILITATE THE DEVELOPMENT OF GENETIC INSTABILITY IN VIVO, PROVIDES INSIGHTS INTO WHY IT FIGURES SO PROMINENTLY IN SKIN CANCER PROGRESSION. 2008