1 6611 101 UHRF1 REGULATES GERMINAL CENTER B CELL EXPANSION AND AFFINITY MATURATION TO CONTROL VIRAL INFECTION. THE PRODUCTION OF HIGH-AFFINITY ANTIBODY IS ESSENTIAL FOR PATHOGEN CLEARANCE. ANTIBODY AFFINITY IS INCREASED THROUGH GERMINAL CENTER (GC) AFFINITY MATURATION, WHICH RELIES ON BCR SOMATIC HYPERMUTATION (SHM) FOLLOWED BY ANTIGEN-BASED SELECTION. GC B CELL PROLIFERATION IS ESSENTIALLY INVOLVED IN THESE PROCESSES; IT PROVIDES ENOUGH TEMPLATES FOR SHM AND ALSO SERVES AS A CRITICAL MECHANISM OF POSITIVE SELECTION. IN THIS STUDY, WE SHOW THAT EXPRESSION OF EPIGENETIC REGULATOR UBIQUITIN-LIKE WITH PHD AND RING FINGER DOMAINS 1 (UHRF1) WAS MARKEDLY UP-REGULATED BY C-MYC-AP4 IN GC B CELLS, AND IT WAS REQUIRED FOR GC RESPONSE. UHRF1 REGULATES CELL PROLIFERATION-ASSOCIATED GENES INCLUDING CDKN1A, SLFN1, AND SLFN2 BY DNA METHYLATION, AND ITS DEFICIENCY INHIBITED THE GC B CELL CYCLE AT G1-S PHASE. SUBSEQUENTLY, GC B CELL SHM AND AFFINITY MATURATION WERE IMPAIRED, AND UHRF1 GC B KNOCKOUT MICE WERE UNABLE TO CONTROL CHRONIC VIRUS INFECTION. COLLECTIVELY, OUR DATA SUGGEST THAT UHRF1 REGULATES GC B CELL PROLIFERATION AND AFFINITY MATURATION, AND ITS EXPRESSION IN GC B CELLS IS REQUIRED FOR VIRUS CLEARANCE. 2018 2 5695 36 SILENCING UHRF1 ENHANCES CELL AUTOPHAGY TO PREVENT ARTICULAR CHONDROCYTES FROM APOPTOSIS IN OSTEOARTHRITIS THROUGH PI3K/AKT/MTOR SIGNALING PATHWAY. OSTEOARTHRITIS (OA) IS A COMMON CHRONIC DEGENERATIVE JOINT DISEASE, AND CHONDROCYTE APOPTOSIS IS ONE OF MOST IMPORTANT PATHOLOGICAL CHANGES OF OA PATHOGENESIS. GROWING STUDIES HAVE SHOWN THAT UBIQUITIN-LIKE WITH PHD AND RING FINGER DOMAINS 1 (UHRF1) IS AN IMPORTANT EPIGENETIC REGULATORY FACTOR THAT REGULATES CELL PROLIFERATION AND APOPTOSIS OF VARIOUS TUMORS, BUT ITS ROLE IN OA REMAINS ILL-DEFINED. IN THE PRESENT STUDY, WE FOUND THAT UHRF1 EXPRESSION WAS INCREASED IN HUMAN OA CARTILAGE TISSUES, COMPARED WITH NORMAL CARTILAGE TISSUES. INTERLEUKIN-1BETA (IL-1BETA), A MAJOR INFLAMMATORY CYTOKINE THAT PROMOTES CARTILAGE DEGRADATION IN OA, WAS USED TO STIMULATE PRIMARY HUMAN CHONDROCYTES IN VITRO. THE EXPRESSION OF UHRF1 WAS ALSO ENHANCED IN IL-1BETA-INDUCED CHONDROCYTES. MOREOVER, DOWN-REGULATION OF UHRF1 INDUCED AN INCREASE ON CELL PROLIFERATION AND AUTOPHAGY, AND A DECREASE ON APOPTOSIS OF CHONDROCYTES AFTER IL-1BETA TREATMENT. FURTHER DATA INDICATED THAT SILENCING UHRF1 ATTENUATED THE UP-REGULATION OF IL-1BETA ON PHOSPHOINOSITIDE 3-KINASE (PI3K)/PROTEIN KINASE B (AKT)/MAMMALIAN TARGET OF RAPAMYCIN (MTOR) SIGNALING PATHWAY IN CHONDROCYTES. THEN, AN ACTIVATOR OF PI3K WEAKENED THE EFFECT OF UHRF1 SILENCING ON CELL PROLIFERATION, AUTOPHAGY, APOPTOSIS OF IL-1BETA-INDUCED CHONDROCYTES, AND THE CELL AUTOPHAGY SPECIAL INHIBITOR 3-METHYLADENINE (3-MA) ALSO SHOWED A SAME IMPACT ON UHRF1, HENCE SUGGESTING THAT KNOCKDOWN OF UHRF1 ENHANCES CELL AUTOPHAGY TO PROTECT CHONDROCYTES FROM APOPTOSIS IN OA THROUGH PI3K/AKT/MTOR SIGNALING PATHWAY. IN CONCLUSION, OUR STUDY SUGGESTS THAT UHRF1 MAY BE A POTENTIAL REGULATOR OF CHONDROCYTE APOPTOSIS IN THE PATHOGENESIS OF OA. 2020 3 3924 35 LIPOSOMAL UHRF1 SIRNA SHOWS LUNG FIBROSIS TREATMENT POTENTIAL THROUGH REGULATION OF FIBROBLAST ACTIVATION. PULMONARY FIBROSIS IS A CHRONIC AND PROGRESSIVE INTERSTITIAL LUNG DISEASE ASSOCIATED WITH THE DECAY OF PULMONARY FUNCTION, WHICH LEADS TO A FATAL OUTCOME. AS AN ESSENTIAL EPIGENETIC REGULATOR OF DNA METHYLATION, THE INVOLVEMENT OF UBIQUITIN-LIKE CONTAINING PHD AND RING FINGER DOMAINS 1 (UHRF1) IN FIBROBLAST ACTIVATION REMAINS LARGELY UNDEFINED IN PULMONARY FIBROSIS. IN THE PRESENT STUDY, WE FOUND THAT TGF-BETA1-MEDIATED UPREGULATION OF UHRF1 REPRESSED BECLIN 1 VIA METHYLATED INDUCTION OF ITS PROMOTER, WHICH FINALLY RESULTED IN FIBROBLAST ACTIVATION AND LUNG FIBROSIS BOTH IN VITRO AND IN VIVO. MOREOVER, KNOCKDOWN OF UHRF1 SIGNIFICANTLY ARRESTED FIBROBLAST PROLIFERATION AND REACTIVATED BECLIN 1 IN LUNG FIBROBLASTS. THUS, INTRAVENOUS ADMINISTRATION OF UHRF1 SIRNA-LOADED LIPOSOMES SIGNIFICANTLY PROTECTED MICE AGAINST EXPERIMENTAL PULMONARY FIBROSIS. ACCORDINGLY, OUR DATA SUGGEST THAT UHRF1 MIGHT BE A NOVEL POTENTIAL THERAPEUTIC TARGET IN THE PATHOGENESIS OF PULMONARY FIBROSIS. 2022 4 3527 29 IL-6 ENHANCES THE NUCLEAR TRANSLOCATION OF DNA CYTOSINE-5-METHYLTRANSFERASE 1 (DNMT1) VIA PHOSPHORYLATION OF THE NUCLEAR LOCALIZATION SEQUENCE BY THE AKT KINASE. THE EPIGENETIC PROGRAMMING OF GENOMIC DNA IS ACCOMPLISHED, IN PART, BY SEVERAL DNA CYTOSINE-5-METHYLTRANSFERASES THAT ACT BY COVALENTLY MODIFYING CYTOSINES WITH THE ADDITION OF A METHYL GROUP. THIS COVALENT MODIFICATION IS MAINTAINED BY THE DNA CYTOSINE-5-METHYLTRANSFERASE-1 ENZYME (DNMT1), WHICH IS CAPABLE OF ACTING IN CONCERT WITH OTHER SIMILAR ENZYMES TO SILENCE IMPORTANT TUMOR SUPPRESSOR GENES. IL-6 IS A MULTIFUNCTIONAL MEDIATOR OF INFLAMMATION, ACTING THROUGH SEVERAL MAJOR SIGNALING CASCADES, INCLUDING THE PHOSPHATIDYLINOSITOL-3-KINASE PATHWAY (PI-3-K), WHICH ACTIVATES PROTEIN KINASE B (AKT/PKB) DOWNSTREAM. HERE, WE SHOW THAT THE SUBCELLULAR LOCALIZATION OF DNMT1 CAN BE ALTERED BY THE ADDITION OF IL-6, INCREASING THE RATE OF NUCLEAR TRANSLOCATION OF THE ENZYME FROM THE CYTOSOLIC COMPARTMENT. THE MECHANISM OF NUCLEAR TRANSLOCATION OF DNMT1 IS GREATLY ENHANCED BY PHOSPHORYLATION OF THE DNMT1 NUCLEAR LOCALIZATION SIGNAL (NLS) BY PKB/AKT KINASE. MUTAGENIC ALTERATION OF THE TWO AKT TARGET AMINO ACIDS WITHIN THE NLS RESULTS IN A MAJOR LOSS OF DNMT1 NUCLEAR TRANSLOCATION, WHILE THE CREATION OF A "PHOSPHO-MIMIC" AMINO ACID (MUTATION TO ACIDIC RESIDUES) RESTORES THIS COMPARTMENTATION ABILITY. THESE OBSERVATIONS SUGGEST AN INTERESTING HYPOTHESIS REGARDING HOW MEDIATORS OF CHRONIC INFLAMMATION MAY DISTURB THE DELICATE BALANCE OF CELLULAR COMPARTMENTALIZATION OF IMPORTANT PROTEINS, AND REVEALS A POTENTIAL MECHANISM FOR THE INDUCTION OR ENHANCEMENT OF TUMOR GROWTH VIA ALTERATION OF THE COMPONENTS INVOLVED IN THE EPIGENETIC PROGRAMMING OF A CELL. 2007 5 3415 31 HSP90 INHIBITION INCREASES SOCS3 TRANSCRIPT AND REGULATES MIGRATION AND CELL DEATH IN CHRONIC LYMPHOCYTIC LEUKEMIA. EPIGENETIC OR TRANSCRIPTIONAL SILENCING OF IMPORTANT TUMOR SUPPRESSORS HAS BEEN DESCRIBED TO CONTRIBUTE TO CELL SURVIVAL AND TUMORIGENESIS IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). USING GENE EXPRESSION MICROARRAY ANALYSIS, WE FOUND THAT THOUSANDS OF GENES ARE REPRESSED MORE THAN 2-FOLD IN CLL COMPARED TO NORMAL B CELLS; HOWEVER THERAPEUTIC APPROACHES TO REVERSE THIS HAVE BEEN LIMITED IN CLL. FOLLOWING TREATMENT WITH THE HSP90 INHIBITOR 17-DMAG, A SIGNIFICANT NUMBER OF THESE REPRESSED GENES WERE SIGNIFICANTLY RE-EXPRESSED. ONE OF THE GENES SIGNIFICANTLY REPRESSED IN CLL AND UP-REGULATED BY 17-DMAG WAS SUPPRESSOR OF CYTOKINE SIGNALING 3, (SOCS3). SOCS3 HAS BEEN SHOWN TO BE SILENCED IN SOLID TUMORS AS WELL AS MYELOID LEUKEMIA; HOWEVER LITTLE IS KNOWN ABOUT THE REGULATION IN CLL. WE FOUND THAT 17-DMAG INDUCES EXPRESSION OF SOCS3 BY VIA THE ACTIVATION OF P38 SIGNALING, AND SUBSEQUENTLY INHIBITS AKT AND STAT3 PHOSPHORYLATION RESULTING IN DOWNSTREAM EFFECTS ON CELL MIGRATION AND SURVIVAL. WE THEREFORE SUGGEST THAT SOCS3 IS AN IMPORTANT SIGNALING PROTEIN IN CLL, AND HSP90 INHIBITORS REPRESENT A NOVEL APPROACH TO TARGET TRANSCRIPTIONAL REPRESSION IN B CELL LYMPHOPROLIFERATIVE DISORDERS WHICH EXHIBIT A SUBSTANTIAL DEGREE OF GENE REPRESSION. 2016 6 3894 26 LAMIN B1 REGULATES SOMATIC MUTATIONS AND PROGRESSION OF B-CELL MALIGNANCIES. SOMATIC HYPERMUTATION (SHM) IS A PIVOTAL PROCESS IN ADAPTIVE IMMUNITY THAT OCCURS IN THE GERMINAL CENTRE AND ALLOWS B CELLS TO CHANGE THEIR PRIMARY DNA SEQUENCE AND DIVERSIFY THEIR ANTIGEN RECEPTORS. HERE, WE REPORT THAT GENOME BINDING OF LAMIN B1, A COMPONENT OF THE NUCLEAR ENVELOPE INVOLVED IN EPIGENETIC CHROMATIN REGULATION, IS REDUCED DURING B-CELL ACTIVATION AND FORMATION OF LYMPHOID GERMINAL CENTRES. CHROMATIN IMMUNOPRECIPITATION-SEQ ANALYSIS SHOWED THAT KAPPA AND HEAVY VARIABLE IMMUNOGLOBULIN DOMAINS WERE RELEASED FROM THE LAMIN B1 SUPPRESSIVE ENVIRONMENT WHEN SHM WAS INDUCED IN B CELLS. RNA INTERFERENCE-MEDIATED REDUCTION OF LAMIN B1 RESULTED IN SPONTANEOUS SHM AS WELL AS KAPPA-LIGHT CHAIN ABERRANT SURFACE EXPRESSION. FINALLY, LAMIN B1 EXPRESSION LEVEL CORRELATED WITH PROGRESSION-FREE AND OVERALL SURVIVAL IN CHRONIC LYMPHOCYTIC LEUKAEMIA, AND WAS STRONGLY INVOLVED IN THE TRANSFORMATION OF FOLLICULAR LYMPHOMA. IN SUMMARY, HERE WE REPORT THAT LAMIN B1 IS A NEGATIVE EPIGENETIC REGULATOR OF SHM IN NORMAL B-CELLS AND A 'MUTATIONAL GATEKEEPER', SUPPRESSING THE ABERRANT MUTATIONS THAT DRIVE LYMPHOID MALIGNANCY. 2018 7 2055 27 EPIGENETIC CONTROL DURING LYMPHOID DEVELOPMENT AND IMMUNE RESPONSES: ABERRANT REGULATION, VIRUSES, AND CANCER. METHYLATION OF CYTOSINES CONTROLS A NUMBER OF BIOLOGIC PROCESSES SUCH AS IMPRINTING AND X CHROMOSOMAL INACTIVATION. DNA HYPERMETHYLATION IS CLOSELY ASSOCIATED WITH TRANSCRIPTIONAL SILENCING, WHILE DNA HYPOMETHYLATION IS ASSOCIATED WITH TRANSCRIPTIONAL ACTIVATION. HYPOACETYLATION OF HISTONES LEADS TO COMPACT CHROMATIN WITH REDUCED ACCESSIBILITY TO THE TRANSCRIPTIONAL MACHINERY. METHYL-CPG BINDING PROTEINS CAN RECRUIT COREPRESSORS AND HISTONE DEACETYLASES; THUS, THE INTERPLAY BETWEEN THESE EPIGENETIC MECHANISMS REGULATES GENE ACTIVATION. METHYLATION HAS BEEN IMPLICATED AS AN IMPORTANT MECHANISM DURING IMMUNE DEVELOPMENT, CONTROLLING VDJ RECOMBINATION, LINEAGE-SPECIFIC EXPRESSION OF CELL SURFACE ANTIGENS, AND TRANSCRIPTIONAL REGULATION OF CYTOKINE GENES DURING IMMUNE RESPONSES. ABERRATIONS IN EPIGENETIC MACHINERY, EITHER BY GENETIC MUTATIONS OR BY SOMATIC CHANGES SUCH AS VIRAL INFECTIONS, ARE ASSOCIATED WITH EARLY ALTERATIONS IN CHRONIC DISEASES SUCH AS IMMUNODEFICIENCY AND CANCER. 2003 8 2025 26 EPIGENETIC CHANGES DURING DISEASE PROGRESSION IN A MURINE MODEL OF HUMAN CHRONIC LYMPHOCYTIC LEUKEMIA. EPIGENETIC ALTERATIONS, INCLUDING GAIN OR LOSS OF DNA METHYLATION, ARE A HALLMARK OF NEARLY EVERY MALIGNANCY. CHANGES IN DNA METHYLATION CAN IMPACT EXPRESSION OF CANCER-RELATED GENES INCLUDING APOPTOSIS REGULATORS AND TUMOR SUPPRESSORS. BECAUSE SUCH EPIGENETIC CHANGES ARE REVERSIBLE, THEY ARE BEING AGGRESSIVELY INVESTIGATED AS POTENTIAL THERAPEUTIC TARGETS. HERE WE USE THE EMU-TCL1 TRANSGENIC MOUSE MODEL OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) TO DETERMINE THE TIMING AND PATTERNS OF ABERRANT DNA METHYLATION, AND TO INVESTIGATE THE MECHANISMS THAT LEAD TO ABERRANT DNA METHYLATION. WE SHOW THAT CLL CELLS FROM EMU-TCL1 MICE AT VARIOUS STAGES RECAPITULATE EPIGENETIC ALTERATIONS SEEN IN HUMAN CLL. ABERRANT METHYLATION OF PROMOTER SEQUENCES IS OBSERVED AS EARLY AS 3 MONTHS OF AGE IN THESE ANIMALS, WELL BEFORE DISEASE ONSET. ABNORMALLY METHYLATED PROMOTER REGIONS INCLUDE BINDING SITES FOR THE TRANSCRIPTION FACTOR FOXD3. WE SHOW THAT LOSS OF FOXD3 EXPRESSION DUE TO AN NF-KAPPAB P50/P50:HDAC1 REPRESSOR COMPLEX OCCURS IN TCL1-POSITIVE B CELLS BEFORE METHYLATION. THEREFORE, SPECIFIC TRANSCRIPTIONAL REPRESSION IS AN EARLY EVENT LEADING TO EPIGENETIC SILENCING OF TARGET GENES IN MURINE AND HUMAN CLL. THESE RESULTS PROVIDE STRONG RATIONALE FOR THE DEVELOPMENT OF STRATEGIES TO TARGET NF-KAPPAB COMPONENTS IN CLL AND POTENTIALLY OTHER B-CELL MALIGNANCIES. 2009 9 3791 31 INTERLEUKIN 6 SUPPORTS THE MAINTENANCE OF P53 TUMOR SUPPRESSOR GENE PROMOTER METHYLATION. A STRONG ASSOCIATION EXISTS BETWEEN STATES OF CHRONIC INFLAMMATION AND CANCER, AND IT IS BELIEVED THAT MEDIATORS OF INFLAMMATION MAY BE RESPONSIBLE FOR THIS PHENOMENON. INTERLEUKIN 6 (IL-6) IS AN INFLAMMATORY CYTOKINE KNOWN TO PLAY A ROLE IN THE GROWTH AND SURVIVAL OF MANY TYPES OF TUMORS, YET THE MECHANISMS EMPLOYED BY THIS PLEOMORPHIC CYTOKINE TO ACCOMPLISH THIS FEAT ARE STILL POORLY UNDERSTOOD. ANOTHER IMPORTANT FACTOR IN TUMOR DEVELOPMENT SEEMS TO BE THE HYPERMETHYLATION OF CPG ISLANDS LOCATED WITHIN THE PROMOTER REGIONS OF TUMOR SUPPRESSOR GENES. THIS COMMON EPIGENETIC ALTERATION ENABLES TUMOR CELLS TO REDUCE OR INACTIVATE THE EXPRESSION OF IMPORTANT TUMOR SUPPRESSOR AND CELL CYCLE REGULATORY GENES. HERE WE SHOW THAT IN THE IL-6-RESPONSIVE HUMAN MULTIPLE MYELOMA CELL LINE KAS 6/1, THE PROMOTER REGION OF P53 IS EPIGENETICALLY MODIFIED BY METHYLTRANSFERASES, RESULTING IN DECREASED LEVELS OF EXPRESSION. FURTHERMORE, CELLS TREATED WITH IL-6 EXHIBIT AN INCREASE IN THE EXPRESSION OF THE DNA MAINTENANCE METHYLATION ENZYME, DNMT-1. THE DNA METHYLTRANSFERASE INHIBITOR ZEBULARINE REVERSES THE METHYLATION OF THE P53 PROMOTER, ALLOWING THE RESUMPTION OF ITS EXPRESSION. HOWEVER, WHEN ZEBULARINE IS WITHDRAWN FROM THE CELLS, THE REESTABLISHMENT OF THE ORIGINAL CPG ISLAND METHYLATION WITHIN THE P53 PROMOTER DOES NOT OCCUR IN THE ABSENCE OF IL-6, AND CELLS WHICH DO NOT RECEIVE IL-6 EVENTUALLY DIE, AS P53 EXPRESSION CONTINUES UNCHECKED BY REMETHYLATION. INTERESTINGLY, THIS LOSS OF VIABILITY SEEMS TO INVOLVE NOT THE WITHDRAWAL OF CYTOKINE, BUT THE INABILITY OF THE CELL TO RESILENCE THE PROMOTER. CONSISTENT WITH THIS MODEL, WHEN CELLS THAT EXPRESS IL-6 IN AN AUTOCRINE FASHION ARE SUBJECTED TO IDENTICAL TREATMENT, P53 EXPRESSION IS REDUCED SHORTLY AFTER WITHDRAWAL OF ZEBULARINE. THEREFORE, IT SEEMS IL-6 IS CAPABLE OF MAINTAINING PROMOTER METHYLATION THUS REPRESENTING ONE OF THE POSSIBLE MECHANISMS USED BY INFLAMMATORY MEDIATORS IN THE GROWTH AND SURVIVAL OF TUMORS. 2005 10 4728 24 NOTCH SIGNALING PROMOTES DISEASE INITIATION AND PROGRESSION IN MURINE CHRONIC LYMPHOCYTIC LEUKEMIA. NOTCH1 GAIN-OF-FUNCTION MUTATIONS ARE RECURRENT IN B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA (B-CLL), WHERE THEY ARE ASSOCIATED WITH ACCELERATED DISEASE PROGRESSION AND REFRACTORINESS TO CHEMOTHERAPY. THE SPECIFIC ROLE OF NOTCH1 IN THE DEVELOPMENT AND PROGRESSION OF THIS MALIGNANCY IS UNCLEAR. HERE, WE ASSESS THE IMPACT OF LOSS OF NOTCH SIGNALING AND PATHWAY HYPERACTIVATION IN AN IN VIVO MOUSE MODEL OF CLL (IGH.TEMU) THAT FAITHFULLY REPLICATES MANY FEATURES OF THE HUMAN PATHOLOGY. ABLATION OF CANONICAL NOTCH SIGNALING USING CONDITIONAL GENE INACTIVATION OF RBP-J IN IMMATURE HEMATOPOIETIC OR B-CELL PROGENITORS DELAYED CLL INDUCTION AND REDUCED INCIDENCE OF MICE DEVELOPING DISEASE. IN CONTRAST, FORCED EXPRESSION OF A DOMINANT ACTIVE FORM OF NOTCH RESULTED IN MORE ANIMALS DEVELOPING CLL WITH EARLY DISEASE ONSET. COMPARATIVE ANALYSIS OF GENE EXPRESSION AND EPIGENETIC FEATURES OF NOTCH GAIN-OF-FUNCTION AND CONTROL CLL CELLS REVEALED DIRECT AND INDIRECT REGULATION OF CELL CYCLE-ASSOCIATED GENES, WHICH LED TO INCREASED PROLIFERATION OF NOTCH GAIN-OF-FUNCTION CLL CELLS IN VIVO. THESE RESULTS DEMONSTRATE THAT NOTCH SIGNALING FACILITATES DISEASE INITIATION AND PROMOTES CLL CELL PROLIFERATION AND DISEASE PROGRESSION. 2021 11 942 27 CHRONIC LYMPHOCYTIC LEUKEMIA PRESENCE IMPAIRS ANTIGEN-SPECIFIC CD8(+) T-CELL RESPONSES THROUGH EPIGENETIC REPROGRAMMING TOWARDS SHORT-LIVED EFFECTORS. T-CELL DYSREGULATION IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) ASSOCIATES WITH LOW RESPONSE RATES TO AUTOLOGOUS T CELL-BASED THERAPIES. HOW CLL AFFECTS ANTIGEN-SPECIFIC T-CELL RESPONSES REMAINS LARGELY UNKNOWN. WE INVESTIGATED (EPI)GENETIC AND FUNCTIONAL CONSEQUENCES OF ANTIGEN-SPECIFIC T-CELL RESPONSES IN PRESENCE OF CLL IN VITRO AND IN AN ADOPTIVE-TRANSFER MURINE MODEL. ALREADY AT STEADY-STATE, ANTIGEN-EXPERIENCED PATIENT-DERIVED T CELLS WERE SKEWED TOWARDS SHORT-LIVED EFFECTOR CELLS (SLEC) AT THE EXPENSE OF MEMORY-PRECURSOR EFFECTOR CELLS (MPEC). STIMULATION OF THESE T CELLS IN VITRO SHOWED RAPID INDUCTION OF EFFECTOR GENES AND SUPPRESSION OF KEY MEMORY TRANSCRIPTION FACTORS ONLY IN PRESENCE OF CLL CELLS, INDICATING EPIGENETIC REGULATION. THIS WAS INVESTIGATED IN VIVO BY FOLLOWING ANTIGEN-SPECIFIC RESPONSES OF NAIVE OT-I CD8(+) CELLS TO MCMV-OVA IN PRESENCE/ABSENCE OF TCL1 B-CELL LEUKEMIA. PRESENCE OF LEUKEMIA RESULTED IN INCREASED SLEC FORMATION, WITH DISTURBED INFLAMMATORY CYTOKINE PRODUCTION. CHROMATIN AND TRANSCRIPTOME PROFILING REVEALED STRONG EPIGENETIC MODIFICATIONS, LEADING TO ACTIVATION OF AN EFFECTOR AND SILENCING OF A MEMORY PROFILE THROUGH PRESENCE OF CLL CELLS. SECONDARY CHALLENGE IN VIVO CONFIRMED DYSFUNCTIONAL MEMORY RESPONSES BY ANTIGEN-EXPERIENCED OT-I CELLS GENERATED IN PRESENCE OF CLL. ALTOGETHER, WE SHOW THAT PRESENCE OF CLL INDUCES A SHORT-LIVED EFFECTOR PHENOTYPE AND IMPAIRED MEMORY RESPONSES BY EPIGENETIC REPROGRAMMING DURING PRIMARY RESPONSES. 2023 12 5972 26 TET REPRESSION AND INCREASED DNMT ACTIVITY SYNERGISTICALLY INDUCE ABERRANT DNA METHYLATION. CHRONIC INFLAMMATION IS DEEPLY INVOLVED IN VARIOUS HUMAN DISORDERS, SUCH AS CANCER, NEURODEGENERATIVE DISORDERS, AND METABOLIC DISORDERS. INDUCTION OF EPIGENETIC ALTERATIONS, ESPECIALLY ABERRANT DNA METHYLATION, IS ONE OF THE MAJOR MECHANISMS, BUT HOW IT IS INDUCED IS STILL UNCLEAR. HERE, WE FOUND THAT EXPRESSION OF TET GENES, METHYLATION ERASERS, WAS DOWNREGULATED IN INFLAMED MOUSE AND HUMAN TISSUES, AND THAT THIS WAS CAUSED BY UPREGULATION OF TET-TARGETING MIRNAS SUCH AS MIR20A, MIR26B, AND MIR29C, LIKELY DUE TO ACTIVATION OF NF-KAPPAB SIGNALING DOWNSTREAM OF IL-1BETA AND TNF-ALPHA. HOWEVER, TET KNOCKDOWN INDUCED ONLY MILD ABERRANT METHYLATION. NITRIC OXIDE (NO), PRODUCED BY NOS2, ENHANCED ENZYMATIC ACTIVITY OF DNA METHYLTRANSFERASES (DNMTS), METHYLATION WRITERS, AND NO EXPOSURE INDUCED MINIMAL ABERRANT METHYLATION. IN CONTRAST, A COMBINATION OF TET KNOCKDOWN AND NO EXPOSURE SYNERGISTICALLY INDUCED ABERRANT METHYLATION, INVOLVING GENOMIC REGIONS NOT METHYLATED BY EITHER ALONE. THE RESULTS SHOWED THAT A VICIOUS COMBINATION OF TET REPRESSION, DUE TO NF-KAPPAB ACTIVATION, AND DNMT ACTIVATION, DUE TO NO PRODUCTION, IS RESPONSIBLE FOR ABERRANT METHYLATION INDUCTION IN HUMAN TISSUES. 2020 13 208 35 ACTIVATION-INDUCED CYTIDINE DEAMINASE (AID) LINKING IMMUNITY, CHRONIC INFLAMMATION, AND CANCER. ACTIVATION-INDUCED CYTIDINE DEAMINASE (AID) IS CRITICALLY INVOLVED IN CLASS SWITCH RECOMBINATION AND SOMATIC HYPERMUTATION OF IG LOCI RESULTING IN DIVERSIFICATION OF ANTIBODIES REPERTOIRE AND PRODUCTION OF HIGH-AFFINITY ANTIBODIES AND AS SUCH REPRESENTS A PHYSIOLOGICAL TOOL TO INTRODUCE DNA ALTERATIONS. THESE PROCESSES TAKE PLACE WITHIN GERMINAL CENTERS OF SECONDARY LYMPHOID ORGANS. UNDER PHYSIOLOGICAL CONDITIONS, AID IS EXPRESSED PREDOMINANTLY IN ACTIVATED B LYMPHOCYTES. BECAUSE OF THE MUTAGENIC AND RECOMBINOGENIC POTENTIAL OF AID, ITS EXPRESSION AND ACTIVITY IS TIGHTLY REGULATED ON DIFFERENT LEVELS TO MINIMIZE THE RISK OF UNWANTED DNA DAMAGE. HOWEVER, CHRONIC INFLAMMATION AND, PROBABLY, COMBINATION OF OTHER NOT-YET-IDENTIFIED FACTORS ARE ABLE TO CREATE A MICROENVIRONMENT SUFFICIENT FOR TRIGGERING AN ABERRANT AID EXPRESSION IN B CELLS AND, IMPORTANTLY, IN NON-B-CELL BACKGROUND. UNDER THESE CIRCUMSTANCES, AID MAY TARGET ALSO NON-IG GENES, INCLUDING CANCER-RELATED GENES AS ONCOGENES, TUMOR SUPPRESSOR GENES, AND GENOMIC STABILITY GENES, AND MODULATE BOTH GENETIC AND EPIGENETIC INFORMATION. DESPITE ONGOING PROGRESS, THE COMPLETE UNDERSTANDING OF FUNDAMENTAL ASPECTS IS STILL LACKING AS (1) WHAT ARE THE CRUCIAL FACTORS TRIGGERING AN ABERRANT AID EXPRESSION/ACTIVITY INCLUDING THE IMPACT OF TH2-DRIVEN INFLAMMATION AND (2) TO WHAT EXTENT MAY ABERRANT AID IN HUMAN NON-B CELLS LEAD TO ABNORMAL CELL STATE ASSOCIATED WITH AN INCREASED RATE OF GENOMIC ALTERATIONS AS POINT MUTATIONS, SMALL INSERTIONS OR DELETIONS, AND/OR RECURRENT CHROMOSOMAL TRANSLOCATIONS DURING SOLID TUMOR DEVELOPMENT AND PROGRESSION. 2012 14 3523 28 IL-10-PRODUCING B CELLS ARE CHARACTERIZED BY A SPECIFIC METHYLATION SIGNATURE. AMONG THE FAMILY OF REGULATORY B CELLS, THE SUBSET ABLE TO PRODUCE INTERLEUKIN-10 (IL-10) IS THE MOST STUDIED, YET ITS BIOLOGY IS STILL A MATTER OF INVESTIGATION. THE DNA METHYLATION PROFILING OF THE IL-10 GENE LOCUS REVEALED A NOVEL EPIGENETIC SIGNATURE CHARACTERIZING MURINE B CELLS READY TO RESPOND THROUGH IL-10 SYNTHESIS: A DEMETHYLATED REGION LOCATED 4.5 KB FROM THE TRANSCRIPTION STARTING SITE (TSS), THAT WE NAMED EARLY IL10 REGULATORY REGION (EIL10RR). THIS FEATURE ALLOWS TO DISTINGUISH B CELLS THAT ARE IMMEDIATELY PRONE AND DEVELOPMENTALLY COMMITTED TO IL-10 PRODUCTION FROM THOSE THAT REQUIRE A PERSISTENT STIMULATION TO EXERT AN IL-10-MEDIATED REGULATORY FUNCTION. THESE LATE IL-10 PRODUCERS ARE INSTEAD CHARACTERIZED BY A DELAYED IL10 REGULATORY REGION (DIL10RR), A PARTIALLY DEMETHYLATED DNA PORTION LOCATED 9 KB UPSTREAM FROM THE TSS. A DEMETHYLATED REGION WAS ALSO FOUND IN HUMAN IL-10-PRODUCING B CELLS AND, VERY INTERESTINGLY, IN SOME B-CELL MALIGNANCIES, SUCH AS CHRONIC LYMPHOCYTIC LEUKEMIA AND MANTLE CELL LYMPHOMA, CHARACTERIZED BY AN IMMUNOSUPPRESSIVE MICROENVIRONMENT. OUR FINDINGS DEFINE MURINE AND HUMAN REGULATORY B CELLS AS AN EPIGENETICALLY CONTROLLED FUNCTIONAL STATE OF MATURE B CELL SUBSETS AND OPEN A NEW PERSPECTIVE ON IL-10 REGULATION IN B CELLS IN HOMEOSTASIS AND DISEASE. 2019 15 1615 27 DNA METHYLTRANSFERASE 3B PLAYS A PROTECTIVE ROLE AGAINST HEPATOCARCINOGENESIS CAUSED BY CHRONIC INFLAMMATION VIA MAINTAINING MITOCHONDRIAL HOMEOSTASIS. MOST HEPATOCELLULAR CARCINOMAS (HCCS) DEVELOP ON THE BASIS OF CHRONIC HEPATITIS, BUT THE MECHANISM OF EPIGENETIC REGULATION IN INFLAMMATORY HEPATOCARCINOGENESIS HAS YET TO BE ELUCIDATED. AMONG DE NOVO DNA METHYLTRANSFERASES (DNMTS), DNMT3B HAS LATELY BEEN REPORTED TO ACT SPECIFICALLY ON ACTIVELY TRANSCRIBED GENES, SUGGESTING THE POSSIBILITY THAT IT PLAYS A ROLE IN THE PATHOGENESIS OF CANCER. WE CONFIRMED THAT DNMT3B ISOFORMS LACKING ITS CATALYTIC DOMAIN WERE HIGHLY EXPRESSED IN HCCS COMPARED WITH NON-TUMOROUS LIVER TISSUE. TO ELUCIDATE THE ROLE OF DNMT3B IN HEPATOCARCINOGENESIS, WE GENERATED A GENETICALLY ENGINEERED MOUSE MODEL WITH HEPATOCYTE-SPECIFIC DNMT3B DELETION. THE LIVER OF THE DNMT3B-DEFICIENT MICE EXHIBITED AN EXACERBATION OF THIOACETAMIDE-INDUCED HEPATITIS, PROGRESSION OF LIVER FIBROSIS AND A HIGHER INCIDENCE OF HCC COMPARED WITH THE LIVER OF THE CONTROL MICE. WHOLE-GENOME BISULFITE SEQUENCING VERIFIED A LOWER CG METHYLATION LEVEL IN THE DNMT3B-DEFICIENT LIVER, DEMONSTRATING DIFFERENTIALLY METHYLATED REGIONS THROUGHOUT THE GENOME. TRANSCRIPTOME ANALYSIS REVEALED DECREASED EXPRESSION OF GENES RELATED TO OXIDATIVE PHOSPHORYLATION IN THE DNMT3B-DEFICIENT LIVER. MOREOVER, PRIMARY HEPATOCYTES ISOLATED FROM THE DNMT3B-DEFICIENT MICE SHOWED REDUCED MITOCHONDRIAL RESPIRATORY CAPACITY, LEADING TO THE ENHANCEMENT OF OXIDATIVE STRESS IN THE LIVER TISSUE. OUR FINDINGS SUGGEST THE PROTECTIVE ROLE OF DNMT3B AGAINST CHRONIC INFLAMMATION AND HCC DEVELOPMENT VIA MAINTAINING MITOCHONDRIAL HOMEOSTASIS. 2020 16 926 28 CHRONIC INFLAMMATION PATHWAY NF-KAPPAB COOPERATES WITH EPIGENETIC REPROGRAMMING TO DRIVE THE MALIGNANT PROGRESSION OF GLIOBLASTOMA. WITHOUT AN EFFECTIVE STRATEGY FOR TARGETED THERAPY, GLIOBLASTOMA IS STILL INCURABLE WITH A MEDIAN SURVIVAL OF ONLY 15 MONTHS. BOTH CHRONIC INFLAMMATION AND EPIGENETIC REPROGRAMMING ARE HALLMARKS OF CANCER. HOWEVER, THE MECHANISMS AND CONSEQUENCES OF THEIR COOPERATION IN GLIOBLASTOMA REMAIN UNKNOWN. HERE, WE DISCOVER THAT CHRONIC INFLAMMATION GOVERNS H3K27ME3 REPROGRAMMING IN GLIOBLASTOMA THROUGH THE CANONICAL NF-KAPPAB PATHWAY TO TARGET EZH2. BEING A CRUCIAL MEDIATOR OF CHRONIC INFLAMMATION, THE CANONICAL NF-KAPPAB SIGNALLING SPECIFICALLY DIRECTS THE EXPRESSION AND REDISTRIBUTION OF H3K27ME3 BUT NOT H3K4ME3, H3K9ME3 AND H3K36ME3. USING RNA-SEQ SCREENING TO FOCUS ON GENES ENCODING METHYLTRANSFERASES AND DEMETHYLASES OF HISTONE, WE IDENTIFY EZH2 AS A KEY METHYLTRANSFERASE TO CONTROL INFLAMMATION-TRIGGERED EPIGENETIC REPROGRAMMING IN GLIOMAGENESIS. MECHANISTICALLY, NF-KAPPAB SELECTIVELY DRIVES THE EXPRESSION OF EZH2 BY ACTIVATING ITS TRANSCRIPTION, CONSEQUENTLY RESULTING IN A GLOBAL CHANGE IN H3K27ME3 EXPRESSION AND DISTRIBUTION. FURTHERMORE, WE FIND THAT CO-ACTIVATION OF NF-KAPPAB AND EZH2 CONFERS THE POOREST CLINICAL OUTCOME, AND THAT THE RISK FOR GLIOBLASTOMA CAN BE ACCURATELY MOLECULARLY STRATIFIED BY NF-KAPPAB AND EZH2. IT IS NOTABLE THAT NF-KAPPAB CAN POTENTIALLY COOPERATE WITH EZH2 IN MORE THAN ONE WAY, AND MOST IMPORTANTLY, WE DEMONSTRATE A SYNERGISTIC EFFECT OF CANCER CELLS INDUCED BY COMBINATORY INHIBITION OF NF-KAPPAB AND EZH2, WHICH BOTH ARE FREQUENTLY OVER-ACTIVATED IN GLIOBLASTOMA. IN SUMMARY, WE UNCOVER A FUNCTIONAL COOPERATION BETWEEN CHRONIC INFLAMMATION AND EPIGENETIC REPROGRAMMING IN GLIOBLASTOMA, COMBINED TARGETING OF WHICH BY INHIBITORS GUARANTEED IN SAFETY AND AVAILABILITY FURNISHES A POTENT STRATEGY FOR EFFECTIVE TREATMENT OF THIS FATAL DISEASE. 2022 17 3795 31 INTERLEUKIN-6 CONTRIBUTES TO GROWTH IN CHOLANGIOCARCINOMA CELLS BY ABERRANT PROMOTER METHYLATION AND GENE EXPRESSION. THE ASSOCIATION BETWEEN CHRONIC INFLAMMATION AND THE DEVELOPMENT AND PROGRESSION OF MALIGNANCY IS EXEMPLIFIED IN THE BILIARY TRACT WHERE PERSISTENT INFLAMMATION STRONGLY PREDISPOSES TO CHOLANGIOCARCINOMA. THE INFLAMMATORY CYTOKINE INTERLEUKIN-6 (IL-6) ENHANCES TUMOR GROWTH IN CHOLANGIOCARCINOMA BY ALTERED GENE EXPRESSION VIA AUTOCRINE MECHANISMS. IL-6 CAN REGULATE THE ACTIVITY OF DNA METHYLTRANSFERASES, AND MOREOVER, ABERRANT DNA METHYLATION CAN CONTRIBUTE TO CARCINOGENESIS. WE THEREFORE INVESTIGATED THE EFFECT OF CHRONIC EXPOSURE TO IL-6 ON METHYLATION-DEPENDENT GENE EXPRESSION AND TRANSFORMED CELL GROWTH IN HUMAN CHOLANGIOCARCINOMA. THE RELATIONSHIP BETWEEN AUTOCRINE IL-6 PATHWAYS, DNA METHYLATION, AND TRANSFORMED CELL GROWTH WAS ASSESSED USING MALIGNANT CHOLANGIOCYTES STABLY TRANSFECTED TO OVEREXPRESS IL-6. TREATMENT WITH THE DNA METHYLATION INHIBITOR 5-AZA-2'-DEOXYCYTIDINE DECREASED CELL PROLIFERATION, GROWTH IN SOFT AGAR, AND METHYLCYTOSINE CONTENT OF MALIGNANT CHOLANGIOCYTES. HOWEVER, THIS EFFECT WAS NOT OBSERVED IN IL-6-OVEREXPRESSING CELLS. IL-6 OVEREXPRESSION RESULTED IN THE ALTERED EXPRESSION AND PROMOTER METHYLATION OF SEVERAL GENES, INCLUDING THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR). EGFR PROMOTER METHYLATION WAS DECREASED AND GENE AND PROTEIN EXPRESSION WAS INCREASED BY IL-6. THUS, EPIGENETIC REGULATION OF GENE EXPRESSION BY IL-6 CAN CONTRIBUTE TO TUMOR PROGRESSION BY ALTERING PROMOTER METHYLATION AND GENE EXPRESSION OF GROWTH-REGULATORY PATHWAYS, SUCH AS THOSE INVOLVING EGFR. MOREOVER, ENHANCED IL-6 EXPRESSION MAY DECREASE THE SENSITIVITY OF TUMOR CELLS TO THERAPEUTIC TREATMENTS USING METHYLATION INHIBITORS. THESE OBSERVATIONS HAVE IMPORTANT IMPLICATIONS FOR CANCER TREATMENT AND PROVIDE A MECHANISM BY WHICH PERSISTENT CYTOKINE STIMULATION CAN PROMOTE TUMOR GROWTH. 2006 18 2389 27 EPIGENETIC REPOLARIZATION OF T LYMPHOCYTES FROM CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS USING 5-AZA-2'-DEOXYCYTIDINE. T CELL IMMUNE DYSFUNCTION HAS AN IMPORTANT ROLE IN THE PROFOUND IMMUNE SUPPRESSION THAT CHARACTERIZES CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). IMPROPER POLARIZATION OF T CELLS HAS BEEN PROPOSED AS ONE OF THE MECHANISM INVOLVED. MOUNTING DATA IMPLICATES CHROMATIN REGULATION, NAMELY PROMOTER METHYLATION, IN THE PLASTICITY OF NAIVE HUMAN T CELLS. RECENT IN VITRO EVIDENCE INDICATES THAT THIS PLASTICITY MAY BE PHENOTYPICALLY ALTERED BY USING METHYLATION INHIBITORS WHICH ARE APPROVED FOR CLINICAL USE IN CERTAIN TYPES OF CANCER. THESE RESULTS BEG THE QUESTION: CAN THE INEFFECTIVE POLARIZATION OF T LYMPHOCYTES IN THE CONTEXT OF CLL BE EFFECTIVELY MODULATED USING METHYLATION INHIBITORS IN A SUSTAINABLE THERAPEUTIC FASHION? TO ANSWER THIS QUESTION OUR LABORATORY HAS STUDIED THE EFFECTS OF 5-AZA-2'-DEOXYCYTIDINE (5A2) IN HELPER AND CYTOTOXIC T LYMPHOCYTES FROM HEALTHY DONORS AND CLL PATIENTS IN WELL CHARACTERIZED MOLECULAR AND EPIGENETIC SIGNALING PATHWAYS INVOLVED IN EFFECTIVE POLARIZATION. MOREOVER, WE SOUGHT TO INVESTIGATE THE CONSEQUENCES OF METHYLATION INHIBITOR TREATMENT ON LYMPHOCYTE SURVIVAL, ACTIVATION INTENSITY, AND NAIVE CELL POLARIZATION. OUR DATA INDICATES THAT 5A2 TREATMENT CAN DEPOLARIZE TH2 CELLS TO EFFECTIVELY SECRETE INTERFERON GAMMA, SIGNAL VIA T-BET, AND ACHIEVE DEMETHYLATION OF CRITICAL TH1 SPECIFIC PROMOTERS. MOREOVER, WE DEMONSTRATE THAT 5A2 CAN FORCE TH1 POLARIZATION OF NAIVE T CELLS DESPITE A STRONG IL-4 STIMULI AND A LACK OF IL-12. IN CONCLUSION OUR DATA SEEKS TO DEFINE A MODALITY IN WHICH IMPROPER OR INEFFECTIVE T CELL POLARIZATION CAN BE ALTERED BY 5AZA AND COULD BE INCORPORATED IN FUTURE THERAPEUTIC INTERVENTIONS. 2011 19 1542 28 DNA METHYLATION IN HAEMATOLOGICAL MALIGNANCIES: THE ROLE OF DECITABINE. NORMAL CELL DEVELOPMENT AND FUNCTION IS DEPENDENT UPON CONTROLLED GENE EXPRESSION. DNA METHYLATION IS AN EPIGENETIC MODIFICATION THAT CAN PLAY AN IMPORTANT ROLE IN THE CONTROL OF GENE EXPRESSION. DNA METHYLATION AT CYTOSINE RESIDUES IN GENE PROMOTER CPG SEQUENCES IS KNOWN TO INHIBIT GENE TRANSCRIPTION. INAPPROPRIATE INHIBITION OF THE TRANSCRIPTION OF TUMOUR SUPPRESSOR GENES, GENES THAT INHIBIT ANGIOGENESIS AND METASTASIS AND GENES INVOLVED IN DNA REPAIR BY UNCONTROLLED METHYLATION, CAN LEAD TO UNREGULATED GROWTH AND PROLIFERATION OF A CELL AND CARCINOGENESIS. PROMOTER HYPERMETHYLATION AFFECTING THE P16 GENE, RESULTING IN GENE SILENCING, HAS BEEN SHOWN TO OCCUR IN MANY HUMAN SOLID TUMOURS AND A 'HYPERMETHYLATION PROFILE' IN SOME LEUKAEMIAS HAS BEEN DEFINED. THE MOLECULAR MECHANISMS BY WHICH ABERRANT DNA METHYLATION TAKES PLACE DURING CARCINOGENESIS ARE STILL NOT CLEAR. HOWEVER, THE LARGE NUMBER OF TARGET GENES (INVOLVED IN TUMORIGENESIS) THAT ARE SILENCED BY ABERRANT METHYLATION SUGGESTS THAT INHIBITION OF THIS PROCESS MAY HAVE POTENTIAL AS CANCER THERAPY. DECITABINE (NSC-127716, DACOGEN; SUPERGEN) IS A POTENT AND SPECIFIC HYPOMETHYLATING AGENT AND AN INHIBITOR OF THE DNA METHYLTRANSFERASE ACTIVITY THAT MEDIATES DNA METHYLATION. DECITABINE HAS BEEN SHOWN TO HAVE A BROAD RANGE OF ANTINEOPLASTIC ACTIVITY IN PRECLINICAL STUDIES. THIS AGENT HAS EXHIBITED SIGNIFICANT ACTIVITY IN THE TREATMENT OF PATIENTS WITH MYELODYSPLASTIC SYNDROME, CHRONIC MYELOID LEUKAEMIA AND ACUTE MYELOID LEUKAEMIA, ALTHOUGH CLINICAL PHASE I AND II STUDIES WITH SOLID TUMOURS HAVE NOT BEEN VERY PROMISING. PHASE II AND III STUDIES ARE CURRENTLY ONGOING TO EVALUATE DECITABINE, BOTH ALONE AND IN COMBINATION, IN VARIOUS STAGES OF THESE HAEMATOLOGICAL MALIGNANCIES. 2003 20 2380 26 EPIGENETIC REGULATION OF WNT SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA. CERTAIN WNT AND WNT NETWORK TARGET GENES ARE EXPRESSED AT HIGHER OR LOWER LEVELS IN CHRONIC LYMPHOCYTIC LEUKEMIA COMPARED WITH NORMAL B-CELLS. THIS INCLUDES UPREGULATION OF NUCLEAR COMPLEX GENES, AS WELL AS GENES FOR CYTOPLASMIC PROTEINS AND WNT LIGANDS AND THEIR COGNATE RECEPTORS. IN ADDITION, EPIGENETIC SILENCING OF SEVERAL NEGATIVE REGULATORS OF THE WNT PATHWAY HAVE BEEN IDENTIFIED. THE BALANCE BETWEEN EPIGENETIC DOWNREGULATION OF NEGATIVE EFFECTOR GENES AND INCREASED EXPRESSION OF POSITIVE EFFECTOR GENES DEMONSTRATE THAT THE EPIGENETIC DOWNREGULATION OF WNT ANTAGONISTS IS ONE MECHANISM, PERHAPS THE MAIN MECHANISM, THAT IS PERMISSIVE TO ACTIVE WNT SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA. MOREOVER, CONSTITUTIVE ACTIVATION OF THE WNT NETWORK AND TARGET GENES IS LIKELY TO IMPACT ON ADDITIONAL INTERACTING SIGNALING PATHWAYS. BASED ON PUBLISHED STUDIES, WE PROPOSE A MODEL OF WNT SIGNALING THAT INVOLVES MAINLY PERMISSIVE EXPRESSION, AND SOMETIMES OVEREXPRESSION, OF POSITIVE EFFECTORS AND DOWNREGULATION OF NEGATIVE REGULATORS IN THE NETWORK. IN THIS MODEL, DNA METHYLATION, HISTONE MODIFICATIONS AND ALTERED EXPRESSION OF MICRORNA MOLECULES INTERACT TO ALLOW CONTINUOUS WNT SIGNALING. 2010