1 3217 127 HEDGEHOG/GLI AND PI3K SIGNALING IN THE INITIATION AND MAINTENANCE OF CHRONIC LYMPHOCYTIC LEUKEMIA. THE INITIATION AND MAINTENANCE OF A MALIGNANT PHENOTYPE REQUIRES COMPLEX AND SYNERGISTIC INTERACTIONS OF MULTIPLE ONCOGENIC SIGNALS. THE HEDGEHOG (HH)/GLI PATHWAY HAS BEEN IMPLICATED IN A VARIETY OF CANCER ENTITIES AND TARGETED PATHWAY INHIBITION IS OF THERAPEUTIC RELEVANCE. SIGNAL CROSS-TALK WITH OTHER CANCER PATHWAYS INCLUDING PI3K/AKT MODULATES HH/GLI SIGNAL STRENGTH AND ITS ONCOGENICITY. IN THIS STUDY, WE ADDRESSED THE ROLE OF HH/GLI AND ITS PUTATIVE INTERACTION WITH THE PI3K/AKT CASCADE IN THE INITIATION AND MAINTENANCE OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). USING TRANSGENIC MOUSE MODELS, WE SHOW THAT B-CELL-SPECIFIC CONSTITUTIVE ACTIVATION OF HH/GLI SIGNALING EITHER AT THE LEVEL OF THE HH EFFECTOR AND DRUG TARGET SMOOTHENED OR AT THE LEVEL OF THE GLI TRANSCRIPTION FACTORS DOES NOT SUFFICE TO INITIATE A CLL-LIKE PHENOTYPE CHARACTERIZED BY THE ACCUMULATION OF CD5(+) B CELLS IN THE LYMPHATIC SYSTEM AND PERIPHERAL BLOOD. FURTHERMORE, HH/GLI ACTIVATION IN PTEN-DEFICIENT B CELLS WITH ACTIVATED PI3K/AKT SIGNALING FAILED TO ENHANCE THE EXPANSION OF LEUKEMIC CD5(+) B CELLS, SUGGESTING THAT GENETIC OR EPIGENETIC ALTERATIONS LEADING TO ABERRANT HH/GLI SIGNALING IN B CELLS DO NOT SUFFICE TO ELICIT A CLL-LIKE PHENOTYPE IN MICE. BY CONTRAST, WE IDENTIFY A CRITICAL ROLE OF GLI AND PI3K SIGNALING FOR THE SURVIVAL OF HUMAN PRIMARY CLL CELLS. WE SHOW THAT COMBINED TARGETING OF GLI AND PI3K/AKT/MTOR SIGNALING CAN HAVE A SYNERGISTIC THERAPEUTIC EFFECT IN CELLS FROM A SUBGROUP OF CLL PATIENTS, THEREBY PROVIDING A BASIS FOR THE EVALUATION OF FUTURE COMBINATION THERAPIES TARGETING HH/GLI AND PI3K SIGNALING IN THIS COMMON HEMATOPOIETIC MALIGNANCY. 2015 2 4693 25 NEXT GENERATION OF TARGETED MOLECULES FOR NON-HODGKIN LYMPHOMAS: SMALL-MOLECULE INHIBITORS OF INTRACELLULAR TARGETS AND SIGNALING PATHWAYS. ADVANCES IN OUR UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF B-CELL LYMPHOMA HAVE GUIDED THE DEVELOPMENT OF TARGETED THERAPIES THAT DISRUPT ABERRANT SIGNALING PATHWAYS IMPORTANT FOR COMMUNICATION WITHIN LYMPHOMA CELLS AND FOR THEIR INTERACTIONS WITH THE TUMOR MICROENVIRONMENT. THIS HAS LED TO UNPRECEDENTED THERAPEUTIC PROGRESS, WITH BIOLOGIC AGENTS THAT HAVE BEGUN TO TRANSFORM THE CARE OF PATIENTS WITH LYMPHOMA AND CHRONIC LYMPHOCYTIC LEUKEMIA. THIS REVIEW DISCUSSES THE MECHANISMS OF ACTION, CLINICAL DEVELOPMENT, AND EMERGING APPLICATIONS OF SMALL-MOLECULE INHIBITORS THAT TARGET B-CELL RECEPTOR SIGNALING PATHWAYS, B-CELL LYMPHOMA-2 INHIBITORS, SELECTIVE INHIBITORS OF NUCLEAR EXPORT, AND EPIGENETIC MODIFIERS. 2016 3 4728 29 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 4 6263 38 THE MULTIPLE WAYS WNT SIGNALING CONTRIBUTES TO ACUTE LEUKEMIA PATHOGENESIS. WNT PROTEINS CONSTITUTE A VERY CONSERVED FAMILY OF SECRETED GLYCOPROTEINS THAT ACT AS SHORT-RANGE LIGANDS FOR SIGNALING WITH CRITICAL ROLES IN HEMATOPOIESIS, EMBRYONIC DEVELOPMENT, AND TISSUE HOMEOSTASIS. THESE PROTEINS TRANSDUCE SIGNALS VIA THE CANONICAL PATHWAY, WHICH IS BETA-CATENIN-MEDIATED AND BETTER-CHARACTERIZED, OR VIA MORE DIVERSE NONCANONICAL PATHWAYS THAT ARE BETA-CATENIN INDEPENDENT AND COMPRISE THE PLANAR CELL POLARITY (PCP) PATHWAY AND THE WNT/CA(++) PATHWAYS. SEVERAL PROTEINS REGULATE WNT SIGNALING THROUGH A VARIETY OF SOPHISTICATED MECHANISMS. DISORDERS WITHIN THE PATHWAY CAN CONTRIBUTE TO VARIOUS HUMAN DISEASES, AND THE DYSREGULATION OF WNT PATHWAYS BY DIFFERENT MOLECULAR MECHANISMS IS IMPLICATED IN THE PATHOGENESIS OF MANY TYPES OF CANCER, INCLUDING THE HEMATOLOGICAL MALIGNANCIES. THE TYPES OF LEUKEMIA DIFFER CONSIDERABLY AND CAN BE SUBDIVIDED INTO CHRONIC, MYELOID OR LYMPHOCYTIC, AND ACUTE, MYELOID OR LYMPHOCYTIC, LEUKEMIA, ACCORDING TO THE DIFFERENTIATION STAGE OF THE PREDOMINANT CELLS, THE PROGENITOR LINEAGE, THE DIAGNOSTIC AGE STRATA, AND THE SPECIFIC MOLECULAR DRIVERS BEHIND THEIR DEVELOPMENT. HERE, WE REVIEW THE ROLE OF WNT SIGNALING IN NORMAL HEMATOPOIESIS AND DISCUSS IN DETAIL THE MULTIPLE WAYS CANONICAL WNT SIGNALING CAN BE DYSREGULATED IN ACUTE LEUKEMIA, INCLUDING ALTERATIONS IN GENE EXPRESSION AND PROTEIN LEVELS, EPIGENETIC REGULATION, AND MUTATIONS. FURTHERMORE, WE HIGHLIGHT THE DIFFERENT IMPACTS OF THESE ALTERATIONS, CONSIDERING THE DISTINCT FORMS OF THE DISEASE, AND THE THERAPEUTIC POTENTIAL OF TARGETING WNT SIGNALING. 2020 5 4695 44 NF-KAPPAB ACTIVATION IN CHRONIC LYMPHOCYTIC LEUKEMIA: A POINT OF CONVERGENCE OF EXTERNAL TRIGGERS AND INTRINSIC LESIONS. THE NUCLEAR FACTOR-KAPPAB (NF-KAPPAB) PATHWAY IS CONSTITUTIVELY ACTIVATED IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) PATIENTS, AND HENCE PLAYS A MAJOR ROLE IN DISEASE DEVELOPMENT AND EVOLUTION. IN CONTRAST TO MANY OTHER MATURE B-CELL LYMPHOMAS, ONLY A FEW RECURRENTLY MUTATED GENES INVOLVED IN CANONICAL OR NON-CANONICAL NF-KAPPAB ACTIVATION HAVE BEEN IDENTIFIED IN CLL (I.E. BIRC3, MYD88 AND NFKBIE MUTATIONS) AND OFTEN AT A LOW FREQUENCY. ON THE OTHER HAND, CLL B CELLS SEEM 'ADDICTED' TO THE TUMOR MICROENVIRONMENT FOR THEIR SURVIVAL AND PROLIFERATION, WHICH IS PRIMARILY MEDIATED BY INTERACTION THROUGH A NUMBER OF CELL SURFACE RECEPTORS, E.G. THE B-CELL RECEPTOR (BCR), TOLL-LIKE RECEPTORS AND CD40, THAT IN TURN ACTIVATE DOWNSTREAM NF-KAPPAB. THE IMPORTANCE OF CELL-EXTRINSIC TRIGGERING FOR CLL PATHOPHYSIOLOGY WAS RECENTLY ALSO HIGHLIGHTED BY THE CLINICAL EFFICACY OF NOVEL DRUGS TARGETING MICROENVIRONMENTAL INTERACTIONS THROUGH THE INHIBITION OF BCR SIGNALING. IN OTHER WORDS, CLL CAN BE CONSIDERED A PROTOTYPE DISEASE FOR STUDYING THE INTRICATE INTERPLAY BETWEEN EXTERNAL TRIGGERS AND INTRINSIC ABERRATIONS AND THEIR COMBINED IMPACT ON DISEASE EVOLUTION. IN THIS REVIEW, WE WILL DISCUSS THE CURRENT UNDERSTANDING OF MECHANISMS UNDERLYING NF-KAPPAB DEREGULATION IN CLL, INCLUDING MICRO-ENVIRONMENTAL, GENETIC AND EPIGENETIC EVENTS, AND SUMMARIZE DATA GENERATED IN MURINE MODELS RESEMBLING HUMAN CLL. FINALLY, WE WILL ALSO DISCUSS DIFFERENT STRATEGIES UNDERTAKEN TO INTERVENE WITH THE NF-KAPPAB PATHWAY AND ITS UPSTREAM MEDIATORS. 2016 6 2380 31 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 7 5030 35 PERSPECTIVES ON PRECISION MEDICINE IN CHRONIC LYMPHOCYTIC LEUKEMIA: TARGETING RECURRENT MUTATIONS-NOTCH1, SF3B1, MYD88, BIRC3. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS HIGHLY HETEROGENEOUS, WITH EXTREMELY VARIABLE CLINICAL COURSE. THE CLINICAL HETEROGENEITY OF CLL REFLECTS DIFFERENCES IN THE BIOLOGY OF THE DISEASE, INCLUDING CHROMOSOMAL ALTERATIONS, SPECIFIC IMMUNOPHENOTYPIC PATTERNS AND SERUM MARKERS. THE APPLICATION OF NEXT-GENERATION SEQUENCING TECHNIQUES HAS DEMONSTRATED THE HIGH GENETIC AND EPIGENETIC HETEROGENEITY IN CLL. THE NOVEL MUTATIONS COULD BE PHARMACOLOGICALLY TARGETED FOR INDIVIDUALIZED APPROACH IN SOME OF THE CLL PATIENTS. POTENTIAL NEUROGENIC LOCUS NOTCH HOMOLOG PROTEIN 1 (NOTCH1) SIGNALLING TARGETING MECHANISMS IN CLL INCLUDE SECRETASE INHIBITORS AND SPECIFIC ANTIBODIES TO BLOCK NOTCH LIGAND/RECEPTOR INTERACTIONS. IN VITRO STUDIES CHARACTERIZING THE EFFECT OF THE SPLICING INHIBITORS RESULTED IN INCREASED APOPTOSIS OF CLL CELLS REGARDLESS OF SPLICING FACTOR 3B SUBUNIT 1 (SF3B1) STATUS. SEVERAL THERAPEUTIC STRATEGIES HAVE BEEN ALSO PROPOSED TO DIRECTLY OR INDIRECTLY INHIBIT THE TOLL-LIKE RECEPTOR/MYELOID DIFFERENTIATION PRIMARY RESPONSE GENE 88 (TLR/MYD88) PATHWAY. ANOTHER POTENTIAL APPROACH IS TARGETING NUCLEAR FACTOR KAPPA-LIGHT-CHAIN-ENHANCER OF ACTIVATED B CELLS (NF-KAPPAB) AND INHIBITION OF THIS PROSURVIVAL PATHWAY. NEWLY DISCOVERED MUTATIONS AND THEIR SIGNALLING PATHWAYS PLAY KEY ROLES IN THE COURSE OF THE DISEASE. THIS OPENS NEW OPPORTUNITIES IN THE MANAGEMENT AND TREATMENT OF CLL. 2021 8 1976 38 EPIGENETIC ALTERATIONS IN A MURINE MODEL FOR CHRONIC LYMPHOCYTIC LEUKEMIA. EARLY STAGES IN THE DEVELOPMENT OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) HAVE NOT BEEN EXPLORED MAINLY DUE TO THE INABILITY TO STUDY NORMAL B-CELLS EN ROUTE TO TRANSFORMATION. IN ORDER TO DETERMINE SUCH EARLY EVENTS OF LEUKEMOGENESIS, WE HAVE USED A WELL ESTABLISHED MOUSE MODEL FOR CLL. OVER-EXPRESSION OF HUMAN TCL1, A KNOWN CLL ONCOGENE IN MURINE B-CELLS LEADS TO THE DEVELOPMENT OF MATURE CD19+/CD5+/IGM+ CLONAL LEUKEMIA WITH A DISEASE PHENOTYPE SIMILAR TO THAT SEEN IN HUMAN CLL. HEREIN, WE REVIEW OUR RECENT STUDY USING THIS TCL1-DRIVEN MOUSE MODEL FOR CLL AND CORRESPONDING HUMAN CLL SAMPLES IN A CROSS-SPECIES EPIGENOMICS APPROACH TO ADDRESS THE TIMING AND RELEVANCE OF EPIGENETIC EVENTS OCCURRING DURING LEUKEMOGENESIS. WE DEMONSTRATED THAT THE MOUSE MODEL RECAPITULATES THE EPIGENETIC EVENTS THAT HAVE BEEN REPORTED FOR HUMAN CLL, AFFIRMING THE POWER AND VALIDITY OF THIS MOUSE MODEL TO STUDY EARLY EPIGENETIC EVENTS IN CANCER PROGRESSION. EPIGENETIC ALTERATIONS ARE DETECTED AS EARLY AS THREE MONTHS AFTER BIRTH, FAR BEFORE DISEASE MANIFESTS AT ABOUT 11 MONTHS OF AGE. THESE MICE UNDERGO NFKAPPAB REPRESSOR COMPLEX MEDIATED INACTIVATION OF THE TRANSCRIPTION FACTOR FOXD3, WHOSE TARGETS BECOME ABERRANTLY METHYLATED AND SILENCED IN MOUSE AND HUMAN CLL. OVERALL, OUR DATA SUGGEST THE ACCUMULATED EPIGENETIC ALTERATIONS DURING CLL PATHOGENESIS AS A CONSEQUENCE OF GENE SILENCING THROUGH TCL1 AND NFKAPPAB REPRESSOR COMPLEX, SUGGESTING THE RELEVANCE FOR NFKAPPAB AS A THERAPEUTIC TARGET IN CLL. 2009 9 5475 29 RESTORING MLL REACTIVATES LATENT TUMOR SUPPRESSION-MEDIATED VULNERABILITY TO PROTEASOME INHIBITORS. MLL UNDERGOES MULTIPLE DISTINCT CHROMOSOMAL TRANSLOCATIONS TO YIELD AGGRESSIVE LEUKEMIA WITH DISMAL OUTCOMES. BESIDES THEIR WELL-ESTABLISHED ROLE IN LEUKEMOGENESIS, MLL FUSIONS ALSO POSSESS LATENT TUMOR-SUPPRESSIVE ACTIVITY, WHICH CAN BE EXPLOITED AS EFFECTIVE CANCER TREATMENT STRATEGIES USING PHARMACOLOGICAL MEANS SUCH AS PROTEASOME INHIBITORS (PIS). HERE, USING MLL-REARRANGED XENOGRAFTS AND MLL LEUKEMIC CELLS AS MODELS, WE SHOW THAT WILD-TYPE MLL IS INDISPENSABLE FOR THE LATENT TUMOR-SUPPRESSIVE ACTIVITY OF MLL FUSIONS. MLL DYSFUNCTION, SHOWN AS LOSS OF THE CHROMATIN ACCUMULATION AND SUBSEQUENT DEGRADATION OF MLL, COMPROMISES THE LATENT TUMOR SUPPRESSION OF MLL-AF4 AND IS INSTRUMENTAL FOR THE ACQUIRED PI RESISTANCE. MECHANISTICALLY, MLL DYSFUNCTION IS CAUSED BY CHRONIC PI TREATMENT-INDUCED EPIGENETIC REPROGRAMMING THROUGH THE H2BUB-ASH2L-MLL AXIS AND CAN BE SPECIFICALLY RESTORED BY HISTONE DEACETYLASE (HDAC) INHIBITORS, WHICH INDUCE HISTONE ACETYLATION AND RECRUITS MLL ON CHROMATIN TO PROMOTE CELL CYCLE GENE EXPRESSION. OUR FINDINGS NOT ONLY DEMONSTRATE THE MECHANISM UNDERLYING THE INEVITABLE ACQUISITION OF PI RESISTANCE IN MLL LEUKEMIC CELLS, BUT ALSO ILLUSTRATE THAT PREVENTING THE EMERGENCE OF PI-RESISTANT CELLS CONSTITUTES A NOVEL RATIONALE FOR COMBINATION THERAPY WITH PIS AND HDAC INHIBITORS IN MLL LEUKEMIAS. 2020 10 358 39 ALTERNATIVE SPLICING IN CHRONIC MYELOID LEUKEMIA (CML): A NOVEL THERAPEUTIC TARGET? ALTHOUGH THE IMATINIB BASED THERAPY OF CHRONIC MYELOID LEUKEMIA (CML) REPRESENTS A TRIUMPH OF MEDICINE, NOT ALL PATIENTS WITH CML BENEFIT FROM THIS DRUG DUE TO THE DEVELOPMENT OF RESISTANCE AND INTOLERANCE. THE INTERRUPTION OF IMATINIB TREATMENT IS OFTEN FOLLOWED BY CLINICAL RELAPSE, SUGGESTING A FAILURE IN THE KILLING OF RESIDUAL LEUKAEMIC STEM CELLS. THERE IS NEED TO IDENTIFY ALTERNATIVE SELECTIVE MOLECULAR TARGETS FOR THIS DISEASE AND DEVELOP MORE EFFECTIVE THERAPEUTIC APPROACHES. ALTERNATIVE PRE-MRNA SPLICING (AS) IS AN EPIGENETIC PROCESS THAT GREATLY DIVERSIFIES THE REPERTOIRE OF THE TRANSCRIPTOME. AS ORCHESTRATES INTERACTIONS BETWEEN VARIOUS TYPES OF PROTEINS AND BETWEEN PROTEINS AND NUCLEIC ACIDS. CHANGES CAUSED BY INDIVIDUAL SPLICING EVENTS IN THE CELLS ARE SMALL, HOWEVER, "SPLICING PROGRAMS" TYPICALLY REACT TO THESE INDIVIDUAL CHANGES WITH CONSIDERABLE EFFECTS IN CELL PROLIFERATION, CELL SURVIVAL, AND APOPTOSIS. CURRENT EVIDENCE SUGGESTS A PIVOTAL ROLE OF AS IN LEUKEMIAS, PARTICULARLY IN MYELODISPLASTIC SYNDROME (MDS) AND CHRONIC LYMPHOCYTE LEUKEMIA (CLL). FROM THESE STUDIES AND STUDIES IN OTHER MALIGNANCES, IT IS CLEAR THAT SPLICING ABNORMALITIES PLAY A SIGNIFICANT ROLE IN MALIGNANT TRANSFORMATION. EVALUATION OF AS EVENTS IN CML CAN BE USED TO IDENTIFY NOVEL DISEASE MARKERS AND DRUGSENSITIVE TARGETS TO OVERCOME THE LIMITS OF THE SMALL MOLECULE INHIBITORS CURRENTLY USED FOR TREATING PATIENTS WITH CML. THE USE OF ABERRANT SPLICE VARIANTS AS DISEASE MARKERS HAS BEEN REPORTED, HOWEVER, LITTLE IS KNOWN ABOUT THE USE OF SPLICING ABNORMALITIES AS DRUG TARGETS IN CML. HEREIN WE DISCUSS POTENTIAL THERAPEUTIC APPROACHES THAT CAN BE USED TO TARGET SPLICING ABNORMALITIES IN CML. 2013 11 1542 30 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 12 6773 19 [ADVANCES OF RESEARCH ON DEMETHYLATION THERAPY FOR HEMATOLOGIC MALIGNANCIES]. DNA METHYLATION IS AN IMPORTANT AND REVERSIBLE EPIGENETIC MODIFICATION WHICH REGULATES GENOMIC STABILITY. METHYLATION IS ESSENTIAL FOR MAMMALIAN DEVELOPMENT. GENERALLY, GENE EXPRESSION LEVEL AND DNA METHYLATION ARE NEGATIVE CORRELATION. TRANSCRIPTIONAL SILENCING VIA METHYLATION OF CPG ISLANDS IN THE PROMOTER IS IMPORTANT FOR CELL GROWTH AND DIFFERENTIATION AND PLAYS A KEY ROLE IN TUMORIGENESIS. DEMETHYLATION DRUG CAN MODIFY CHROMATIN AND RESTORE THE ABILITY OF ANTI-ONCOGENE. DEMETHYLATION THERAPY AS A NEW THERAPY MAY TREAT EFFICIENTLY HEMATOLOGICAL MALIGNANCIES WITH RESISTANCE AND RELAPSE. IN THIS REVIEW, DNA METHYLATION MECHANISM, RELATIONSHIP BETWEEN ABERRANT METHYLATION AND HEMATOLOGIC MALIGNANCIES, MECHANISM OF DEMETHYLATION THERAPY, THE ADVANCE OF RESEARCH ON THE DEMETHYLATION THERAPY OF HEMATOLOGICAL MALIGNANCIES, SUCH AS ACUTE AND CHRONIC LEUKEMIA, LYMPHOMA, MYELODYSPLASTIC SYNDROME WERE SUMMARIZED. 2009 13 160 27 ABERRANT PROMOTER HYPOMETHYLATION IN CLL: DOES IT MATTER FOR DISEASE DEVELOPMENT? OVER THE LAST 30 YEARS, STUDIES OF ABERRANT DNA METHYLATION IN HEMATOLOGIC MALIGNANCIES HAVE BEEN DOMINATED BY THE PRIMARY FOCUS OF UNDERSTANDING PROMOTER HYPERMETHYLATION. THESE EFFORTS NOT ONLY RESULTED IN A BETTER UNDERSTANDING OF THE BASIS OF EPIGENETIC SILENCING OF TUMOR SUPPRESSOR GENES BUT ALSO RESULTED IN APPROVAL OF HYPOMETHYLATING AGENTS FOR THE TREATMENT OF SEVERAL MALIGNANCIES, SUCH AS MYELODYSPLASTIC SYNDROME AND ACUTE MYELOID LEUKEMIA. RECENT ADVANCES IN GLOBAL METHYLATION PROFILING COUPLED WITH THE USE OF MOUSE MODELS SUGGEST THAT ABERRANT PROMOTER HYPOMETHYLATION IS ALSO A FREQUENT EVENT IN HEMATOLOGIC MALIGNANCIES, PARTICULARLY IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). PROMOTER HYPOMETHYLATION AFFECTS GENE EXPRESSION AND, THEREFORE, MAY PLAY AN IMPORTANT ROLE IN DISEASE PATHOGENESIS. HERE, WE REVIEW RECENT FINDINGS AND DISCUSS THE POTENTIAL INVOLVEMENT OF ABERRANT PROMOTER HYPOMETHYLATION IN CLL. 2016 14 5477 36 RESTORING THE FUNCTIONAL IMMUNOGENICITY OF CHRONIC LYMPHOCYTIC LEUKEMIA USING EPIGENETIC MODIFIERS. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS A MALIGNANCY ARISING FROM IMMUNE CELLS (B-LYMPHOCYTES) ENDOWED WITH INTRINSIC ANTIGEN-PRESENTING CAPABILITIES. SUCH A FUNCTION HOWEVER IS LOST DURING MALIGNANT TRANSFORMATION AND CLL CELLS ARE WELL KNOWN FOR THEIR INABILITY TO PROCESS AND PRESENT ANTIGENS TO THE T-CELL ARM OF THE IMMUNE SYSTEM. INSTEAD, MALIGNANT CLL CELLS ELICIT A VAST ARRAY OF IMMUNE REGULATORY MECHANISMS CONDUCIVE TO T-CELL DYSFUNCTION AND IMMUNOSUPPRESSION. PREVIOUSLY, WE HAVE SHOWN THAT TREATMENT OF CLL CELLS WITH THE DEMETHYLATING AGENT 5-AZA-2'-DEOXYCYTIDINE UNLEASHED TARGET ANTIGEN EXPRESSION. HERE WE SHOW FOR THE FIRST TIME THAT COMBINING TWO EPIGENETIC MODIFIERS, 5-AZA-2'-DEOXYCYTIDINE AND THE HISTONE DEACETYLASE INHIBITOR LAQ824 EFFECTIVELY RESTORES THE IMMUNOGENICITY OF CLL CELL LINES AS WELL AS PRIMARY CELLS OBTAINED FROM CLL PATIENTS. INDEED, SUCH A COMBINATION INDUCES THE EXPRESSION OF NOVEL AND HIGHLY ANTIGENIC CANCER-TESTIS ANTIGENS (CTAS) AND COSTIMULATORY MOLECULES. THESE CHANGES FACILITATE THE FORMATION OF ROBUST SUPRAMOLECULAR ACTIVATION COMPLEXES (SMAC) BETWEEN CLL CELLS AND RESPONDER T-CELLS LEADING TO INTRACELLULAR SIGNALING, LYTIC GRANULE MOBILIZATION, AND POLARIZATION OF FUNCTIONAL AND RELEVANT T-CELL RESPONSES. THIS CASCADE OF T-CELL ACTIVATING EVENTS TRIGGERED BY CLL CELLS WITH RESTORED APC FUNCTION, POINTS TO COMBINED EPIGENETIC MODIFIER TREATMENT AS A POTENTIAL IMMUNOTHERAPEUTIC STRATEGY FOR CLL PATIENTS. 2011 15 2652 29 EPIGENOMICS OF LEUKEMIA: FROM MECHANISMS TO THERAPEUTIC APPLICATIONS. LEUKEMOGENESIS IS A MULTISTEP PROCESS IN WHICH SUCCESSIVE TRANSFORMATIONAL EVENTS ENHANCE THE ABILITY OF A CLONAL POPULATION ARISING FROM HEMATOPOIETIC PROGENITOR CELLS TO PROLIFERATE, DIFFERENTIATE AND SURVIVE. CLINICALLY AND PATHOLOGICALLY, LEUKEMIA IS SUBDIVIDED INTO FOUR MAIN CATEGORIES: CHRONIC LYMPHOCYTIC LEUKEMIA, CHRONIC MYELOID LEUKEMIA, ACUTE LYMPHOCYTIC LEUKEMIA AND ACUTE MYELOID LEUKEMIA. LEUKEMIA HAS BEEN PREVIOUSLY CONSIDERED ONLY AS A GENETIC DISEASE. HOWEVER, IN RECENT YEARS, SIGNIFICANT ADVANCES HAVE BEEN MADE IN THE ELUCIDATION OF THE LEUKEMOGENESIS-ASSOCIATED PROCESSES. THUS, WE HAVE COME TO UNDERSTAND THAT EPIGENETIC ALTERATIONS INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS AND MIRNA ARE INVOLVED IN THE PERMANENT CHANGES OF GENE EXPRESSION CONTROLLING THE LEUKEMIA PHENOTYPE. IN THIS ARTICLE, WE WILL FOCUS ON THE EPIGENETIC DEFECTS ASSOCIATED WITH LEUKEMIA AND THEIR IMPLICATIONS AS BIOMARKERS FOR DIAGNOSTIC, PROGNOSTIC AND THERAPEUTIC APPLICATIONS. 2011 16 6326 26 THE ROLE OF BCL-2 FAMILY PROTEINS IN CHRONIC LYMPHOCYTIC LEUKAEMIA. BCL-2 FAMILY PROTEINS HAVE LONG BEEN IMPLICATED IN THE PATHOLOGY OF CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL). INDEED, A NUMBER OF THESE PROTEINS HAVE BEEN SHOWN TO HAVE PROGNOSTIC IMPORTANCE IN THIS DISEASE. THE PRECISE WAYS IN WHICH THESE PROTEINS IMPACT UPON CLL AND THE WAYS IN WHICH THEY ARE REGULATED REMAIN INCOMPLETELY RESOLVED. HOWEVER, SIGNIFICANT ADVANCES HAVE BEEN RECENTLY MADE IN OUR UNDERSTANDING OF HOW THESE PROTEINS ARE CONTROLLED BY GENETIC, EPIGENETIC AND MICROENVIRONMENTAL CUES. FURTHERMORE, MAJOR PROGRESS HAS BEEN MADE IN TRYING TO TARGET THESE PROTEINS THERAPEUTICALLY. HERE WE REVIEW THE CURRENT KNOWLEDGE ABOUT THIS FAMILY OF APOPTOSIS-REGULATING PROTEINS AND HOW THEY IMPACT UPON DRUG RESISTANCE AND DISEASE PROGRESSION. WE ALSO SUMMARISE EVOLUTION IN THE DEVELOPMENT OF BCL-2 FAMILY INHIBITORS FOR THE TREATMENT OF CLL AND OTHER CANCERS. 2010 17 5589 33 ROLE OF SIRT1 IN THE GROWTH AND REGULATION OF NORMAL HEMATOPOIETIC AND LEUKEMIA STEM CELLS. PURPOSE OF REVIEW: RECENT STUDIES HAVE ENHANCED OUR UNDERSTANDING OF THE ROLE OF THE SIRT1 DEACETYLASE IN REGULATION OF NORMAL HEMATOPOIETIC STEM CELLS (HSCS) AND LEUKEMIA STEM CELLS (LSCS), AND ITS IMPORTANCE IN REGULATING AUTOPHAGY AND EPIGENETIC REPROGRAMMING IN RESPONSE TO METABOLIC ALTERATIONS. RECENT FINDINGS: STUDIES EMPLOYING CONDITIONAL DELETION MOUSE MODELS INDICATE AN IMPORTANT ROLE OF SIRT1 IN MAINTENANCE OF ADULT HSCS UNDER CONDITIONS OF STRESS. SIRT1 IS SIGNIFICANTLY OVEREXPRESSED IN LSC POPULATIONS FROM ACUTE MYELOID LEUKEMIA (AML) PATIENTS WITH THE FLT3-ITD MUTATION, AND MAINTAINS THEIR SURVIVAL, GROWTH AND DRUG RESISTANCE, AS PREVIOUSLY DESCRIBED FOR CHRONIC MYELOGENOUS LEUKEMIA (CML). SIRT1 CAN ALSO ENHANCE LEUKEMIA EVOLUTION AND DRUG RESISTANCE BY PROMOTING GENETIC INSTABILITY. RECENT STUDIES INDICATE AN IMPORTANT ROLE OF SIRT1 IN REGULATING AUTOPHAGY IN RESPONSE TO OXIDATIVE STRESS AND NUTRIENT REQUIREMENTS, AND HAVE ELUCIDATED COMPLEX MECHANISMS BY WHICH SIRT1 REGULATES EPIGENETIC REPROGRAMMING OF STEM CELLS. SUMMARY: SIRT1 INHIBITION HOLDS PROMISE AS A NOVEL APPROACH FOR ABLATION OF LSCS IN CHRONIC PHASE CML OR FLT3-ITD-ASSOCIATED AML. ADDITIONAL STUDIES TO UNDERSTAND THE ROLE OF SIRT1 IN LINKING METABOLIC ALTERATIONS TO GENOMIC STABILITY, AUTOPHAGY AND EPIGENETIC REPROGRAMMING OF STEM CELLS ARE WARRANTED. 2015 18 4284 31 MICRORNA CIRCUITS REGULATE THE CANCER-INFLAMMATION LINK. GENETIC AND EPIGENETIC PERTURBATIONS ARE REQUIRED TO TRANSFORM NORMAL CELLS INTO CANCER CELLS. INFLAMMATORY SIGNALING PATHWAYS ARE ACTIVATED IN VARIOUS CANCERS, LINKING CHRONIC INFLAMMATION TO ONCOGENESIS. HOWEVER, THE MOLECULAR CIRCUITS THAT RESULT IN SUSTAINED ACTIVATION OF THESE INFLAMMATORY FACTORS ARE NOT YET WELL UNDERSTOOD. IN THE 28 JANUARY 2014 ISSUE OF SCIENCE SIGNALING, XIANG ET AL. IDENTIFIED A MICRORNA-MEDIATED ANTI-INFLAMMATORY CIRCUIT THAT IS REPRESSED EPIGENETICALLY IN RECEPTOR-NEGATIVE BREAST CANCERS. A HIGH-THROUGHPUT SCREEN FOR SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 3 (STAT3)-REGULATED MICRORNAS REVEALED MICRORNA MIR-146B AS A DIRECT STAT3 TARGET IN MAMMARY EPITHELIAL CELLS, BUT DNA METHYLATION IN ITS PROMOTER AREA SUPPRESSED MIR-146B EXPRESSION IN CANCER CELLS. OVEREXPRESSION OF MIR-146B SUPPRESSED NUCLEAR FACTOR KAPPAB (NF-KAPPAB)-DEPENDENT EXPRESSION OF IL6 AND SUBSEQUENT STAT3 ACTIVATION AND DECREASED THE STAT3-INDUCED INVASIVENESS AND MESENCHYMAL PHENOTYPE OF BREAST CANCER CELLS. OVERALL, THIS STUDY CONTRIBUTES TO OUR UNDERSTANDING OF HOW INFLAMMATION IS INVOLVED IN ONCOGENIC TRANSFORMATION. FURTHER STUDIES COULD EVALUATE THE THERAPEUTIC POTENTIAL OF TARGETING THIS CIRCUIT IN ESTROGEN RECEPTOR-NEGATIVE BREAST CANCERS. 2014 19 2928 33 GENERATION OF IPSCS FROM CULTURED HUMAN MALIGNANT CELLS. INDUCED PLURIPOTENT STEM CELLS (IPSCS) CAN BE GENERATED FROM VARIOUS DIFFERENTIATED CELL TYPES BY THE EXPRESSION OF A SET OF DEFINED TRANSCRIPTION FACTORS. SO FAR, IPSCS HAVE BEEN GENERATED FROM PRIMARY CELLS, BUT IT IS UNCLEAR WHETHER HUMAN CANCER CELL LINES CAN BE REPROGRAMMED. HERE WE DESCRIBE THE GENERATION AND CHARACTERIZATION OF IPSCS DERIVED FROM HUMAN CHRONIC MYELOID LEUKEMIA CELLS. WE SHOW THAT, DESPITE THE PRESENCE OF ONCOGENIC MUTATIONS, THESE CELLS ACQUIRED PLURIPOTENCY BY THE EXPRESSION OF 4 TRANSCRIPTION FACTORS AND UNDERWENT DIFFERENTIATION INTO CELL TYPES DERIVED OF ALL 3 GERM LAYERS DURING TERATOMA FORMATION. INTERESTINGLY, ALTHOUGH THE PARENTAL CELL LINE WAS STRICTLY DEPENDENT ON CONTINUOUS SIGNALING OF THE BCR-ABL ONCOGENE, ALSO TERMED ONCOGENE ADDICTION, REPROGRAMMED CELLS LOST THIS DEPENDENCY AND BECAME RESISTANT TO THE BCR-ABL INHIBITOR IMATINIB. THIS FINDING INDICATES THAT THE THERAPEUTIC AGENT IMATINIB TARGETS CELLS IN A SPECIFIC EPIGENETIC DIFFERENTIATED CELL STATE, AND THIS MAY CONTRIBUTE TO ITS INABILITY TO FULLY ERADICATE DISEASE IN CHRONIC MYELOID LEUKEMIA PATIENTS. 2010 20 6371 37 THE ROLE OF MICRORNAS IN THE PATHOGENESIS AND TREATMENT OF HEMATOPOIETIC MALIGNANCIES. MICRORNAS (MIRNAS) COMPRISE A RECENTLY DISCOVERED CLASS OF NON-CODING RNAS WITH REGULATORY FUNCTIONS IN POST-TRANSCRIPTIONAL GENE EXPRESSION CONTROL. MANY MIRNAS ARE LOCATED IN GENOMIC REGIONS THAT ARE FREQUENTLY DELETED IN CANCER, OR ARE SUBJECT TO EPIGENETIC AND TRANSCRIPTIONAL DEREGULATION IN CANCER CELLS. THE MIRNA TRANSCRIPTOME OF CANCER CELLS IS VERY DIFFERENT FROM THAT OF THEIR NORMAL CELL COUNTERPARTS. MIRNAS CAN EXHIBIT ONCOGENIC OR TUMOR SUPPRESSIVE OR EVEN BOTH PROPERTIES DEPENDING ON THE SPECIFIC TARGETS AND CELLULAR CONTEXT. IT IS BECOMING INCREASINGLY CLEAR THAT MIRNAS NOT ONLY SERVE AS USEFUL TUMOR BIOMARKERS WITH IMPLICATIONS FOR DIAGNOSIS, PROGNOSIS AND THE PREDICTION OF TREATMENT RESPONSES, BUT MAY ALSO BE USED FOR TARGETED CANCER TREATMENT AND EVEN AS THERAPEUTICS. IN THIS REVIEW, WE PROVIDE AN OVERVIEW OF RECENT ADVANCES IN OUR UNDERSTANDING OF THE TUMOR SUPPRESSOR MIRNAS AND ONCOMIRS INVOLVED IN THE PATHOGENESIS OF LEUKEMIAS AND LYMPHOMAS, AND THEIR TARGET TRANSCRIPTS IN CANCER SIGNALING NETWORKS. IN PARTICULAR, WE FOCUS ON THE ROLE OF MIRNAS IN CHRONIC LYMPHOCYTIC AND ACUTE LYMPHOBLASTIC LEUKEMIA AND IN B-CELL LYMPHOMAS. IN THE SECOND PART, WE REVIEW THE VARIOUS ALTERNATIVE STRATEGIES OF TARGETING MIRNAS IN CANCER THERAPY. METHODS OF ONCOMIR ANTAGONIZATION BY ANTAGOMIRS OR LOCKED NUCLEID ACIDS ARE CONTRASTED WITH STRATEGIES THAT HARNESS THE TUMOR SUPPRESSIVE PROPERTIES OF CERTAIN MIRNAS FOR CANCER TREATMENT. PRECLINICAL PROGRESS, ALSO WITH REGARD TO DELIVERY STRATEGIES, POSSIBLE SIDE EFFECTS AND OTHER PHARMACOLOGICAL ASPECTS, IS PRESENTED ALONG WITH RESULTS FROM THE FIRST HUMAN TRIALS ASSESSING THE SAFETY AND EFFICACY OF MIRNA-TARGETING THERAPEUTICS. 2013