1 6134 52 THE EPIGENETICALLY-REGULATED MIR-34A TARGETING C-SRC SUPPRESSES RAF/MEK/ERK SIGNALING PATHWAY IN K-562 CELLS. PREVIOUS REPORTS SHOW THAT MIR-34A SUPPRESSED K-562 CELL PROLIFERATION AND CONTRIBUTED TO MEGAKARYOCYTIC DIFFERENTIATION OF K-562 CELLS. HERE, WE REPORTED THAT MIR-34A, A TUMOR SUPPRESSOR GENE, IS DOWN-REGULATED IN THE K-562 CELLS AND CHRONIC MYELOID LEUKEMIA (CML) PATIENTS DUE TO ABERRANT DNA HYPERMETHYLATION. C-SRC IS A TARGET OF MIR-34A. RESTORING MIR-34A EXPRESSION RESULTED IN DOWN-REGULATION OF C-SRC AND PHOSPHORYLATED (TYR416) C-SRC PROTEIN IN K-562 CELLS, WHICH CONSEQUENTLY TRIGGERED SUPPRESSION OF THE RAF/MEK/ERK SIGNALING PATHWAY TO DECREASE CELL PROLIFERATION. 2017 2 671 22 BOTHROPS MOOJENI L-AMINO ACID OXIDASE INDUCES APOPTOSIS AND EPIGENETIC MODULATION ON BCR-ABL(+) CELLS. BACKGROUND: RESISTANCE TO APOPTOSIS IN CHRONIC MYELOID LEUKEMIA (CML) IS ASSOCIATED WITH CONSTITUTIVE TYROSINE KINASE ACTIVITY OF THE BCR-ABL ONCOPROTEIN. THE DEREGULATED EXPRESSION OF APOPTOSIS-RELATED GENES AND ALTERATION IN EPIGENETIC MACHINERY MAY ALSO CONTRIBUTE TO APOPTOSIS RESISTANCE IN CML. TYROSINE KINASE INHIBITORS TARGET THE BCR-ABL ONCOPROTEIN AND ARE USED IN CML TREATMENT. THE RESISTANCE OF CML PATIENTS TO TYROSINE KINASE INHIBITORS HAS GUIDED THE SEARCH FOR NEW COMPOUNDS THAT MAY INDUCE APOPTOSIS IN BCR-ABL(+) LEUKEMIC CELLS AND IMPROVE THE DISEASE TREATMENT. METHODS: IN THE PRESENT STUDY, WE INVESTIGATED WHETHER THE L-AMINO ACID OXIDASE ISOLATED FROM BOTHROPS MOOJENI SNAKE VENOM (BMOOLAAO-I) (I) WAS CYTOTOXIC TO BCR-ABL(+) CELL LINES (HL-60.BCR-ABL, K562-S, AND K562-R), HL-60 (ACUTE PROMYELOCYTIC LEUKEMIA) CELLS, THE NON-TUMOR CELL LINE HEK-293, AND PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMC); AND (II) AFFECTED EPIGENETIC MECHANISMS, INCLUDING DNA METHYLATION AND MICRORNAS EXPRESSION IN VITRO. RESULTS: BMOOLAAO-I INDUCED ROS PRODUCTION, APOPTOSIS, AND DIFFERENTIAL DNA METHYLATION PATTERN OF REGULATORY APOPTOSIS GENES. THE TOXIN UPREGULATED EXPRESSION OF THE PRO-APOPTOTIC GENES BID AND FADD AND DOWNREGULATED DFFA EXPRESSION IN LEUKEMIC CELL LINES, AS WELL AS INCREASED MIR-16 EXPRESSION - WHOSE MAJOR PREDICTED TARGET IS THE ANTI-APOPTOTIC GENE BCL2 - IN BCR-ABL(+) CELLS. CONCLUSION: BMOOLAAO-I EXERTS SELECTIVE ANTITUMOR ACTION MEDIATED BY H(2)O(2) RELEASE AND INDUCES APOPTOSIS, AND ALTERATIONS IN EPIGENETIC MECHANISMS. THESE RESULTS SUPPORT FUTURE INVESTIGATIONS ON THE EFFECT OF BMOOLAAO-I ON IN VIVO MODELS TO DETERMINE ITS POTENTIAL IN CML THERAPY. 2020 3 5101 23 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 4 1334 19 DEREGULATION OF AIOLOS EXPRESSION IN CHRONIC LYMPHOCYTIC LEUKEMIA IS ASSOCIATED WITH EPIGENETIC MODIFICATIONS. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS CHARACTERIZED BY A CLONAL ACCUMULATION OF MATURE NEOPLASTIC B CELLS THAT ARE RESISTANT TO APOPTOSIS. AIOLOS, A MEMBER OF THE IKAROS FAMILY OF ZINC-FINGER TRANSCRIPTION FACTORS, PLAYS AN IMPORTANT ROLE IN THE CONTROL OF MATURE B LYMPHOCYTE DIFFERENTIATION AND MATURATION. IN THIS STUDY, WE SHOWED THAT AIOLOS EXPRESSION IS UP-REGULATED IN B-CLL CELLS. THIS OVEREXPRESSION DOES NOT IMPLICATE ISOFORM IMBALANCE OR DISTURB AIOLOS SUBCELLULAR LOCALIZATION. THE CHROMATIN STATUS AT THE AIOLOS PROMOTER IN CLL IS DEFINED BY THE DEMETHYLATION OF DNA AND AN ENRICHMENT OF EUCHROMATIN ASSOCIATED HISTONE MARKERS, SUCH AS THE DIMETHYLATION OF THE LYSINE 4 ON HISTONE H3. THESE EPIGENETIC MODIFICATIONS SHOULD ALLOW ITS UPSTREAM EFFECTORS, SUCH AS NUCLEAR FACTOR-KAPPAB, CONSTITUTIVELY ACTIVATED IN CLL, TO GAIN ACCESS TO PROMOTER, RESULTING UP-REGULATION OF AIOLOS. TO DETERMINE THE CONSEQUENCES OF AIOLOS DEREGULATION IN CLL, WE ANALYZED THE EFFECTS OF AIOLOS OVEREXPRESSION OR DOWN-REGULATION ON APOPTOSIS. AIOLOS IS INVOLVED IN CELL SURVIVAL BY REGULATING THE EXPRESSION OF SOME BCL-2 FAMILY MEMBERS. OUR RESULTS STRONGLY SUGGEST THAT AIOLOS DEREGULATION BY EPIGENETIC MODIFICATIONS MAY BE A HALLMARK OF CLL. 2011 5 2432 26 EPIGENETIC SILENCING OF MIR-708 ENHANCES NF-KAPPAB SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA. MICRORNAS (MIRNAS) ARE POST-TRANSCRIPTIONAL REGULATORS OF GENE EXPRESSION AND THEIR DEREGULATION IS INVOLVED IN TUMOR DEVELOPMENT. EPIGENETIC GENE SILENCING IN CANCER BY DNA METHYLATION CONTRIBUTES TO THE SILENCING OF TUMOR-SUPPRESSOR GENES, INCLUDING MIRNAS. WE HAVE RECENTLY SHOWN THAT THE PROMOTER OF MIR-708 IS ABERRANTLY METHYLATED IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). TO CHARACTERIZE THE MOLECULAR SIGNALING NETWORKS THAT ARE INFLUENCED BY MIR-708, WE PERFORMED A LUCIFERASE-BASED SCREEN EVALUATING THE EFFECTS OF ECTOPIC MIR-708 EXPRESSION ON LEUKEMIA-RELEVANT SIGNALING PATHWAYS. WE FOUND THAT MIR-708 STRONGLY REPRESSED NF-KAPPAB SIGNALING, A PATHWAY KNOWN TO BE DEREGULATED IN CLL. AMONG THE PREDICTED MIR-708 TARGETS WAS IKKBETA (INHIBITOR OF KAPPA LIGHT POLYPEPTIDE GENE ENHANCER IN B CELLS, KINASE-BETA/IKBKB), A KEY KINASE FACILITATING NF-KAPPAB SIGNALING. WE VALIDATED THE INTERACTION OF MIR-708 WITH THE 3'-UNTRANSLATED REGION OF IKKBETA AND FOUND THAT MIR-708 OVEREXPRESSION REPRESSES ENDOGENOUS IKKBETA. PHOSPHORYLATION OF THE IKKBETA TARGET IKAPPABALPHA AND EXPRESSION OF KNOWN NF-KAPPAB TARGET GENES WERE IMPAIRED BY MIR-708. FURTHERMORE, WE IDENTIFIED AN ENHANCER REGION DOWNSTREAM OF THE MIR-708 PROMOTER THAT DISPLAYS A DISTINCT DNA METHYLATION STATUS IN CLL. HIGH ENHANCER METHYLATION IS SIGNIFICANTLY CORRELATED WITH LOWER MIR-708 EXPRESSION AND IS PREDOMINANTLY FOUND IN PATIENTS WITH POOR PROGNOSIS AND SHORTER TIME TO TREATMENT. THESE RESULTS DEMONSTRATE THAT MIR-708 REGULATES THE NF-KAPPAB PATHWAY BY TARGETING IKKBETA, AND THAT METHYLATION OF A KEY ENHANCER REGION CONTRIBUTES TO ITS SUPPRESSION IN CLL. 2015 6 1629 21 DNMT3A ARG882 MUTATION DRIVES CHRONIC MYELOMONOCYTIC LEUKEMIA THROUGH DISTURBING GENE EXPRESSION/DNA METHYLATION IN HEMATOPOIETIC CELLS. THE GENE ENCODING DNA METHYLTRANSFERASE 3A (DNMT3A) IS MUTATED IN APPROXIMATELY 20% OF ACUTE MYELOID LEUKEMIA CASES, WITH ARG882 (R882) AS THE HOTSPOT. HERE, WE ADDRESSED THE TRANSFORMATION ABILITY OF THE DNMT3A-ARG882HIS (R882H) MUTANT BY USING A RETROVIRAL TRANSDUCTION AND BONE MARROW TRANSPLANTATION (BMT) APPROACH AND FOUND THAT THE MUTANT GENE CAN INDUCE ABERRANT PROLIFERATION OF HEMATOPOIETIC STEM/PROGENITOR CELLS. AT 12 MO POST-BMT, ALL MICE DEVELOPED CHRONIC MYELOMONOCYTIC LEUKEMIA WITH THROMBOCYTOSIS. RNA MICROARRAY ANALYSIS REVEALED ABNORMAL EXPRESSIONS OF SOME HEMATOPOIESIS-RELATED GENES, AND THE DNA METHYLATION ASSAY IDENTIFIED CORRESPONDING CHANGES IN METHYLATION PATTERNS IN GENE BODY REGIONS. MOREOVER, DNMT3A-R882H INCREASED THE CDK1 PROTEIN LEVEL AND ENHANCED CELL-CYCLE ACTIVITY, THEREBY CONTRIBUTING TO LEUKEMOGENESIS. 2014 7 102 20 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 8 1234 22 CRYPTOTANSHINONE SUPPRESSES KEY ONCO-PROLIFERATIVE AND DRUG-RESISTANT PATHWAYS OF CHRONIC MYELOID LEUKEMIA BY TARGETING STAT5 AND STAT3 PHOSPHORYLATION. C-MYC AND SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION (STAT) FAMILY PROTEINS HAVE BEEN PROPOSED TO BE IMPORTANT DOWNSTREAM GENES OF BCR-ABL, WHICH CHARACTERIZES MOST CASES OF CHRONIC MYELOID LEUKEMIA (CML). HERE, WE REPORT A C-MYC PATHWAY-TARGETED SCREENING OF SEVEN NATURAL ANTICANCER COMPOUNDS, IN WHICH WE IDENTIFIED CRYPTOTANSHINONE AS A HIGHLY PROMISING AGENT FOR CML THERAPY. CRYPTOTANSHINONE DEPLETES C-MYC IN CML BY REPRESSING THE PHOSPHORYLATION OF STAT5. DECREASED VIABILITY OF K562 CELLS CORRELATED WITH P-STAT5 SUPPRESSION. UNEXPECTEDLY, IMATINIB ACTIVATES RATHER THAN INHIBITS THE PHOSPHORYLATION OF STAT3 IN K562 CELLS. WE DEMONSTRATED THAT CRYPTOTANSHINONE, AS A DUAL INHIBITOR OF P-STAT5 AND P-STAT3, CAN EFFECTIVELY BLOCK IL-6-MEDIATED STAT3 ACTIVATION AND REVERSE BCR-ABL KINASE-INDEPENDENT DRUG RESISTANCE. MOREOVER, WE SHOWED THAT THE EPIGENETIC REBALANCE BETWEEN DECREASED BCR-ABL/STAT5/C-MYC AND ENHANCED STAT3/MULTI-DRUG RESISTANCE (MDR) PATHWAYS IS CHARACTERISTIC OF THE CANCER STEM CELL-LIKE PROPERTY OF K562/ADR. SIMULTANEOUSLY SUPPRESSING THESE TWO PATHWAYS USING CRYPTOTANSHINONE PROVES TO BE CRITICAL FOR THE MALIGNANT NETWORK REDRESS AND MDR REVERSAL OF K562/ADR. THESE STUDIES REVEAL THE DUAL FUNCTIONS OF CRYPTOTANSHINONE THAT SUPPRESS KEY ONCOGENIC PROLIFERATION AND DRUG-RESISTANT PATHWAYS IN CML CELLS BY TARGETING P-STAT5 AND P-STAT3, PROVIDING A NEW STRATEGY FOR CML THERAPY THAT TAKES ADVANTAGE OF NATURAL PRODUCTS. 2018 9 2128 24 EPIGENETIC INACTIVATION OF PLCD1 IN CHRONIC MYELOID LEUKEMIA. PHOSPHOLIPASE C DELTA1 (PLCD1), IS LOCATED AT THE IMPORTANT TUMOR SUPPRESSOR LOCUS 3P22. IT ENCODES AN ENZYME THAT MEDIATES REGULATORY SIGNALING OF ENERGY METABOLISM, CALCIUM HOMEOSTASIS AND INTRACELLULAR MOVEMENTS. PLCD1 HAS BEEN STUDIED IN SOME HUMAN SOLID TUMORS RELATING TO THE CPG ISLAND METHYLATION OF THE GENE PROMOTER AS A FUNCTIONAL TUMOR SUPPRESSOR. HOWEVER, NO SUCH INFORMATION IS AVAILABLE IN CHRONIC MYELOID LEUKEMIA (CML). IN THIS STUDY, WE INVESTIGATED PLCD1 EXPRESSION IN THE CML K562 CELL LINE (0/1) AND 15% (2/13) OF BONE MARROW MONONUCLEAR CELLS WITH CML BY USING SEMI-QUANTITATIVE PCR. THE CPG ISLAND (CGI) METHYLATION STATUS OF THE PLCD1 PROMOTER WAS DETECTED IN K562 (0/1) AND 56% (23/41) OF CML PATIENTS BY METHYLATION-SPECIFIC PCR (MSP), BUT NOT IN THE NORMAL ADULT BONE MARROW MONONUCLEAR CELLS. FURTHERMORE, THE DNA DEMETHYLATION AGENT 5'-AZA-2'DEOXYCYTIDINE RESTORED THE EXPRESSION OF PLCD1 IN K562 CELLS. FUNCTIONAL STUDIES SHOWED THAT ECTOPIC EXPRESSION OF PLCD1 IN K562 CELLS WAS ABLE TO DRAMATICALLY INHIBIT THEIR COLONY FORMATION AND INDUCE CELL CYCLE G1 ARREST, SUGGESTING THAT PLCD1 ACTS AS A FUNCTIONAL TUMOR SUPPRESSOR AND MAY SERVE AS A BIOMARKER FOR POSSIBLE EARLY DETECTION AND PROGNOSIS OF CML. 2012 10 6028 26 THE BMI1 POLYCOMB PROTEIN REPRESSES CYCLIN G2-INDUCED AUTOPHAGY TO SUPPORT PROLIFERATION IN CHRONIC MYELOID LEUKEMIA CELLS. THE BMI1 POLYCOMB PROTEIN REGULATES SELF-RENEWAL, PROLIFERATION AND SURVIVAL OF CANCER-INITIATING CELLS ESSENTIALLY THROUGH EPIGENETIC REPRESSION OF THE CDKN2A TUMOR SUPPRESSOR LOCUS. WE DEMONSTRATE HERE FOR THE FIRST TIME THAT BMI1 ALSO PREVENTS AUTOPHAGY IN CHRONIC MYELOID LEUKEMIA (CML) CELL LINES, TO SUPPORT THEIR PROLIFERATION AND CLONOGENIC ACTIVITY. USING CHROMATIN IMMUNOPRECIPITATION, WE IDENTIFIED CCNG2/CYCLIN G2 (CCNG2) AS A DIRECT BMI1 TARGET. BMI1 DOWNREGULATION IN CD34+ CML CELLS BY PTC-209 PHARMACOLOGICAL TREATMENT OR SHBMI1 TRANSDUCTION TRIGGERED CCNG2 EXPRESSION AND DECREASED CLONOGENIC ACTIVITY. ALSO, ECTOPIC EXPRESSION OF CCNG2 IN CD34+ CML CELLS STRONGLY DECREASED THEIR CLONOGENICITY. CCNG2 WAS SHOWN TO ACT BY DISRUPTING THE PHOSPHATASE 2A COMPLEX, WHICH ACTIVATES A PKCZETA-AMPK-JNK-ERK PATHWAY THAT ENGAGES AUTOPHAGY. WE OBSERVED THAT BMI1 AND CCNG2 LEVELS EVOLVED INVERSELY DURING THE PROGRESSION OF CML TOWARDS AN ACUTE DEADLY PHASE, AND THEREFORE HYPOTHESIZED THAT BMI1 COULD SUPPORT ACUTE TRANSFORMATION OF CML THROUGH THE SILENCING OF A CCNG2-MEDIATED TUMOR-SUPPRESSIVE AUTOPHAGY RESPONSE. 2015 11 2763 21 EXPRESSION OF THE LEUKEMIC PROGNOSTIC MARKER CD7 IS LINKED TO EPIGENETIC MODIFICATIONS IN CHRONIC MYELOID LEUKEMIA. BACKGROUND: EXPRESSION LEVELS OF THE CELL SURFACE GLYCOPROTEIN, CD7, AND THE SERINE PROTEASE, ELASTASE 2 (ELA2), IN THE LEUKEMIC CELLS OF PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) HAVE BEEN ASSOCIATED WITH CLINICAL OUTCOME. HOWEVER, LITTLE IS KNOWN ABOUT THE MECHANISMS THAT UNDERLIE THE VARIABLE EXPRESSION OF THESE GENES IN THE LEUKEMIC CELLS. RESULTS: TO ADDRESS THIS QUESTION, WE COMPARED THE LEVEL OF THEIR EXPRESSION WITH THE DNA METHYLATION AND HISTONE ACETYLATION STATUS OF 5' SEQUENCES OF BOTH GENES IN LEUKEMIC CELL LINES AND PRIMITIVE (LIN-CD34+) LEUKEMIC CELLS FROM CHRONIC PHASE CML PATIENTS. DNA METHYLATION OF THE ELA2 GENE PROMOTER DID NOT CORRELATE WITH ITS EXPRESSION PATTERN IN LIN-CD34+ CELLS FROM CHRONIC PHASE CML PATIENT SAMPLES EVEN THOUGH THERE WAS CLEAR DIFFERENTIAL DNA METHYLATION OF THIS LOCUS IN ELA2-EXPRESSING AND NON-EXPRESSING CELL LINES. IN CONTRAST, WE FOUND A STRONG RELATION BETWEEN CD7 EXPRESSION AND TRANSCRIPTION-PERMISSIVE CHROMATIN MODIFICATIONS, BOTH AT THE LEVEL OF DNA METHYLATION AND HISTONE ACETYLATION WITH EVIDENCE OF HYPOMETHYLATION OF THE CD7 PROMOTER REGION IN THE LIN-CD34+ CELLS FROM CML PATIENTS WITH HIGH CD7 EXPRESSION. CONCLUSION: THESE FINDINGS INDICATE A LINK BETWEEN EPIGENETIC MODIFICATIONS AND CD7 EXPRESSION IN PRIMITIVE CML CELLS. 2010 12 1843 21 EFFECTS OF TELOMERASE INHIBITOR ON EPIGENETIC CHROMATIN MODIFICATION ENZYMES IN MALIGNANCIES. TELOMERASE HAS A CRITICAL ROLE IN CELL PROLIFERATION, TUMOR MAINTAINING, AND THERAPY RESISTANCE, WHICH ACT BY MODIFYING MANY SIGNALING PATHWAYS. 2-[(E)-3-NAPHTALEN-2-YL-BUT-2-ENOYLAMINO]-BENZOIC ACID (BIBR1532) IS ONE OF THE MOST STUDIED TELOMERASE INHIBITORS, AND IT TARGETS TELOMERASE COMPONENTS TERC AND TERT. IN THIS NOVEL STUDY, WE AIMED TO INVESTIGATE THE EPIGENETIC EFFECTS OF BIBR1532 ON BOTH HEMATOLOGIC MALIGNANCIES AND SOLID TUMORS. K-562 HUMAN CHRONIC MYELOID LEUKEMIA CELL LINE AND U87MG GLIOBLASTOMA CELL LINE WERE COMPARED WITH CONTROL GROUPS WITHOUT BIBR1532 TREATMENT. CYTOTOXIC EFFECTS OF BIBR1532 WERE DETERMINED BY USING WST-1 ASSAY. APOPTOTIC EFFECTS OF BIBR1532 WERE DETECTED BY USING ANNEXIN V METHOD. TO ASSESS EXPRESSION CHANGES IN THE HUMAN EPIGENETIC CHROMATIN MODIFICATION ENZYME GENES, TOTAL RNA WAS ISOLATED FROM K-562 AND U87MG CELLS TREATED WITH BIBR1532 AND UNTREATED CONTROL CELLS. BIBR1532 INDUCED 2.41-FOLD APOPTOTIC CELL DEATH IN U87MG CELL LINES COMPARED WITH CONTROL GROUPS. APOPTOSIS WAS SLIGHTLY INDUCED IN K-562 CELLS WITH BIBR1532 TREATMENT COMPARED WITH CONTROL CELLS. WE OBSERVED THAT BIBR1532 ALSO REGULATES SIMILAR GENES IN BOTH CELL LINES, AND IT IS USEFUL ON EPIGENETIC MECHANISMS. AS A RESULT, TELOMERASE INHIBITOR BIBR1532 HAS A SIGNIFICANT EFFECT ON BOTH HEMATOLOGICAL MALIGNANCIES AND SOLID TUMORS. 2018 13 3352 18 HISTONE DEMETHYLASE RBP2 MEDIATES THE BLAST CRISIS OF CHRONIC MYELOID LEUKEMIA THROUGH AN RBP2/PTEN/BCR-ABL CASCADE. EPIGENETIC DISORDERS PLAY A KEY ROLE IN TUMORIGENESIS AND DEVELOPMENT, AMONG WHICH HISTONE METHYLATION ABNORMALITIES ARE COMMON. WHILE PATIENTS LIVING WITH CHRONIC MYELOID LEUKEMIA IN THE CHRONIC PHASE (CML-CP) HAVE A GOOD RESPONSE TO TKI, BLASTIC PHASE (CML-BP) PATIENTS DEMONSTRATE POOR EFFICACY AND HIGH FATALITY RATES. HOWEVER, WHILE THE MECHANISM OF BLAST CRISIS OF CHRONIC MYELOID LEUKEMIA REMAINS UNCLEAR, HIGH EXPRESSION AND ACTIVATION OF BCR-ABL ARE USUALLY RELATED TO CML BLAST CRISIS TRANSITION. WE FOUND THAT HISTONE H3 LYSINE 4 (H3K4) DEMETHYLASE RBP2 EXPRESSION IS NEGATIVELY CORRELATED WITH BCR-ABL EXPRESSION, WHICH SUGGESTS A REGULATORY LINK BETWEEN THESE TWO GENES. WE ALSO DISCOVERED THAT RBP2 MEDIATES THE DEPHOSPHORYLATION OF BCR-ABL BY DIRECTLY DOWNREGULATING PTEN EXPRESSION, DEPENDING ON HISTONE DEMETHYLASE ACTIVITY, WHILE PTEN TARGETS PROTEIN PHOSPHATASE ACTIVITY OF BCR-ABL, A PHOSPHATASE WHICH DIRECTLY DEPHOSPHORYLATES BCR-ABL. IN CLINICAL SPECIMENS, THE MRNA EXPRESSION OF RBP2 WAS FOUND TO BE POSITIVELY CORRELATED WITH THAT OF PTEN. THESE DATA SUGGEST THAT THE UNDER-EXPRESSION OF RBP2 PROMOTES BLAST CRISIS TRANSITION BY ACTIVATING AN RBP2/PTEN/BCR-ABL CASCADE. 2019 14 1966 22 EPIGENETIC ALTERATION OF PRKCDBP IN COLORECTAL CANCERS AND ITS IMPLICATION IN TUMOR CELL RESISTANCE TO TNFALPHA-INDUCED APOPTOSIS. PURPOSE: PRKCDBP IS A PUTATIVE TUMOR SUPPRESSOR IN WHICH ALTERATION HAS BEEN OBSERVED IN SEVERAL HUMAN CANCERS. WE INVESTIGATED EXPRESSION AND FUNCTION OF PRKCDBP IN COLORECTAL CELLS AND TISSUES TO EXPLORE ITS CANDIDACY AS A SUPPRESSOR IN COLORECTAL TUMORIGENESIS. EXPERIMENTAL DESIGN: EXPRESSION AND METHYLATION STATUS OF PRKCDBP AND ITS EFFECT ON TUMOR GROWTH WERE EVALUATED. TRANSCRIPTIONAL REGULATION BY NF-KAPPAB SIGNALING WAS DEFINED BY LUCIFERASE REPORTER AND CHROMATIN IMMUNOPRECIPITATION ASSAYS. RESULTS: PRKCDBP EXPRESSION WAS HARDLY DETECTABLE IN 29 OF 80 (36%) PRIMARY TUMORS AND 11 OF 19 (58%) CELL LINES, AND ITS ALTERATION CORRELATED WITH TUMOR STAGE AND GRADE. PROMOTER HYPERMETHYLATION WAS COMMONLY FOUND IN CANCERS. PRKCDBP EXPRESSION INDUCED THE G(1) CELL-CYCLE ARREST AND INCREASED CELLULAR SENSITIVITY TO VARIOUS APOPTOTIC STRESSES. PRKCDBP WAS INDUCED BY TNFALPHA, AND ITS LEVEL CORRELATED WITH TUMOR CELL SENSITIVITY TO TNFALPHA-INDUCED APOPTOSIS. PRKCDBP INDUCTION BY TNFALPHA WAS DISRUPTED BY BLOCKING NF-KAPPAB SIGNALING WHILE IT WAS ENHANCED BY RELA TRANSFECTION. THE PRKCDBP PROMOTER ACTIVITY WAS INCREASED IN RESPONSE TO TNFALPHA, AND THIS RESPONSE WAS ABOLISHED BY DISRUPTION OF A KAPPAB SITE IN THE PROMOTER. PRKCDBP DELAYED THE FORMATION AND GROWTH OF XENOGRAFT TUMORS AND IMPROVED TUMOR RESPONSE TO TNFALPHA-INDUCED APOPTOSIS. CONCLUSIONS: PRKCDBP IS A PROAPOPTOTIC TUMOR SUPPRESSOR WHICH IS COMMONLY ALTERED IN COLORECTAL CANCER BY PROMOTER HYPERMETHYLATION, AND ITS GENE TRANSCRIPTION IS DIRECTLY ACTIVATED BY NF-KAPPAB IN RESPONSE TO TNFALPHA. THIS SUGGESTS THAT PRKCDBP INACTIVATION MAY CONTRIBUTE TO TUMOR PROGRESSION BY REDUCING CELLULAR SENSITIVITY TO TNFALPHA AND OTHER STRESSES, PARTICULARLY UNDER CHRONIC INFLAMMATORY MICROENVIRONMENT. 2011 15 4741 25 NOVEL HDAC INHIBITOR MAKV-8 AND IMATINIB SYNERGISTICALLY KILL CHRONIC MYELOID LEUKEMIA CELLS VIA INHIBITION OF BCR-ABL/MYC-SIGNALING: EFFECT ON IMATINIB RESISTANCE AND STEM CELLS. BACKGROUND: CHRONIC MYELOID LEUKEMIA (CML) PATHOGENESIS IS MAINLY DRIVEN BY THE ONCOGENIC BREAKPOINT CLUSTER REGION-ABELSON MURINE LEUKEMIA VIRAL ONCOGENE HOMOLOG 1 (BCR-ABL) FUSION PROTEIN. SINCE BCR-ABL DISPLAYS ABNORMAL CONSTITUTIVE TYROSINE KINASE ACTIVITY, THERAPIES USING TYROSINE KINASE INHIBITORS (TKIS) SUCH AS IMATINIB REPRESENT A MAJOR BREAKTHROUGH FOR THE OUTCOME OF CML PATIENTS. NEVERTHELESS, THE DEVELOPMENT OF TKI RESISTANCE AND THE PERSISTENCE OF LEUKEMIA STEM CELLS (LSCS) REMAIN BARRIERS TO CURE THE DISEASE, JUSTIFYING THE DEVELOPMENT OF NOVEL THERAPEUTIC APPROACHES. SINCE THE ACTIVITY OF HISTONE DEACETYLASE (HDAC) IS DEREGULATED IN NUMEROUS CANCERS INCLUDING CML, PAN-HDAC INHIBITORS MAY REPRESENT PROMISING THERAPEUTIC REGIMENS FOR THE TREATMENT OF CML CELLS IN COMBINATION WITH TKI. RESULTS: WE ASSESSED THE ANTI-LEUKEMIC ACTIVITY OF A NOVEL HYDROXAMATE-BASED PAN-HDAC INHIBITOR MAKV-8, WHICH COMPLIED WITH THE LIPINSKI'S "RULE OF FIVE," IN VARIOUS CML CELLS ALONE OR IN COMBINATION WITH IMATINIB. WE VALIDATED THE IN VITRO HDAC-INHIBITORY POTENTIAL OF MAKV-8 AND DEMONSTRATED EFFICIENT BINDING TO THE LIGAND-BINDING POCKET OF HDAC ISOENZYMES. IN CELLULO, MAKV-8 SIGNIFICANTLY INDUCED TARGET PROTEIN ACETYLATION, DISPLAYED CYTOSTATIC AND CYTOTOXIC PROPERTIES, AND TRIGGERED CONCOMITANT ER STRESS/PROTECTIVE AUTOPHAGY LEADING TO CANONICAL CASPASE-DEPENDENT APOPTOSIS. CONSIDERING THE SPECIFIC UPREGULATION OF SELECTED HDACS IN LSCS FROM CML PATIENTS, WE INVESTIGATED THE DIFFERENTIAL TOXICITY OF A CO-TREATMENT WITH MAKV-8 AND IMATINIB IN CML VERSUS HEALTHY CELLS. WE ALSO SHOWED THAT BECLIN-1 KNOCKDOWN PREVENTED MAKV-8-IMATINIB COMBINATION-INDUCED APOPTOSIS. MOREOVER, MAKV-8 AND IMATINIB CO-TREATMENT SYNERGISTICALLY REDUCED BCR-ABL-RELATED SIGNALING PATHWAYS INVOLVED IN CML CELL GROWTH AND SURVIVAL. SINCE OUR RESULTS SHOWED THAT LSCS FROM CML PATIENTS OVEREXPRESSED C-MYC, IMPORTANTLY MAKV-8-IMATINIB CO-TREATMENT REDUCED C-MYC LEVELS AND THE LSC POPULATION. IN VIVO, TUMOR GROWTH OF XENOGRAFTED K-562 CELLS IN ZEBRAFISH WAS COMPLETELY ABROGATED UPON COMBINED TREATMENT WITH MAKV-8 AND IMATINIB. CONCLUSIONS: COLLECTIVELY, THE PRESENT FINDINGS SHOW THAT COMBINATIONS HDAC INHIBITOR-IMATINIB ARE LIKELY TO OVERCOME DRUG RESISTANCE IN CML PATHOLOGY. 2020 16 2888 20 GAIN-OF-FUNCTION MUTATION OF GATA-2 IN ACUTE MYELOID TRANSFORMATION OF CHRONIC MYELOID LEUKEMIA. ACQUISITION OF ADDITIONAL GENETIC AND/OR EPIGENETIC ABNORMALITIES OTHER THAN THE BCR/ABL FUSION GENE IS BELIEVED TO CAUSE DISEASE PROGRESSION IN CHRONIC MYELOID LEUKEMIA (CML) FROM CHRONIC PHASE TO BLAST CRISIS (BC). TO GAIN INSIGHTS INTO THE UNDERLYING MECHANISMS OF PROGRESSION TO BC, WE SCREENED DNA SAMPLES FROM CML PATIENTS DURING BLAST TRANSFORMATION FOR MUTATIONS IN A NUMBER OF TRANSCRIPTION FACTOR GENES THAT ARE CRITICAL FOR MYELOID-LYMPHOID DEVELOPMENT. IN 85 CASES OF CML BLAST TRANSFORMATION, WE IDENTIFIED TWO NEW MUTATIONS IN THE CODING REGION OF GATA-2, A NEGATIVE REGULATOR OF HEMATOPOIETIC STEM/PROGENITOR CELL DIFFERENTIATION. A L359V SUBSTITUTION WITHIN ZINC FINGER DOMAIN (ZF) 2 OF GATA-2 WAS FOUND IN EIGHT CASES WITH MYELOMONOBLASTIC FEATURES, WHEREAS AN IN-FRAME DELETION OF 6 AA (DELTA341-346) SPANNING THE C-TERMINAL BORDER OF ZF1 WAS DETECTED IN ONE PATIENT AT MYELOID BC WITH EOSINOPHILIA. FURTHER STUDIES INDICATED THAT L359V NOT ONLY INCREASED TRANSACTIVATION ACTIVITY OF GATA-2 BUT ALSO ENHANCED ITS INHIBITORY EFFECTS ON THE ACTIVITY OF PU.1, A MAJOR REGULATOR OF MYELOPOIESIS. CONSISTENT WITH THE MYELOMONOBLASTIC FEATURES OF CML TRANSFORMATION WITH THE GATA-2 L359V MUTANT, TRANSDUCTION OF THE GATA-2 L359V MUTANT INTO HL-60 CELLS OR BCR/ABL-HARBORING MURINE CELLS DISTURBED MYELOMONOCYTIC DIFFERENTIATION/PROLIFERATION IN VITRO AND IN VIVO, RESPECTIVELY. THESE DATA STRONGLY SUGGEST THAT GATA-2 MUTATIONS MAY PLAY A ROLE IN ACUTE MYELOID TRANSFORMATION IN A SUBSET OF CML PATIENTS. 2008 17 3128 22 GIPC-REGULATED IGFBP-3 PROMOTES HSC MIGRATION IN VITRO AND PORTAL HYPERTENSION IN VIVO THROUGH A BETA1-INTEGRIN PATHWAY. BACKGROUND & AIMS: TRANSFORMING GROWTH FACTOR (TGF-BETA)-INDUCED ACTIVATION OF QUIESCENT HEPATIC STELLATE CELLS (HSCS) AND THEIR TRANSFORMATION TO MYOFIBROBLASTS IS A KEY EVENT IN LIVER FIBROSIS AND PORTAL HYPERTENSION. GIPC (ALSO REFERRED TO AS SYNECTIN) IS A DOWNSTREAM SIGNAL ACTIVATION MOLECULE OF TGF-BETA AND OTHER RECEPTORS. IN THIS STUDY, WE SOUGHT TO IDENTIFY NOVEL GENES TARGETED BY TGF-BETA AND GIPC AND ELUCIDATE IF AND HOW THEY MAY CONTRIBUTE TO LIVER FIBROSIS. METHODS: WE PERFORMED SEQUENTIAL MESSENGER RNA SEQUENCING ANALYSIS ON TGF-BETA-STIMULATED HSCS AND THEN ON TGF-BETA-STIMULATED HSCS IN THE PRESENCE AND ABSENCE OF GIPC ALSO REFERRED TO AS SYNECTIN (GIPC) KNOCKDOWN. INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN-3 (IGFBP-3) TRANSPORT PROTEIN EMERGED AS A TOP ACTIVATION TARGET OF BOTH TGF-BETA AND GIPC. QUANTITATIVE POLYMERASE CHAIN REACTION, ENZYME-LINKED IMMUNOSORBENT ASSAY, TARGETED CHROMATIN IMMUNOPRECIPITATION, AND WESTERN BLOT ANALYSIS WERE DONE FOR FURTHER CONFIRMATION. RESULTS: IGFBP-3, AN INSULIN GROWTH FACTOR TRANSPORT PROTEIN, EMERGED AS A TOP ACTIVATION TARGET OF BOTH TGF-BETA AND GIPC, WHICH WAS CONFIRMED BY QUANTITATIVE POLYMERASE CHAIN REACTION, ENZYME-LINKED IMMUNOSORBENT ASSAY, AND WESTERN BLOT ANALYSIS. TARGETED CHROMATIN IMMUNOPRECIPITATION SHOWED THAT GIPC INCREASES THE HISTONE 3 LYSINE 27 (H3K27) ACETYLATION ACTIVATING MARK AND CONCURRENTLY DECREASES THE H3K27 INHIBITORY TRIMETHYLATION (H3K27M3) MARK, PROVIDING AN EPIGENETIC CORRELATE TO THE GENE REGULATION CHANGES. IN VIVO, GLOBAL KNOCKOUT OF IGFBP-3 MICE RESULTED IN ATTENUATION OF HSC ACTIVATION MARKERS AND ATTENUATION OF PORTAL PRESSURE IN RESPONSE TO CHRONIC LIVER INJURY MODELS. ANALYSIS OF SERUM LEVELS FROM CIRRHOTIC PATIENTS ALSO SHOWED AN IGFBP-3 INCREASE OF MORE THAN 2-FOLD COMPARED WITH HEALTHY CONTROLS. FINALLY, IN VITRO MECHANISM STUDIES SHOWED THAT IGFBP-3 PROMOTES HSC MIGRATION THROUGH INTEGRIN-DEPENDENT PHOSPHORYLATION OF PROTEIN KINASE B. CONCLUSIONS: TGF-BETA UP-REGULATES IGFBP-3 THROUGH GIPC, LEADING TO INCREASED HSC MIGRATION IN VITRO AND PROMOTES PORTAL HYPERTENSION IN VIVO. THESE STUDIES SUPPORT THE ROLE OF IGFBP-3 AS A POTENTIAL PATHOPHYSIOLOGIC TARGET OR BIOMARKER IN CHRONIC LIVER DISEASE. 2020 18 4877 22 OVEREXPRESSION OF MIR-4433 BY SUBEROYLANILIDE HYDROXAMIC ACID SUPPRESSES GROWTH OF CML CELLS AND INDUCES APOPTOSIS THROUGH TARGETING BCR-ABL. BACKGROUND: TARGETING BCR-ABL IS THE KEY FOR THE TREATMENT OF CML. ALTHOUGH GREAT PROGRESS HAS BEEN ACHIEVED FOR THE TREATMENT OF CML PATIENTS IN CHRONIC STAGE, EFFECTIVE DRUGS WITH GOOD SAFETY ARE NOT AVAILABLE FOR THOSE IN ADVANCED STAGES OF CML PATIENTS. IN PRESENT STUDY, A HISTONE DEACETYLASE INHIBITOR, SUBEROYLANILIDE HYDROXAMIC ACID (SAHA), WAS USED TO SCREEN FOR MICRORNA THAT CAN TARGET BCR-ABL. METHODS: RT-QPCR WAS USED TO DETERMINE BCR-ABL AND MIR-4433 TRANSCRIPTION LEVEL IN CML CELLS. IN CML CELLS, PROTEINS INCLUDING PARP, CASPASE-3, ACETYL-HISTONE 3, HISTONE 3 AND BCR-ABL, AS WELL AS BCR-ABL DOWNSTREAM PROTEINS WERE DETECTED USING WESTERN BLOT. CELL VIABILITY AND APOPTOSIS WERE MONITORED RESPECTIVELY BY MTS ASSAY AND FLOW CYTOMETRY. THE CORRELATION BETWEEN MIR-4433 AND BCR-ABL WAS DETERMINED BY LUCIFERASE REPORTER ASSAY. THE ANTI-TUMOR EFFECT OF MIR-4433 TO K562 CELLS WAS EVALUATED BY NUDE MOUSE XENOGRAFT MODEL IN VIVO. RESULTS: SAHA UP-REGULATED THE ACETYLATION LEVEL OF HISTONE 3, AND EFFECTIVELY INHIBITED BCR-ABL MRNA LEVEL AND ITS DOWNSTREAM SIGNAL TRANSDUCTION PATHWAY, WHILE INHIBITING THE GROWTH OF CML CELLS AND INDUCING APOPTOSIS. FURTHERMORE, BIOINFORMATICS TOOLS PREDICTED THAT MIR-4433 IS A PUTATIVE MICRORNA TARGETING BCR-ABL AND THAT THE EXPRESSION LEVEL OF MIR-4433 WAS SIGNIFICANTLY INCREASED AFTER SAHA TREATMENT IN K562 CELLS. LUCIFERASE ACTIVITY ANALYSIS REVEALED THAT MIR-4433 DIRECTLY TARGETS BCR-ABL. ADDITIONALLY, TRANSIENT EXPRESSION OF MIR-4433 ABROGATED BCR-ABL ACTIVITY AND ITS DOWNSTREAM SIGNALING PATHWAYS WHILE INDUCING APOPTOSIS IN K562 CELLS. MOREOVER, STABLE EXPRESSION OF MIR-4433 SUPPRESSED BCR-ABL AND ITS DOWNSTREAM SIGNALING PATHWAY, AND INHIBITED THE GROWTH OF K562 CELLS IN VITRO AND THE GROWTH OF K562-XENOGRAFTS IN NUDE MICE. CONCLUSION: MIR-4433 WAS IDENTIFIED AS A MICRORNA TARGETING BCR-ABL, WHICH MAY BE SUBJECT TO EPIGENETIC REGULATION OF SAHA, A HISTONE DEACETYLASE INHIBITOR THAT HAS BEEN APPROVED BY THE US FDA FOR THE TREATMENT OF CUTANEOUS T-CELL LYMPHOMA. THE FINDINGS OF THIS STUDY PROVIDE A MOLECULAR BASIS FROM ANOTHER ANGLE FOR THE USE OF SAHA IN THE TREATMENT OF CML. 2019 19 2088 24 EPIGENETIC DYSREGULATION OF SECRETED FRIZZLED-RELATED PROTEINS IN MYELOPROLIFERATIVE NEOPLASMS COMPLEMENTS THE JAK2V617F-MUTATION. BACKGROUND: SECRETED FRIZZLED-RELATED PROTEINS (SFRPS) ARE ANTAGONISTS OF THE WNT SIGNALING PATHWAY, WHICH PLAYS A CENTRAL ROLE IN STEM CELL MAINTENANCE AND DIFFERENTIATION OF STEM CELLS AND HEMATOPOIETIC PROGENITORS. EPIGENETIC DOWNREGULATION OF SFRPS BY PROMOTER HYPERMETHYLATION HAS BEEN DESCRIBED TO BE INVOLVED IN THE PATHOGENESIS OF HEMATOPOIETIC MALIGNANCIES. THERE IS AN ASSOCIATION BETWEEN ABERRANT WNT SIGNALING AND THE ESTABLISHED CANCER STEM CELL CONCEPT. IN CONTRAST TO BCR-ABL1-POSITIVE CHRONIC MYELOID LEUKEMIA CML, BCR-ABL1-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS (PH-MPN) ARE CHARACTERIZED BY THE FREQUENT OCCURRENCE OF AN AUTOACTIVATING MUTATION IN THE JAK2 TYROSINE KINASE (JAK2V617F) OR OTHER MUTATIONS IN THE JAK-STAT PATHWAY. HOWEVER, PATHOGENETIC MECHANISMS OF JAK2 MUTATED OR UNMUTATED PH-MPN REMAIN NOT COMPLETELY UNDERSTOOD. WE DETERMINED THE PROMOTER METHYLATION STATUS OF SFRP-1, -2, -4, AND -5 IN 57 MPN PATIENT SAMPLES BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION (PCR) (MSP). JAK2V617F WAS ASSESSED BY ALLELE-SPECIFIC PCR. RESULTS: ABERRANT METHYLATION AMONG PRIMARY MPN SAMPLES WAS 4% FOR SFRP-1, 25% FOR SFRP-2, 2% FOR SFRP-4, AND 0% FOR SFRP-5. HYPERMETHYLATION OF SFRP-2, WHICH WAS THE MOST FREQUENTLY HYPERMETHYLATED GENE IN OUR STUDY, COULD NOT BE CORRELATED TO ANY SPECIFIC MPN SUBTYPE. HOWEVER, WE DETECTED A SIGNIFICANT CORRELATION BETWEEN SFRP-2 METHYLATION AND PRESENCE OF A JAK2V617F MUTATION (P = 0.008). NONE OF THE 10 CML SAMPLES SHOWED ANY SFRP-METHYLATION. CONCLUSIONS: OUR DATA INDICATE THAT EPIGENETIC DYSREGULATION OF THE WNT SIGNALING PATHWAY IS A COMMON EVENT IN MPN WITH ABERRANT METHYLATION OF AT LEAST ONE SFRP BEING DETECTED IN 25% OF THE PRIMARY PATIENT SAMPLES AND IN 30% IF ONLY ACCOUNTING FOR PH-MPN. A SIGNIFICANT CORRELATION BETWEEN SFRP-2 METHYLATION AND PRESENCE OF JAK2V617F IN OUR DATA SUPPORTS THE HYPOTHESIS THAT EPIGENETIC DYSREGULATION MAY BE A COMPLEMENTARY MECHANISM TO GENETIC ABERRATIONS. ABERRANT METHYLATION OF CRUCIAL STEM CELL MAINTENANCE GENES SEEMS TO CONTRIBUTE TO DISEASE PATHOGENESIS IN PH-MPN. 2012 20 136 20 ABERRANT DNA HYPERMETHYLATION PATTERNS LEAD TO TRANSCRIPTIONAL SILENCING OF TUMOR SUPPRESSOR GENES IN UVB-EXPOSED SKIN AND UVB-INDUCED SKIN TUMORS OF MICE. OVEREXPOSURE OF THE HUMAN SKIN TO SOLAR ULTRAVIOLET (UV) RADIATION IS THE MAJOR ETIOLOGIC FACTOR FOR DEVELOPMENT OF SKIN CANCERS. HERE, WE REPORT THE RESULTS OF EPIGENETIC MODIFICATIONS IN UV-EXPOSED SKIN AND SKIN TUMORS IN A SYSTEMATIC MANNER. THE SKIN AND TUMOR SAMPLES WERE COLLECTED AFTER CHRONIC EXPOSURE OF THE SKIN OF SKH-1 HAIRLESS MICE TO UVB RADIATION USING A WELL-ESTABLISHED PHOTOCARCINOGENESIS PROTOCOL. WE FOUND A DISTINCT DNA HYPERMETHYLATION PATTERN IN THE UVB-EXPOSED EPIDERMAL SKIN AND UVB-INDUCED SKIN TUMORS THAT WAS ASSOCIATED WITH THE ELEVATED EXPRESSION AND ACTIVITY OF THE DNA METHYLTRANSFERASES (DNMT) 1, DNMT3A AND DNMT3B. TO EXPLORE THE ROLE OF HYPERMETHYLATION IN SKIN PHOTOCARCINOGENESIS, WE FOCUSED ON THE P16(INK4A) AND RASSF1A TUMOR SUPPRESSOR GENES, WHICH ARE TRANSCRIPTIONALLY SILENCED ON METHYLATION. WE ESTABLISHED THAT THE SILENCING OF THESE GENES IN UVB-EXPOSED EPIDERMIS AND UVB-INDUCED SKIN TUMORS IS ASSOCIATED WITH A NETWORK OF EPIGENETIC MODIFICATIONS, INCLUDING HYPOACETYLATION OF HISTONE H3 AND H4 AND INCREASED HISTONE DEACETYLATION, AS WELL AS RECRUITMENT OF METHYL-BINDING PROTEINS, INCLUDING MECP2 AND MBD1, TO THE METHYLATED CPGS. HIGHER LEVELS OF DNA METHYLATION AND DNMT ACTIVITY IN HUMAN SQUAMOUS CELL CARCINOMA SPECIMENS THAN IN NORMAL HUMAN SKIN SUGGEST THAT THE DATA ARE RELEVANT CLINICALLY. OUR DATA INDICATE FOR THE FIRST TIME THAT UVB-INDUCED DNA HYPERMETHYLATION, ENHANCED DNMT ACTIVITY AND HISTONE MODIFICATIONS OCCUR IN UVB-EXPOSED SKIN AND UVB-INDUCED SKIN TUMORS AND SUGGEST THAT THESE EVENTS ARE INVOLVED IN THE SILENCING OF TUMOR SUPPRESSOR GENES AND IN SKIN TUMOR DEVELOPMENT. 2011