1 4436 93 MOLECULAR EVOLUTION OF CHRONIC MYELOID LEUKAEMIA. CHRONIC MYELOID LEUKAEMIA (CML) IS A CLONAL DISORDER OF THE PLURIPOTENT HAEMATOPOIETIC STEM CELL. THE TYPICAL TRIPHASIC COURSE OF CML STARTS WITH THE PREMALIGNANT CHRONIC PHASE INITIATED BY BCR-ABL HYBRID ONCOGENE FORMATION. SECONDARY GENETIC AND EPIGENETIC ABERRATIONS ACCOMPANY THE PROGRESSION TO THE ACCELERATED PHASE AND FATAL BLASTIC CRISIS. PROPERLY TIMED BONE MARROW TRANSPLANTATION IN ELIGIBLE PATIENTS CAN RESULT IN DURABLE REMISSIONS OR CURE. BOTH OF THESE STATES ARE OFTEN ACCOMPANIED BY A LONG-TERM PERSISTENCE OF QUIESCENT LEUKAEMIC CELLS. ACCORDINGLY, A "FUNCTIONAL CURE" (I.E. TUMOUR DORMANCY INDUCTION), RATHER THAN COMPLETE ERADICATION OF THE MALIGNANT CELLS, IS AN ADEQUATE THERAPEUTICAL GOAL. THE LEVEL OF THE RESIDUAL BCR-ABL-POSITIVE CLONES SHOULD BE MONITORED AND SALVAGE TREATMENT INITIATED WHENEVER THESE QUIESCENT LEUKAEMIC CELLS EXIT THEIR DORMANT STATE. 2001 2 6587 23 TUMOR DORMANCY AND RELAPSE: FROM A NATURAL BYPRODUCT OF EVOLUTION TO A DISEASE STATE. SPECIES EVOLVE BY MUTATIONS AND EPIGENETIC CHANGES ACTING ON INDIVIDUALS IN A POPULATION; TUMORS EVOLVE BY SIMILAR MECHANISMS AT A CELLULAR LEVEL IN A TISSUE. THIS ARTICLE REVIEWS GROWING EVIDENCE ABOUT TUMOR DORMANCY AND SUGGESTS THAT (I) CELLULAR MALIGNANCY IS A NATURAL BYPRODUCT OF EVOLUTIONARY MECHANISMS, SUCH AS GENE MUTATIONS AND EPIGENETIC MODIFICATIONS, WHICH IS MANIFESTED IN THE FORM OF TUMOR DORMANCY IN HEALTHY INDIVIDUALS AS WELL AS IN CANCER SURVIVORS; (II) CANCER METASTASIS COULD BE AN EARLY DISSEMINATION EVENT THAT COULD OCCUR DURING MALIGNANT DORMANCY EVEN BEFORE PRIMARY CANCER IS CLINICALLY DETECTABLE; AND (III) CHRONIC INFLAMMATION IS A KEY FACTOR IN AWAKENING DORMANT MALIGNANT CELLS AT THE PRIMARY SITE, LEADING TO PRIMARY CANCER DEVELOPMENT, AND AT DISTANT SITES, LEADING TO ADVANCED STAGE DISEASES. ON THE BASIS OF THIS EVIDENCE, IT IS REASONABLE TO PROPOSE THAT WE ARE ALL CANCER SURVIVORS RATHER THAN CANCER-FREE INDIVIDUALS BECAUSE OF HARBORING DORMANT MALIGNANT CELLS IN OUR ORGANS. A BETTER UNDERSTANDING OF LOCAL AND METASTATIC TUMOR DORMANCY COULD LEAD TO NOVEL CANCER THERAPEUTICS FOR THE PREVENTION OF CANCER. CANCER RES; 77(10); 2564-9. (C)2017 AACR. 2017 3 4952 21 PATHOGENESIS OF CHRONIC CHIKUNGUNYA ARTHRITIS: RESEMBLANCES AND LINKS WITH RHEUMATOID ARTHRITIS. CHIKUNGUNYA VIRUS (CHIKV) INFECTION RESULTS FROM TRANSMISSION BY THE MOSQUITO VECTOR. FOLLOWING AN INCUBATION PERIOD OF 5-7 DAYS, PATIENTS DEVELOP AN ACUTE FEBRILE ILLNESS, CHIKUNGUNYA FEVER (CHIKF), CHARACTERIZED BY HIGH FEVERS, MACULOPAPULAR RASH, HEADACHES, POLYARTHRITIS/ARTHRALGIAS, MYALGIAS, NAUSEA, VOMITING, AND DIARRHEA. JOINT PAIN IS OFTEN SEVERE, AND MOST OFTEN INVOLVES THE HANDS, THE WRISTS, THE ANKLES, AND THE METATARSAL-PHALANGEAL JOINTS OF THE FEET. MANY PATIENTS RECOVER WITHIN SEVERAL WEEKS, BUT UP TO 50% DEVELOP CHRONIC JOINT PAIN AND SWELLING FOR MORE THAN 12 WEEKS, THEN WE REFER TO THESE SYMPTOMS AS CHRONIC CHIKUNGUNYA ARTHRITIS (CCA). THE PATHOGENESIS OF CCA IS NOT WELL UNDERSTOOD. IN THIS ARTICLE, WE SUGGEST THAT MESENCHYMAL STEM CELLS (MSCS) MAY PLAY AN IMPORTANT ROLE IN THIS PATHOGENESIS. THIS HETEROGENEOUS GROUP OF MULTIPOTENT CELLS, MORPHOLOGICALLY SIMILAR TO FIBROBLASTS, MAY UNDERGO EPIGENETIC CHANGES CAPABLE OF GENERATING ABERRANT PROGENIES. HOWEVER, WE BELIEVE THAT THERE IS NO NEED FOR A LATENT INFECTION. IN OUR PATHOGENIC HYPOTHESIS, CHIKV INFECTION OF MSCS WOULD CAUSE EPIGENETIC CHANGES BOTH IN MSCS THEMSELVES AND IN THEIR PROGENIES, WITHOUT THE NEED FOR REACTIVATION OF DORMANT VIRUSES. 2023 4 82 25 A NON-GENETIC BASIS FOR CANCER PROGRESSION AND METASTASIS: SELF-ORGANIZING ATTRACTORS IN CELL REGULATORY NETWORKS. IT IS COMMONLY ASSUMED THAT SOMATIC EVOLUTION DRIVES THE MULTI-STEP PROCESS THAT PRODUCES METASTATIC CANCER. BUT IT IS DIFFICULT TO RECONCILE THE INEXORABLE PROGRESSION TOWARDS METASTASIS IN VIRTUALLY ALL CARCINOMAS AND THE ASSOCIATED COMPLEX CHANGE OF CANCER CELL PHENOTYPE, CHARACTERIZED BY AN EPITHELIAL-TO-MESENCHYMAL TRANSITION, WITH THE RANDOM NATURE OF GENE MUTATIONS. GIVEN THEIR IRREVERSIBLE NATURE, IT IS ALSO DIFFICULT TO EXPLAIN WHY CERTAIN METASTATIC CARCINOMAS CAN REFORM NORMAL TISSUE BOUNDARIES AND REMAIN DORMANT FOR YEARS AT DISTANT SITES. HERE WE PROPOSE AN ENCOMPASSING CONCEPTUAL FRAMEWORK BASED ON SYSTEM-LEVEL DYNAMICS OF GENE REGULATORY NETWORKS THAT MAY HELP RECONCILE THESE INCONSISTENCIES. THE CONCEPTS OF GENE EXPRESSION STATE SPACE AND ATTRACTORS ARE INTRODUCED WHICH PROVIDE A MATHEMATICAL AND MOLECULAR BASIS FOR AN "EPIGENETIC LANDSCAPE". WE THEN DESCRIBE HOW CANCER CELLS ARE TRAPPED IN "EMBRYONIC ATTRACTORS" BECAUSE OF DISTORTIONS OF THIS LANDSCAPE CAUSED BY MUTATIONAL REWIRING OF THE REGULATORY NETWORK. THE IMPLICATIONS OF THIS CONCEPT FOR A NEW INTEGRATIVE UNDERSTANDING OF TUMOR FORMATION AND METASTATIC PROGRESSION ARE DISCUSSED. THIS FORMAL FRAMEWORK OF CANCER PROGRESSION UNITES MAINSTREAM GENETIC DETERMINISM WITH ALTERNATIVE IDEAS THAT EMPHASIZE NON-GENETIC INFLUENCES, INCLUDING CHRONIC GROWTH STIMULATION,EXTRACELLULAR MATRIX REMODELING, ALTERATION OF CELL MECHANICS AND DISRUPTION OF TISSUE ARCHITECTURE. 2006 5 4533 32 MULTIPLE GENE KNOCKDOWN STRATEGIES FOR INVESTIGATING THE PROPERTIES OF HUMAN LEUKEMIA STEM CELLS AND EXPLORING NEW THERAPIES. THE PAST TWO DECADES HAVE WITNESSED SIGNIFICANT STRIDES IN LEUKEMIA THERAPIES THROUGH APPROVAL OF THERAPEUTIC INHIBITORS TARGETING ONCOGENE-DRIVING DYSREGULATED TYROSINE KINASE ACTIVITIES AND KEY EPIGENETIC AND APOPTOSIS REGULATORS. ALTHOUGH THESE DRUGS HAVE BROUGHT ABOUT COMPLETE REMISSION IN THE MAJORITY OF PATIENTS, MANY PATIENTS FACE RELAPSE OR HAVE REFRACTORY DISEASE. THE MAIN FACTOR CONTRIBUTING TO RELAPSE IS THE PRESENCE OF A SMALL SUBPOPULATION OF DORMANT DRUG-RESISTANT LEUKEMIA CELLS THAT POSSESS STEM CELL FEATURES (TERMED AS LEUKEMIA STEM CELLS OR LSCS). THUS, OVERCOMING DRUG RESISTANCE AND TARGETING LSCS REMAIN MAJOR CHALLENGES FOR CURATIVE TREATMENT OF HUMAN LEUKEMIA. CHRONIC MYELOID LEUKEMIA (CML) IS A GOOD EXAMPLE, WITH RARE, PROPAGATING LSCS AND DRUG-RESISTANT CELLS THAT CANNOT BE ERADICATED BY BCR-ABL-DIRECTED TYROSINE KINASE INHIBITOR (TKI) MONOTHERAPY AND THAT ARE RESPONSIBLE FOR DISEASE RELAPSE/PROGRESSION. THEREFORE, IT IS IMPERATIVE TO IDENTIFY KEY PLAYERS IN REGULATING BCR-ABL1-DEPENDENT AND INDEPENDENT DRUG-RESISTANCE MECHANISMS, AND THEIR KEY PATHWAYS, SO THAT CML LSCS CAN BE SELECTIVELY TARGETED OR SENSITIZED TO TKIS. HERE, WE DESCRIBE SEVERAL EASILY ADAPTABLE GENE KNOCKDOWN APPROACHES IN CD34(+) CML STEM/PROGENITOR CELLS THAT CAN BE USED TO INVESTIGATE THE BIOLOGICAL PROPERTIES OF LSCS AND MOLECULAR EFFECTS OF GENES OF INTEREST (GOI), WHICH CAN BE FURTHER EXPLORED AS THERAPEUTIC MODALITIES AGAINST LSCS IN THE CONTEXT OF HUMAN LEUKEMIA. 2022 6 955 31 CHRONIC MYELOID LEUKEMIA: MECHANISMS OF BLASTIC TRANSFORMATION. THE BCR-ABL1 ONCOPROTEIN TRANSFORMS PLURIPOTENT HSCS AND INITIATES CHRONIC MYELOID LEUKEMIA (CML). PATIENTS WITH EARLY PHASE (ALSO KNOWN AS CHRONIC PHASE [CP]) DISEASE USUALLY RESPOND TO TREATMENT WITH ABL TYROSINE KINASE INHIBITORS (TKIS), ALTHOUGH SOME PATIENTS WHO RESPOND INITIALLY LATER BECOME RESISTANT. IN MOST PATIENTS, TKIS REDUCE THE LEUKEMIA CELL LOAD SUBSTANTIALLY, BUT THE CELLS FROM WHICH THE LEUKEMIA CELLS ARE DERIVED DURING CP (SO-CALLED LEUKEMIA STEM CELLS [LSCS]) ARE INTRINSICALLY INSENSITIVE TO TKIS AND SURVIVE LONG TERM. LSCS OR THEIR PROGENY CAN ACQUIRE ADDITIONAL GENETIC AND/OR EPIGENETIC CHANGES THAT CAUSE THE LEUKEMIA TO TRANSFORM FROM CP TO A MORE ADVANCED PHASE, WHICH HAS BEEN SUBCLASSIFIED AS EITHER ACCELERATED PHASE OR BLASTIC PHASE DISEASE. THE LATTER RESPONDS POORLY TO TREATMENT AND IS USUALLY FATAL. HERE, WE DISCUSS WHAT IS KNOWN ABOUT THE MOLECULAR MECHANISMS LEADING TO BLASTIC TRANSFORMATION OF CML AND PROPOSE SOME NOVEL THERAPEUTIC APPROACHES. 2010 7 953 31 CHRONIC MYELOID LEUKEMIA STEM CELLS. ALTHOUGH RARE, CHRONIC MYELOID LEUKEMIA (CML) REPRESENTS AN IMPORTANT PARADIGM FOR UNDERSTANDING THE MOLECULAR EVENTS LEADING TO MALIGNANT TRANSFORMATION OF PRIMITIVE HEMATOPOIETIC PROGENITORS. CML WAS THE FIRST CANCER TO BE ASSOCIATED WITH A DEFINED GENETIC ABNORMALITY, BCR-ABL, THAT IS NECESSARY AND SUFFICIENT FOR INITIATING CHRONIC PHASE DISEASE AS WELL AS THE FIRST CANCER TO BE TREATED WITH MOLECULAR TARGETED THERAPY. MALIGNANT PROGENITORS OR LEUKEMIA STEM CELLS (LSCS) EVOLVE AS A RESULT OF BOTH EPIGENETIC AND GENETIC EVENTS THAT ALTER HEMATOPOIETIC PROGENITOR DIFFERENTIATION, PROLIFERATION, SURVIVAL, AND SELF-RENEWAL. LSCS ARE RARE AND DIVIDE LESS FREQUENTLY, AND THUS, REPRESENT A RESERVOIR FOR RELAPSE AND RESISTANCE TO A MOLECULARLY TARGETED SINGLE AGENT. ON SUBVERTING DEVELOPMENTAL PROCESSES NORMALLY RESPONSIBLE FOR MAINTAINING ROBUST LIFE-LONG HEMATOPOIESIS, THE LSCS ARE ABLE TO EVADE THE MAJORITY OF CURRENT CANCER TREATMENTS THAT TARGET RAPIDLY DIVIDING CELLS. ENTHUSIASM FOR THE ENORMOUS SUCCESS OF TYROSINE KINASE INHIBITORS AT CONTROLLING THE CHRONIC PHASE DISEASE IS TEMPERED SOMEWHAT BY THE PERSISTENCE OF THE LSC POOL IN THE MAJORITY OF THE PATIENTS. COMBINED THERAPIES TARGETING ABERRANT PROPERTIES OF LSC MAY OBVIATE THERAPEUTIC RESISTANCE AND RELAPSE IN ADVANCED PHASE AND THERAPEUTICALLY RECALCITRANT CML. 2008 8 5212 29 PRESERVATION OF QUIESCENT CHRONIC MYELOGENOUS LEUKEMIA STEM CELLS BY THE BONE MARROW MICROENVIRONMENT. THE MAJORITY OF LEUKEMIA PATIENTS ACHIEVING REMISSION ULTIMATELY RELAPSE. PERSISTENCE OF LEUKEMIA STEM CELLS (LSC) CAPABLE OF REGENERATING LEUKEMIA IS A MAJOR CAUSE OF RELAPSE. THERE IS A PRESSING NEED TO BETTER UNDERSTAND MECHANISMS OF LSC REGULATION AND THEIR RESISTANCE TO THERAPY IN ORDER TO IMPROVE OUTCOMES FOR LEUKEMIA. CHRONIC MYELOGENOUS LEUKEMIA (CML) IS A LETHAL MYELOPROLIFERATIVE DISORDER THAT THAT IS CAUSED BY HEMATOPOIETIC STEM CELL (HSC) TRANSFORMATION BY THE BCR-ABL TYROSINE KINASE. TREATMENT WITH TYROSINE KINASE INHIBITORS (TKI) HAS REVOLUTIONIZED CML TREATMENT, BUT FAILS TO ELIMINATE LSC RESPONSIBLE FOR PROPAGATING AND REGENERATING LEUKEMIA. THEREFORE, PATIENTS REQUIRE CONTINUED TREATMENT TO PREVENT RELAPSE. LEUKEMIC AND NORMAL STEM CELLS SHARE PROPERTIES OF QUIESCENCE AND SELF-RENEWAL, THAT ARE SUPPORTED BY BONE MARROW NICHES. PERSISTENCE OF LSC AFTER TKI TREATMENT IS RELATED TO TYROSINE KINASE INDEPENDENT MECHANISMS WHICH INCLUDE INTRINSIC PROPERTIES OF LSCS DETERMINED BY EPIGENETIC ALTERATIONS, ALTERED TRANSCRIPTIONAL REGULATORY NETWORKS OR MITOCHONDRIAL/METABOLIC CHANGES. IN ADDITION TO CELL INTRINSIC CHANGES, SIGNALS FROM THE BONE MARROW MICROENVIRONMENT (BMM) PLAY A CRITICAL ROLE IN PROTECTING LSC FROM TKI TREATMENT. EACH TYPE OF ALTERATION MAY OFFER POTENTIAL POINTS OF INTERVENTION FOR THERAPEUTIC TARGETING OF LSC. 2018 9 952 26 CHRONIC MYELOID LEUKEMIA STEM CELL BIOLOGY. LEUKEMIA PROGRESSION AND RELAPSE IS FUELED BY LEUKEMIA STEM CELLS (LSC) THAT ARE RESISTANT TO CURRENT TREATMENTS. IN THE PROGRESSION OF CHRONIC MYELOID LEUKEMIA (CML), BLAST CRISIS PROGENITORS ARE CAPABLE OF ADOPTING MORE PRIMITIVE BUT DEREGULATED STEM CELL FEATURES WITH ACQUIRED RESISTANCE TO TARGETED THERAPIES. THIS IN TURN PROMOTES LSC BEHAVIOR CHARACTERIZED BY ABERRANT SELF-RENEWAL, DIFFERENTIATION, AND SURVIVAL CAPACITY. MULTIPLE REPORTS SUGGEST THAT CELL CYCLE ALTERATIONS, ACTIVATION OF CRITICAL SIGNALING PATHWAYS, ABERRANT MICROENVIRONMENTAL CUES FROM THE HEMATOPOIETIC NICHE, AND ABERRANT EPIGENETIC EVENTS AND DEREGULATION OF RNA PROCESSING MAY FACILITATE THE ENHANCED SURVIVAL AND MALIGNANT TRANSFORMATION OF CML PROGENITORS. HERE WE REVIEW THE MOLECULAR EVOLUTION OF CML LSC THAT PROMOTES CML PROGRESSION AND RELAPSE. RECENT ADVANCES IN THESE AREAS HAVE IDENTIFIED NOVEL TARGETS THAT REPRESENT IMPORTANT AVENUES FOR FUTURE THERAPEUTIC APPROACHES AIMED AT SELECTIVELY ERADICATING THE LSC POPULATION WHILE SPARING NORMAL HEMATOPOIETIC PROGENITORS IN PATIENTS SUFFERING FROM CHRONIC MYELOID MALIGNANCIES. 2012 10 359 33 ALWAYS STRESSED BUT NEVER EXHAUSTED: HOW STEM CELLS IN MYELOID NEOPLASMS AVOID EXTINCTION IN INFLAMMATORY CONDITIONS. CHRONIC OR RECURRENT EPISODES OF ACUTE INFLAMMATION CAUSE ATTRITION OF NORMAL HEMATOPOIETIC STEM CELLS (HSCS) THAT CAN LEAD TO HEMATOPOIETIC FAILURE BUT THEY DRIVE PROGRESSION IN MYELOID MALIGNANCIES AND THEIR PRECURSOR CLONAL HEMATOPOIESIS. MECHANISTIC PARALLELS EXIST BETWEEN HEMATOPOIESIS IN CHRONIC INFLAMMATION AND THE CONTINUOUSLY INCREASED PROLIFERATION OF MYELOID MALIGNANCIES, PARTICULARLY MYELOPROLIFERATIVE NEOPLASMS (MPNS). THE ABILITY TO ENTER DORMANCY, A STATE OF DEEP QUIESCENCE CHARACTERIZED BY LOW OXIDATIVE PHOSPHORYLATION, LOW GLYCOLYSIS, REDUCED PROTEIN SYNTHESIS, AND INCREASED AUTOPHAGY IS CENTRAL TO THE PRESERVATION OF LONG-TERM HSCS AND LIKELY MPN SCS. THE METABOLIC FEATURES OF DORMANCY RESEMBLE THOSE OF DIAPAUSE, A STATE OF ARRESTED EMBRYONIC DEVELOPMENT TRIGGERED BY ADVERSE ENVIRONMENTAL CONDITIONS. TO OUTCOMPETE THEIR NORMAL COUNTERPARTS IN THE INFLAMMATORY MPN ENVIRONMENT, MPN SCS CO-OPT MECHANISMS USED BY HSCS TO AVOID EXHAUSTION, INCLUDING SIGNAL ATTENUATION BY NEGATIVE REGULATORS, INSULATION FROM ACTIVATING CYTOKINE SIGNALS, ANTI-INFLAMMATORY SIGNALING, AND EPIGENETIC REPROGRAMMING. WE PROPOSE THAT NEW THERAPEUTIC STRATEGIES MAY BE DERIVED FROM CONCEPTUALIZING MYELOID MALIGNANCIES AS AN ECOSYSTEM OUT OF BALANCE, IN WHICH RESIDUAL NORMAL AND MALIGNANT HEMATOPOIETIC CELLS INTERACT IN MULTIPLE WAYS, ONLY FEW OF WHICH HAVE BEEN CHARACTERIZED IN DETAIL. DISRUPTING MPN SC INSULATION TO OVERCOME DORMANCY, INTERFERING WITH ABERRANT CYTOKINE CIRCUITS THAT FAVOR MPN CELLS, AND DIRECTLY BOOSTING RESIDUAL NORMAL HSCS ARE POTENTIAL STRATEGIES TO TIP THE BALANCE IN FAVOR OF NORMAL HEMATOPOIESIS. ALTHOUGH ERADICATING THE MALIGNANT CELL CLONES REMAINS THE GOAL OF THERAPY, REBALANCING THE ECOSYSTEM MAY BE A MORE ATTAINABLE OBJECTIVE IN THE SHORT TERM. 2023 11 791 30 CELLULAR AND MOLECULAR NETWORKS IN CHRONIC MYELOID LEUKEMIA: THE LEUKEMIC STEM, PROGENITOR AND STROMAL CELL INTERPLAY. THE USE OF IMATINIB, SECOND AND THIRD GENERATION ABL TYROSINE KINASE INHIBITORS (TKI) (I.E. DASATINIB, NILOTINIB, BOSUTINIB AND PONATINIB) MADE CML A CLINICALLY MANAGEABLE AND, IN A SMALL PERCENTAGE OF CASES, A CURED DISEASE. TKI THERAPY ALSO TURNED CML BLASTIC TRANSFORMATION INTO A RARE EVENT; HOWEVER, DISEASE PROGRESSION STILL OCCURS IN THOSE PATIENTS WHO ARE REFRACTORY, NOT COMPLIANT WITH TKI THERAPY OR DEVELOP RESISTANCE TO MULTIPLE TKIS. IN THE PAST FEW YEARS, IT BECAME CLEAR THAT THE BCRABL1 ONCOGENE DOES NOT OPERATE ALONE TO DRIVE DISEASE EMERGENCE, MAINTENANCE AND PROGRESSION. INDEED, IT SEEMS THAT BONE MARROW (BM) MICROENVIRONMENT-GENERATED SIGNALS AND CELL AUTONOMOUS BCRABL1 KINASE-INDEPENDENT GENETIC AND EPIGENETIC ALTERATIONS ALL CONTRIBUTE TO: I. PERSISTENCE OF A QUIESCENT LEUKEMIC STEM CELL (LSC) RESERVOIR, II. INNATE OR ACQUIRED RESISTANCE TO TKIS, AND III. PROGRESSION INTO THE FATAL BLAST CRISIS STAGE. HEREIN, WE REVIEW THE INTRICATE LEUKEMIC NETWORK IN WHICH ABERRANT, BUT FINELY TUNED, SURVIVAL, MITOGENIC AND SELF-RENEWAL SIGNALS ARE GENERATED BY LEUKEMIC PROGENITORS, STROMAL CELLS, IMMUNE CELLS AND METABOLIC MICROENVIRONMENTAL CONDITIONS (E.G. HYPOXIA) TO PROMOTE LSC MAINTENANCE AND BLASTIC TRANSFORMATION. 2017 12 3234 19 HEMATOPOIETIC AND CHRONIC MYELOID LEUKEMIA STEM CELLS: MULTI-STABILITY VERSUS LINEAGE RESTRICTION. THERE IS COMPELLING EVIDENCE TO SUPPORT THE VIEW THAT THE CELL-OF-ORIGIN FOR CHRONIC MYELOID LEUKEMIA IS A HEMATOPOIETIC STEM CELL. UNLIKE NORMAL HEMATOPOIETIC STEM CELLS, THE PROGENY OF THE LEUKEMIA STEM CELLS ARE PREDOMINANTLY NEUTROPHILS DURING THE DISEASE CHRONIC PHASE AND THERE IS A MILD ANEMIA. THE HALLMARK ONCOGENE FOR CHRONIC MYELOID LEUKEMIA IS THE BCR-ABLP210 FUSION GENE. VARIOUS STUDIES HAVE EXCLUDED A ROLE FOR BCR-ABLP210 EXPRESSION IN MAINTAINING THE POPULATION OF LEUKEMIA STEM CELLS. STUDIES OF BCR-ABLP210 EXPRESSION IN EMBRYONAL STEM CELLS THAT WERE DIFFERENTIATED INTO HEMATOPOIETIC STEM CELLS AND OF THE EXPRESSION IN TRANSGENIC MICE HAVE REVEALED THAT BCR-ABLP210 IS ABLE TO VEER HEMATOPOIETIC STEM AND PROGENITOR CELLS TOWARDS A MYELOID FATE. FOR THE TRANSGENIC MICE, GLOBAL CHANGES TO THE EPIGENETIC LANDSCAPE WERE OBSERVED. IN CHRONIC MYELOID LEUKEMIA, THE ABILITY OF THE LEUKEMIA STEM CELLS TO CHOOSE FROM THE MANY FATES THAT ARE AVAILABLE TO NORMAL HEMATOPOIETIC STEM CELLS APPEARS TO BE DEREGULATED BY BCR-ABLP210 AND CHANGES TO THE EPIGENOME ARE ALSO IMPORTANT. EVEN SO, WE STILL DO NOT HAVE A PRECISE PICTURE AS TO WHY NEUTROPHILS ARE ABUNDANTLY PRODUCED IN CHRONIC MYELOID LEUKEMIA. 2022 13 2050 19 EPIGENETIC COMPONENTS OF MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME UNCOVER POTENTIAL TRANSPOSABLE ELEMENT ACTIVATION. PURPOSE: STUDIES TO DETERMINE EPIGENETIC CHANGES ASSOCIATED WITH MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) REMAIN SCARCE; HOWEVER, CURRENT EVIDENCE CLEARLY SHOWS THAT METHYLATION PATTERNS OF GENOMIC DNA AND NONCODING RNA PROFILES OF IMMUNE CELLS DIFFER BETWEEN PATIENTS AND HEALTHY SUBJECTS, SUGGESTING AN ACTIVE ROLE OF THESE EPIGENETIC MECHANISMS IN THE DISEASE. THE PRESENT STUDY COMPARES AND CONTRASTS THE AVAILABLE ME/CFS EPIGENETIC DATA IN AN EFFORT TO EVIDENCE OVERLAPPING PATHWAYS CAPABLE OF EXPLAINING AT LEAST SOME OF THE DYSFUNCTIONAL IMMUNE PARAMETERS LINKED TO THIS DISEASE. METHODS: A SYSTEMATIC SEARCH OF THE LITERATURE EVALUATING THE ME/CFS EPIGENOME LANDSCAPE WAS PERFORMED FOLLOWING THE PREFERRED REPORTING ITEMS FOR SYSTEMATIC REVIEWS AND META-ANALYSES CRITERIA. DIFFERENTIAL DNA METHYLATION AND NONCODING RNA DIFFERENTIAL EXPRESSION PATTERNS ASSOCIATED WITH ME/CFS WERE USED TO SCREEN FOR THE PRESENCE OF TRANSPOSABLE ELEMENTS USING THE DFAM BROWSER, A SEARCH PROGRAM NURTURED WITH THE REPBASE REPETITIVE SEQUENCE DATABASE AND THE REPEATMASKER ANNOTATION TOOL. FINDINGS: UNEXPECTEDLY, PARTICULAR ASSOCIATIONS OF TRANSPOSABLE ELEMENTS AND ME/CFS EPIGENETIC HALLMARKS WERE UNCOVERED. A MODEL FOR THE DISEASE EMERGED INVOLVING TRANSCRIPTIONAL INDUCTION OF ENDOGENOUS DORMANT TRANSPOSONS AND STRUCTURED CELLULAR RNA INTERACTIONS, TRIGGERING THE ACTIVATION OF THE INNATE IMMUNE SYSTEM WITHOUT A CONCOMITANT ACTIVE INFECTION. IMPLICATIONS: REPETITIVE SEQUENCE FILTERS (IE, REPEATMASKER) SHOULD BE AVOIDED WHEN ANALYZING TRANSCRIPTOMIC DATA TO ASSESS THE POTENTIAL PARTICIPATION OF REPETITIVE SEQUENCES ("JUNK REPETITIVE DNA"), REPRESENTING >45% OF THE HUMAN GENOME, IN THE ONSET AND EVOLUTION OF ME/CFS. IN ADDITION, TRANSPOSABLE ELEMENT SCREENINGS AIMED AT DESIGNING COST-EFFECTIVE, FOCUSED EMPIRICAL ASSAYS THAT CAN CONFIRM OR DISPROVE THE SUSPECTED INVOLVEMENT OF TRANSPOSON TRANSCRIPTIONAL ACTIVATION IN THIS DISEASE, FOLLOWING THE PILOT STRATEGY PRESENTED HERE, WILL REQUIRE DATABASES GATHERING LARGE ME/CFS EPIGENETIC DATASETS. 2019 14 1685 30 DRUGGABLE BIOCHEMICAL PATHWAYS AND POTENTIAL THERAPEUTIC ALTERNATIVES TO TARGET LEUKEMIC STEM CELLS AND ELIMINATE THE RESIDUAL DISEASE IN CHRONIC MYELOID LEUKEMIA. CHRONIC MYELOID LEUKEMIA (CML) IS A DISEASE ARISING IN STEM CELLS EXPRESSING THE BCR-ABL ONCOGENIC TYROSINE KINASE THAT TRANSFORMS ONE HEMATOPOIETIC STEM/PROGENITOR CELL INTO A LEUKEMIC STEM CELL (LSC) AT THE ORIGIN OF DIFFERENTIATED AND PROLIFERATING LEUKEMIC CELLS IN THE BONE MARROW (BM). CML-LSCS ARE RECOGNIZED AS BEING RESPONSIBLE FOR RESISTANCES AND RELAPSES THAT OCCUR DESPITE THE ADVENT OF BCR-ABL-TARGETING THERAPIES WITH TYROSINE KINASE INHIBITORS (TKIS). LSCS SHARE A LOT OF FUNCTIONAL PROPERTIES WITH HEMATOPOIETIC STEM CELLS (HSCS) ALTHOUGH SOME PHENOTYPICAL AND FUNCTIONAL DIFFERENCES HAVE BEEN DESCRIBED DURING THE LAST TWO DECADES. SUBVERTED MECHANISMS AFFECTING EPIGENETIC PROCESSES, APOPTOSIS, AUTOPHAGY AND MORE RECENTLY METABOLISM AND IMMUNOLOGY IN THE BONE MARROW MICROENVIRONMENT (BMM) HAVE BEEN REPORTED. THE AIM OF THIS REVIEW IS TO BRING TOGETHER THE MODIFICATIONS AND MOLECULAR MECHANISMS THAT ARE KNOWN TO ACCOUNT FOR TKI RESISTANCE IN PRIMARY CML-LSCS AND TO FOCUS ON THE POTENTIAL SOLUTIONS THAT CAN CIRCUMVENT THESE RESISTANCES, IN PARTICULAR THOSE THAT HAVE BEEN, OR WILL BE TESTED IN CLINICAL TRIALS. 2019 15 6609 29 TYROSINE KINASE INHIBITORS IN PH+ CHRONIC MYELOID LEUKEMIA THERAPY: A REVIEW. CHRONIC MYELOID LEUKAEMIA (CML) IS A CLONAL MYELOPROLIFERATIVE HEMATOPOIETIC STEM CELL DISORDER. DEREGULATED BCRABL FUSION TYROSINE KINASE ACTIVITY IS THE MAIN CAUSE OF CML DISEASE PATHOGENESIS, MAKING BCRABL AN IDEAL TARGET FOR INHIBITION. CURRENT TYROSINE KINASE INHIBITORS (TKIS) DESIGNED TO INHIBIT BCRABL ONCOPROTEIN ACTIVITY, HAVE COMPLETELY TRANSFORMED THE PROGNOSIS OF CML. INTERRUPTION OF TKI TREATMENT LEADS TO MINIMAL RESIDUAL DISEASE RESIDE (MRD), THOUGHT TO RESIDE IN TKIINSENSITIVE LEUKAEMIA STEM CELLS WHICH REMAIN A POTENTIAL RESERVOIR FOR DISEASE RELAPSE. THIS HIGHLIGHTS THE NEED TO DEVELOP NEW THERAPEUTIC STRATEGIES FOR CML EITHER AS SMALL MOLECULE MASTER TKIS OR PHYTOPHARMACEUTICALS DERIVED FROM NATURE TO ACHIEVE CHRONIC MOLECULAR REMISSION. THIS REVIEW OUTLINES THE PAST, PRESENT AND FUTURE THERAPEUTIC APPROACHES FOR CML INCLUDING COVERAGE OF RELEVANT MECHANISMS, WHETHER ABL DEPENDENT OR INDEPENDENT, AND EPIGENETIC FACTORS RESPONSIBLE FOR DEVELOPING RESISTANCE AGAINST TKIS. APPEARANCE OF MUTANT CLONES ALONG THE COURSE OF THERAPY EITHER PREEXISTING OR INDUCED DUE TO THERAPY IS STILL A CHALLENGE FOR THE CLINICIAN. A PROPOSED INVITRO MODEL OF GENERATING COLONY FORMING UNITS FROM CML STEM CELLS DERIVED FROM DIAGNOSTIC SAMPLES SEEMS TO BE ACHIEVABLE IN THE ERA OF HIGH THROUGHPUT TECHNOLOGY WHICH CAN TAKE CARE OF SINGLE CELL GENOMIC PROFILING. 2016 16 570 32 BCR-ABL INDEPENDENT MECHANISMS OF RESISTANCE IN CHRONIC MYELOID LEUKEMIA. NOT ALL CHRONIC MYELOID LEUKEMIA (CML) PATIENTS ARE CURED WITH TYROSINE KINASE INHIBITORS (TKIS), AND A PROPORTION OF THEM DEVELOP RESISTANCE. RECENTLY, CONTINUOUS BCR-ABL GENE EXPRESSION HAS BEEN FOUND IN RESISTANT CELLS WITH UNDETECTABLE BCR-ABL PROTEIN EXPRESSION, INDICATING THAT RESISTANCE MAY OCCUR THROUGH KINASE INDEPENDENT MECHANISMS, MAINLY DUE TO THE PERSISTENCE OF LEUKEMIA STEM CELLS (LSCS). LSCS RESIDE IN THE BONE MARROW NICHE IN A QUIESCENT STATE, AND ARE CHARACTERIZED BY A HIGH HETEROGENEITY IN GENETIC, EPIGENETIC, AND TRANSCRIPTIONAL MECHANISMS. NEW APPROACHES BASED ON SINGLE CELL GENOMICS HAVE OFFERED THE OPPORTUNITY TO IDENTIFY DISTINCT SUBPOPULATIONS OF LSCS AT DIAGNOSIS AND DURING TREATMENT. IN THE ONE HAND, TKIS ARE NOT ABLE TO EFFICIENTLY KILL CML-LSCS, BUT THEY MAY BE RESPONSIBLE FOR THE MODIFICATION OF SOME LSCS CHARACTERISTICS, THUS CONTRIBUTING TO HETEROGENEITY WITHIN THE TUMOR. IN THE OTHER HAND, THE BONE MARROW NICHE IS RESPONSIBLE FOR THE INTERACTIONS BETWEEN SURROUNDING STROMAL CELLS AND LSCS, RESULTING IN THE GENERATION OF SPECIFIC SIGNALS WHICH COULD FAVOR LSCS CELL CYCLE ARREST AND ALLOW THEM TO PERSIST DURING TREATMENT WITH TKIS. ADDITIONALLY, LSCS MAY THEMSELVES ALTER THE NICHE BY EXPRESSING VARIOUS COSTIMULATORY MOLECULES AND SECRETING SUPPRESSIVE CYTOKINES, ABLE TO TARGET METABOLIC PATHWAYS, CREATE AN ANTI-APOPTOTIC ENVIRONMENT, AND ALTER IMMUNE SYSTEM FUNCTIONS. ACCORDINGLY, THE PRODUCTION OF AN IMMUNOSUPPRESSANT MILIEU MAY FACILITATE TUMOR ESCAPE FROM IMMUNE SURVEILLANCE AND INDUCE CHEMO-RESISTANCE. IN THIS REVIEW WE WILL FOCUS ON BCR-ABL-INDEPENDENT MECHANISMS, ANALYZING ESPECIALLY THOSE WITH A POTENTIAL CLINICAL IMPACT IN THE MANAGEMENT OF CML PATIENTS. 2019 17 6143 24 THE EVOLVING LANDSCAPE OF CANCER STEM CELLS AND WAYS TO OVERCOME CANCER HETEROGENEITY. CANCER STEM CELLS (CSCS) WITH THERAPEUTIC RESISTANCE AND PLASTICITY CAN BE FOUND IN VARIOUS TYPES OF TUMORS AND ARE RECOGNIZED AS ATTRACTIVE TARGETS FOR TREATMENTS. AS CSCS ARE DERIVED FROM TISSUE STEM OR PROGENITOR CELLS, AND/OR DEDIFFERENTIATED MATURE CELLS, THEIR SIGNAL TRANSDUCTION PATHWAYS ARE CRITICAL IN THE REGULATION OF CSCS; CHRONIC INFLAMMATION CAUSES THE ACCUMULATION OF GENETIC MUTATIONS AND ABERRANT EPIGENETIC CHANGES IN THESE CELLS, POTENTIALLY LEADING TO THE PRODUCTION OF CSCS. HOWEVER, THE NATURE OF CSCS APPEARS TO BE STRONGER THAN THE TREATMENTS OF THE PAST. TO IMPROVE THE TREATMENTS TARGETING CSCS, IT IS IMPORTANT TO INHIBIT SEVERAL MOLECULES ON THE SIGNALING CASCADES IN CSCS SIMULTANEOUSLY, AND TO OVERCOME CANCER HETEROGENEITY CAUSED BY THE PLASTICITY. TO SELECT SUITABLE TARGET MOLECULES FOR CSCS, WE HAVE TO EXPLORE THE LANDSCAPE OF CSCS FROM THE PERSPECTIVE OF CANCER STEMNESS AND SIGNALING SYSTEMS, BASED ON THE CURATED DATABASES OF CANCER-RELATED GENES. WE HAVE BEEN STUDYING THE INTEGRATION OF A BROAD RANGE OF KNOWLEDGE AND EXPERIENCES FROM CANCER BIOLOGY, AND ALSO FROM OTHER INTERDISCIPLINARY BASIC SCIENCES. IN THIS REVIEW, WE HAVE INTRODUCED THE CONCEPT OF DEVELOPING NOVEL STRATEGIES TARGETING CSCS. 2019 18 1142 25 CONCISE REVIEW: CHRONIC MYELOID LEUKEMIA: STEM CELL NICHE AND RESPONSE TO PHARMACOLOGIC TREATMENT. NOWADAYS, MORE THAN 90% OF PATIENTS AFFECTED BY CHRONIC MYELOID LEUKEMIA (CML) SURVIVE WITH A GOOD QUALITY OF LIFE, THANKS TO THE CLINICAL EFFICACY OF TYROSINE KINASE INHIBITORS (TKIS). NEVERTHELESS, POINT MUTATIONS OF THE ABL1 POCKET OCCURRING DURING TREATMENT MAY REDUCE BINDING OF TKIS, BEING RESPONSIBLE OF ABOUT 20% OF CASES OF RESISTANCE AMONG CML PATIENTS. IN ADDITION, THE PRESENCE OF LEUKEMIC STEM CELLS (LSCS) REPRESENTS THE MOST IMPORTANT EVENT IN LEUKEMIA PROGRESSION RELATED TO TKI RESISTANCE. LSCS EXPRESS STEM CELL MARKERS, INCLUDING ACTIVE EFFLUX PUMPS AND GENETIC AND EPIGENETIC ALTERATIONS TOGETHER WITH DEREGULATED CELL SIGNALING PATHWAYS INVOLVED IN SELF-RENEWAL, SUCH AS WNT/BETA-CATENIN, NOTCH, AND HEDGEHOG. MOREOVER, THE INTERACTION WITH THE BONE MARROW MICROENVIRONMENT, ALSO KNOWN AS HEMATOPOIETIC NICHE, MAY INFLUENCE THE PHENOTYPE OF SURROUNDING CELLS, WHICH EVADE MECHANISMS CONTROLLING CELL PROLIFERATION AND ARE LESS SENSITIVE OR FRANKLY RESISTANT TO TKIS. THIS REVIEW FOCUSES ON THE ROLE OF LSCS AND STEM CELL NICHE IN RELATION TO RESPONSE TO PHARMACOLOGICAL TREATMENTS. A LITERATURE SEARCH FROM PUBMED DATABASE WAS PERFORMED UNTIL APRIL 30, 2017, AND IT HAS BEEN ANALYZED ACCORDING TO KEYWORDS SUCH AS CHRONIC MYELOID LEUKEMIA, STEM CELL, LEUKEMIC STEM CELLS, HEMATOPOIETIC NICHE, TYROSINE KINASE INHIBITORS, AND DRUG RESISTANCE. STEM CELLS TRANSLATIONAL MEDICINE 2018;7:305-314. 2018 19 572 30 BCR-ABL1 KINASE-DEPENDENT ALTERATION OF MRNA METABOLISM: POTENTIAL ALTERNATIVES FOR THERAPEUTIC INTERVENTION. THE USE OF FIRST- AND SECOND-GENERATION TYROSINE KINASE INHIBITORS (TKIS) SIGNIFICANTLY IMPROVES PROGNOSIS FOR PATIENTS WITH EARLY CHRONIC PHASE CHRONIC MYELOID LEUKEMIA (CML) AND EFFICIENTLY COUNTERACTS LEUKEMIA IN MOST PATIENTS WITH CML BEARING A DISEASE CHARACTERIZED BY THE EXPRESSION OF BCR-ABL1 MUTANTS. HOWEVER, THE SO-CALLED 'TINIB' TKIS (E.G. IMATINIB, NILOTINIB, DASATINIB, AND BOSUTINIB) ARE BOTH INEFFECTIVE IN PATIENTS WHO UNDERGO BLASTIC TRANSFORMATION AND UNABLE TO ERADICATE CML AT THE STEM CELL LEVEL. THIS RAISES A FEW IMPORTANT QUESTIONS. IS BCR-ABL1 EXPRESSION AND/OR ACTIVITY ESSENTIAL FOR BLASTIC TRANSFORMATION? IS BLASTIC TRANSFORMATION THE RESULT OF GENETIC OR EPIGENETIC EVENTS THAT OCCUR AT THE STEM CELL LEVEL WHICH ONLY BECOME APPARENT IN THE GRANULOCYTE-MACROPHAGE PROGENITOR (GMP) CELL POOL, OR DOES IT ARISE DIRECTLY AT THE GMP LEVEL? AS ALTERED MRNA METABOLISM CONTRIBUTES TO THE PHENOTYPE OF BLAST CRISIS CML PROGENITORS (DECREASED TRANSLATION OF TUMOR SUPPRESSOR GENES AND TRANSCRIPTION FACTORS ESSENTIAL FOR TERMINAL DIFFERENTIATION AND INCREASED TRANSLATION OF ANTI-APOPTOTIC GENES), ONE ATTRACTIVE CONCEPT IS TO RESTORE LEVELS OF THESE ESSENTIAL MOLECULES TO THEIR NORMAL LEVELS. IN THIS REVIEW, WE DISCUSS THE MECHANISMS BY WHICH MRNA PROCESSING, TRANSLATION, AND DEGRADATION ARE DEREGULATED IN BCR-ABL1 MYELOID BLAST CRISIS CML PROGENITORS, AND PRESENT ENCOURAGING RESULTS FROM STUDIES WITH PHARMACOLOGIC INHIBITORS WHICH SUPPORT THEIR INCLUSION IN THE CLINIC. 2011 20 1082 33 CML - NOT ONLY BCR-ABL1 MATTERS. BCR-ABL1 IS IN THE CENTER OF CHRONIC MYELOID LEUKEMIA (CML) PATHOLOGY, DIAGNOSIS AND TREATMENT, AS CONFIRMED BY THE SUCCESS OF TYROSINE KINASE INHIBITOR (TKI) THERAPY. HOWEVER, ADDITIONAL MECHANISMS AND EVENTS, MANY OF WHICH FUNCTION INDEPENDENTLY OF BCR-ABL1, PLAY IMPORTANT ROLES, PARTICULARLY IN TERMS OF LEUKEMIC STEM CELL (LSC) PERSISTENCE, PRIMARY AND SECONDARY RESISTANCE, AND DISEASE PROGRESSION. PROMISING THERAPEUTIC APPROACHES AIM TO DISRUPT PATHWAYS WHICH MEDIATE LSC SURVIVAL DURING SUCCESSFUL TKI TREATMENT, IN THE HOPE OF IMPROVING LONG-TERM TREATMENT-FREE-REMISSION AND PERHAPS PROVIDE A FUNCTIONAL CURE FOR SOME PATIENTS. OVER THE YEARS THROUGH ADVANCES IN SEQUENCING TECHNOLOGY FREQUENT MOLECULAR ABERRATIONS IN ADDITION TO BCR-ABL1 HAVE BEEN IDENTIFIED NOT ONLY IN ADVANCED DISEASE BUT ALSO IN CHRONIC PHASE CML, OFTEN AFFECTING EPIGENETIC REGULATORS SUCH AS ASXL1, DNMT3A AND TET2. ANALYSES OF SERIAL SAMPLES HAVE REVEALED VARIOUS PATTERNS OF CLONAL EVOLUTION WITH SOME MUTATIONS PRECEDING THE BCR-ABL1 ACQUISITION. SUCH MUTATIONS CAN BE CONSIDERED TO BE IMPORTANT CO-FACTORS IN THE PATHOGENESIS OF CML AND COULD POTENTIALLY INFLUENCE THERAPEUTIC STRATEGIES IN THE FUTURE. 2020