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Under the recently adopted Kunming-Montreal Global Biodiversity Framework, 196 Parties committed to reporting the status of genetic diversity for all species. To facilitate reporting, three genetic diversity indicators were developed, two of which focus on processes contributing to genetic diversity conservation: maintaining genetically distinct populations and ensuring populations are large enough to maintain genetic diversity. The major advantage of these indicators is that they can be estimated with or without DNA-based data. However, demonstrating their feasibility requires addressing the methodological challenges of using data gathered from diverse sources, across diverse taxonomic groups, and for countries of varying socio-economic status and biodiversity levels. Here, we assess the genetic indicators for 919 taxa, representing 5271 populations across nine countries, including megadiverse countries and developing economies. Eighty-three percent of the taxa assessed had data available to calculate at least one indicator. Our results show that although the majority of species maintain most populations, 58% of species have populations too small to maintain genetic diversity. Moreover, genetic indicator values suggest that IUCN Red List status and other initiatives fail to assess genetic status, highlighting the critical importance of genetic indicators.
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Biodiversidad , Conservación de los Recursos Naturales , Variación Genética , AnimalesRESUMEN
AbstractAbiotic factors (e.g., temperature, precipitation) vary markedly along elevational gradients and differentially affect major groups of pollinators. Ectothermic bees, for example, are impeded in visiting flowers by cold and rainy conditions common at high elevations, while endothermic hummingbirds may continue foraging under such conditions. Despite the possibly far-reaching effects of the abiotic environment on plant-pollinator interactions, we know little about how these factors play out at broad ecogeographic scales. We address this knowledge gap by investigating how pollination systems vary across elevations in 26 plant clades from the Americas. Specifically, we explore Cruden's 1972 hypothesis that the harsh montane environment drives a turnover from insect to vertebrate pollination at higher elevations. We compared the elevational distribution and bioclimatic attributes for a total of 2,232 flowering plants and found that Cruden's hypothesis holds only in the tropics. Above 30°N and below 30°S, plants pollinated by vertebrates (mostly hummingbirds) tend to occur at lower elevations than those pollinated by insects. We hypothesize that this latitudinal transition is due to the distribution of moist, forested habitats favored by vertebrate pollinators, which are common at high elevations in the tropics but not in the temperate Americas.
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Altitud , Polinización , Abejas , Animales , Flores , Ecosistema , Insectos , Plantas , Aves , AméricasRESUMEN
BACKGROUND: Patients with Coronavirus Disease 2019 (COVID-19) who required mechanical ventilation and had prolonged hospital stay present with medical instability and functional impairments after the acute hospitalization. OBJECTIVE: To present the rehabilitation outcome of three patients with COVID-19 admitted to an inpatient rehabilitation unit using a case series method. METHODS: Subjects included three consecutive male patients admitted to the rehabilitation unit with a diagnosis of deconditioning and critical illness myopathy. On admission, patients were evaluated by a multidisciplinary team using outcome measures such as 6-min walk test (6 MWT), 10-m walk test (10 MWT), berg balance scale (BBS), and dynamometry. Each patient received daily therapy with a minimum of 900 min per week during their rehabilitation stay. Treatment strategies included fatigue management, training of mobility and activities for daily living tasks, muscle strengthening, and cognitive retraining. RESULTS: All patients showed significant improvements across all the outcome measures, specifically, the 6MWT (minimal clinically identifiable difference (MCID) range: 14-30.5 m) and the 10MWT (MCID range: 0.10-0.20 m/s) which exceeded the MCID for all three patients. The BBS also demonstrated significant improvement, surpassing the minimum detectable change of 5-7 points. Of the three patients, two were able to be discharged at an independent level, while one required supervision for safety. CONCLUSION: Patients with COVID-19, who experienced prolonged hospital stay present with severe impairments in muscle strength, functional mobility, and participation in daily living tasks. Inpatient rehabilitation may have the potential to reduce impairments and accelerate the recovery process while managing ongoing medical issues.
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PREMISE: A switch in pollinator can occur when a plant lineage enters a new habitat where the ancestral pollinator is less common, and a novel pollinator is more common. Because pollinator communities vary according to environmental tolerances and availability of resources, there may be consistent associations between pollination mode and specific regions and habitats. Such associations can be studied in lineages that have experienced multiple pollinator transitions, representing evolutionary replicates. METHODS: Our study focused on a large clade of Penstemon wildflower species in western North America, which has repeatedly evolved hummingbird-adapted flowers from ancestral bee-adapted flowers. For each species, we estimated geographic ranges from occurrence data and inferred environmental niches from climate, topographical, and soil data. Using a phylogenetic comparative approach, we investigated whether hummingbird-adapted species occupy distinct geographic regions or habitats relative to bee-adapted species. RESULTS: Hummingbird-adapted species occur at lower latitudes and lower elevations than bee-adapted species, resulting in a difference in their environmental niche. Bee-adapted species sister to hummingbird-adapted species are also found in relatively low elevations and latitudes, similar to their hummingbird-adapted sister species, suggesting ecogeographic shifts precede pollinator divergence. Sister species pairs-regardless of whether they differ in pollinator-show relatively little geographic range overlap. CONCLUSIONS: Adaptation to a novel pollinator may often occur in geographic and ecological isolation from ancestral populations. The ability of a given lineage to adapt to novel pollinators may critically depend on its ability to colonize regions and habitats associated with novel pollinator communities.
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Aves/fisiología , Penstemon/fisiología , Polinización , Altitud , Animales , Abejas/fisiología , Evolución Biológica , Ecosistema , Flores/anatomía & histología , América del Norte , Filogenia , Polinización/fisiologíaRESUMEN
PURPOSE: Volume-assured pressure support in noninvasive ventilation (VAPS-NIV) is a newer mode providing automatic pressure support adjustment to ensure a constant alveolar ventilation. Previous studies have shown that NIV effectiveness depends on patient adherence and tolerance. The aim of this study was to determine the adherence and efficacy of VAPS-NIV compared to spontaneous-time (S/T) mode in pediatric patients with neuromuscular disease (NMD). METHODS: This was a prospective observational study. Children with NMD who utilized NIV at home for ≥ 3 months were recruited from the Long-term ventilation clinic at The Hospital for Sick Children, Toronto, Canada, from July 1, 2015, to July 1, 2019. Baseline characteristics, date of initiation of NIV, and pulmonary function tests were recorded. Polysomnogram (PSG) data and adherence were recorded and analyzed comparing VAPS and S/T modes. RESULTS: Twenty children with NMD (17 male, 85%) were enrolled. The mean (SD) age at initiation of NIV was 11.6 ± 4.6 years. The median (IQR) duration of ventilation was 1.36 (0.80-2.98) years. The mean average daily usage and the median daily usage for VAPS mode and S/T mode were 8.4 ± 1.6 versus 7.2 ± 2.5 h (p = 0.012) and 8.6 ± 1.4 versus 7.8 ± 2.1 h (p = 0.022), respectively. There was no difference in sleep architecture, gas exchange, or parent proxy report of NIV tolerance between S/T and VAPS modes. CONCLUSION: VAPS was associated with an improvement in adherence to therapy in children with NMD compared to S/T mode. Longitudinal studies are required to evaluate long-term clinical outcomes using VAPS mode in children with NMD.
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Enfermedades Neuromusculares/terapia , Ventilación no Invasiva , Cooperación del Paciente , Adolescente , Niño , Femenino , Humanos , Masculino , Ventilación no Invasiva/métodos , Evaluación de Resultado en la Atención de Salud , Estudios ProspectivosRESUMEN
BACKGROUND: The number of different antimicrobial recommendations between hospital trusts for the same indication in England is unknown. AIM: We aimed to evaluate the heterogeneity of antimicrobial recommendations for seven common inpatient infections across hospital trusts in England and evaluate changes to recommendations following introduction of national (National Institute for Healthcare and Excellence, NICE) and international (WHO) antimicrobial guidelines. METHODS: Guidelines published on the MicroGuide smartphone application were collected from December 2017 to February 2018 and re-evaluated between December 2019 and February 2020. The following indications were assessed: community-acquired pneumonia (CAP) CURB65 score ≥3, hospital-acquired pneumonia (HAP), infective exacerbation of chronic obstructive pulmonary disease (iCOPD), cellulitis, uncomplicated urinary tract infection (uUTI), intra-abdominal infection (IAI) and sepsis of unknown source (SUS). On follow-up, compliance against WHO WATCH antibiotic and NICE recommendations was evaluated. RESULTS: Guidelines were obtained predominantly from England. Antibiotic regimens between hospitals became increasingly diverse across indications in the following order: uUTI, cellulitis, iCOPD, CAP, HAP, IAI and SUS. A piperacillin/tazobactam-based regimen was recommended in HAP (59%), SUS (39%) and IAI (30%). After 2 years, 107 changes were made to 357 antibiotic regimen recommendations; the overall number of regimens using piperacillin-tazobactam and WHO WATCH antibiotics remained similar. Compliance of recommendations with NICE guidelines as follows: iCOPD (100% adherent), uUTI (98%), cellulitis (90%), CAP (43%) and HAP (27%). CONCLUSION: The heterogeneity of antibiotic recommendations increased as the indicated infection was more severe, with broader underlying bacterial causes. Piperacillin-tazobactam remains favoured in antibiotic regimens, despite not recommended in WHO and NICE guidance.
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Antibacterianos/uso terapéutico , Infección Hospitalaria/tratamiento farmacológico , Guías como Asunto/normas , Pacientes Internos , Infección Hospitalaria/microbiología , Inglaterra , Hospitales , HumanosRESUMEN
Acute myeloid leukemia (AML) disrupts the generation of normal blood cells, predisposing patients to hemorrhage, anemia, and infections. Differentiation and proliferation of residual normal hematopoietic stem and progenitor cells (HSPCs) are impeded in AML-infiltrated bone marrow (BM). The underlying mechanisms and interactions of residual hematopoietic stem cells (HSCs) within the leukemic niche are poorly understood, especially in the human context. To mimic AML infiltration and dissect the cellular crosstalk in human BM, we established humanized ex vivo and in vivo niche models comprising AML cells, normal HSPCs, and mesenchymal stromal cells (MSCs). Both models replicated the suppression of phenotypically defined HSPC differentiation without affecting their viability. As occurs in AML patients, the majority of HSPCs were quiescent and showed enrichment of functional HSCs. HSPC suppression was largely dependent on secreted factors produced by transcriptionally remodeled MSCs. Secretome analysis and functional validation revealed MSC-derived stanniocalcin 1 (STC1) and its transcriptional regulator HIF-1α as limiting factors for HSPC proliferation. Abrogation of either STC1 or HIF-1α alleviated HSPC suppression by AML. This study provides a humanized model to study the crosstalk among HSPCs, leukemia, and their MSC niche, and a molecular mechanism whereby AML impairs normal hematopoiesis by remodeling the mesenchymal niche.
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Glicoproteínas/metabolismo , Hematopoyesis , Células Madre Hematopoyéticas/metabolismo , Leucemia Mieloide Aguda/metabolismo , Células Madre Mesenquimatosas/metabolismo , Proteínas de Neoplasias/metabolismo , Animales , Femenino , Glicoproteínas/genética , Células HL-60 , Células Madre Hematopoyéticas/patología , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Masculino , Células Madre Mesenquimatosas/patología , Ratones , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Proteínas de Neoplasias/genética , Células U937RESUMEN
AIM: The chemical composition of layered double hydroxides (LDHs) affects their structure and properties. The method of ibuprofen (IBU) intercalation into LDHs may modify its release, reduce adverse effects and decrease the required dosing frequency. METHODOLOGY: This study investigates the effects of four different LDHs; MgAl-LDH, MgFe-LDH, NiAl-LDH and NiFe-LDH on in vitro release of IBU intercalated by coprecipitation and anionic-exchange. RESULTS: MgAl-LDH was the most crystalline and substitution of either cation decreased LDH order. Fourier-transform infrared spectra and power x-ray diffractograms confirmed the intercalation of IBU within the lamellar structure of MgAl-LDH and MgFe-LDH. Intercalation of IBU by anion-exchange resulted in slower, partial, drug release compared with coprecipitation. CONCLUSION: The chemical composition of LDHs affects their crystallinity, IBU intercalation and subsequent release.
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Antiinflamatorios no Esteroideos/farmacocinética , Portadores de Fármacos/química , Hidróxidos/química , Ibuprofeno/farmacocinética , Antiinflamatorios no Esteroideos/administración & dosificación , Preparaciones de Acción Retardada/administración & dosificación , Preparaciones de Acción Retardada/farmacocinética , Composición de Medicamentos/métodos , Liberación de Fármacos , Humanos , Ibuprofeno/administración & dosificación , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
The BM niche comprises a tightly controlled microenvironment formed by specific tissue and cells that regulates the behavior of hematopoietic stem cells (HSCs). Here, we have provided a 3D model that is tunable in different BM niche components and useful, both in vitro and in vivo, for studying the maintenance of normal and malignant hematopoiesis. Using scaffolds, we tested the capacity of different stromal cell types to support human HSCs. Scaffolds coated with human mesenchymal stromal cells (hMSCs) proved to be superior in terms of HSC engraftment and long-term maintenance when implanted in vivo. Moreover, we found that hMSC-coated scaffolds can be modulated to form humanized bone tissue, which was also able to support human HSC engraftment. Importantly, hMSC-coated humanized scaffolds were able to support the growth of leukemia patient cells in vivo, including the growth of samples that would not engraft the BM of immunodeficient mice. These results demonstrate that an s.c. implantation approach in a 3D carrier scaffold seeded with stromal cells is an effective in vivo niche model for studying human hematopoiesis. The various niche components of this model can be changed depending on the context to improve the engraftment of nonengrafting acute myeloid leukemia (AML) samples.
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Hematopoyesis/inmunología , Células Madre Hematopoyéticas/inmunología , Leucemia Mieloide Aguda/inmunología , Células Madre Mesenquimatosas/inmunología , Modelos Biológicos , Nicho de Células Madre/inmunología , Microambiente Tumoral/inmunología , Animales , Células Madre Hematopoyéticas/patología , Humanos , Leucemia Mieloide Aguda/patología , Células Madre Mesenquimatosas/patología , RatonesRESUMEN
A major obstacle to curing chronic myeloid leukemia (CML) is residual disease maintained by tyrosine kinase inhibitor (TKI)-persistent leukemic stem cells (LSC). These are BCR-ABL1 kinase independent, refractory to apoptosis, and serve as a reservoir to drive relapse or TKI resistance. We demonstrate that Polycomb Repressive Complex 2 is misregulated in chronic phase CML LSCs. This is associated with extensive reprogramming of H3K27me3 targets in LSCs, thus sensitizing them to apoptosis upon treatment with an EZH2-specific inhibitor (EZH2i). EZH2i does not impair normal hematopoietic stem cell survival. Strikingly, treatment of primary CML cells with either EZH2i or TKI alone caused significant upregulation of H3K27me3 targets, and combined treatment further potentiated these effects and resulted in significant loss of LSCs compared to TKI alone, in vitro, and in long-term bone marrow murine xenografts. Our findings point to a promising epigenetic-based therapeutic strategy to more effectively target LSCs in patients with CML receiving TKIs. SIGNIFICANCE: In CML, TKI-persistent LSCs remain an obstacle to cure, and approaches to eradicate them remain a significant unmet clinical need. We demonstrate that EZH2 and H3K27me3 reprogramming is important for LSC survival, but renders LSCs sensitive to the combined effects of EZH2i and TKI. This represents a novel approach to more effectively target LSCs in patients receiving TKI treatment. Cancer Discov; 6(11); 1248-57. ©2016 AACR.See related article by Xie et al., p. 1237This article is highlighted in the In This Issue feature, p. 1197.
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Proteína Potenciadora del Homólogo Zeste 2/genética , Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/administración & dosificación , Animales , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Reprogramación Celular/genética , Resistencia a Antineoplásicos/genética , Proteína Potenciadora del Homólogo Zeste 2/antagonistas & inhibidores , Epigénesis Genética/efectos de los fármacos , Células Madre Hematopoyéticas/efectos de los fármacos , Células Madre Hematopoyéticas/patología , Humanos , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Ratones , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patologíaRESUMEN
Osteosarcoma (OS) is the most common type of primary solid tumor that develops in bone. Although standard chemotherapy has significantly improved long-term survival over the past few decades, the outcome for those patients with metastatic or recurrent OS remains dismally poor and, therefore, novel agents and treatment regimens are urgently required. A hypothesis to explain the resistance of OS to chemotherapy is the existence of drug resistant CSCs with progenitor properties that are responsible of tumor relapses and metastasis. These subpopulations of CSCs commonly emerge during tumor evolution from the cell-of-origin, which are the normal cells that acquire the first cancer-promoting mutations to initiate tumor formation. In OS, several cell types along the osteogenic lineage have been proposed as cell-of-origin. Both the cell-of-origin and their derived CSC subpopulations are highly influenced by environmental and epigenetic factors and, therefore, targeting the OS-CSC environment and niche is the rationale for many recently postulated therapies. Likewise, some strategies for targeting CSC-associated signaling pathways have already been tested in both preclinical and clinical settings. This review recapitulates current OS cell-of-origin models, the properties of the OS-CSC and its niche, and potential new therapies able to target OS-CSCs.
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INTRODUCTION: Hypoxia inducible factors (HIF-1α and HIF-2α) are the main mediators of hypoxic responses that operate in both normal and pathological conditions. Recent evidence indicates that HIF-1α and HIF-2α could have overlapping, unique and even sometimes opposing activities in both normal physiology and disease. Despite an increase in our understanding of the different pathways regulated by HIF-1α and HIF-2α, the role played by each factor in HSC maintenance and leukemogenesis is still controversial. AREAS COVERED: This review summarizes our current understanding of HIF-1α and HIF-2α activities and discusses the implications and challenges of using HIF inhibitors therapeutically in blood malignancies. EXPERT OPINION: As HIF inhibitors are currently under clinical evaluation in different cancers, including hematological malignancies, a more thorough understanding of the unique roles performed by HIF-1α and HIF-2α in human neoplasia is warranted.
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Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Células Madre Hematopoyéticas/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Leucemia/metabolismo , Células Madre Neoplásicas/metabolismo , Hematopoyesis , Humanos , Leucemia/patología , Células Madre Neoplásicas/patologíaRESUMEN
BACKGROUND AND AIMS: Brief alcohol interventions in medical settings are efficacious in improving self-reported alcohol consumption among those with low-severity alcohol problems. Screening, Brief Intervention and Referral to Treatment initiatives presume that brief interventions are efficacious in linking patients to higher levels of care, but pertinent evidence has not been evaluated. We estimated main and subgroup effects of brief alcohol interventions, regardless of their inclusion of a referral-specific component, in increasing the utilization of alcohol-related care. METHODS: A systematic review of English language papers published in electronic databases to 2013. We included randomized controlled trials (RCTs) of brief alcohol interventions in general health-care settings with adult and adolescent samples. We excluded studies that lacked alcohol services utilization data. Extractions of study characteristics and outcomes were standardized and conducted independently. The primary outcome was post-treatment alcohol services utilization assessed by self-report or administrative data, which we compared across intervention and control groups. RESULTS: Thirteen RCTs met inclusion criteria and nine were meta-analyzed (n = 993 and n = 937 intervention and control group participants, respectively). In our main analyses the pooled risk ratio (RR) was = 1.08, 95% confidence interval (CI) = 0.92-1.28. Five studies compared referral-specific interventions with a control condition without such interventions (pooled RR = 1.08, 95% CI = 0.81-1.43). Other subgroup analyses of studies with common characteristics (e.g. age, setting, severity, risk of bias) yielded non-statistically significant results. CONCLUSIONS: There is a lack of evidence that brief alcohol interventions have any efficacy for increasing the receipt of alcohol-related services.
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Trastornos Relacionados con Alcohol/terapia , Consejo/estadística & datos numéricos , Ensayos Clínicos Controlados Aleatorios como Asunto , Derivación y Consulta/estadística & datos numéricos , Consejo/métodos , Humanos , Trastornos Relacionados con Sustancias/terapiaRESUMEN
The historical use of clay minerals for the treatment of wounds and other skin ailments is well documented and continues within numerous human cultures the world over. However, a more scientific inquiry into the chemistry and properties of clay minerals emerged in the 19th century with work investigating their role within health gathering pace since the second half of the 20th century. This review gives an overview of clay minerals and how their properties can be manipulated to facilitate the treatment of infected wounds. Evidence of the antimicrobial and healing effects of some natural clay minerals is presented alongside a range of chemical modifications including metal-ion exchange, the formation of clay-drug composites and the development of various polymer-clay systems. While the evidence for applying these materials to infected wounds is limited, we contextualize and discuss the future of this research.
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Silicatos de Aluminio/química , Silicatos de Aluminio/uso terapéutico , Antiinfecciosos/química , Antiinfecciosos/uso terapéutico , Cicatrización de Heridas/efectos de los fármacos , Animales , Arcilla , Humanos , Metales/química , Metales/uso terapéutico , Polímeros/química , Polímeros/uso terapéuticoRESUMEN
BACKGROUND: All investigators seeking funding to conduct implementation research face the challenges of preparing a high-quality proposal and demonstrating their capacity to conduct the proposed study. Applicants need to demonstrate the progressive nature of their research agenda and their ability to build cumulatively upon the literature and their own preliminary studies. Because implementation science is an emerging field involving complex and multilevel processes, many investigators may not feel equipped to write competitive proposals, and this concern is pronounced among early stage implementation researchers. DISCUSSION: This article addresses the challenges of preparing grant applications that succeed in the emerging field of dissemination and implementation. We summarize ten ingredients that are important in implementation research grants. For each, we provide examples of how preliminary data, background literature, and narrative detail in the application can strengthen the application. SUMMARY: Every investigator struggles with the challenge of fitting into a page-limited application the research background, methodological detail, and information that can convey the project's feasibility and likelihood of success. While no application can include a high level of detail about every ingredient, addressing the ten ingredients summarized in this article can help assure reviewers of the significance, feasibility, and impact of the proposed research.
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Organización de la Financiación , Investigación sobre Servicios de Salud/organización & administración , Proyectos de Investigación , Investigación Biomédica Traslacional/organización & administración , Escritura , Conducta Cooperativa , Medicina Basada en la Evidencia , Humanos , Innovación OrganizacionalRESUMEN
Recent evidence suggests chronic myeloid leukemia (CML) stem cells are insensitive to kinase inhibitors and responsible for minimal residual disease in treated patients. We investigated whether CML stem cells, in a transgenic mouse model of CML-like disease or derived from patients, are dependent on Bcr-Abl. In the transgenic model, after retransplantation, donor-derived CML stem cells in which Bcr-Abl expression had been induced and subsequently shut off were able to persist in vivo and reinitiate leukemia in secondary recipients on Bcr-Abl reexpression. Bcr-Abl knockdown in human CD34(+) CML cells cultured for 12 days in physiologic growth factors achieved partial inhibition of Bcr-Abl and downstream targets p-CrkL and p-STAT5, inhibition of proliferation and colony forming cells, but no reduction of input cells. The addition of dasatinib further inhibited p-CrkL and p-STAT5, yet only reduced input cells by 50%. Complete growth factor withdrawal plus dasatinib further reduced input cells to 10%; however, the surviving fraction was enriched for primitive leukemic cells capable of growth in a long-term culture-initiating cell assay and expansion on removal of dasatinib and addition of growth factors. Together, these data suggest that CML stem cell survival is Bcr-Abl kinase independent and suggest curative approaches in CML must focus on kinase-independent mechanisms of resistance.
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Proteínas de Fusión bcr-abl/metabolismo , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Células Madre Neoplásicas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Antígenos CD34/metabolismo , Apoptosis/efectos de los fármacos , Western Blotting , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Dasatinib , Relación Dosis-Respuesta a Droga , Citometría de Flujo , Proteínas de Fusión bcr-abl/antagonistas & inhibidores , Proteínas de Fusión bcr-abl/genética , Regulación Leucémica de la Expresión Génica , Técnicas de Inactivación de Genes , Células HEK293 , Humanos , Células K562 , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Ratones , Ratones Transgénicos , Células Madre Neoplásicas/patología , Proteínas Nucleares/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor de Transcripción STAT5/metabolismo , Tiazoles/farmacologíaRESUMEN
In a previously developed inducible transgenic mouse model of chronic myeloid leukemia, we now demonstrate that the disease is transplantable using BCR-ABL(+) Lin(-)Sca-1(+)c-kit(+) (LSK) cells. Interestingly, the phenotype is more severe when unfractionated bone marrow cells are transplanted, yet neither progenitor cells (Lin(-)Sca-1(-)c-kit(+)), nor mature granulocytes (CD11b(+)Gr-1(+)), nor potential stem cell niche cells (CD45(-)Ter119(-)) are able to transmit the disease or alter the phenotype. The phenotype is largely independent of BCR-ABL priming before transplantation. However, prolonged BCR-ABL expression abrogates the potential of LSK cells to induce full-blown disease in secondary recipients and increases the fraction of multipotent progenitor cells at the expense of long-term hematopoietic stem cells (LT-HSCs) in the bone marrow. BCR-ABL alters the expression of genes involved in proliferation, survival, and hematopoietic development, probably contributing to the reduced LT-HSC frequency within BCR-ABL(+) LSK cells. Reversion of BCR-ABL, or treatment with imatinib, eradicates mature cells, whereas leukemic stem cells persist, giving rise to relapsed chronic myeloid leukemia on reinduction of BCR-ABL, or imatinib withdrawal. Our results suggest that BCR-ABL induces differentiation of LT-HSCs and decreases their self-renewal capacity.
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Diferenciación Celular/genética , Transformación Celular Neoplásica/patología , Proteínas de Fusión bcr-abl/fisiología , Células Madre Hematopoyéticas/patología , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Animales , Separación Celular , Transformación Celular Neoplásica/genética , Modelos Animales de Enfermedad , Citometría de Flujo , Genes abl/fisiología , Trasplante de Células Madre Hematopoyéticas , Ratones , Ratones Transgénicos , Estadificación de Neoplasias , Trasplante de Neoplasias , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The recent and rapid development of molecularly targeted therapy is best illustrated by advances in the management of haematological malignancy. In myeloid diseases we have seen dramatic improvements in the overall survival and quality of life for patients with chronic myeloid leukaemia treated with ABL and Src/ABL kinase inhibitors and we are poised to discover whether JAK2 inhibitors may offer similar benefit in myeloproliferative diseases. For acute myeloid leukaemia, the introduction of ATRA and myelotarg have had major impacts on the design of therapy regimens and many novel targeted agents, including farnesyl transferase, FLT3 and histone deacetylase inhibitors, are now in clinical trial. In lymphoid malignancies the highlight has been the introduction of rituximab, with significant improvements in the management of non-Hodgkin lymphoma and chronic lymphocytic leukaemia. The last 10 years has experienced a rapidly expanding interest and acceptance that leukaemic stem cells, including an improved ability to target them, may hold the key to improved response and reduced relapse rates across both myeloid and lymphoid disease. We now eagerly anticipate an era in which a wealth of preclinical discoveries are progressed to the clinic.
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Antineoplásicos/uso terapéutico , Neoplasias Hematológicas/tratamiento farmacológico , Antineoplásicos/administración & dosificación , Sistemas de Liberación de Medicamentos/métodos , Diseño de Fármacos , Neoplasias Hematológicas/genética , Humanos , Leucemia Mieloide/tratamiento farmacológico , Leucemia Mieloide/genética , Trastornos Linfoproliferativos/tratamiento farmacológico , Trastornos Linfoproliferativos/genética , Trastornos Mieloproliferativos/tratamiento farmacológico , Trastornos Mieloproliferativos/genéticaRESUMEN
Imatinib mesylate (IM), a potent inhibitor of the BCR/ABL tyrosine kinase, has become standard first-line therapy for patients with chronic myeloid leukemia (CML), but the frequency of resistance increases in advancing stages of disease. Elimination of BCR/ABL-dependent intracellular signals triggers apoptosis, but it is unclear whether this activates additional cell survival and/or death pathways. We have shown here that IM induces autophagy in CML blast crisis cell lines, CML primary cells, and p210BCR/ABL-expressing myeloid precursor cells. IM-induced autophagy did not involve c-Abl or Bcl-2 activity but was associated with ER stress and was suppressed by depletion of intracellular Ca2+, suggesting it is mechanistically nonoverlapping with IM-induced apoptosis. We further demonstrated that suppression of autophagy using either pharmacological inhibitors or RNA interference of essential autophagy genes enhanced cell death induced by IM in cell lines and primary CML cells. Critically, the combination of a tyrosine kinase inhibitor (TKI), i.e., IM, nilotinib, or dasatinib, with inhibitors of autophagy resulted in near complete elimination of phenotypically and functionally defined CML stem cells. Together, these findings suggest that autophagy inhibitors may enhance the therapeutic effects of TKIs in the treatment of CML.