RESUMO
Acute megakaryoblastic leukemia in patients without Down syndrome is a rare malignancy with a poor prognosis. RNA sequencing of fourteen pediatric cases previously identified novel fusion transcripts that are predicted to be pathological including CBFA2T3-GLIS2, GATA2-HOXA9, MN1-FLI and NIPBL-HOXB9. In contrast to CBFA2T3-GLIS2, which is insufficient to induce leukemia, we demonstrate that the introduction of GATA2-HOXA9, MN1-FLI1 or NIPBL-HOXB9 into murine bone marrow induces overt disease in syngeneic transplant models. With the exception of MN1, full penetrance was not achieved through the introduction of fusion partner genes alone, suggesting that the chimeric transcripts possess a unique gain-of-function phenotype. Leukemias were found to exhibit elements of the megakaryocyte erythroid progenitor gene expression program, as well as unique leukemia-specific signatures that contribute to transformation. Comprehensive genomic analyses of resultant murine tumors revealed few cooperating mutations confirming the strength of the fusion genes and their role as pathological drivers. These models are critical for both the understanding of the biology of disease as well as providing a tool for the identification of effective therapeutic agents in preclinical studies.
Assuntos
Transformação Celular Neoplásica/genética , Regulação Leucêmica da Expressão Gênica/genética , Leucemia Megacarioblástica Aguda/genética , Proteínas de Fusão Oncogênica/fisiologia , Fatores de Transcrição/fisiologia , Animais , Medula Óssea/patologia , Autorrenovação Celular , Feminino , Perfilação da Expressão Gênica , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Genéticos , Células Mieloides/patologia , Transplante de Neoplasias , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Proteínas de Fusão Oncogênica/genética , Fenótipo , RNA Interferente Pequeno/genética , Quimera por Radiação , Trombopoese/genética , Fatores de Transcrição/genéticaRESUMO
To determine the clinical significance of minimal residual disease (MRD) in patients with prognostically relevant subtypes of childhood acute lymphoblastic leukemia (ALL), we analyzed data from 488 patients treated in St Jude Total Therapy Study XV with treatment intensity based mainly on MRD levels measured during remission induction. MRD levels on day 19 predicted treatment outcome for patients with hyperdiploid >50 ALL, National Cancer Institute (NCI) standard-risk B-ALL or T-cell ALL, while MRD levels on day 46 were prognostic for patients with NCI standard-risk or high-risk B-ALL. Patients with t(12;21)/(ETV6-RUNX1) or hyperdiploidy >50 ALL had the best prognosis; those with a negative MRD on day 19 had a particularly low risk of relapse: 1.9% and 3.8%, respectively. Patients with NCI high-risk B-ALL or T-cell ALL had an inferior outcome; even with undetectable MRD on day 46, cumulative risk of relapse was 12.7% and 15.5%, respectively. Among patients with NCI standard-risk B-ALL, the outcome was intermediate overall but was poor if MRD was ⩾1% on day 19 or MRD was detectable at any level on day 46. Our results indicate that the clinical impact of MRD on treatment outcome in childhood ALL varies considerably according to leukemia subtype and time of measurement.
Assuntos
Neoplasia Residual/patologia , Neoplasia Residual/terapia , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Adolescente , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Criança , Pré-Escolar , Terapia Combinada , Feminino , Transplante de Células-Tronco Hematopoéticas , Humanos , Lactente , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Prognóstico , Recidiva , Indução de Remissão , Análise de Sobrevida , Resultado do TratamentoRESUMO
Somatic mutations that lead to constitutive activation of NRAS and KRAS proto-oncogenes are among the most common in human cancer and frequently occur in acute myeloid leukemia (AML). An inducible NRAS(V12)-driven AML mouse model has established a critical role for continued NRAS(V12) expression in leukemia maintenance. In this model genetic suppression of NRAS(V12) expression results in rapid leukemia remission, but some mice undergo spontaneous relapse with NRAS(V12)-independent (NRI) AMLs providing an opportunity to identify mechanisms that bypass the requirement for Ras oncogene activity and drive leukemia relapse. We found that relapsed NRI AMLs are devoid of NRAS(V12) expression and signaling through the major oncogenic Ras effector pathways, phosphatidylinositol-3-kinase and mitogen-activated protein kinase, but express higher levels of an alternate Ras effector, Ralb, and exhibit NRI phosphorylation of the RALB effector TBK1, implicating RALB signaling in AML relapse. Functional studies confirmed that inhibiting CDK5-mediated RALB activation with a clinically relevant experimental drug, dinaciclib, led to potent RALB-dependent antileukemic effects in human AML cell lines, induced apoptosis in patient-derived AML samples in vitro and led to a 2-log reduction in the leukemic burden in patient-derived xenograft mice. Furthermore, dinaciclib potently suppressed the clonogenic potential of relapsed NRI AMLs in vitro and prevented the development of relapsed AML in vivo. Our findings demonstrate that Ras oncogene-independent activation of RALB signaling is a therapeutically targetable mechanism of escape from NRAS oncogene addiction in AML.
Assuntos
GTP Fosfo-Hidrolases/genética , Regulação Neoplásica da Expressão Gênica , Leucemia Experimental/patologia , Leucemia Mieloide Aguda/patologia , Proteínas de Membrana/genética , Mutação/genética , Proteínas ral de Ligação ao GTP/metabolismo , Animais , Apoptose , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Proliferação de Células , Feminino , Humanos , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Masculino , Camundongos , Camundongos SCID , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas Monoméricas de Ligação ao GTP/genética , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Invasividade Neoplásica , Oncogenes , Transdução de Sinais , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto , Proteínas ral de Ligação ao GTP/genéticaRESUMO
With improved contemporary therapy, we reassess long-term outcome in patients completing treatment for childhood acute lymphoblastic leukemia (ALL) to determine when cure can be declared with a high degree of confidence. In six successive clinical trials between 1984 and 2007, 1291 (84.5%) patients completed all therapies in continuous complete remission. The post-therapy cumulative risk of relapse or development of a second neoplasm and the event-free survival rate and overall survival were analyzed according to the presenting features and the three treatment periods defined by relative outcome. Over the three treatment periods, there has been progressive increase in the rate of event-free survival (65.2% vs 74.8% vs 85.1% (P<0.001)) and overall survival (76.5% vs 81.1% vs 91.7% (P<0.001)) at 10 years. The most important predictor of outcome after completion of therapy was the type of treatment. In the most recent treatment period, which omitted the use of prophylactic cranial irradiation, the post-treatment cumulative risk of relapse was 6.4%, death in remission 1.5% and development of a second neoplasm 2.3% at 10 years, with all relapses except one occurring within 4 years of therapy. None of the 106 patients with the t(9;22)/BCR-ABL1, t(1;19)/TCF3-PBX1 or t(4;11)/MLL-AFF1 had relapsed after 2 years from completion of therapy. These findings demonstrate that with contemporary effective therapy that excludes cranial irradiation, approximately 6% of children with ALL may relapse after completion of treatment, and those who remain in remission at 4 years post treatment may be considered cured (that is, less than 1% chance of relapse).
Assuntos
Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Adolescente , Criança , Pré-Escolar , Ensaios Clínicos como Assunto , Terapia Combinada/efeitos adversos , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Mortalidade , Segunda Neoplasia Primária , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Recidiva , Indução de Remissão , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoAssuntos
Cromossomos Humanos Par 1 , Cromossomos Humanos Par 22 , Exoma , Leucemia Megacarioblástica Aguda/genética , Metaloproteinase 8 da Matriz/genética , Mutação , Translocação Genética , Criança , Proteínas de Ligação a DNA/genética , Humanos , Leucemia Megacarioblástica Aguda/tratamento farmacológico , Masculino , Proteínas de Fusão Oncogênica/genética , Polimorfismo de Nucleotídeo Único , Proteínas de Ligação a RNA/genética , TransativadoresRESUMO
Thin cell-layer explants (TCLs) have been proposed as favorable tissues for the study of root, vegetative shoot and flower formation. We tested the effects of pH, light quality, light quantity, and IBA and kinetin concentrations on the morphogenesis of TCLs cultured individually on a liquid medium. Alterations of the amounts of exogenously supplied IBA and kinetin were sufficient to induce the formation of roots, vegetative shoots and flowers on TCLs cultured on otherwise identical media. The type and number of organs formed were sensitive to the intensity of light (55, 75, 100 and 120 muEinsteins m-2 sec-1) under which TCLs were grown. Evidence was obtained that the effects of light on TCL morphogenesis were associated with photochemical degradation of IBA in the medium. Evaluation of the organogenesis that occurred in TCLs cultured on a medium containing a range of IBA and kinetin concentrations showed that the number and type of organs formed, and overall growth, were dependent upon the initial concentrations of auxin and cytokinin. We have developed the TCL culture system into a sensitive and reproducible bioassay for the study of morphogenesis. The advantages of using the TCL morphogenesis bioassay for the identification and study of molecules (e.g. cell wall oligosaccharides) that may regulate morphogenesis are discussed.
Assuntos
Técnicas de Cultura , Nicotiana , Plantas Tóxicas , Adenina/análogos & derivados , Adenina/farmacologia , Concentração de Íons de Hidrogênio , Cinetina , Luz , MorfogêneseRESUMO
The mercury levels in 69 muscle samples from fish weighing from 0.3 to 200 kg caught in Moreton Bay, Queensland, in the latter half of 1976 ranged from less than 10 to 2,030 ng/g. Mercury levels in blood samples from 53 humans and 100 dogs in Brisbane almost all contained less than 10 ng/ml while the level in 162 cats sampled ranged from less than 10 to 329 ng/ml. Chronic methylmercurialism developed in 2 cats dosed daily with methylmercury, bound to cysteine, at the rate of 0.6 mg/kg body weight for 74 and 77 days respectively. Terminal clinical signs included anorexia, weight loss, knuckling over at the carpus and tarsus, hypermetria initially involving the forelegs and later the hindlegs, sluggish reflexes, paresis involving all limbs, persistent crying, apparent blindness, tonic and clonic convulsions and salivation. Pathological changes were confined to the nervous system and included degeneration of neurones and perivascular cuffing in the cerebrocortical grey matter, focal atrophy of the granular layer, focal spongiosus of the molecular layer and degeneration and loss of Purkinje cells in the cerebellum and demyelination in the fibre tracts of the dorsal funiculus, mainly the fasciculus cuneatus and in the lateral and ventral corticospinal tracts. Terminal blood methylmercury levels were in excess of 18 microgram/ml, while brain methylmercury levels ranged from 21.0 to 28.4 microgram/g. The liver and kidney contained the highest total levels of mercury of 50 to 80 microgram/g, of which 23 to 37% was inorganic.