RESUMO
BACKGROUND: The molecular determinants of clinical responses to decitabine therapy in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) are unclear. METHODS: We enrolled 84 adult patients with AML or MDS in a single-institution trial of decitabine to identify somatic mutations and their relationships to clinical responses. Decitabine was administered at a dose of 20 mg per square meter of body-surface area per day for 10 consecutive days in monthly cycles. We performed enhanced exome or gene-panel sequencing in 67 of these patients and serial sequencing at multiple time points to evaluate patterns of mutation clearance in 54 patients. An extension cohort included 32 additional patients who received decitabine in different protocols. RESULTS: Of the 116 patients, 53 (46%) had bone marrow blast clearance (<5% blasts). Response rates were higher among patients with an unfavorable-risk cytogenetic profile than among patients with an intermediate-risk or favorable-risk cytogenetic profile (29 of 43 patients [67%] vs. 24 of 71 patients [34%], P<0.001) and among patients with TP53 mutations than among patients with wild-type TP53 (21 of 21 [100%] vs. 32 of 78 [41%], P<0.001). Previous studies have consistently shown that patients with an unfavorable-risk cytogenetic profile and TP53 mutations who receive conventional chemotherapy have poor outcomes. However, in this study of 10-day courses of decitabine, neither of these risk factors was associated with a lower rate of overall survival than the rate of survival among study patients with intermediate-risk cytogenetic profiles. CONCLUSIONS: Patients with AML and MDS who had cytogenetic abnormalities associated with unfavorable risk, TP53 mutations, or both had favorable clinical responses and robust (but incomplete) mutation clearance after receiving serial 10-day courses of decitabine. Although these responses were not durable, they resulted in rates of overall survival that were similar to those among patients with AML who had an intermediate-risk cytogenetic profile and who also received serial 10-day courses of decitabine. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT01687400 .).
Assuntos
Antimetabólitos Antineoplásicos/administração & dosagem , Azacitidina/análogos & derivados , Medula Óssea/patologia , Leucemia Mieloide Aguda/tratamento farmacológico , Mutação , Síndromes Mielodisplásicas/tratamento farmacológico , Proteína Supressora de Tumor p53/genética , 5-Metilcitosina/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Antimetabólitos Antineoplásicos/efeitos adversos , Azacitidina/administração & dosagem , Azacitidina/efeitos adversos , Biomarcadores Tumorais/análise , Medula Óssea/química , Decitabina , Exoma , Feminino , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/mortalidade , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/mortalidade , Estudos Prospectivos , Fatores de Risco , Taxa de SobrevidaRESUMO
The retinoblastoma gene Rb is the prototype tumor suppressor and is conserved in Drosophila. We use the developing fly retina as a model system to investigate the role of Drosophila Rb (rbf) during differentiation. This report shows that mutation of rbf and rhinoceros (rno), which encodes a PHD domain protein, leads to a synergistic delay in photoreceptor cell differentiation in the developing eye disc. We show that this differentiation delay phenotype is caused by decreased levels of different components of the Epidermal Growth Factor Receptor (EGFR) signaling pathway in the absence of rbf and rno. We show that rbf is required for normal expression of Rhomboid proteins and activation of MAP kinase in the morphogenetic furrow (MF), while rno is required for the expression of Pointed (Pnt) and Ebi proteins, which are key factors that mediate EGFR signaling output in the nucleus. Interestingly, while removing the transcription activation function of dE2F1 is sufficient to suppress the synergistic differentiation delay, a mutant form of de2f1 that disrupts the binding with RBF but retains the transcription activation function does not mimic the effect of rbf loss. These observations suggest that RBF has additional functions besides dE2F1 binding that regulates EGFR signaling and photoreceptor differentiation.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Receptores ErbB/metabolismo , Olho/metabolismo , Proteínas Nucleares/metabolismo , Células Fotorreceptoras de Invertebrados/metabolismo , Proteína do Retinoblastoma/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Diferenciação Celular/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Ativação Enzimática , Receptores ErbB/genética , Olho/crescimento & desenvolvimento , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Homeodomínio , Imuno-Histoquímica , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Mutação , Proteínas Nucleares/genética , Fenótipo , Células Fotorreceptoras de Invertebrados/citologia , Proteína do Retinoblastoma/genética , Transdução de Sinais/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The retinoblastoma gene Rb is a prototype tumor suppressor which is conserved in Drosophila. Although much is known about the roles of Rb in cell proliferation and apoptosis, much less is known about how Rb regulates cell differentiation. Inactivation of Drosophila Rb (rbf) exhibited subtle differentiation defects similar to inactivation of Rb in mice, suggesting the existence of redundant mechanisms in the control of cell differentiation. To test this possibility and to characterize the role of Rbf in cell differentiation during retinal development, we carried out a genetic screen and identified a mutation in rhinoceros (rno), which leads to synergistic differentiation defects in conjunction with rbf inactivation. Characterization of an early differentiation defect, the multiple-R8 phenotype, revealed that this phenotype was caused by limiting amounts of Notch signaling due to reduced expression of the Notch ligand, Delta (Dl). Decreasing the gene dosage of Dl enhanced the multiple-R8 phenotype, while increasing the level of Dl suppressed this phenotype. Interestingly, removal of the transcriptional activation of dE2F1 partially restores Dl expression in rbf,rno mutant clones and suppresses the associated differentiation defects, indicating that this differentiation function of RBF is mediated by its regulation of dE2F1 activity.
Assuntos
Diferenciação Celular/fisiologia , Proteínas de Drosophila/metabolismo , Fator de Transcrição E2F1/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteína do Retinoblastoma/metabolismo , Fatores de Transcrição/metabolismo , Animais , Animais Geneticamente Modificados , Proteínas de Drosophila/genética , Drosophila melanogaster/anatomia & histologia , Drosophila melanogaster/fisiologia , Fator de Transcrição E2F1/genética , Feminino , Dosagem de Genes , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Células Fotorreceptoras de Invertebrados/citologia , Células Fotorreceptoras de Invertebrados/patologia , Células Fotorreceptoras de Invertebrados/fisiologia , Proteína do Retinoblastoma/genética , Fatores de Transcrição/genéticaRESUMO
Cell differentiation and cell cycle exit are coordinately regulated during development; however, the molecular logic underlying this regulation is not known. The Drosophila cdk inhibitor Dacapo (Dap) is one of the key cell cycle regulators that exhibit dynamic expression during development and contribute to the developmental regulation of the cell cycle. In this study, regulation of Dap expression during cell type specification was investigated. The expression of Dap in the R2 and R5 precursors of the developing eye and in the newly recruited leg disc femoral sense organ precursors was found to be controlled by the epidermal growth factor receptor signaling-regulated transcription factor Pointed (Pnt) and the proneural basic helix-loop-helix proteins Atonal (Ato) and Daughterless (Da). We show that Pnt, Ato, and Da regulate Dap expression directly through their respective binding sites precisely at the time when these transcription factors function to specify neural fates. These results show that Dap expression is directly regulated by developmental mechanisms that simultaneously control cell type specification. This is potentially a general mechanism by which the expression of key cell cycle regulators is coordinated with differentiation during normal development. The direct regulation of key cell cycle regulators by the differentiation factors ensures coordinated regulation of cell cycle and differentiation.