Assuntos
Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Janus Quinase 2/metabolismo , Animais , Complexo CD3/metabolismo , Granulócitos/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Mutação/genética , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismoAssuntos
Adesão Celular/fisiologia , Granulócitos/patologia , Integrina beta1/fisiologia , Janus Quinase 2/metabolismo , Transtornos Mieloproliferativos/patologia , Molécula 1 de Adesão de Célula Vascular/metabolismo , Doença Crônica , Humanos , Transtornos Mieloproliferativos/enzimologia , Transtornos Mieloproliferativos/metabolismoRESUMO
Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a MPN characterized by bone marrow fibrosis, cytopenias, splenomegaly and constitutional symptoms. Pomalidomide, an immune-modifying drug, is reported to improve anaemia and thrombocytopenia in some patients with MPN-associated myelofibrosis. We designed a phase 2 study of pomalidomide in patients with MPN-associated myelofibrosis and anaemia and/or thrombocytopenia and/or neutropenia. Subjects received pomalidomide 2.0 mg/day in cohort 1 (n=38) or 0.5 mg/day in cohort 2 (n=58). Prednisolone was added if there was no response after 3 months in cohort 1 and based on up-front randomization in cohort 2 if there was no response at 3 or 6 months. Response rates were 39% (95% confidence interval (CI), 26-55%) in cohort 1 and 24% (95% CI, 15-37%) in cohort 2. In a multivariable logistic regression model pomalidomide at 2.0 mg/day (odds ratio (OR), 2.62; 95% CI, 1.00-6.87; P=0.05) and mutated TET2 (OR, 5.07; 95% CI, 1.16-22.17; P=0.03) were significantly associated with responses. Median duration of responses was 13.0 months (range 0.9-52.7). There was no significant difference in response rates or duration in subjects receiving or not receiving prednisolone. Clinical trial MPNSG 01-09 is registered at ClinicalTrials.gov (NCT00949364) and clinicaltrialsregister.eu (EudraCT Number: 2009-010738-23).
Assuntos
Fatores Imunológicos/uso terapêutico , Transtornos Mieloproliferativos/complicações , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/etiologia , Talidomida/análogos & derivados , Idoso , Idoso de 80 Anos ou mais , Alelos , Biomarcadores , Bandeamento Cromossômico , Feminino , Humanos , Fatores Imunológicos/administração & dosagem , Fatores Imunológicos/efeitos adversos , Masculino , Pessoa de Meia-Idade , Mutação , Transtornos Mieloproliferativos/diagnóstico , Transtornos Mieloproliferativos/genética , Fenótipo , Prednisolona/administração & dosagem , Prednisolona/efeitos adversos , Prednisolona/uso terapêutico , Mielofibrose Primária/diagnóstico , Talidomida/administração & dosagem , Talidomida/efeitos adversos , Talidomida/uso terapêutico , Resultado do TratamentoRESUMO
Activating mutations of FMS-like tyrosine kinase 3 (FLT3), notably internal tandem duplications (ITDs), are associated with a grave prognosis in acute myeloid leukemia (AML). Transforming FLT3ITD signal transduction causes formation of reactive oxygen species (ROS) and inactivation of the protein-tyrosine phosphatase (PTP) DEP-1/PTPRJ, a negative regulator of FLT3 signaling. Here we addressed the underlying mechanisms and biological consequences. NADPH oxidase 4 (NOX4) messenger RNA and protein expression was found to be elevated in FLT3ITD-positive cells and to depend on FLT3ITD signaling and STAT5-mediated activation of the NOX4 promoter. NOX4 knockdown reduced ROS levels, restored DEP-1 PTP activity and attenuated FLT3ITD-driven transformation. Moreover, Nox4 knockout (Nox4(-/-)) murine hematopoietic progenitor cells were refractory to FLT3ITD-mediated transformation in vitro. Development of a myeloproliferative-like disease (MPD) caused by FLT3ITD-transformed 32D cells in C3H/HeJ mice, and of a leukemia-like disease in mice transplanted with MLL-AF9/ FLT3ITD-transformed murine hematopoietic stem cells were strongly attenuated by NOX4 downregulation. NOX4-targeting compounds were found to counteract proliferation of FLT3ITD-positive AML blasts and MPD development in mice. These findings reveal a previously unrecognized mechanism of oncoprotein-driven PTP oxidation, and suggest that interference with FLT3ITD-STAT5-NOX4-mediated overproduction of ROS and PTP inactivation may have therapeutic potential in a subset of AML.
Assuntos
Transformação Celular Neoplásica , Leucemia Mieloide Aguda/patologia , NADPH Oxidases/fisiologia , Proteínas Tirosina Fosfatases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tirosina Quinase 3 Semelhante a fms/fisiologia , Animais , Células Cultivadas , Humanos , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , NADPH Oxidase 4 , NADPH Oxidases/genética , Proteínas Tirosina Fosfatases Classe 3 Semelhantes a Receptores/análise , Sequências de Repetição em Tandem , Tirosina Quinase 3 Semelhante a fms/análiseAssuntos
Doença Enxerto-Hospedeiro/imunologia , Janus Quinases/antagonistas & inibidores , Transtornos Mieloproliferativos/imunologia , Inibidores de Proteínas Quinases/farmacologia , Linfócitos T/imunologia , Animais , Benzamidas/farmacologia , Células Cultivadas , Modelos Animais de Doenças , Doença Enxerto-Hospedeiro/tratamento farmacológico , Doença Enxerto-Hospedeiro/metabolismo , Doença Enxerto-Hospedeiro/patologia , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Transtornos Mieloproliferativos/tratamento farmacológico , Transtornos Mieloproliferativos/metabolismo , Transtornos Mieloproliferativos/patologia , Pirimidinas/farmacologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/patologiaAssuntos
Leucemia Mieloide Aguda/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Tirosina Quinases/antagonistas & inibidores , Tirosina Quinase 3 Semelhante a fms/genética , Sequência de Aminoácidos , Animais , Proliferação de Células , Relação Dose-Resposta a Droga , Humanos , Técnicas In Vitro , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Camundongos , Camundongos Endogâmicos BALB C , MutaçãoRESUMO
Erythropoiesis is a tightly regulated process. Development of red blood cells occurs through differentiation of hematopoietic stem cells (HSCs) into more committed progenitors and finally into erythrocytes. Binding of erythropoietin (Epo) to its receptor (EpoR) is required for erythropoiesis as it promotes survival and late maturation of erythroid progenitors. In vivo and in vitro studies have highlighted the requirement of EpoR signaling through Janus kinase 2 (Jak2) tyrosine kinase and Stat5a/b as a central pathway. Here, we demonstrate that phospholipase C gamma 1 (Plcγ1) is activated downstream of EpoR-Jak2 independently of Stat5. Plcγ1-deficient pro-erythroblasts and erythroid progenitors exhibited strong impairment in differentiation and colony-forming potential. In vivo, suppression of Plcγ1 in immunophenotypically defined HSCs (Lin(-)Sca1(+)KIT(+)CD48(-)CD150(+)) severely reduced erythroid development. To identify Plcγ1 effector molecules involved in regulation of erythroid differentiation, we assessed changes occurring at the global transcriptional and DNA methylation level after inactivation of Plcγ1. The top common downstream effector was H2afy2, which encodes for the histone variant macroH2A2 (mH2A2). Inactivation of mH2A2 expression recapitulated the effects of Plcγ1 depletion on erythroid maturation. Taken together, our findings identify Plcγ1 and its downstream target mH2A2, as a 'non-canonical' Epo signaling pathway essential for erythroid differentiation.