RESUMO
Several studies reported that patients with acute myeloid leukemia (AML) who remain in long-term remission after allogeneic or autologous transplant have a shorter life expectancy, compared to the general population. However, little is known about the life expectancy of adult long-term survivors of AML who were treated with chemotherapy alone without a transplant and there have been no comparisons with survival among the general population. The current study indicates that the life expectancy of AML patients who achieved and maintained CR for at least 3 years is shorter than expected for age in the US population. This was observed also in patients who did not undergo a transplant including those who have not relapsed during the entire long follow-up period. Thus, late relapse does not explain why patients without transplants have a shortened life expectancy. Taken together, these data strongly suggest that prior chemotherapy for the underlying AML is at least a major contributing factor for the known shortened life expectancy post-transplant.
RESUMO
In this study, a protein that interacts with sequences encoded by the first exon of the protein kinase Bcr was cloned. The Bcr-associated protein 1 (Bap-1) is a member of the 14-3-3 family of proteins. Bap-1 interacts with full-length c-Bcr and with the chimeric Bcr-Abl tyrosine kinase of Philadelphia chromosome (Ph1)-positive human leukemias. Bap-1 is a substrate for the Bcr serine-threonine kinase and is also phosphorylated on tyrosine by Bcr-Abl but not by c-Abl. Bap-1 may function in the regulation of c-Bcr and may contribute to the transforming activity of Bcr-Abl in vivo. 14-3-3 proteins are essential for cell proliferation and have a role in determining the timing of mitosis in yeast. Through direct binding to sequences present in Bcr and in other proteins implicated in signaling, the mammalian 14-3-3 proteins may link specific signaling protein components to mitogenic and cell-cycle control pathways.
Assuntos
Proteínas de Fusão bcr-abl/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Tirosina 3-Mono-Oxigenase , Proteínas 14-3-3 , Animais , Divisão Celular , Linhagem Celular , Transformação Celular Neoplásica , Humanos , Camundongos , Fosforilação , Poli(ADP-Ribose) Polimerases/metabolismo , Proteínas/isolamento & purificação , Proteínas Proto-Oncogênicas c-bcr , Ratos , Proteínas Recombinantes de Fusão/metabolismoRESUMO
A relationship was proved between constitutive activity of leukemic cell c-jun-N-terminal kinase (JNK) and treatment failure in AML. Specifically, early treatment failure was predicted by the presence of constitutive JNK activity. The mechanistic origins of this association was sought. A multidrug resistant leukemic cell line, HL-60/ADR, characterized by hyperexpression of c-jun and JNK activity, was transfected with a mutant c-jun vector, whose substrate N-terminal c-jun serines were mutated. Down-regulated expression occurred of c-jun/AP-1-dependent genes, catalase and glutathione-S-transferase (GST) pi, which participate in cellular homeostasis to oxidative stress and xenobiotic exposure. MRP-efflux was abrogated in HL-60/ADR cells with dominant-negative c-jun, perhaps because MRP1 protein expression was also lost. Heightened sensitivity to daunorubicin resulted in cells subjected to this change. Biochemical analysis in 67 primary adult AML samples established a statistical correlation between cellular expression of c-jun and JNK activity, JNK activity with hyperleukocytosis at presentation of disease, and with exuberant MRP efflux. These findings reflect the survival role for c-jun/AP-1 and its regulatory kinase previously demonstrated for yeast in homeostatic response to oxidative stress and in operation of ATP-binding cassette efflux pumps, and may support evolutionary conservation of such function. Thus, JNK and c-jun may be salient drug targets in multidrug resistant AML.
Assuntos
Resistencia a Medicamentos Antineoplásicos/fisiologia , Leucemia Mieloide/enzimologia , Proteínas Quinases Ativadas por Mitógeno/fisiologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Doença Aguda , Células da Medula Óssea/patologia , Divisão Celular , Daunorrubicina , Resistência a Múltiplos Medicamentos/fisiologia , Células HL-60 , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno , Leucemia Mieloide/tratamento farmacológico , Leucemia Mieloide/patologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas c-jun/metabolismo , Transdução de SinaisRESUMO
Among hematologic malignancies, there are three disorders whose behavior is governed principally by the abnormal proliferation of a malignant megakaryocytic clone or a product thereof. These disorders are essential thrombocythemia, agnogenic myeloid metaplasia, and acute megakaryoblastic leukemia. Although there are other myeloproliferative diseases that can have high platelet counts, the major pathobiology of those diseases most commonly results from the proliferation of other hematopoietic lineages. Despite the rarity of the three disorders of malignant megakaryopoiesis mentioned above, advances have been made in the diagnosis, prognosis, and treatment of these disorders in recent years. However, understanding of the cellular and especially molecular pathobiology lags far behind.
Assuntos
Neoplasias Hematológicas , Megacariócitos , Humanos , Leucemia Megacarioblástica Aguda/diagnóstico , Leucemia Megacarioblástica Aguda/terapia , Mielofibrose Primária/diagnóstico , Mielofibrose Primária/terapia , Prognóstico , Trombocitemia Essencial/diagnóstico , Trombocitemia Essencial/terapiaRESUMO
2-Chlorodeoxyadenosine (2-CdA) is a purine analog which has anti-leukemic activity in phase II trials in pediatric acute myeloid leukemia (AML) patients. An adult phase I trial suggested possible similar activity although neurotoxicity at higher doses was seen. We conducted a phase II trial of 2-CdA in patients with relapsed or refractory AML. 2-CdA was administered by continuous intravenous infusion at a dose of 17 mg/m(2) per day x5 days. Patients not achieving aplasia by day 21 were eligible for a second course of therapy. Fifteen patients (nine relapsed and six refractory AML) were enrolled including seven men and eight women with a median age of 60 years and median ECOG PS of 1. There were five deaths on study due to infections (two), AML (two), or hepatic failure (one). The 2-CdA was well tolerated without severe nausea, vomiting or stomatitis (all Assuntos
Antineoplásicos/uso terapêutico
, Cladribina/uso terapêutico
, Leucemia Mieloide Aguda/tratamento farmacológico
, Adulto
, Idoso
, Cladribina/efeitos adversos
, Feminino
, Humanos
, Masculino
, Pessoa de Meia-Idade
, Recidiva
RESUMO
Antagonism of norepinephrine (NE) and 5-hydroxytryptamine (5-HT) by sulpiride was studied in vitro on rabbit aortic strips. Concentrations of sulpiride ranging from 3 X 10(-5) to 3 X 10(-3) M caused a progressive shift of the dose response curves of both NE and 5-HT to the right without inhibiting the responses to KCl. pA2 values of sulpiride calculated from Schild plots against NE and 5-HT were 4.6 and 4.4, respectively. Thus, sulpiride, which has been previously shown to be the most potent antagonist of the dopamine vascular receptors, is a very weak alpha-adrenergic or 5-HT antagonist.
Assuntos
Norepinefrina/antagonistas & inibidores , Antagonistas da Serotonina , Sulpirida/farmacologia , Animais , Aorta/efeitos dos fármacos , Aorta/fisiologia , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , CoelhosRESUMO
Acute hyperleukocytic leukemias (AHL) are associated with a very high early mortality rate mostly due to respiratory failure or intracranial bleeding. The pathophysiological process leading to these complications is called leukostasis but the biological mechanisms underlying its development and progression remain unclear. Although traditionally related to "over-crowding" of leukemic blasts in the capillaries of the microcirculation, leukostasis is likely to result from direct endothelial cell damage. This damage is probably mediated by soluble cytokines released during the interaction between leukemic cells and vascular endothelium and by the subsequent migration of leukemic blasts in the perivascular space. Leukemic cell's ability to respond to chemotactic cytokines and their expression of specific adhesion molecules are probably more important in determining whether leukostasis will develop than the number of circulating blasts. This could explain why leukostasis does not develop in all patients with AHL. The identification of the adhesion molecules, cytokines and receptors mediating endothelial cell damage in AHL should become a priority if therapeutic improvements are desired. Leukapheresis is widely used but it is unclear whether it provides additional benefit to a simpler and less invasive intervention with allopurinol, hydroxyurea and intravenous fluids. Cranial irradiation is not generally recommended. Induction chemotherapy should be started without delay. It is hoped that specific pharmacological inhibitors of the interaction between leukemic cells and vascular endothelium will result in an improved outcome for this very high-risk population.
Assuntos
Leucemia Mieloide/sangue , Leucostasia/etiologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangue , Doença Aguda , Adolescente , Adulto , Criança , Pré-Escolar , Citogenética , Citocinas/efeitos adversos , Citocinas/sangue , Endotélio Vascular/lesões , Endotélio Vascular/patologia , Feminino , Humanos , Lactente , Leucemia Mieloide/complicações , Leucemia Mieloide/patologia , Leucostasia/sangue , Leucostasia/terapia , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/complicações , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologiaRESUMO
Untreated acute leukemia is a uniformly fatal disease with a median survival time shorter than 3 months. Current treatment strategies provide a significant increase in survival time for most patients, some of whom may be cured. The majority of patients with acute leukemia, however, ultimately die of the disease or complications of treatment. The effective treatment of acute leukemia requires (1) differentiation of acute myeloid leukemia (AML) from acute lymphoblastic leukemia (ALL) and recognition of clinically relevant subtypes; (2) identification of patients who are more likely or less likely than average to benefit from a conventional treatment; and (3) selection of therapy that provides a reasonable likelihood of response with acceptable risk of toxic effects. The diagnosis of acute leukemia is established in most cases by a bone marrow aspirate that demonstrates at least 30% blast cells. The traditional criteria to distinguish between AML and ALL rely on morphology and cytochemical reactions. Immunologic analysis of antigen expression and analysis for numerical or structural chromosomal abnormalities of leukemia cells are routinely feasible. Karyotypic analysis is of prognostic importance and should be performed on all diagnostic specimens of bone marrow aspirate. Immunophenotypic analysis may be useful to confirm the disease classification in selected cases. The importance of the routine immunophenotypic characterization of acute leukemia, however, is controversial. The subtypes that must be recognized because of the need for specific treatment include (a) acute promyelocytic leukemia (APL), which is the M3 subtype of AML, and (b) the L3 subtype or mature B-cell ALL. Induction therapy for acute leukemia is treatment intended to achieve induction of complete remission (CR). Complete remission is defined as the absence of morphologic evidence of leukemia after recovery of the peripheral blood cell counts. Failure to achieve CR may be attributed to death during chemotherapy-induced bone marrow hypoplasia or to drug resistance manifested either as failure to achieve hypoplasia or as persistent leukemia after recovery from hypoplasia. Postremission therapy is treatment administered in CR to prevent or delay relapse of the leukemia. However, the majority of patients have disease relapse. Intensification of therapy is a treatment strategy designed to overcome resistance to chemotherapy. Recent clinical trials of intensified induction or postremission therapy suggest improved outcome. However, the toxic effects of dose intensification can be substantial, limiting any potential benefit of this approach. Identification of prognostic factors may allow one to estimate the likelihood of an outcome, to determine an optimal treatment strategy. It is well established that age at the time of diagnosis, leukemia cell karyotype, and whether the leukemia is de novo or secondary are factors that influence treatment decisions. Patients with favorable prognostic factors should probably receive conventional therapy. Patients with unfavorable prognostic factors have shown little benefit from conventional therapy. In addition, factors that indicate poor outcome with conventional therapy are also predictive of poor outcome with intensified therapy. Consequently, these patients should be considered for investigational therapeutic strategies. The bias may be to counsel them to accept the potential increased morbidity of such treatment before there is definite evidence of the possibility of improved outcome. Induction chemotherapy for younger patients with AML (less than 55 years of age) in general consists of one or more courses of cytarabine (ara-C) and an anthracycline or an anthracycline derivative. Randomized trials have failed to confirm that treatment with either etoposide or high-dose ara-C induces disease remission. Patients with secondary AML, high levels of CD34 antigen expression, or an unfavorable karyotype, however, may benefit from ind
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Leucemia Mieloide/terapia , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Doença Aguda , Adulto , Fatores Etários , Transplante de Medula Óssea , Humanos , Leucemia Mieloide/diagnóstico , Leucemia Promielocítica Aguda/terapia , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Prognóstico , Recidiva , Indução de RemissãoRESUMO
This study of vosaroxin evaluated dose-limiting toxicity (DLT), maximum-tolerated dose (MTD), pharmacokinetics (PK), clinical activity and pharmacodynamics in relapsed/refractory leukemia. Dosing was weekly (days 1, 8 and 15) or twice weekly (days 1, 4, 8 and 11). Seventy-three treated patients had a median age of 65 years, 85% had acute myeloid leukemia and 78% had refractory disease. Weekly schedule: 42 patients received 18-90 mg/m(2); MTD was 72 mg/m(2). Twice-weekly schedule: 31 patients received 9-50 mg/m(2); MTD was 40 mg/m(2). DLT was stomatitis; primary non-hematologic toxicity was reversible gastrointestinal symptoms and febrile neutropenia. Thirty-day all-cause mortality was 11%. Five patients had complete or incomplete remissions; median duration was 3.1 months. A morphologic leukemia-free state (bone marrow blast reduction to <5%) occurred in 11 additional patients. Antileukemic activity was associated with total dose or weekly time above 1 µmol/l plasma vosaroxin concentration (P<0.05). Vosaroxin exposure was dose proportional over 9-90 mg/m(2). The average terminal half-life was ~25 h and clearance was non-renal. No induction or inhibition of vosaroxin metabolism was evident. Vosaroxin-induced DNA damage was detected as increased intracellular γH2AX. Vosaroxin had an acceptable safety profile, linear PK and encouraging clinical activity in relapsed/refractory leukemia.
Assuntos
Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Leucemia Mieloide Aguda/tratamento farmacológico , Naftiridinas/uso terapêutico , Recidiva Local de Neoplasia/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Terapia de Salvação , Tiazóis/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Resultado do Tratamento , Adulto JovemRESUMO
A total of 50 consecutive patients (median age, 57.5 years) with AML (n=30) or myelodysplasia (MDS, n=20) underwent HLA matched related donor (MRD, n=27) or unrelated donor (MUD, n=23) peripheral blood hematopoietic cell transplantation after nonmyeloablative CY/fludarabine (Flu) conditioning. GVHD prophylaxis included CsA (n=19)+/-mycophenolate mofetil (n=31). At a median follow-up of 59 months, 21 patients (42%) were alive without evidence of disease. By Kaplan-Meier analysis, year 1-4 disease-free survival (DFS) and OS estimates were 0.50/0.58, 0.40/0.46, 0.37/0.43 and 0.37/0.41. MUD recipients were engrafted quickly (13.5 days) compared to MRD recipients (16 days) and relapsed/progressed less frequently (P=0.005). Overall grade 3/4 acute GVHD (aGVHD) occurred in 26% in the absence of antecedent mucositis and was associated with chronic GVHD (cGVHD) and poor OS. Extensive cGVHD developed in 51.2% of 100 day survivors. Rates of aGVHD, cGVHD and survival were similar between MRD and MUD recipients. Of 14 survivors with cGVHD, 5 (35.7%) experienced resolution off immunosuppression, suggesting that tolerance with HLA matched grafts is possible at an advanced age by this method. This study provides further evidence for prolonged DFS after CY/Flu MRD allotransplantation for AML/MDS, and extends the findings to older patients and those with unrelated donors.
Assuntos
Transplante de Células-Tronco Hematopoéticas/métodos , Leucemia Mieloide Aguda/terapia , Síndromes Mielodisplásicas/terapia , Condicionamento Pré-Transplante/métodos , Adolescente , Adulto , Fatores Etários , Idoso , Ciclofosfamida/uso terapêutico , Intervalo Livre de Doença , Feminino , Seguimentos , Doença Enxerto-Hospedeiro/tratamento farmacológico , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Transplante de Células-Tronco Hematopoéticas/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Sobrevida , Transplante Homólogo , Vidarabina/análogos & derivados , Vidarabina/uso terapêutico , Adulto JovemRESUMO
The treatment outcome for most adults with acute myeloid leukemia (AML) remains unacceptable. Additional agents or substitution of high-dose cytarabine for conventional-dose cytarabine during induction does not improve the remission rate or overall survival. There is substantial toxicity with high-dose cytarabine during induction. Thus, induction therapy for newly diagnosed patients with AML should consist of cytarabine (100 mg/m(2) as a continuous intravenous infusion over 24 hours for 7 days) and daunorubicin, idarubicin, or mitoxantrone. Meta-analysis demonstrates a modest benefit for idarubicin. Most patients who achieve a remission should receive further therapy with two to four cycles of high-dose cytarabine. Allogeneic stem cell transplant is reserved for patients with poor risk features. There is no role for autologous stem cell transplant in first remission outside a clinical trial. The majority of adults relapse. Salvage therapy usually consists of high-dose cytarabine. Allogeneic or autologous stem cell transplantation is preferred in second or subsequent remission. Uncommon diseases such as AML, for which the outcome remains poor, should be treated on clinical trials whenever possible.
Assuntos
Leucemia Mieloide/terapia , Doença Aguda , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Transplante de Medula Óssea , Ensaios Clínicos como Assunto , Terapia Combinada , Transplante de Células-Tronco Hematopoéticas , Humanos , Leucemia Mieloide/patologia , Prognóstico , Indução de Remissão , Fatores de Risco , Taxa de SobrevidaRESUMO
Activated factor V (Va) serves as an essential protein cofactor for the conversion of prothrombin to thrombin by factor Xa. Analysis of the factor V cDNA indicates that the protein contains several types of internal repeats with the following domain structure: A1-A2-B-A3-C1-C2. In this report we describe the isolation and characterization of genomic DNA coding for human factor V. The factor V gene contains 25 exons which range in size from 72 to 2820 bp. The structure of the gene for factor V is similar to the previously characterized gene for factor VIII. Based on the aligned amino acid sequences of the two proteins, 21 of the 24 intron-exon boundaries in the factor V gene occur at the same location as in the factor VIII gene. In both genes, the junctions of the A1-A2 and A2-A3 domains are each encoded by a single exon. In contrast, the boundaries between domains A3-C1 and C1-C2 occur at intron-exon boundaries, which is consistent with evolution through domain duplication and exon shuffling. The connecting region or B domain of factor V is encoded by a single large exon of 2820 bp. The corresponding exon of the factor VIII gene contains 3106 bp. The 5' and 3' ends of both of these exons encode sequences homologous to the carboxyl-terminal end of domain A2 and the amino-terminal end of domain A3 in ceruloplasmin. There is otherwise no homology between the B domain exons.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Fator V/genética , Sequência de Aminoácidos , Sequência de Bases , Southern Blotting , DNA/genética , Éxons , Humanos , Íntrons , Dados de Sequência Molecular , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
The regulation of macrophage colony-stimulating factor (M-CSF) gene expression by phorbol esters and calcium ionophore (A23187) was studied in HL-60 cells. In untreated HL-60 cells, M-CSF transcripts were undetectable, but transcripts were present within 2 h of A23187 treatment or within 8 h of phorbol 12,13-dibutyrate (PdBu) treatment. Concurrent treatment of HL-60 cells with A23187 and cycloheximide (CHX) for 6 h led to a superinduction of message over A23187 treatment alone. But concurrent treatment with PdBu and CHX for 24 h abolished expression of the message normally present after 24 h of PdBu treatment. The role of new protein synthesis in transcriptional regulation of M-CSF was studied by run-on transcription assay. Untreated HL-60 cells or cells treated with CHX alone do not transcribe M-CSF mRNA. However, cells treated with A23187 for 6 h and CHX for 1, 3, or 6 h transcribed more M-CSF than cells treated with A23187 alone for 6 h. CHX also regulates M-CSF expression by message stabilization. The t1/2 of M-CSF mRNA was 45 min in cells treated with A23187 for 6 h or in cells treated with PdBu for 24 h, was over 2 h in HL-60 cells treated with A23187 for 6 h and CHX for 1 h, and was 3 h in cells treated with PdBu for 24 h and CHX for 1 h. We conclude that M-CSF gene expression can be differentially regulated in HL-60 cells and that new protein synthesis plays an important role in both the transcriptional and posttranscriptional regulation.
Assuntos
Fator Estimulador de Colônias de Macrófagos/genética , Macrófagos/fisiologia , Northern Blotting , Calcimicina/farmacologia , Cicloeximida/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Técnicas In Vitro , Dibutirato de 12,13-Forbol/farmacologia , RNA Mensageiro/genética , Transcrição Gênica/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
Multicentric Castleman's disease (MCD), or multicentric angiofollicular lymph node hyperplasia, is an uncommon lymphoproliferative disorder which typically present with constitutional symptoms, multicentric lymphadenopathy, hepatosplenomegaly, effusions, and ascites. We describe a patient with several novel manifestations of MCD: sicca syndrome, lacrimal and salivary gland enlargement, cardiomyopathy, and palmar and plantar rash. Treatment of MCD with chlorambucil and prednisone was effective in the short term followup of this patient. MCD merits consideration in patients with lymphadenopathy and multisystem disease, including sicca syndrome, heart failure or rash.
Assuntos
Cardiomiopatias/etiologia , Hiperplasia do Linfonodo Gigante/complicações , Pé , Mãos , Síndrome de Sjogren/etiologia , Dermatopatias/etiologia , Adulto , Cardiomiopatias/patologia , Hiperplasia do Linfonodo Gigante/tratamento farmacológico , Hiperplasia do Linfonodo Gigante/patologia , Clorambucila/uso terapêutico , Feminino , Humanos , Prednisona/uso terapêuticoRESUMO
Activity of the c-jun N-terminal kinase (JNK) has been shown in hematopoietic cells transformed by p210 BCR-ABL. However, analysis has not been reported for hematopoietic cells on the consequences of this activity for c-jun promoter regulation within its distinctive proximal 8-base consensus CRE-like element, an element linked to JNK-mediated increase in c-jun transcription. In the present study, regulation of the proximal c-jun promoter was studied in murine myeloid cells transformed by p210 BCR-ABL. Promoter regulation in p210 BCR-ABL transformed cells was compared with regulation of the promoter in nontransformed interleukin-3 (IL-3)-dependent parental cells. The composition of nuclear AP-1 proteins contained within cells with p210 BCR-ABL, and their binding to the c-jun promoter proximal CRE-like element, was compared with the composition and binding of AP-1 proteins in IL-3-treated parental cells without p210 BCR-ABL. The present analysis found fivefold increased c-jun transcription occurring in p210 BCR-ABL transformed murine myeloid cells possessing a corresponding magnitude of increased kinase activity of JNK, compared with IL-3-stimulated parental cells. Augmented JNK activity was accompanied by increased nuclear abundance of c-jun and c-fos proteins that bound specifically to the proximal c-jun promoter CRE element. Also, representative human leukemic cell lines expressing p210 BCR-ABL and possessing abundant kinase activity of JNK, when compared with parental cells that were deficient in JNK activity, had increased c-jun and c-fos proteins. Finally, to show the relevance of these observations in model systems, we studied blast cells from patients with Philadelphia chromosome-positive acute leukemic transformation, and observed comparable activities of JNK catalysis and c-jun/AP-1 protein relative to the cell lines that possessed p210 BCR-ABL and JNK activity. These studies provide a basis for investigating the set of downstream genes which augmented c-jun/AP-1 activity enlists in the process of transformation by p210 BCR-ABL.
Assuntos
Proteínas de Fusão bcr-abl/fisiologia , Genes jun , Células-Tronco Hematopoéticas/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno , Quinases de Proteína Quinase Ativadas por Mitógeno , Proteínas de Neoplasias/fisiologia , Proteínas Quinases/fisiologia , Animais , Transformação Celular Neoplásica , Ativação Enzimática , Proteínas de Fusão bcr-abl/genética , Células HL-60 , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , MAP Quinase Quinase 4 , Substâncias Macromoleculares , Camundongos , Mutagênese Sítio-Dirigida , Fosforilação , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas c-jun/biossíntese , Proteínas Recombinantes de Fusão/fisiologia , Transcrição Gênica , Transfecção , Células Tumorais CultivadasRESUMO
BCR-ABL is a chimeric oncoprotein that exhibits deregulated tyrosine kinase activity and is implicated in the pathogenesis of Philadelphia chromosome (Ph1)-positive human leukemias. Sequences within the first exon of BCR are required to activate the transforming potential of BCR-ABL. The SH2/SH3 domain-containing GRB-2 protein links tyrosine kinases to Ras signaling. We demonstrate that BCR-ABL exists in a complex with GRB-2 in vivo. Binding of GRB-2 to BCR-ABL is mediated by the direct interaction of the GRB-2 SH2 domain with a phosphorylated tyrosine, Y177, within the BCR first exon. The BCR-ABL-GRB-2 interaction is required for activation of the Ras signaling pathway. Mutation of Y177 to phenylalanine (Y177F) abolishes GRB-2 binding and abrogates BCR-ABL-induced Ras activation. The BCR-ABL (Y177F) mutant is unable to transform primary bone marrow cultures and is impaired in its ability to transform Rat1 fibroblasts. These findings implicate activation of Ras function as an important component in BCR-ABL-mediated transformation and demonstrate that GRB-2 not only functions in normal development and mitogenesis but also plays a role in oncogenesis.