RESUMO
The 90-kDa heat shock protein (HSP90) is implicated in the conformational maturation and stabilization of a variety of client proteins with receptor and signal transduction functions. The objective of this study was to assess its expression in primary acute myeloid leukemia (AML) cells and to evaluate its biological and clinical significance. The in vitro effects of 17-AAG, a selective inhibitor of HSP90, was also evaluated. Cells from 65 patients with newly diagnosed AML were studied. The expression of HSP90 correlated with that of CD34, p170, and bcl-2 proteins but not with white cell counts, FAB or WHO subtype, or cytogenetics. HSP90 levels were also higher in samples exhibiting an autonomous growth in liquid culture or forming spontaneous colonies. A concomitant constitutive activation of the extracellular signal-regulated kinase and phosphatidylinositol 3-kinase/AKT pathways was observed in a majority of samples and was significantly correlated with HSP90 expression. All patients received induction chemotherapy. The percentages of HSP90-, CD34-, bcl-2-, and p170-positive cells were higher in patients who did not attain complete remission. Survival was also shorter in patients with high levels of HSP90. In vitro exposure of leukemic cells to 17-allylamino-demethoxy geldanamycin (17-AAG) resulted in inhibition of growth in liquid and clonogeneic cultures and in apoptosis, at concentrations which in most cases were not toxic for normal CD34-positive or progenitor cells. The concentration inhibiting 50% growth at 72 h in liquid culture correlated with HSP90 expression. Our study suggests that HSP90 is overexpressed in poor-prognosis AML cells and plays a role in cell survival and resistance to chemotherapy. Targeted therapy with 17-AAG represents a promising antileukemic strategy in adult AML.
Assuntos
Proteínas de Choque Térmico HSP90/metabolismo , Leucemia Mieloide Aguda/metabolismo , Adulto , Idoso , Antígenos CD34/metabolismo , Benzoquinonas/farmacologia , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Proteínas de Choque Térmico HSP90/genética , Humanos , Lactamas Macrocíclicas/farmacologia , Pessoa de Meia-Idade , Células Mieloides/citologia , Células Mieloides/efeitos dos fármacos , Células Mieloides/metabolismo , Estatística como Assunto , Taxa de SobrevidaRESUMO
Using flow cytometry, we investigated the clinical and hematologic relevance of expression of heat-shock proteins (HSP) HSP27, HSP60, HSP70, HSP90 and HSP110 in bone marrow of 142 patients with newly diagnosed myelodysplastic syndromes, together with that of the membrane differentiation antigen CD34 and the drug-resistance related protein, P170 (Pgp).
Assuntos
Proteínas de Choque Térmico/biossíntese , Síndromes Mielodisplásicas/metabolismo , Subfamília B de Transportador de Cassetes de Ligação de ATP , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD34/biossíntese , Antígenos CD34/genética , Apoptose , Progressão da Doença , Feminino , Citometria de Fluxo , Regulação da Expressão Gênica , Genes bcl-2 , Glicoproteínas/biossíntese , Glicoproteínas/genética , Proteínas de Choque Térmico/genética , Hematopoese , Humanos , Leucemia Mieloide/epidemiologia , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/mortalidade , Prognóstico , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Índice de Gravidade de Doença , Análise de Sobrevida , Proteína bcl-X/biossíntese , Proteína bcl-X/genéticaRESUMO
In mammals, the limited regenerating potential of the central nervous system (CNS) in adults contrasts with the plasticity of the embryonic and perinatal periods. SCO (subcommissural organ)-spondin is a protein secreted early by the developing central nervous system, potentially involved in the development of commissural fibers. SCO-spondin stimulates neuronal differentiation and neurite growth in vitro. NX210 oligopeptide was designed from SCO-spondin's specific thrombospondin type 1 repeat (TSR) sequences that support the main neurogenic properties of the molecule. The objective of this work was to assess the neuroprotective and neuroregenerative properties of NX210 in vitro and in vivo for the treatment of spinal cord injury (SCI). In vitro studies were carried out on the B104 neuroblastoma cell line demonstrating neuroprotection by the resistance to oxidative damage using hydrogen peroxide and the measure of cell viability by metabolic activity. In vivo studies were performed in two rat models of SCI: (1) a model of aspiration of dorsal funiculi followed by the insertion of a collagen tube in situ to limit collateral sprouting; white matter regeneration was assessed using neurofilament immunostaining; (2) a rat spinal cord contusion model to assess functional recovery using BBB scale and reflex testing. We demonstrate for the first time that NX210 (a) provides neuroprotection to oxidative stress in the B104 neuroblastoma cells, (b) stimulates axonal regrowth in longitudinally oriented neofibers in the aspiration model of SCI and (c) significantly improves functional recovery in the contusive model of SCI.
Assuntos
Moléculas de Adesão Celular Neuronais/química , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Fragmentos de Peptídeos/farmacologia , Recuperação de Função Fisiológica/efeitos dos fármacos , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/fisiopatologia , Animais , Linhagem Celular Tumoral , Feminino , Peróxido de Hidrogênio/farmacologia , Neuritos/efeitos dos fármacos , Neuritos/patologia , Neurogênese/efeitos dos fármacos , Neurônios/patologia , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/uso terapêutico , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/uso terapêutico , Ratos , Traumatismos da Medula Espinal/tratamento farmacológicoRESUMO
We analysed, by flow cytometry, the "adhesive" phenotype of acute myelogenous leukemia (AML) cells from 36 patients treated in our institution. In univariate analysis, the main prognostic factor for CR achievement was lower CXCR4 expression (p=0.03). Overall survival (OS) was negatively influenced by higher CXC chemokine receptor 4 (CXCR4) (p=0.01), very late antigen-4 (VLA-4) (p=0.01), and focal adhesion kinase (FAK) expression (p=0.04). Combination of these markers allowed to distinguish two prognostic groups: patients overexpressing 2 or 3 factors had a significantly shorter OS (p=0.015). CXCR4, VLA-4 and FAK are new phenotypic markers which could be helpful to establish risk-stratified therapeutic strategies.