RESUMEN
High-throughput screening for the induction of a luciferase reporter gene in a thrombopoietin (TPO)-responsive cell line resulted in the identification of 4-diazo-3-hydroxy-1-naphthalenesulfonic acids as TPO mimics. Modification of the core structure and adjustment of unwanted functionality resulted in the development of (5-oxo-1,5-dihydropyrazol-4-ylidene)hydrazines which exhibited efficacies equivalent to those of TPO in several cell-based assays designed to measure thrombopoietic activity. Furthermore, these compounds elicited biochemical responses in TPO-receptor-expressing cells similar to those in TPO itself, including kinase activation and protein phosphorylation. Potencies for the best compounds were high for such low molecular weight compounds (MW < 500) with EC(50) values in the region of 1-20 nM.
Asunto(s)
Compuestos Azo/síntesis química , Hidrazinas/síntesis química , Megacariocitos/efectos de los fármacos , Naftalenosulfonatos/síntesis química , Proteínas de Neoplasias , Pirazoles/síntesis química , Receptores de Citocinas , Trombopoyetina/química , Animales , Compuestos Azo/química , Compuestos Azo/farmacología , División Celular , Línea Celular , Evaluación Preclínica de Medicamentos , Ensayo de Cambio de Movilidad Electroforética , Activación Enzimática , Genes Reporteros , Hidrazinas/química , Hidrazinas/farmacología , Luciferasas/genética , Luciferasas/metabolismo , Ratones , Imitación Molecular , Peso Molecular , Naftalenosulfonatos/química , Naftalenosulfonatos/farmacología , Fosforilación , Fosfotransferasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Pirazoles/química , Pirazoles/farmacología , Receptores de Trombopoyetina , Relación Estructura-Actividad , Trombopoyetina/metabolismoRESUMEN
Hematopoietic growth factors are glycoproteins of 15-70 kDa. Although much clinical success has been obtained using recombinant proteins produced in mammalian cell lines and in microbial fermentation processes, the full-length polypeptides necessarily are expensive to produce, require parenteral administration, and in some cases have provoked detrimental immune responses. With the availability of high throughput biological function and receptor binding assays it has become possible to screen millions, if not billions, of randomly produced organic compounds and relatively short peptides to identify lead compounds for the development of small molecular mimetics of hematopoietic growth factors. Herein the strategies used to screen libraries of small molecules and peptides and the successes in finding mimetics and antagonists for/to erythropoietin, granulocyte colony-stimulating factor, and thrombopoietin are reviewed. Finally, the structural study of mimetic-receptor complexes has provided us with many molecular details of growth factor-induced receptor activation and is likely to yield new insights into the molecular basis of hematopoietic signal transduction.
Asunto(s)
Diseño de Fármacos , Hematopoyesis/efectos de los fármacos , Factores de Crecimiento de Célula Hematopoyética/química , Proteínas de Neoplasias , Biblioteca de Péptidos , Receptores de Citocinas , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Bacteriófagos , Unión Competitiva , Dimerización , Evaluación Preclínica de Medicamentos/métodos , Eritropoyetina/química , Eritropoyetina/aislamiento & purificación , Eritropoyetina/farmacología , Factor Estimulante de Colonias de Granulocitos/química , Factor Estimulante de Colonias de Granulocitos/farmacología , Factores de Crecimiento de Célula Hematopoyética/farmacología , Humanos , Ratones , Datos de Secuencia Molecular , Péptidos/química , Péptidos/farmacología , Péptidos Cíclicos/química , Péptidos Cíclicos/aislamiento & purificación , Péptidos Cíclicos/farmacología , Unión Proteica , Proteínas Proto-Oncogénicas/efectos de los fármacos , Conejos , Receptores de Eritropoyetina/efectos de los fármacos , Receptores de Factor Estimulante de Colonias de Granulocito/efectos de los fármacos , Receptores de Trombopoyetina , Recuento de Reticulocitos , Relación Estructura-Actividad , Trombopoyetina/química , Trombopoyetina/farmacologíaRESUMEN
Megakaryocyte growth and development factor (MGDF) is a potent inducer of megakaryopoiesis in vitro and thrombopoiesis in vivo. The effects of MGDF appear to be lineage-selective, making this cytokine an ideal candidate for use in alleviating clinically relevant thrombocytopenias. This report describes a murine model of life-threatening thrombocytopenia that results from the combination treatment of carboplatin and sublethal irradiation. Mortality of this regimen is 94% and is associated with widespread internal bleeding. The daily administration of pegylated recombinant human MGDF (PEG-rMGDF) significantly reduced mortality (to < 15%) and ameliorated the depth and duration of thrombocytopenia. The severity of leucopenia and anemia was also reduced, although it was not clear whether these effects were direct. Platelets generated in response to PEG-rMGDF were morphologically indistinguishable from normal platelets. PEG-rMGDF administered in combination with murine granulocyte colony-stimulating factor completely prevented mortality and further reduced leukopenia and thrombocytopenia. These data support the concept that PEG-rMGDF may be useful to treat iatrogenic thrombocytopenias.