RESUMO
Neuroblastoma is the most common extracranial solid tumor of childhood. While survival rates are high for localized disease, treatment response remains poor for a subset of patients with large tumors or disseminated disease. Thus, there remains much room for improvement in treatment strategies for this disease. Using in vitro and in vivo systems, we present glycogen synthase kinase-3ß (GSK-3ß) inhibition as a potential mechanism to treat neuroblastoma. Using the specific GSK-3ß inhibitor SB415286, we demonstrate that GSK-3ß inhibition decreases the viability of Neuro-2A cells, as determined by cell proliferation assay and clonogenic survival. Moreover, we show that GSK-3ß inhibition induces apoptosis in neuroblastoma cells, as determined by Annexin V staining and confirmed with DAPI staining. Using flow cytometry, we are able to demonstrate that SB415286 induces the accumulation of cells in the G2/M phase of the cell cycle. Finally, we show that these in vitro results translate into delayed tumor growth in vivo using a heterotopic tumor model in nude mice treated with SB415286. These findings suggest that GSK-3ß is a potential molecular target for the treatment of neuroblastoma.
Assuntos
Aminofenóis/farmacologia , Apoptose/fisiologia , Inibidores Enzimáticos/farmacologia , Quinase 3 da Glicogênio Sintase/metabolismo , Maleimidas/farmacologia , Neuroblastoma/patologia , Animais , Apoptose/efeitos dos fármacos , Biomarcadores Tumorais/metabolismo , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colorimetria , Relação Dose-Resposta a Droga , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/genética , Glicogênio Sintase Quinase 3 beta , Humanos , Camundongos , RNA Interferente Pequeno/metabolismo , Fatores de Tempo , Ensaio Tumoral de Célula-Tronco/métodos , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismoRESUMO
Translation initiation from the ribosomal P-site is the specialty of the initiator tRNAs (tRNA(fMet)). Presence of the three consecutive G-C base pairs (G29-C41, G30-C40 and G31-C39) in their anticodon stems, a highly conserved feature of the initiator tRNAs across the three kingdoms of life, has been implicated in their preferential binding to the P-site. How this feature is exploited by ribosomes has remained unclear. Using a genetic screen, we have isolated an Escherichia coli strain, carrying a G122D mutation in folD, which allows initiation with the tRNA(fMet) containing mutations in one, two or all the three G-C base pairs. The strain shows a severe deficiency of methionine and S-adenosylmethionine, and lacks nucleoside methylations in rRNA. Targeted mutations in the methyltransferase genes have revealed a connection between the rRNA modifications and the fundamental process of the initiator tRNA selection by the ribosome.