RESUMEN
Neuroblastoma is one of the most common solid tumours in children (8-10% of all malignancies). Over 22% of cases have N-myc amplification associated with aggressively growing neuroblastomas. Oncogene-induced sensitization of cells to apoptosis is an important mechanism for suppression of tumorigenesis. Tumour suppressors often play a critical role in linking oncogenes to apoptotic machinery. For example, activated p53 then targets both intrinsic and extrinsic pathways to promote apoptosis through transcription-dependent and -independent mechanisms. Understanding of the involved mechanisms has important clinical implications. We have employed DNA-damaging drug-induced apoptosis sensitized by oncogene N-myc as a model. DNA damaging drugs trigger high levels of p53, leading to caspase-9 activation in neuroblastoma cells. Inactivation of p53 protects cells from drug-triggered apoptosis sensitized by N-myc. These findings thus define a molecular pathway for mediating DNA-damaging drug-induced apoptosis sensitized by oncogene, and suggest that inactivation of p53 or other components of this apoptotic pathway may confer drug resistance in neuroblastoma cells. The data also suggests that inactivation of apoptotic pathways through co-operating oncogenes may be necessary for the pathogenesis of neuroblastoma with N-myc amplification.
Asunto(s)
Antineoplásicos/farmacología , ADN de Neoplasias/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Neuroblastoma/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Apoptosis/efectos de los fármacos , Caspasa 9/genética , Caspasa 9/metabolismo , Línea Celular Tumoral , Niño , Fragmentación del ADN , Doxorrubicina/farmacología , Etopósido/farmacología , Vectores Genéticos , Humanos , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/patología , Proteínas Proto-Oncogénicas c-myc/genética , Retroviridae , Transducción de Señal/efectos de los fármacos , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
The nectar of Camellia reticulata Lindl. contains sugar, amino acids and other nutritional components, suggesting that it could be developed for food and food additives. To understand the effects of the nectar on human health, we investigated its chemical constituents. Two new flavonoid glycosides, cameretiins A and B (1 and 2), and two known flavonoid glycosides, kaempferol 3-O-(2''-O-E-p-coumaroyl)-ß-D-glucopyranoside (3) and tiliroside (4) were obtained from the nectar of Camellia reticulata Lindl. Their structures were determined based on analysis of their spectroscopic data and by comparison with 1D NMR spectroscopic data of known compounds reported in the literature. Compounds (1-4) were first isolated from the nectar of Camellia reticulata Lindl.