RESUMO
Fas (APO-1/CD95/TNFRSF6) is a member of the tumor necrosis/nerve growth factor receptor family that signals apoptotic cell death in sensitive cells. Expression of Fas and its agonistic ligand (FasL/TNFSF6) was investigated in ex vivo pediatric brain tumor specimens of various histologic types. Fas expression was identified in all of the 18 tumors analyzed by flow cytometry and immunohistochemistry. FasL expression was identified in most of the 13 tumors analyzed by both Western analysis and immunohistochemistry. Nine of these tumor specimens were treated with either the agonistic anti-Fas antibody (APO-1) in combination with protein A or FasL in short-term cytotoxicity assays. Sensitivity to apoptosis induced by the topoisomerase II inhibitor, etoposide, was also assessed. Despite the presence of Fas, all the specimens analyzed demonstrated a high degree of resistance to Fas-mediated apoptosis. These 9 specimens also showed a high degree of resistance to etoposide. Only 2 of the 9 specimens were susceptible to etoposide-induced cell death, whereas only 3 were sensitive to Fas-mediated apoptosis. One brain tumor was sensitive to both Fas ligation and etoposide treatment. This contrasted with the high degree of susceptibility to both etoposide- and Fas-induced apoptosis observed in the reference Jurkat cell line. The results suggest that Fas expression may be a general feature of tumors of the CNS and that a significant degree of resistance to Fas-mediated apoptosis may exist in ex vivo pediatric brain tumor specimens.
Assuntos
Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/química , Resistencia a Medicamentos Antineoplásicos , Glicoproteínas de Membrana/análise , Proteínas de Neoplasias/análise , Receptor fas/análise , Adolescente , Animais , Antineoplásicos/farmacologia , Astrocitoma/química , Sobrevivência Celular , Criança , Pré-Escolar , Colorimetria , Meios de Cultivo Condicionados , DNA Complementar/genética , Etoposídeo/farmacologia , Proteína Ligante Fas , Feminino , Ganglioglioma/química , Germinoma/química , Glioblastoma/química , Humanos , Lactente , Células Jurkat/efeitos dos fármacos , Masculino , Meduloblastoma/química , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/fisiologia , Camundongos , Proteínas de Neoplasias/fisiologia , Neuroblastoma/patologia , Tumores Neuroectodérmicos Primitivos/química , Glândula Pineal/química , Pinealoma/química , Proteínas Recombinantes de Fusão/fisiologia , Transfecção , Células Tumorais Cultivadas , Receptor fas/fisiologiaRESUMO
The processus vaginalis (PV) is a peritoneal diverticulum which forms to allow descent of the fetal testis to the scrotum. During human development fusion and obliteration of the PV often fails to occur with the result that inguinal hernias are the most prevalent congenital abnormality requiring surgery in childhood. Androgen is proposed to regulate testicular descent via the genitofemoral nerve which releases the neuropeptide calcitonin gene-related peptide (CGRP). It is possible that subsequent fusion of the PV and tissue remodelling following descent is indirectly controlled by androgen via CGRP action. An organ culture assay was developed to assess fusion of the PV taken from inguinal herniotomy in infants. Fusion was induced in vitro by CGRP but not by CGRP 8-37, CGRP 27-37 or dihydrotestosterone in equimolar concentrations. Fusion was accompanied by transformation of the epithelium, as shown by staining of intermediate filament proteins, cytokeratin and vimentin. Localization studies for CGRP receptors on 25 specimens indicated CGRP acts on mesenchymal fibroblasts but not directly on PV epithelium suggesting an indirect pathway. Hepatocyte growth factor/scatter factor was found to induce fusion of PV and may be involved as an intermediate molecule in the fusion cascade. This study represents the first approach to understanding the humoral control and underlying mechanism by which the PV fuses.