RESUMEN
In some neurological diseases, injury to neurones reflects an over-stimulation of their receptors for excitatory amino acids. This response may disturb the Ca(2+)-homeostasis and lead to a pronounced and sustained increase in the intracellular concentration of this ion. On the basis of data derived from correlative studies, calcium-binding proteins have been postulated to play a protective role in these pathologies. We tested, directly, the capacity of the three calcium-binding proteins calretinin (CR), calbindin D-28k (CB) and parvalbumin (PV) to buffer [Ca(2+)], and to protect cells against excitotoxic death. We used P19 murine embryonic carcinoma cells, which can be specifically induced (by retinoic acid) to transform into nerve-like ones. The differentiated cells express functional glutamate-receptors and are susceptible to excitotoxic shock. Undifferentiated P19-cells were stably transfected with the cDNA for CR, CB or PV, induced to differentiate, and then exposed to NMDA, a glutamate-receptor agonist. The survival rates of clones expressing CR, CB or PV were compared with those of untransfected P19-cells using the lactate-dehydrogenase assay. CR- and CB-expressing cells were protected from death during the first 2 h of exposure to NMDA. This protection was, however, transient, and did not suffice to rescue P19-cells after prolonged stimulation. Two of the three PV-transfected clones raised were vulnerable to NMDA-induced excitotoxicity; the third, which expressed the lowest level of PV, was protected to a similar degree as that found for the CR- and CB-transfected clones. Our results indicate that in the P19-cell model, CR and CB can help to delay the onset of cell death after excitotoxic stimulation.
Asunto(s)
Proteínas de Unión al Calcio/genética , Muerte Celular/fisiología , Enfermedades del Sistema Nervioso Central/tratamiento farmacológico , Sistema Nervioso Central/metabolismo , Neuronas/metabolismo , Fármacos Neuroprotectores/metabolismo , Neurotoxinas/metabolismo , Animales , Calbindina 2 , Calbindinas , Calcio/metabolismo , Proteínas de Unión al Calcio/metabolismo , Muerte Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Tamaño de la Célula/efectos de los fármacos , Tamaño de la Célula/fisiología , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/fisiopatología , Enfermedades del Sistema Nervioso Central/metabolismo , Enfermedades del Sistema Nervioso Central/fisiopatología , Agonistas de Aminoácidos Excitadores/farmacología , Aminoácidos Excitadores/metabolismo , Glicina/farmacología , Inmunohistoquímica , L-Lactato Deshidrogenasa/metabolismo , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Ratones , N-Metilaspartato/farmacología , Células Madre Neoplásicas/citología , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/metabolismo , Neuronas/efectos de los fármacos , Neuronas/patología , Parvalbúminas/genética , Parvalbúminas/metabolismo , Receptores de N-Metil-D-Aspartato/efectos de los fármacos , Receptores de N-Metil-D-Aspartato/metabolismo , Proteína G de Unión al Calcio S100/genética , Proteína G de Unión al Calcio S100/metabolismo , Tretinoina/farmacologíaRESUMEN
Human mesothelioma cell lines were studied concerning the expression of the calcium-binding protein calretinin (CR), and the relation of the DNA index to their cell cycle. The results obtained for cell lines with different morphological characteristics, were compared to those from human mesothelial cells transfected with SV40 to escape senescence. Immunocytochemical expression of calretinin (confirmed by immunoblot) was observed in all mesothelioma cell lines but not in the control cells. It is suggested that calretinin is active in the first steps of carcinogenesis in all human mesotheliomas and during several stages in the evolution towards malignancy.