Fast neutrons-induced apoptosis is Fas-independent in lymphoblastoid cells.
We have previously shown that ionizing radiation-induced apoptosis in human lymphoblastoid cells differs according to their p53 status, and that caspase 8-mediated cleavage of BID is involved in the p53-dependent pathway. In the present study, we investigated the role of Fas signaling in caspase 8 activation induced by fast neutrons irradiation in these cells. Fas and FasL expression was assessed by flow cytometry and by immunoblot. We also measured Fas aggregation after irradiation by fluorescence microscopy. We found a decrease of Fas expression after irradiation, but no change in Fas ligand expression. We also showed that, in contrast to the stimulation of Fas by an agonistic antibody, Fas aggregation did not occur after irradiation. Altogether, our data strongly suggest that fast neutrons induced-apoptosis is Fas-independent, even in p53-dependent apoptosis.
Fischer
Barbara
B
Laboratoire de Cancérologie Expérimentale et de Radiobiologie EA 3430, Université Louis Pasteur, Institut de Recherche contre les Cancers de l'Appareil Digestif, Strasbourg, France.
Benzina
Sami
S
Jeannequin
Pierre
P
Dufour
Patrick
P
Bergerat
Jean-Pierre
JP
Denis
Jean-Marc
JM
Gueulette
John
J
Bischoff
Pierre L
PL
D017209:Apoptosis / Q000528:radiation effects*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism* / Q000528:radiation effects*; D009502:Neutrons; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000528:radiation effects*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*
C491901:FAS protein, human; D018124:Receptors, Tumor Necrosis Factor; D016159:Tumor Suppressor Protein p53; D019014:fas Receptor