Dual mechanism of Fas-induced cell death in neuroglioma cells: a role for reactive oxygen species

ApoI/Fas belongs to the tumor necrosis factor receptor (TNFR) superfamily a nd mediates cell death in various cell types. A dual mode of Fas-triggered cell death has been reported depending on cell types used in the experiment s. The present study was carried out to test the possible role of reactive oxygen species in this dual mechanism in neuroglioma cells. Anti-Fas antibo dy caused dose-dependent and time-dependent increase in cell death measured by lactate dehydrogenase (LDH) release in control neuroglioma cells and in cells that were transfected with catalase cDNA. However, cells transfected with copper/zinc superoxide dismutase (Cu/ZnSOD) cDNA showed marked attenu ation of Fas-induced LDH release. Moreover, flow cytometry and confocal mic roscopy revealed that Fas-induced cell death in control cells occur mostly through an apoptotic process. This process was also completely abrogated in cells overexpressing catalase or copper/zinc superoxide dismutase (Cu/ZnSO D). Further experiments revealed that Fas-induced cell death was associated with increased formation of superoxide anions in control neuroglioma cells and in cells overexpressing catalase. These increases were significantly s uppressed by Cu/ZnSOD overexpression. These data indicate that Fas-mediated cell death in neuroglioma cells occur, in part, through the production of reactive oxygen species (ROS). These observations also suggest that Fas-ind uced cell death in these cells occur through apoptosis and necrosis. Thus o verexpression of Cu/ZnSOD caused the suppression of both types of Fas-induc ed cell death whereas catalase prevented apoptotic but not necrotic cell de ath. These observations are discussed in terms of their support for a role for both peroxides and superoxide radicals in Fas-induced cell death. (C) 1 999 Published by Elsevier Science B.V. All rights reserved.