Expression of glutathione-S-transferase isozyme in the SY5Y neuroblastoma cell, line increases resistance to oxidative stress

Glutathione-S-transferases (GSTs) are a superfamily of enzymes that functio n to catalyze the nucleophilic attack of glutathione on electrophilic group s of a second substrate. GSTs are present in many organs and have been impl icated in the detoxification of endogenous alpha, beta unsaturated aldehyde s, including 4-hydroxynonenal (HNE). Exogenous GST protects hippocampal neu rons against HNE in culture. To test the hypothesis that overexpression of GST in cells would increase resistance to exogenous or endogenous HNE induc ed by oxidative stress, stable transfectants of SY5Y neuroblastoma cells wi th GST were established. Stable GST transfectants demonstrated enzyme activ ities 13.7 times (Clone 1) and 30 times (Clone 2) higher than cells transfe cted with vector alone. GST transfectants (both Clones 1 and 2) demonstrate d significantly (p < .05) increased resistance to ferrous sulfate/hydrogen peroxide (20.9% for Clone 1; 46.5% for Clone 2), amyloid <beta>-peptide (12 .2% for Clone 1; 27.5% for Clone 2), and peroxynitrite (24.3% for Clone 1; 43.9% for Clone 2), but not to exogenous application of HNE in culture medi um. GST transfectants treated with 1,1,4-tris (acetyloxy)nonane, a nontoxic derivative of HNE that is degraded to HNE intracellularly, demonstrated a statistically significant (p < .05) increase in viability in a dose-depende nt manner compared with SY5Y cells transfected with vector alone. These res ults suggest that overexpression of GST increases resistance to endogenous HNE induced by oxidative stress or released in the degradation of 1,1,4-tri s (acetyloxy)nonane, but not to exogenous application of HNE. (C) 2001 Else vier Science Inc.