Distinct oxidoresistance phenotype of human T47D cells transfected by rat glutathione S-transferase Yc expression vectors.

We have investigated the role of a glutathione S-transferase (GST) with inherent peroxidase activity in the cellular defense against lipid peroxidation and free radical-mediated oxidative damage. Stable transfectants of human T47D cells were generated which express recombinant rat GST-Yc from a human cytomegalovirus promoter-based expression vector. Among several GST-Yc transfectants characterized, two of them contained, respectively, 2- and 3-fold higher GST activity than parental cells or control transfectants and, respectively, 4-5- and 8-10-fold higher selenium-independent glutathione peroxidase activity. Cellular growth kinetics and rates of [3H]thymidine incorporation showed that both transfectants were more resistant to oxidative shocks mediated by cumene hydroperoxide or singlet oxygen generated by photosensitized rose bengal than were T47D cells and control transfectants. In contrast, a T47D transfectant, which expressed high levels of recombinant selenoglutathione peroxidase and showed enhanced resistance to cumene hydroperoxide (Mirault, M.-E., Tremblay, A., Beaudoin, N., and Tremblay, M. J. (1991) J. Biol. Chem. 266, 20752-20760), was as sensitive as parental cells to singlet oxygen. No difference was found in growth sensitivity to 1-h shock treatments with the quinonoid drug daunomycin, irrespective of GST-Yc or selenoglutathione peroxidase overexpression in these cells.