CHINESE-HAMSTER FIBROBLASTS OVEREXPRESSING CUZN-SUPEROXIDE DISMUTASE UNDERGO A GLOBAL REDUCTION IN ANTIOXIDANTS AND AN INCREASING SENSITIVITY OF DNA TO OXIDATIVE DAMAGE

Transfection of a CuZn-superoxide dismutase (SOD) expression vector in to V79 Chinese hamster cells produced clones in which CuZn-SOD activit ies were 2.2-3.5-fold higher than in the parental cells. An overall mo derate reduction of glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase activities and of both GSSG and tota l glutathione levels was found. In one particular clone the catalase a ctivity was also reduced. The pro-oxidant status established by the lo wer level of antioxidant defence rendered the SOD-overexpressing cells more sensitive to the production of 8-oxo-2'-deoxyguanosine by hydrog en peroxide. The data are discussed in terms of a model resembling the bacterial sox RS system.