THE CHANGES OF PROOXIDANT AND ANTIOXIDANT ENZYME-ACTIVITIES IN BOVINELEUKEMIA VIRUS-TRANSFORMED CELLS - THEIR INFLUENCE ON QUINONE CYTOTOXICITY

It was found that the activities of prooxidant enzymes (NAD(P)H oxidas es and NAD(P)H:cytochrome c reductases) in bovine leukemia virus-trans formed calf and lamb embryo kidney fibroblasts (lines Mi-18 and FLK) w ere by 1.25-18 times higher when compared to corresponding nontransfor med calf cells. The activity of DT-diaphorase was also increased by ab out one order of magnitude in transformed cells. The activities of ant ioxidant enzymes were almost unchanged (superoxide dismutase), decreas ed by 13% or 53% (catalase) or increased by 25% or 90% (glutathione re ductase) in Mi-18 or FLK cells, respectively. These changes of enzyme activity increased the toxicity of simple redox-cycling quinones (duro quinone, naphthazarin) towards transformed cells, but did not affect t he toxicity of daunorubicin. The latter was most probably related to t he inhibition of plasma membrane NADH dehydrogenase.