TRANSFECTION OF A 4-HYDROXYNONENAL METABOLIZING GLUTATHIONE-S-TRANSFERASE ISOZYME, MOUSE GSTA4-4, CONFERS DOXORUBICIN RESISTANCE TO CHINESE-HAMSTER OVARY CELLS

IB,has previously been suggested that adriamycin (doxorubicin, DOX), w hich is used to treat various types orf malignancies, exerts its cytot oxic effects through interactions with DNA and by accelerating membran e lipid peroxidation. Our previous studies have indicated that a mouse glutathione S-transferases isozyme, mGSTA4-4, which shows high activi ty toward 4-hyroxyalkenals and the hydroperoxides formed during lipid peroxidation, may play an important role in defense mechanism against lipid peroxidation. In order to test the hypothesis that the enhanced protection against lipid peroxidation confers DOX-resistance to cells, we have compared the cytotoxicity of DOX to Chinese hamster ovary cel ls transfected with mGSTA4-4 with that of controls cells transfected w ith the vector alone. The results of these studies show that mGSTA4-4- transfected cells have a twofold higher resistance to DOX as compared to tile controls. Upon exposure to DOX, the transfected cells showed a bout 40% less membrane lipid peroxidation as compared to the controls, indicating a positive relationship between DOX-cytotoxicity and lipid peroxidation, These results suggest that mGSTA4-4 provides protection to cells against lipid peroxidation and that DOX cytotoxicity, at lea st in part, is mediated through oxidative stress resulting in peroxida tion of membrane lipids which would explain the results of previous st udies showing that DOX can kill cells without being internalized (T. R . Tritton and G. Yee (1982) Science 217, 248-260). (C) 1996 Academic P ress, Inc.