IN-VITRO MODULATION OF ANTIOXIDANT ENZYME LEVELS IN NORMAL HAMSTER-KIDNEY AND ESTROGEN-INDUCED HAMSTER-KIDNEY TUMOR

Antioxidant enzyme (AE) activities were studied in normal hamster kidn ey proximal tubules and in estrogen-induced hamster kidney cancer. In vivo, kidney tumor had lower activities of manganese superoxide dismut ase (MnSOD), copper, zinc superoxide dismutase, catalase, and glutathi one peroxidase than kidney proximal tubules. Differences in AE activit ies were, in general, maintained in tissue culture, with AE activities remaining low in tumor cells compared to normal cells. Normal proxima l tubular cells showed significant induction of MnSOD activity as a fu nction of time in culture or following exposure to diethylstilbestrol, a synthetic estrogen, while MnSOD activity remained low in tumor cell s under these conditions. Our results suggest that antioxidant enzymes , particularly MnSOD, are regulated differently in estrogen-induced ha mster kidney tumor cells than in normal kidney proximal tubular cells, demonstrating that cancers arising from hormonal influence have simil ar AE profiles to those previously described in cancers arising from v iral or chemical etiologies.