Antioxidant enzymes in epidermal tumor cell lines.

DURÁN, H.; POLICASTRO, L.; FERNÁNDEZ, M.L.; DE REY, B.M

Pucón

Congreso; VIII Congreso de la Pan-American Association for Biochemistry and Molecular Biology; 1996

There is evidence that the generation of reactive oxygen species is a critical event in the promotion of neoplastic transformation in the mouse cells. The aim of this work was to correlate the degree of malignancy of tumor cells with the peroxidant state by evaluating the levels of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Several epidermal tumor cell lines were used: PB, CH72-T4, AT5, PDV, PDVC57, whose tumoral phenotypes in terms of mutant ras expression, tumorigenicity, expression of simple epithelial cytokeratins , etc., have been previously characterized. Normal keratinocytes from SENCAR mouse were used as control. Both enzymes were assessed spectrophotometrically by measuring the disappearance of H2O2 at 240 nm for CAT and using the inhibition of the NBT reduction technique for SOD. Our results showed that different epidermal cell lines and normal keratinocytes differed in their catalase activity, revealing decreasing values as function of malignancy, ranging from 29 % (PB cell line) to 4 % (PDVC57 cell line) of the normal keratinocyte activity. SOD measurements revelaled significant differences in this enzyme activity among cell lines, which seem not to correlate clearly with malignancy. We conclude that, in several transformed epidermal cell lines of diverse origins, a gradual decrease in catalase activity correlates with malignancy, irrespective of the origin of the cell line. Thus, a decrease in catalase levels during malignant transformation could favor the prooxidant state related with the induction of the tumor cell phenotype.