EVALUATION OF SOME ANTIOXIDANT ENZYMES IN LUNG-CARCINOMA TISSUE

This investigation was effected to determine the levels of the two ant ioxidant enzymes, superoxide dismutase (SOD) (EC 1.15.1.1) and catalas e (CAT) (EC 1.11.1.6) in lung cancerous tissues and to compare with no rmal lung tissue in order to evaluate the antioxidant status in lung c ancer. Fifteen lung carcinoma tissue samples and the normal counterpar ts from the same cases were homogenized and the cytosols obtained by u ltracentrifugation (100 000 x g). SOD was assayed using a modification of the indirect nitroblue tetrazolium assay method, while CAT was mea sured by a spectrophotometric method. The data obtained are as follows : 1.42 +/- 0.24 U/mg protein (means +/- SEM) of SOD in lung cancer and 3.13 +/- 0.51 U/mg protein in normal lung tissue and 33.53 +/- 6.09 U /mg protein of CAT in lung cancer and 71.33 +/- 14.38 in normal lung t issue. The differences were found to be significant at the level of P < 0.01 for both enzymes. These low levels of the antioxidant enzymes i n lung cancerous tissues can lead to elevated levels of reactive oxyge n metabolites, resulting in damage to the key subcellular structures s uch as DNA, cell membranes, and other vital cellular components.