OXIDATIVE DNA-BASE DAMAGE AND ANTIOXIDANT ENZYME-ACTIVITIES IN HUMAN LUNG-CANCER

We have investigated levels of antioxidant enzymes and free radical-in duced DNA base modifications in human cancerous lung tissues and in th eir cancer-free surrounding tissues. Various DNA base lesions in chrom atin of lung tissues were measured by gas chromatography-mass spectrom etry. Activities of superoxide dismutase, catalase and glutathione per oxidase were also measured in lung tissues. Higher levels of DNA lesio ns were observed in cancerous tissues than in cancer-free surrounding tissues. Antioxidant enzyme levels were lower in cancerous tissues. Th e results indicate an association between decreased activities of anti oxidant enzymes and increased levels of DNA lesions in cancerous tissu es. Higher levels of DNA lesions suggest that free radical reactions m ay be increased in malignant tumor cells.