Activities of DNA turnover and free radical metabolizing enzymes in cancerous human prostate tissue

Activities of adenosine deaminase (ADA), 5'nucleotidase (5'NT), xanthine ox idase (XO), superoxide dismutase (SOD), glutathione pel oxidase (GSH-Px), a nd catalase (CAT) and levels of thiobarbituric acid reagent substances (TBA RS) were measured in 10 cancerous and 10 noncancerous human prostate tissue s. Decreased activities of DNA turnover enzymes (ADA and 5'NT), increased a ctivities of GSH-Px and CAT, and unchanged activities of SOD and XO were ob served in cancerous prostate tissues compared with those of noncancerous on es. TEARS levels were found to be higher in cancerous tissues than noncance rous ones. In correlation analysis, mostly positive correlations were estab lished between enzyme activities of the cancerous tissues, whereas no meani ngful correlations were found between enzyme activities of the noncancerous tissues except for a positive correlation between XO and SOD. The results indicate that the activities of DNA turnover enzymes were reduced, which wa s possibly an attempt to lower the rate of purine catabolism, and the activ ities of GSH-Px a,td CAT enzymes were increased, probably in response to in creased free radical stress occurring in cancerous prostate tissues. Increa sed concentrations of TEARS suggested oxidant stress and thus accelerated p er oxidative reactions in the cancerous tissues, even though antioxidant de fense mechanisms were e activated These findings suggest that enzymatic ant ioxidant systems of cancerous prostate tissues cannot sufficiently eliminat e oxidant factors and prevent cellular peroxidative reactions occurring dur ing the carcinogenic process.