Antioxidant status and proteolytic-antiproteolytic balance in colorectal cancer

Free radicals participate in the development of cancer. When the antioxidant defence system is not longer capable to destroy free radicals they may cause lipid and protein oxidation. Lipid peroxidation products also modify proteins. In such a situation the proteolytic-antiproteolytic balance existing in the blood may be changed. Therefore the aim of this study was to examine the correlation between antioxidant status and activity of proteolytic enzymes and their inhibitors in cases of colorectal cancer. This study included 55 patients with colorectal cancer. The blood was taken before surgery and plasma was collected. Total antioxidant status, the levels of lipid peroxidation products (malondialdehyde and 4-hydroxynonenal) and activity of cathepsin G, elastase and their inhibitors (alpha-1-antitrypsin and alpha-2-macroglobulin) were determined in plasma. It was shown that during the development of cancer total antioxidant status was signficantly decreased while lipid peroxidation products were increased. Activity of alpha-2-macroglobulin was decreased and activity of determined enzymes was not significantly changed. The observed changes indicate a shift in proteolytic-antiproteolytic balance which may enhance carcinogenesis.