Résumé
Colorectal cancer represents a significant cause of morbidity and mortality worldwide. It is known that reactive oxygen species [ROS] are formed in excess in chronic diseases of the colon but the precise mechanisms of oxidative stress being induced in cancer cell and the role of ROS in colorectal cancer progression are still not exactly understood. The present study aimed to investigate the oxidative status of plasma as lipid peroxidation end products and the level of glutathione [GSH] in colorectal patients. The level of Selenium was also assessed by atomic absorption in association with the activities of GSH peroxidase isoenzymes [total, Se-dependent and non-Se-dependent]. Also the level of tumor necrosis factor-alpha [TNF-alpha] in plasma was assessed. The study was carried out on 30 colorectal cancer patients at different stages and grades and 10 healthy control subjects of matched age and sex. The results demonstrate that, colorectal cancer patients suffer from oxidative stress which is dependent on the grade and stage of the disease as indicated by elevated levels of lipid peroxidation end products, TNF-alpha and oxidized glutathione and by decreased levels of total and reduced GSH. Also, Se was significantly decreased in patients compared to control with the lowest level observed in grade III patients. This decrease in Se was associated with inhibited activities of total and Se-dependent GSH peroxidase while no change was observed in the activity of non-Se-dependent isoenzyme. Colorectal carcinogenesis is associated with serious oxidative stress and depletion of Selenium