Antioxidant status and lipid peroxidation in colorectal cancer

Colon carcinogenesis is a multistep process where oxygen radicals were foun d to enhance carcinogenesis at all stages: initiation, promotion, and progr ession. Since insufficient capacity of protective antioxidant system can re sult in cancer, the aim of this study was to examine the activity of antiox idant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and the levels of reduced glutathione, vitamin C, an d vitamin E. The lipid peroxidation products were also determined by measur ing malondialdehyde and 4-hydroxynonenal levels in colorectal cancer tissue collected from 55 patients. In these cases the activity of superoxide dism utase, glutathione peroxidase, and glutathione reductase was significantly increased while the activity of catalase was significantly decreased in can cer tissue. However, the level of nonenzymatic antioxidant parameters (glut athione, vitamin C, and vitamin E) was significantly decreased in cancer ti ssue. Further lipid peroxidation was enhanced during cancer development, ma nifested by a significant increase in malondialdehyde and 4-hydroxynonenal levels. The obtained results indicate significant changes in antioxidant ca pacity of colorectal cancer tissues, which lead to enhanced action of oxyge n radicals, resulting in lipid peroxidation.