Sahu S C
Molecular Toxicology Laboratory, Food and Drug Administration, Washington, D.C. 20204.
Biomed Environ Sci. 1990 Jun;3(2):183-201.
The role that free radicals in general and oxygen radicals in particular play in carcinogenesis has attracted considerable attention in recent years. The oxygen radicals are undesirable but inevitable products of aerobic metabolism in the normal living cell. The cellular antioxidant defense system maintains an appropriate balance between necessary oxidative events and those that are excessive. When this critical balance cannot be maintained because of the overloading of the cellular redox system, oxygen radicals can induce cell damage. They can influence carcinogenesis by inducing DNA damage from direct oxidation or indirectly from DNA-binding products of lipid peroxidation. Oxygen radicals can induce conformational changes in the plasma membrane by lipid peroxidation and protein degradation, thus influencing membrane-associated cellular activities. They are capable of affecting membrane-bound protein kinases, growth factors and their receptors, and, therefore, signal transduction and oncogene activation. Thus, the oxygen radicals can have a major influence on oncogenes and oncogenesis.
近年来，自由基尤其是氧自由基在致癌过程中所起的作用已引起了相当大的关注。氧自由基是正常活细胞有氧代谢中不良但不可避免的产物。细胞抗氧化防御系统在必要的氧化事件和过度的氧化事件之间维持适当的平衡。当由于细胞氧化还原系统过载而无法维持这种关键平衡时，氧自由基会诱导细胞损伤。它们可通过直接氧化诱导DNA损伤或间接通过脂质过氧化的DNA结合产物诱导DNA损伤，从而影响致癌作用。氧自由基可通过脂质过氧化和蛋白质降解诱导质膜构象变化，从而影响与膜相关的细胞活动。它们能够影响膜结合蛋白激酶、生长因子及其受体，进而影响信号转导和癌基因激活。因此，氧自由基可对癌基因和肿瘤发生产生重大影响。
