Chapter category: Ischemia-Reperfusion
Therapeutic Utilities of SOD Mimetics Cancer, Radiotherapy and SOD Mimetics
Chapter authors:
Daila S. Gridley, Lora M. Green, Gregory A. Nelson, Michael J. Pecaut
and James M. Slater
Radiation is a major form of cancer therapy that has been successfully utilized for many decades. Over the years, substantial improvements have been made in radiotherapy regimens, resulting in increased survival time and improved quality of life. However, normal tissues in the vicinity of the tumor invariably are also exposed during radiation therapy; as a result serious side effects sometimes supervene. Ionizing radiations, such as X-rays, g-rays, and protons, damage cells by transferring sufficient energy to atoms and biomolecules to modify their characteristics. The generation of reactive oxygen radicals, which occurs primarily through the decomposition of cellular water, is an important consequence of this energy transfer in that secondary ionization is produced, resulting in further damaging effects to the cells’ component molecules. Free oxygen radicals are also formed by phagocytic cells as an indirect consequence of the irradiation (i.e., neutrophils and cells of the monocyte-macrophage lineage); these become activated in response to radiation-injured tissues. Among the most critical antioxidants that ameliorate the effects of oxidative stress within cells are enzymes such as the superoxide dismutases (SODs). Because of their importance, the SODs have received much attention in efforts to minimize oxygen radical-induced damage to normal tissues. Since the administration of exogenous SODs themselves has often proven to be problematic, a variety of innovative approaches are currently being explored in conjunction with radiotherapy. Among these are SOD mimetics.
