Superoxide dismutase and cancer therapy

The primary superoxide scavenger, SOD, has become an important potential therapeutic modality for cancer treatment in view of the link between reactive oxygen species (ROS) and carcinogenesis. Ironically, these same ROS also play a critical role in anticancer therapies that depend on ROS generation for their action rendering the use of SOD, in these settings, as a potential interfering factor that could decrease therapeutic efficacy. This complicating situation arises since ROS are well recognized for playing a dual role as both beneficial signaling molecules as well as deleterious damaging species in biological systems. A growing body of evidence has shown that ROS act as secondary messengers in intracellular signaling cascades, which stimulate and support the oncogenic phenotype of cancer cells. On the other hand, ROS also function as antitumorigenic species since they can induce cellular senescence and death. Therefore, the appropriate application of these antioxidant enzymes is a critical consideration in designing proper strategies for both prevention and treatment of malignant disorders. This chapter reviews evidence that suggests SOD as an emerging therapeutic agent as well as a target for cancer treatment. A discussion is also devoted to the practical challenges that limit the use of SOD manipulation as an anticancer approach.