title: The Antitumor Effect of Singlet Oxygen.
abstract: Tumor cells are protected against intercellular apoptosis-inducing signaling through expression of membrane-associated catalase and superoxide dismutase. Exogenous singlet oxygen derived from activated photosensitizers or from cold atmospheric plasma causes local inactivation of protective catalase which is followed by the generation of secondary extracellular singlet oxygen. This process is specific for tumor cells and is driven by a complex interaction between H2O2and peroxynitrite. Secondary singlet oxygen has the potential for autoamplification of its generation, resulting in optimal inactivation of protective catalase and reactivation of intercellular apoptosis-inducing signaling. An increase in the endogenous NO concentration also causes inactivation of catalase and autoamplificatory generation of secondary singlet oxygen. This principle is essential for the antitumor activity of secondary plant products, such as cyanidins and other inhibitors of NO dioxygenase. It seems that the action of the established chemotherapeutic taxol and the recently established antitumor effect of certain azoles are based on the same principles.
authors: Institute of Virology, Medical Faculty, University Medical Center Freiburg, Freiburg, Germany georg.bauer@uniklinik-freiburg.de.
authors: Georg
authors: G
authors: Bauer
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002374:Catalase / Q000037:antagonists & inhibitors; D006801:Humans; D009369:Neoplasms / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; D009569:Nitric Oxide; D002374:Catalase
keywords: NOX1; Singlet oxygen; catalase; peroxynitrite; review; superoxide anion