Enhancement of the Antitumor Effect of Glucose Oxidase by Combined Administration of Hydrogen Peroxide Decomposition Inhibitors Together with an Oxygenated Fluorocarbon

Glucose oxidase (GO) catalyzes the conversion ofβ‐D‐glucose and molecular oxygen to Dδ‐glucono‐δ‐lactone and H(2)O(2). H(2)O(2) produced by GO was effective in preventing tumor growth in mice bearing not only ascites tumor but also solid tumor. The effect of GO was enhanced by the combined administration of catalase inhibitors such as 3‐aminotriazole, hydroxylamine and sodium azide or the GSH synthesis inhibitor buthionine‐(S,R)‐sulfoximine in vivo. The cytolytic activity of GO against T‐24 cultured cells in vitro was also enhanced by addition of these inhibitors together with GO. In the peritoneal cavity of mice the antitumor effect of GO seemed to be dependent on the amount of oxygen released from oxygenated fluorocarbon‐43 (FC‐O(2)), an oxygen‐supplying substance. Furthermore, the combined administration of H(2)O(2)‐decomposing enzyme inhibitors and FC‐O(2) synergistically enhanced the antitumor effect of GO. These results suggest that GO is suitable for antitumor chemotherapy and that the use of inhibitors of H(2)O(2)‐decomposing enzymes and FC‐O(2) potentiated the GO therapy.