XANTHINE DEHYDROGENASE AND ITS ROLE IN CANCER-CHEMOTHERAPY

Xanthine dehydrogenase (EC 1.1.1.204) is a molybdenum iron-sulfur, fla vin hydroxylase whose physiological role is ascribed to purine catabol ism. Its ready conversion to its oxidase counterpart, xanthine oxidase (EC 1.1.3.22), under normal isolation conditions has complicated stud ies of this enzyme in the past. Many studies in the past have looked a t the role of xanthine oxidase in the metabolism of chemotherapeutic a gents requiring bioreductive activation for their antineoplastic activ ities. This paper reviews some of xanthine dehydrogenase's biological and physiological parameters as well as recent studies into the xanthi ne dehydrogenase-induced activation of bioreductive agents. Studies ar e also presented that point out this enzyme's potential role in mitomy cin C-induced cytotoxicity to EMT6 cells under aerobic and hypoxic con ditions. The potential importance of xanthine dehydrogenase as an enzy me targeted in chemotherapeutic regimens is discussed.