Vásquez-Vivar J, Martasek P, Hogg N, Masters B S, Pritchard K A, Kalyanaraman B
Biophysics Research Institute and Department of Pathology, Caridiovascular Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Biochemistry. 1997 Sep 23;36(38):11293-7. doi: 10.1021/bi971475e.
Adriamycin (or doxorubicin) is an active and broad spectrum chemotherapeutic agent. Unfortunately, its clinical use is severely restricted by a dose-limiting cardiotoxicity which has been linked to the formation of superoxide. Enzymatic one-electron reduction of adriamycin forms adriamycin semiquinone radical, which rapidly reacts with oxygen to form superoxide and adriamycin. In this way, adriamycin provides a kinetic mechanism for the one-electron reduction of oxygen by flavoenzymes such as NADPH-cytochrome P450 reductase and mitochondrial NADH dehydrogenase. We demonstrate here that the endothelial isoform of nitric oxide synthase (eNOS) reduces adriamycin to the semiquinone radical. As a consequence, superoxide formation is enhanced and nitric oxide production is decreased. Adriamycin binds to eNOS with a Km of approximately 5 microM, as calculated from both eNOS-dependent NADPH consumption and superoxide generation. Adriamycin stimulated superoxide formation is not affected by calcium/calmodulin and is abolished by the flavoenzyme inhibitor, diphenyleneiodonium. This strongly suggests that adriamycin undergoes reduction at the reductase domain of eNOS. A consequence of eNOS-mediated reductive activation of adriamycin is the disruption of the balance between nitric oxide and superoxide. This may lead eNOS to generate peroxynitrite and hydrogen peroxide, potent oxidants implicated in several vascular pathologies.
阿霉素（或多柔比星）是一种活性广泛的化疗药物。不幸的是，其临床应用受到剂量限制性心脏毒性的严重限制，这种毒性与超氧化物的形成有关。阿霉素的酶促单电子还原形成阿霉素半醌自由基，该自由基迅速与氧气反应生成超氧化物和阿霉素。通过这种方式，阿霉素为黄素酶（如NADPH-细胞色素P450还原酶和线粒体NADH脱氢酶）对氧气的单电子还原提供了一种动力学机制。我们在此证明，一氧化氮合酶（eNOS）的内皮亚型可将阿霉素还原为半醌自由基。结果，超氧化物的形成增加，一氧化氮的产生减少。根据eNOS依赖的NADPH消耗和超氧化物生成计算，阿霉素与eNOS的结合常数Km约为5 microM。阿霉素刺激的超氧化物形成不受钙/钙调蛋白的影响，并被黄素酶抑制剂二苯碘鎓消除。这强烈表明阿霉素在eNOS的还原酶结构域发生还原。eNOS介导的阿霉素还原激活的一个后果是一氧化氮和超氧化物之间的平衡被破坏。这可能导致eNOS产生过氧亚硝酸盐和过氧化氢，这两种强效氧化剂与多种血管病变有关。
