Stiborova Marie, Levova Katerina, Barta Frantisek, Dracinska Helena, Sulc Miroslav, Hodek Petr, Frei Eva, Arlt Volker M, Schmeiser Heinz H
Neuro Endocrinol Lett. 2014;35 Suppl 2:123-32.
Dicoumarol is known to act as an inhibitor of
NAD(P)H: quinone oxidoreductase (NQO1). This cytosolic reductase significantly contributes to the genotoxicity of the nephrotoxic and carcinogenic alkaloid aristolochic acid I (AAI). Aristolochic acid causes aristolochic acid nephropathy (AAN), and Balkan endemic nephropathy (BEN), as well as associated urothelial malignancies. NQO1 is the most efficient enzyme responsible for the reductive bioactivation of AAI to species forming covalent AAI-DNA adducts. However, it is still not known how dicoumarol influences the NQO1-mediated reductive bioactivation of AAI.
AAI-DNA adduct formation was determined by 32P-postlabeling. Expression of NQO1 mRNA and NQO1 protein was determined by real-time polymerase chain reaction and Western blotting, respectively.
In this study, dicoumarol inhibited AAI bioactivation to form AAI-DNA adducts mediated by rat and human NQO1 in vitro as expected. We however, demonstrated that dicoumarol acts as an inducer of NQO1 in kidney and lung of rats treated with this NQO1 inhibitor in vivo, both at protein and activity levels. This NQO1 induction increased the potency of kidney cytosol to bioactivate AAI and elevated AAI-DNA adduct levels were found in ex-vivo incubations of AAI with renal cytosols and DNA. NQO1 mRNA levels were induced in liver only by dicoumarol.
Our results indicate a dual role of dicoumarol in NQO1-mediated genotoxicty of AAI. It acts both as an NQO1 inhibitor mainly in vitro and as an NQO1 inducer if administered to rats.
已知双香豆素可作为烟酰胺腺嘌呤二核苷酸磷酸（NAD(P)H）：醌氧化还原酶（NQO1）的抑制剂。这种胞质还原酶对肾毒性和致癌性生物碱马兜铃酸I（AAI）的遗传毒性有显著影响。马兜铃酸会导致马兜铃酸肾病（AAN）、巴尔干地方性肾病（BEN）以及相关的尿路上皮恶性肿瘤。NQO1是负责将AAI还原生物活化成形成共价AAI - DNA加合物物种的最有效酶。然而，双香豆素如何影响NQO1介导的AAI还原生物活化仍不清楚。
通过³²P后标记法测定AAI - DNA加合物的形成。分别通过实时聚合酶链反应和蛋白质印迹法测定NQO1 mRNA和NQO1蛋白的表达。
在本研究中，正如预期的那样，双香豆素在体外抑制了由大鼠和人NQO1介导的AAI生物活化以形成AAI - DNA加合物。然而，我们证明，在体内用这种NQO1抑制剂处理的大鼠的肾脏和肺中，双香豆素在蛋白质和活性水平上均作为NQO1的诱导剂起作用。这种NQO1诱导增加了肾细胞溶胶生物活化AAI的能力，并且在AAI与肾细胞溶胶和DNA的体外孵育中发现AAI - DNA加合物水平升高。仅双香豆素可诱导肝脏中的NQO1 mRNA水平。
我们的结果表明双香豆素在NQO1介导的AAI遗传毒性中具有双重作用。它主要在体外作为NQO1抑制剂起作用，而如果给予大鼠则作为NQO1诱导剂起作用。
