Human Cytochrome P450 4F Enzymes and Drug Interactions

描述(由申请人提供)：由于多种药物疗法的广泛流行，药物间的相互作用在临床不良事件中扮演着重要的角色。最近研究表明，人细胞色素P450 4F(CYP4F)亚家族在内源性化合物(包括花生四烯酸和白三烯B4)以及药物/营养物质(包括帕夫嘧啶、Fingolimod和维生素E)的代谢中发挥重要作用。然而，CYP4F酶在介导潜在药物相互作用中的作用尚不清楚。据报道，广泛使用的降胆固醇药物“他汀类药物”和抗凝剂华法林之间存在许多临床上重要的不良反应，包括严重和致命的出血事件。预计这些药物的联合给药将会增加，部分原因是据称他汀类药物具有多效性。深入了解他汀类药物与华法林相互作用的分子机制，将为开发无相互作用的他汀类药物和华法林药物组合提供必要的科学依据和方法，并允许制定相关的监管措施，限制某些高风险的他汀类药物和华法林药物组合每年被开给数十万人，这对公共卫生具有重要意义。PI研究计划的长期目标是加深我们对人类CYP4F酶的药理和生理作用的理解。这项研究的具体目标是从机制上理解他汀类药物和华法林之间的相互作用中细胞色素P4F2的作用。将采用一种创新的转化性实验方法来验证中心假设，即某些他汀类药物在人类体内诱导细胞色素P4F2介导的维生素K1代谢，并增强华法林的抗凝作用。新的方法，包括基于质谱仪(MS)的蛋白质定量蛋白质组学方法，CYP4F2的标记底物活性分析，以及双盲、随机、安慰剂对照的两期交叉临床研究将被用于解决以下关键问题：1)通过CYP4F2的？-羟化作用使维生素K1失活；2)他汀类药物诱导CYP4F2的蛋白表达和酶活性；以及3)他汀类药物对华法林抗凝疗效的临床相关性。拟议的翻译研究结果将为理解CYP4F酶的药理和生理作用奠定基础，并将为开发更安全的他汀类药物提供重要信息，并提供一种机制，使批准的他汀类药物可以根据其CYP4F2诱导潜力进行排序，以指导同时给药时华法林的剂量调整。这项拟议的工作有以下具体目标：1)鉴定和鉴定由CYP4F2产生的维生素K1代谢物(K1-？-OH)；2)确定他汀类药物对HepG2细胞和原代人类肝细胞中CYP4F2的诱导作用；以及3)评估他汀类药物对健康志愿者华法林抗凝作用的影响。

DESCRIPTION (provided by applicant): Drug-drug interactions play an important role in clinical adverse events due to the wide prevalence of multi-drug therapies. The human cytochrome P450 4F (CYP4F) subfamily of enzymes has recently been demonstrated to play a significant role in the metabolism of both endogenous compounds, including arachidonic acid and leukotrienes B4 (LTB4), and drugs/nutrients, including pafuramidine, fingolimod, and vitamin E. However, the role of CYP4F enzymes in mediating potential drug interactions remains uncharacterized. Numerous clinically significant adverse interactions, including major and fatal bleeding episodes, have been reported between the widely-prescribed cholesterol-lowering agents, the "statins", and the anticoagulant warfarin. Co-administration of these drugs is expected to be on the rise due in part to the purported pleiotropic effects of statins. An improved understanding of the molecular mechanisms underlying the statin-warfarin interaction will provide necessary scientific basis and methodologies to develop an interaction-free statin-warfarin combination, and allow enactment of pertinent regulatory measures limiting certain high-risk statin-warfarin combinations to be prescribed to hundreds of thousands of people each year, which has great public health importance. The long-term goal of the PI's research program is to further our understanding of the pharmacologic and physiologic roles of the human CYP4F enzymes. The specific goal of the proposed research is to develop a mechanistic understanding of the role of CYP4F2 in the interaction between statins and warfarin. An innovative and translational experimental approach will be employed to test the central hypothesis that certain statins induce CYP4F2-mediated vitamin K1 metabolism and potentiate the anticoagulant effect of warfarin in humans. Novel methodologies, including a mass spectrometry (MS)-based quantitative proteomic approach for protein quantification, a marker substrate activity assay for CYP4F2, and a double-blind, randomized, placebo-controlled, 2-period cross-over clinical study will be utilized to address key issues regarding 1) the deactivation of vitamin K1 upon ?-hydroxylation by CYP4F2; 2) the induction of CYP4F2 protein expression and enzymatic activity by statin treatment; and 3) the clinical relevance of the effect of statins on warfarin anticoagulation efficacy. Results obtained from the proposed translational research will serve as a foundation for understanding the pharmacologic and physiologic role of CYP4F enzymes, and will provide important information useful in the development of safer statins, and a mechanism by which approved statins can be rank-ordered according to their CYP4F2-inducing potential to guide warfarin dosage adjustment when administered concomitantly. The proposed work has the following specific aims: 1) identify and characterize the vitamin K1 metabolite (K1-?-OH) generated by CYP4F2; 2) determine the induction profiles of statins towards CYP4F2 in HepG2 cells and primary human hepatocytes; and 3) assess the influence of statin treatment on the anticoagulant effect of warfarin in healthy volunteers.