靶向细胞色素P450酶系：抗肿瘤药物发展的新思路

细胞色素P450(CYP)代表了一大类可催化大量内源性和外源性底物代谢的亚铁血红素酶系。肿瘤治疗中靶向CYP酶系的第一个成功应用是治疗乳腺癌的高效CYP19抑制剂(芳香酶)的开发。芳香酶抑制剂为雌激素依赖型肿瘤的激素去势疗法开辟了新纪元。本文首次全面分析了在药物开发中通过抑制或利用CYP酶系治疗肿瘤的策略。     

食物,细胞色素P450酶与药物代谢

细胞色素Ｐ４５０系列酶对药物及外源性化合物的人体内代谢具有影响，有的可使之提高药效，减少毒副反应，有的可降低药效，增加毒性，甚至致癌。而食物可改变体内各种Ｐ４５０异检酶的含量和活性，因而可对药物代谢发挥间接作用。     

细胞色素P450酶系和药物不良反应

细胞色素P450酶系在药物代谢中扮演了重要角色。本描述了许多环境和基因的因素,这些因素调整人体酶和它们的药物底物的活性。在一些情况下,细胞色素P450酶具有基因的多态性,导致对某些药物在表型上明显慢和明显快的代谢。慢代谢（PMs）易发生与浓度相关的药物不良反应,而快代谢（EMs）则对药物相互作用易感;其中抑制的相互作用可能会由于血浆浓度的增中而导致毒性。药物代谢被改变是药物不良反应的重要原因。     

细胞色素P450酶系及其在药物代谢中的作用

综述了细胞色素P450酶系近年来的研究进展，对P450认识的不断深入，使人们有可能预测药物的相互作用和环境因素对药物代谢的影响     

细胞色素P450酶与药物选用

目的了解细胞色素P450酶与药物代谢关系,加强认识有利于临床药物选用。方法通过收集文献了解细胞色素P450酶在药物代谢中的作用。结果与结论正确认识细胞色素P450酶的特点,有利于临床药物选用,提高合理用药的水平。     

细胞色素P450酶系体外药物代谢研究方法进展

目的 综述细胞色素P450 (CYP 450)酶影响药物代谢的体外研究方法.方法 参考国内外文献,对与药物代谢相关的CYP酶亚型、CYP酶种属差异、CYP酶体外反应体系、药物主要代谢酶的确认方法及体外CYP酶的抑制和诱导,进行分类、归纳和整理.结果与结论 CYP 450在药物代谢中具有重要作用,药物代谢研究是新药评价体系中重要的一部分.     

细胞色素P450与药物代谢的研究现状

细胞色素P450(CYP)在众多中西药物代谢中起着非常重要的作用。本文综述了与药物代谢相关的CYP亚型、CYP与药物相互作用的关系及中药对CYP的影响，旨在合理解释和预测临床上药物间相互作用和药物不良反应等。同时选择适当的药物作为探针来评价CYP的活性，为实现临床个体化给药提供科学依据。     

细胞色素P450酶在药物代谢及开发研究中的应用

肝细胞色素Ｐ４５０酶技术在药物研究和筛选中的应用是创新药物开发研究的一个重要环节。本文综述了国外就肝Ｐ４５０酶应用于药物代谢研究及创新药物开发的现状,指出运用肝细胞色素Ｐ４５０酶技术筛选和开发研究创新药物是行之有效的。     

细胞色素P450基因突变及其效应的研究进展

细胞色素P450(CYP450)作为一组重要的氧化酶在人体药物代谢中发挥着重要作用，随着基因组学的发展，其基因多态性逐步得到深入研究。近年来，对于CYP450的研究重点也逐渐由基因定位和单纯的突变位点发现，转移到等位基因功能多态性和基因突变导致的酶学改变这些基因与蛋白的效应关系上来。本文综述了CYP450新的单核苷酸多态性的出现及相应功能的研究进展。     

细胞色素氧化酶P450及其遗传多态性

细胞色素氧化酶P45 0是药物代谢中的一个重要的酶系。近年来 ,对细胞色素P45 0氧化酶与药物氧化代谢多态性的关系进行了研究。CYP2C19与CYP2D6等在表型和基因型水平上均发现存在氧化代谢多态性 ,并对其分子机制有了深入的了解 ,而CYP2C9,CYP1A1等其他酶可能存在多态性 ,但其分子机制尚不清楚。本文综述了这些P45 0酶的底物 ,种族差异 ,遗传多态性 ,以及其对药物代谢和疾病易感性的影响     

细胞色素氧化酶CYP2C9的研究进展

CYP2C9是人类肝脏中含量丰富的一种CYP450酶,它能代谢和／或活化许多种药物、前致癌物、前毒物和致突变剂。CYP2C9基因具有遗传多态性,在人类存在几种等位基因的突变体。本文从基因结构、底物和探针药、影响其活性的因素、遗传多态性的分子机制等方面综述CYP2C9的研究进展。     

Cocktail 探针药物法评价辣椒素对大鼠CYP450亚型的影响

目的：采用cocktail 探针药物法研究辣椒素在体外对大鼠肝微粒体CYP 450四种亚型的影响。方法：分为试验组和对照组,试验组采用大鼠肝微粒体孵育体系、探针药物和系列浓度的辣椒素（对照组仅加入缓冲液）共同孵育20 min,反应终止后用HPLC方法检测代谢产物的生成量以代表酶的活性。采用Graphpad prism 5.0计算辣椒素对各亚型的IC50值。将辣椒素与大鼠肝微粒体分别预孵育0,5,10,15,20,30 min,计算不同预孵育时间下各亚型的相对活性百分比。结果：辣椒素对大鼠肝微粒体CYP1A2、CYP2C11、CYP2E1和CYP3A2的IC50值分别为36.21,17.19,51.64,18.86μmol·L-1。预孵育没有增强辣椒素对CYP450的抑制作用。结论：辣椒素在体外对大鼠肝微粒CYP1A2、CYP2C11、CYP2E1和CYP3A2具有抑制作用,且未呈现出预孵育时间依赖性。     

Cytochrome P450 isoform selectivity in human hepatic theobromine metabolism

AIMS: The plasma clearance of theobromine (TB; 3,7-dimethylxanthine) is known to be induced in cigarette smokers. To determine whether TB may serve as a model substrate for cytochrome P450 (CYP) 1A2, or possibly other isoforms, studies were undertaken to identify the individual human liver microsomal CYP isoforms responsible for the conversion of TB to its primary metabolites. METHODS: The kinetics of formation of the primary TB metabolites 3-methylxanthine (3-MX), 7-methylxanthine (7-MX) and 3,7-dimethyluric acid (3,7-DMU) by human liver microsomes were characterized using a specific hplc procedure. Effects of CYP isoform-selective xenobiotic inhibitor/substrate probes on each pathway were determined and confirmatory studies with recombinant enzymes were performed to define the contribution of individual isoforms to 3-MX, 7-MX and 3,7-DMU formation. RESULTS: The CYP1A2 inhibitor furafylline variably inhibited (0-65%) 7-MX formation, but had no effect on other pathways. Diethyldithiocarbamate and 4-nitrophenol, probes for CYP2E1, inhibited the formation of 3-MX, 7-MX and 3,7-DMU by approximately 55-60%, 35-55% and 85%, respectively. Consistent with the microsomal studies, recombinant CYP1A2 and CYP2E1 exhibited similar apparent Km values for 7-MX formation and CYP2E1 was further shown to have the capacity to convert TB to both 3-MX and 3,7-DMU. CONCLUSIONS: Given the contribution of multiple isoforms to 3-MX and 7-MX formation and the negligible formation of 3,7-DMU in vivo, TB is of little value as a CYP isoform-selective substrate in humans.     

基于醛酮还原酶1C3的抗肿瘤药物研究进展

醛酮还原酶（aldo-keto reductase,AKR）1C3是AKR超家族的成员之一,在多种恶性实体瘤和血液肿瘤细胞中的表达水平高于正常细胞,并与癌症的发生和发展以及肿瘤对化疗/免疫疗法的耐药性和对放疗的抵抗性密切相关。研究已证明,AKR1C3既可以作为生物标志物,用于肿瘤病人筛选、指导用药和预后诊断,也可作为抗肿瘤药物的新靶标,用于药物设计和研发。基于AKR1C3的抗肿瘤药物有望为临床用药提供新的解决方案。回顾了近年来基于AKR1C3的抗肿瘤药物的研究进展,并对该研究领域进行了展望。     

肿瘤组织中的CYP1B1及其抑制剂的抗肿瘤活性

综述细胞色素P450酶（CYP）1B1在肿瘤组织中的表达、在肿瘤的发生发展和诊断与干预中的作用以及其抑制剂的研发和抗肿瘤活性。CYP1B1在正常组织中低表达,而在许多肿瘤组织中则特异性高表达,可激活和代谢产生致癌物质,并可致多种抗癌药物代谢失活而使肿瘤耐药,因此它既可用于早期癌症的诊断,又可作为理想的抗肿瘤作用靶点而用于药物研发。     

Inhibition of cytochrome P450 by ethambutol in human liver microsomes

Although cytochrome P450 inhibition is the major drug–drug interaction (DDI) mechanism in clinical pharmacotherapy, DDI of a number of well-established drugs have not been investigated. Rifampicin, isoniazid, pyrazinamide and ethambutol combination therapy inhibits clearance of theophylline in patients with tuberculosis. We determined the inhibitory effects of ethambutol on the activities of nine CYP isoforms including CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1 and 3A4 in pooled human liver microsomes (HLM). As measured by liquid chromatography–electrospray ionization tandem mass spectrometry, ethambutol exhibited strong inhibitory potential against CYP1A2 and CYP2E1, moderate against CYP2C19 and CYP2D6 and weak against CYP2A6, CYP2C9 and CYP3A4, based on the IC₅₀ values. The K_i value of ethambutol for CYP1A2 was 1.4 μM and for CYP2E1 was 2.9 μM. Inhibition of CYP1A2 and CYP2E1 was not increased by preincubation with ethambutol and β-nicotinamideadenine dinucleotide phosphate (NADPH), suggesting that the ethambutol-induced CYP inhibition may not be metabolism-dependent. Kinetic analysis showed that the inhibition of CYP1A2 and CYP2E1 by ethambutol was best fit to a competitive inhibition model. Formation of 1-methylxanthene and 1,3-dimethyluric acid from theophylline in HLM was decreased to 47% and 36%, respectively, by 3.0 μM ethambutol, which is comparable to its IC₅₀ value against CYP1A2. Considering its maximal plasma concentrations of ∼10 μM and long half-life of ∼22 h, our findings raise the possibility that ethambutol causes significant DDIs in clinical situations with drugs with narrow therapeutic index, such as theophylline, in clinical situations.     

In vitro inhibitory effects of Friedelin on human liver cytochrome P450 enzymes

Context: Friedelin is a triterpenoid with several biological activities. However, the affects of Friedelin on the activity of human liver cytochrome P450 (CYP) enzymes remains unclear.

Objective: This study investigates the inhibitory effects of Friedelin on the major human liver CYP isoforms (CYP3A4, 1A2, 2A6, 2E1, 2D6, 2C9, 2C19 and 2C8).

Materials and methods: First, the inhibitory effects of Friedelin (100?μM) on the eight human liver CYP isoforms were investigated in vitro using human liver microsomes (HLMs), and then enzyme inhibition, kinetic studies, and time-dependent inhibition studies were conducted to investigate the IC₅₀, K_i and K_inact/K_I values of Friedelin.

Results: The results indicate that Friedelin inhibited the activity of CYP3A4 and 2E1, with the IC₅₀ values of 10.79 and 22.54?μM, respectively, but other CYP isoforms were not affected. Enzyme kinetic studies showed that Friedelin is not only a noncompetitive inhibitor of CYP3A4, but also a competitive inhibitor of CYP2E1, with K_i values of 6.16 and 18.02?μM, respectively. In addition, Friedelin is a time-dependent inhibitor of CYP3A4 with K_inact/K_i value of 4.84?nM/min.

Discussion and conclusion: The in vitro studies of Friedelin with CYP isoforms suggested that Friedelin has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP3A4 and 2E1. Further clinical studies are needed to evaluate the significance of this interaction.     

Metabolism of 4-Aminopiperidine Drugs by Cytochrome P450s: Molecular and Quantum Mechanical Insights into Drug Design

4-Aminopiperidines are a variety of therapeutic agents that are extensively metabolized by cytochrome P450s with CYP3A4 as a major isoform catalyzing their N-dealkylation reaction. However, its catalytic mechanism has not been fully elucidated in a molecular interaction level. Here, we applied theoretical approaches including the molecular mechanics-based docking to study the binding patterns and quantum mechanics-based reactivity calculations. They were supported by the experimental human liver microsomal clearance and P450 isoform phenotyping data. Our results herein suggested that the molecular interactions between substrates and CYP3A4 active site residues are essential for the N-dealkylation of 4-aminopiperidines. We also found that the serine 119 residue of CYP3A4 may serve as a key hydrogen-bonding partner to interact with the 4-amino groups of the studied drugs. The reactivity of the side chain α-carbon hydrogens drives the direction of catalysis as well. As a result, structure-based drug design approaches look promising to guide drug discovery programs into the optimized drug metabolism space.