CYP450氧化还原酶的药物基因组学研究进展

细胞色素P450氧化酶(cytochrome P450enzymes,CYP)的氧化还原反应是人体内重要的生理生化反应,参与许多内、外源化合物的代谢和激素类化合物的合成.CYP450氧化还原酶(cytochrome P450 oxidoreductase,POR)是所有肝微粒体内CYP酶的唯一电子供体.POR不仅可作为电子供体参与由CYP介导的药物代谢,而且可通过1-电子还原反应直接介导一些抗肿瘤前体药物的代谢和转化.可见,POR在药物代谢过程中发挥着极其重要的作用.众多研究证实,编码人POR的基因具有遗传多态性,对临床药物代谢乃至疗效有着显著影响,具有重要的临床意义.下面对近年来POR的药物基因组学最新研究进展作一综述.     

核受体对细胞色素P450的调控作用研究进展

核受体是一组配体依赖性转录因子超家族,与药物代谢过程中的基因表达调控密切相关,在机体的生长发育、新陈代谢、以及许多生理过程中发挥着重要作用,体内主要由组成型雄甾烷复体(CAR)、PXR、GR、AhR和PPAR几种核受体调控细胞色素P450基因表达介导药物代谢。本文综述了这几种核受体对细胞色素P450基因的调控作用,为药物-药物相互作用研究提供分子学机制。     

细胞色素P450 氧化还原酶缺陷症研究进展

细胞色素P450氧化还原酶缺陷症(cytochrome P450 oxidoreductase deficiency,PORD)是一种较罕见的常染色体隐性遗传病,典型表现包括类固醇合成异常、两性畸形及Antley-Bixler综合征(Antley-Bixler syndrome,ABS)样骨骼畸形等[1-4]。细胞色素P450氧化还原酶(cytochrome P450 oxidoreductase,POR)可作为细胞色素P450酶(cytochrome P450,CYP)的电子转运体,参与类固醇激素的合成等[2-3]。PORD可导致性激素和糖皮质激素合成障碍,因此它属于先天性肾上腺皮质增生症(congenital adrenal hyperplasia,CAH)的一种亚型[1-3]。Flück C E等[1]于2004年首次描述了PORD病例,至今已报道了140余例。本文汇总了常见POR基因突变类型、体外功能研究及临床病例,并从分子水平到疾病诊疗等方面介绍PORD的研究进展。     

人细胞色素P450同工酶探针底物特异性的研究进展

细胞色素P450(CYP450)同工酶活性测定可用于药物/毒物代谢、药物相互作用和代谢多态性等研究,探针底物的特异性和实验条件的合理性对CYP450同工酶活性测定的准确性有着极其重要的意义。该文就近年来常用和新出现的CYP450同工酶探针底物的研究进展作一综述和评价。     

CYP450氧化还原酶遗传多态性对CYP酶影响的研究进展

细胞色素P450氧化还原酶(Cytochrome P450 0xidoreductase,POR)是将电子从NADPH转运至所有肝微粒体的细胞色素P450氧化酶(Cytochrome P450 monooxygenases,CYP)中的唯一供体.药物、类固醇激素等物质的代谢和转化需要CYP参与.POR基因具有遗传多态性,遗传变异可以改变CYP活性,引起P450氧化还原酶缺陷(P450 0xidoreductase deficiency,PORD)、临床药物代谢和反应差异.本文将从POR的结构功能、基因突变引起的疾病及其对酶活性影响三个方面进行论述,总结近年来POR遗传多态性对CYP酶影响的最新研究进展.     

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。     

白木香细胞色素P450还原酶基因的克隆、表达与功能鉴定

细胞色素P450还原酶(cytochrome P450 reductase, CPR)是细胞色素P450酶电子传递链的组成部分,在生物体内起着重要的电子传递作用。本研究从白木香(Aquilaria sinensis)愈伤组织细胞中克隆得到1个CPR基因(Ascpr1), Ascpr1含有一个2 124 bp的开放阅读框,编码707个氨基酸残基,其蛋白分子质量为78.82 kD。系统进化分析显示, AsCPR1为Ⅱ型CPR蛋白,与来源于可可树(Theobroma cacao)的CPR蛋白亲缘关系较近。跨膜预测结果显示该蛋白的第52～71位氨基酸为跨膜区,在大肠杆菌Transetta (DE3)中成功表达了N-端缺失67个氨基酸残基的融合蛋白,经亲和色谱纯化后获得对细胞色素C具有还原能力的融合蛋白AsCPR1。本研究结果为进一步研究P450酶参与的白木香防御物质合成及CPR在白木香防御反应中的作用奠定基础。     

细胞色素P450原核功能表达系统概述

1955年,Axelrod[1]在鼠肝内质网上发现存在一些能参与氧化代谢的酶系,并且以还原型烟酰胺腺嘌呤二核苷酸磷酸(NADPH)作为还原剂.Omura和Sato[2]证实该酶系被还原后能与一氧化碳(CO)结合,并在450 nm处有特征吸收峰(Soret吸收峰),并命名为细胞色素 P450(Cytochrome P45...     

外源物对细胞色素P450同工酶表达的基因调控

细胞色素P450（CYP450）酶系中的1,2,3,4家族是代谢外来化合物的主要酶系。外源物进入体内,因其代谢活性的不同以及CYP450各家族敏感程度的差异,使CYP450的活性和表达受到不同程度的影响。近年来,可通过分子诊断学（如分子探针等）实验方法鉴定受影响的CYP450同工酶的种类,并精确了解外源物在代谢过程中对CYP450的调控方式。本文从的物在CYP450基因水平上的调节（包括对DNA、转录、mRNA及蛋白质合成水平的影响）和芳烃受体（AhR)对CYP450基因的调节等方面进行了综述。CYP450同工酶的存在类型及表达水平可直接影响机体对外源物的代谢转化,这与环境致癌物、化学毒物、药物等外源物对机体的致癌风险、中毒反应及药物间相互作用密切相关。对CYP450同工酶的合理调控将对防治疾病、维护人类健康有重要意义。     

肠道细胞色素P450代谢酶研究进展

细胞色素P450(CYP450s)为肠道主要I相代谢酶,目前发现有CYP1A1、CYP2C9、CYP2C19、CYP2J2、CYP2D6、CYP3A4、CYP3A5 7种同工酶。肠道CYP在药物代谢及药物相互作用中发挥重要作用,与药物疗效及不良反应密切相关。基因多态性及个体差异均影响药物代谢,导致临床疗效差别。该文就肠道CYP各亚型相关研究进展做一综述。     

Involvement of microsomal NADPH‐cytochrome P450 reductase in metabolic reduction of drug ketones

Recently, it was found that the carbonyl group of 1‐[3‐(4‐phenoxyphenoxy)‐2‐oxopropyl]indole‐5‐carboxylic acid ( 5 ), an inhibitor of the pro‐inflammatory enzyme cytosolic phospholipase A₂α, is easily reduced by rat liver S9 fractions in vitro. Determination of the inhibitory potency of certain putative inhibitors of carbonyl reducing enzymes on the transformation of the ketone derivative 5 to its alcohol 6 by recombinant microsomal NADPH‐cytochrome P450 reductase and by recombinant cytosolic carbonyl reductase‐1 now reveals that these compounds show a lack of specificity for these two enzymes in part. Thus, an assignment of the roles of different carbonyl reductases in metabolic keto reduction by the use of inhibitors is problematic. In addition, the ability of NADPH‐cytochrome P450 reductase and carbonyl reductase‐1 to reduce the ketone groups of the drugs haloperidol and daunorubicin was examined. Under the conditions applied, a pronounced reductive metabolism was only observed for daunorubicin in the presence of microsomal NADPH‐cytochrome P450 reductase. Similarly, in rat liver S9 fractions a marked reduction of daunorubicin was seen, while haloperidol was only slightly metabolized to its alcohol. After separation of the S9 homogenate into a microsomal and a cytosolic fraction, it became evident that the ketone groups of daunorubicin, haloperidol and compound 5 were mainly reduced by cytosolic enzymes. However, since microsomes also catalysed these carbonyl reductions to some extent, it can be concluded that microsomal NADPH‐cytochrome P450 reductase can contribute to metabolic keto reductions in xenobiotics. Copyright © 2015 John Wiley & Sons, Ltd.     

Cytochrome P450 reductase dependent inhibition of cytochrome P450 2B1 activity: Implications for gene directed enzyme prodrug therapy

Cytochrome P450 (P450) enzymes are often used in suicide gene cancer therapy strategies to convert an inactive prodrug into its therapeutic active metabolites. However, P450 activity is dependent on electrons supplied by cytochrome P450 reductase (CPR). Since endogenous CPR activity may not be sufficient for optimal P450 activity, the overexpression of additional CPR has been considered to be a valuable approach in gene directed enzyme prodrug therapy (GDEPT). We have analysed a set of cell lines for the effects of CPR on cytochrome P450 isoform 2B1 (CYP2B1) activity. CPR transfected human embryonic kidney 293 (HEK293) cells showed both strong CPR expression in Western blot analysis and 30-fold higher activity in cytochrome c assays as compared to parental HEK293 cells. In contrast, resorufin and 4-hydroxy-ifosfamide assays revealed that CYP2B1 activity was up to 10-fold reduced in CPR/CYP2B1 cotransfected HEK293 cells as compared to cells transfected with the CYP2B1 expression plasmid alone. Determination of ifosfamide-mediated effects on cell viability allowed independent confirmation of the reduction in CYP2B1 activity upon CPR coexpression. Inhibition of CYP2B1 activity by CPR was also observed in CYP2B1/CPR transfected or infected pancreatic tumour cell lines Panc-1 and Pan02, the human breast tumour cell line T47D and the murine embryo fibroblast cell line NIH3T3. A CPR mediated increase in CYP2B1 activity was only observed in the human breast tumour cell line Hs578T. Thus, our data reveal an effect of CPR on CYP2B1 activity dependent on the cell type used and therefore demand a careful evaluation of the therapeutic benefit of combining cytochrome P450 and CPR in respective in vivo models in each individual target tissue to be treated.     

文拉法辛与细胞色素P450酶的相关性研究进展

文拉法辛是具有5-HT和NE双重再摄取抑制作用的新型抗抑郁药,与文拉法辛代谢密切相关的2种酶是CYP3A4和CYP2D6。CYP2D6将其生物转化为主要的活性代谢产物——O-去甲基文拉法辛（ODV）,同时CYP3A4将文拉法辛转化为非活性代谢产物N-去甲基文拉法辛（NDV）。在常规治疗剂量下文拉法辛对于CYP3A4缺乏明显的诱导或抑制作用。而CYP2D6的活性直接影响文拉法辛和ODV的代谢和浓度,由于CYP2D6存在着基因遗传多态性,不同表型有着不同的文拉法辛代谢能力,而慢代谢者更易发生不良反应。研究证实文拉法辛与ODV的浓度比log（VENL／ODV）可作为异常代谢的指标,较简便地发现大多数异常基因型患者。     

酮康唑对大鼠肝脏CYP450酶系的影响*

目的:观察酮康唑对大鼠肝细胞色素P450及其主要亚型的影响。方法:Sprague-Dawley大鼠用140,280,420μmol.kg-1.d-1酮康唑连续灌胃7 d,测定肝脏微粒体中总CYP450含量和CYP1A1,1A2,1B1,2B1/2,2E1和3A亚型活性。结果:不同剂量酮康唑给药后大鼠肝脏脏器系数、CYP1A1和1B1亚型活性明显增高(P<0.05,P<0.01);总CYP450含量和CYP3A活性显著降低(P<0.01);低剂量的酮康唑抑制CYP1A2和CYP2B1/2亚型的活性,高剂量却出现了诱导作用(P<0.05,P<0.01)。各剂量组对CYP2E1均无明显影响。结论:酮康唑对大鼠肝脏CYP450及主要药物代谢亚型CYP1A1,1A2,1B1,2B1/2和3A有影响,临床长期用药或与经肝脏CYP450代谢的药物联合应用时要注意监测血药浓度和肝脏功能,防止药物代谢减缓出现蓄积中毒或药物代谢加快而降低药效。     

植物成分与细胞色素P450相互作用的研究进展

细胞色素P450（CYP450）是体内参与药物代谢的重要酶系,其活性在受到诱导或抑制后将干扰药物的作用。植物成分普遍存在于食物与药物中,与CYP450的相互作用将产生广泛影响。总结近年来植物成分与细胞色素P450的7个亚型CYP1A2、CYP2A6、CYP2C9、CYP2C19、CYP2D6、CYP2E1、CYP3A4相互作用的研究结果,为临床上合理用药提供参考。     

细胞色素P450调节剂对DNA加合物形成的影响

人羊膜上皮细胞ＦＬ系分别接触ａ－萘黄酮（０．６ｍｍｏｌ·Ｌ￣（－１））β－萘黄酮（２０ｐｍｏｌ·Ｌ￣（－１））２４ｈ后，再用苯并（ａ）芘［Ｂ（ａ）Ｐ，１０ｕｍｏｌ·Ｌ￣（－１）］处理２４ｈ，用３２Ｐ后标记技术测定以Ｂ（ａ）－ＤＮＡ加合物。结果发现，阳性对照组，ａ－萘黄酮预处理组及β－萘黄酮预处理组加合物的量分别为（加合物个数／１０’个核苷酸）：４．７±０．２（１００％），１．８±０．９（３８．３％），１６．０±２．２（３４０．１％）．该实验结果直接显示了纳胞色素Ｐ４５０调节剂对肿瘤发生影响的作用水平。亦为药物对致癌物代谢影响的研究提供了一种方法．     

Cancer treatment and pharmacogenetics of cytochrome P450 enzymes

Summary For the treatment of cancer, the window between drug toxicity and suboptimal therapy is often narrow. Interindividual variation in drug metabolism therefore complicates therapy. Genetic polymorphisms in phase I and phase II enzymes may explain part of the observed interindividual variation in pharmacokinetics and pharmacodynamics of anticancer drugs. The cytochrome P450 superfamily is involved in many drug metabolizing reactions. Information on variant alleles for the different isoenzymes of this family, encoding proteins with decreased enzymatic activity, is rapidly growing. The ultimate goal of ongoing research on these enzymes would be to enable pharmacogenetic screening prior to anticancer therapy. At this moment, potential clinically relevant application of CYP450 pharmacogenetics for anticancer therapy may be found for CYP1A2 and flutamide, CYP2A6 and tegafur, CYP2B6 and cyclophosphamide, CYP2C8 and paclitaxel, CYP2D6 and tamoxifen, and CYP3A5. For this latter enzyme, the drugs of interest still need to be identified.     

植物成分与细胞色素P450相互作用的研究进展

细胞色素P450（CYP450）是体内参与药物代谢的重要酶系,其活性在受到诱导或抑制后将干扰药物的作用。植物成分普遍存在于食物与药物中,与CYP450的相互作用将产生广泛影响。总结近年来植物成分与细胞色素P450的7个亚型CYP1A2、CYP2A6、CYP2C9、CYP2C19、CYP2D6、CYP2E1、CYP3A4相互作用的研究结果,为临床上合理用药提供参考。     

The role of renal proximal tubule P450 enzymes in chloroform-induced nephrotoxicity: Utility of renal specific P450 reductase knockout mouse models

The kidney is a primary target for numerous toxic compounds. Cytochrome P450 enzymes (P450) are responsible for the metabolic activation of various chemical compounds, and in the kidney are predominantly expressed in proximal tubules. The aim of this study was to test the hypothesis that renal proximal tubular P450s are critical for nephrotoxicity caused by chemicals such as chloroform. We developed two new mouse models, one having proximal tubule-specific deletion of the cytochrome P450 reductase (Cpr) gene (the enzyme required for all microsomal P450 activities), designated proximal tubule-Cpr-null (PTCN), and the other having proximal tubule-specific rescue of CPR activity with the global suppression of CPR activity in all extra-proximal tubular tissues, designated extra-proximal tubule-Cpr-low (XPT-CL). The PTCN, XPT-CL, Cpr-low (CL), and wild-type (WT) mice were treated with a single oral dose of chloroform at 200 mg/kg. Blood, liver and kidney samples were obtained at 24 h after the treatment. Renal toxicity was assessed by measuring BUN and creatinine levels, and by pathological examination. The blood and tissue levels of chloroform were determined. The severity of toxicity was less in PTCN and CL mice, compared with that of WT and XPT-CL mice. There were no significant differences in chloroform levels in the blood, liver, or kidney, between PTCN and WT mice, or between XPT-CL and CL mice. These findings indicate that local P450-dependent activities play an important role in the nephrotoxicity induced by chloroform. Our results also demonstrate the usefulness of these novel mouse models for studies of chemical-induced kidney toxicity.