细胞因子与细胞色素P450

随着生物技术的发展,细胞因子的生物工程产品已越来越多地应用于临床治疗。本文通过对近年国外文献分析总结,综述了细胞因子对细胞色素P450的活性及其使RNA的表达影响,从中可以了解细胞因子对细胞色素P450的调节作用,对细胞因子在临床上的合理应用的重要意义。     

细胞色素P450和医学

细胞色素P450(CYP,P450)是一个血红蛋白家族的通用名称.这是一个非常巨大、种类丰富的酶家族,广泛存在于进化谱系所有生物体中(从细菌到人).已经发现和命名的不同CYP蛋白超过11500个(截止至2009年2月),但只有少数进行了详细研究.该家族参与到生命进程中众多的新陈代谢反应,包括羟基化、N-,O-,和S-脱烷基化、磺化氧化、环氧化、脱氨、脱硫、脱卤、过氧化和N-氧化还原作用.本文介绍了细胞色素P450的研究历史、结构、命名法、分类及功能.人类和动物细胞色素P450酶类与诸多疾病相关,尤其是肝病和癌症.三个细胞色素P450基因家族(CYP 1,CYP2和CYP3)似乎参与大量抗生素代谢反应.人们正在深入研究CYP450的功能,为不久的将来能战胜肝病、癌症和其他疾病提供可能性.     

Oxidation of ethanol to acetaldehyde and free radicals by rat testicular microsomes

A large number of epidemiological studies evidencing that excessive alcohol consumption is associated with impaired testosterone production and testicular atrophy are available in the literature. One hypothesis to explain the deleterious action of alcohol involves the in situ biotransformation to acetaldehyde, but it strongly suggests the need to learn more about the enzymatic processes governing alcohol metabolism to acetaldehyde in different cellular fractions since limited information is available in the literature. In this article we report studies on the metabolic conversion of alcohol to acetaldehyde and to 1-hydroxyethyl radicals in rat testicular microsomal fractions. The oxidation of ethanol to acetaldehyde in rat testes microsomal fraction was mostly of enzymatic nature and strongly dependent on the presence of NADPH and oxygen. Several compounds were able to significantly decrease the production of acetaldehyde: SKF 525A; diethyldithiocarbamate; esculetin; gossypol; curcumin; quercetin; dapsone; and diphenyleneiodonium. Microsomal preparations in the presence of NADPH were also able to produce both hydroxyl and 1-hydroxyethyl free radicals. Their generation was modulated by the presence of diphenyleneiodonium, gossypol, and deferoxamine. Results show that rat microsomal fractions are able to metabolize alcohol to deleterious chemicals, such as acetaldehyde and free radicals, that may be involved in ethanol toxic effects. Enzymes involved could include CYP2E1, P450 reductase, and other enzymes having lipoxygenase- /peroxidase-like behavior.     

Cytochrome P450 and liver diseases

Cytochrome P-450 (CYPs) are involved in the metabolism of drugs, chemicals and endogenous substrates. The hepatic CYPs are also involved in the pathogenesis of several liver diseases. CYP-mediated activation of drugs to toxic metabolites induces hepatotoxicity. Well-known examples include acetaminophen and halothane. In some instances, covalent binding of the toxic metabolite to CYP leads to the formation of anti-CYP antibodies and immune-mediated hepatotoxicity (hydralazine, tienilic acid). Anti-CYP2D6 antibodies are also present in the serum of patients with type II autoimmune hepatitis, but the mechanism leading to their presence and their pathogenic significance remains unclear. Several studies support a role for CYP2E1 in the pathogenesis of alcoholic liver disease and non-alcoholic steatohepatitis. In these conditions, enhanced CYP2E1 activity is associated with lipid peroxidation and the production of reactive oxygen species with secondary damage to cellular membranes and mitochondria. Because of its ability to activate carcinogens, a role for CYP2E1 as a cofactor for hepatocellular carcinoma has also been postulated. On the other hand, drug metabolism is impaired in patients with liver disease, particularly that mediated by CYPs. The content and activity of CYP1A, 2C19 and 3A appear to be particularly vulnerable to the effect of liver disease while CYP2D6, 2C9 and 2E1 are less affected. The pattern of CYPs isoenzymes alterations also differs according to the etiology of liver disease. A strong relationship between the activity of CYPs and the severity of cirrhosis has been demonstrated, but the usefulness of measuring CYP activity to assess hepatic functional reserve remains uncertain.     

Cytochrome P450 and anticancer drugs

Cytochrome P450 (CYP) is involved in the metabolism of a variety of anticancer drugs. CYP activities are known to be modified by several factors including genetic polymorphisms, changes in physiological conditions such as age, disease status or intake of certain drugs or foods or environmental factors such as smoking. These factors may cause interindividual differences in the pharmacokinetic profiles of anticancer drugs, leading to the variations of efficacy or toxicity of the drugs. Genetic polymorphisms present in CYPs sometimes result in the reduced activity of the enzymes causing low metabolic clearance of drugs or low production of active metabolites. For example, the formation of endoxifen, which is an active metabolite of tamoxifen, was less in patients with inactive polymorphic CYP2D6 than those with the wild type enzyme. CYP3A is the most abundant CYP expressed in the human liver and the small intestine that is involved in the metabolism of various anticancer drugs. The catalytic activity of CYP3A shows a large interindividual variability giving rise to large interindividual differences in the pharmacokinetic profiles of some anticancer drugs. So far, many attempts have been made to monitor the phenotypic activity of CYP3A in order to reduce the pharmacokinetic variations of anticancer drugs. Erythromycin, midazolam and cortisol are commonly used to monitor in vivo hepatic CYP3A activity. These methods have been applied to reduce the pharmacokinetic variations of docetaxel. Drug-drug interactions related to CYPs also modulate the pharmacokinetic profiles of anticancer drugs. These factors should be considered when trying to optimize and individualize chemotherapy.     

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     

Cytochrome P450 polymorphisms and response to antipsychotic therapy

Antipsychotic drugs are used for the treatment of schizophrenia and other related psychotic disorders. The antipsychotics currently available include older or classical compounds and newer or atypical agents. Most antipsychotic drugs are highly lipophilic compounds and undergo extensive metabolism by cytochrome P450 (CYP) enzymes in order to be excreted. There is a wide interindividual variability in the biotransformation of antipsychotic drugs, resulting in pronounced differences in steady-state plasma concentrations and, possibly, in therapeutic and toxic effects, during treatment with fixed doses. Many classical and some newer antipsychotics are metabolized to a significant extent by the polymorphic CYP2D6, which shows large interindividual variation in activity. Other CYPs, especially CYP1A2 and CYP3A4, also contribute to the interindividual variability in the kinetics of antipsychotics and occurrence of drug interactions. No relationship between CYP2D6 genotype or activity and therapeutic effects of classical antipsychotic drugs has been found in the few studies performed. On the other hand, some investigations suggest that poor metabolizers (PMs) of CYP2D6 would be more prone to over-sedation and, possibly, Parkinsonism during treatment with classical antipsychotics, while other studies, mostly retrospective, have been negative or inconclusive. For the newer antipsychotics, such data are lacking. To date, CYP2D6 phenotyping and genotyping appear, therefore, to be clinically useful for dose predicting only in special cases and for a limited number of antipsychotics, while their usefulness in predicting clinical effects must be further explored.     

人细胞色素P450 1A2的异源表达及代谢活性测定

目的获得单一的具有活性的人细胞色素P450 1A2（CYP1A2）重组酶,以进一步进行该酶参与的药物代谢研究。方法以人肝组织提取的总RNA为模板,RT-PCR扩增全长的人类CYP1A2基因片段,插入转座载体pFastBac构建重组转座质粒pFastBac-CYP1A2,转化入DH10Bac大肠杆菌,获得重组杆状病毒穿梭质粒Bacmid-CYP1A2,以之转染草地夜蛾细胞（Sf9）,与细胞色素氧化还原酶（CYPOR）进行共表达。利用蛋白质印迹分析鉴定其表达,并以非那西丁为底物,利用HPLC对其进行代谢活性测定。结果蛋白质印迹分析表明人CYP1A2蛋白在Sf9细胞中成功表达,且该重组酶对非那西丁的Km值为（82.04±11.39）μmol·L^-1（n=3）,Vmax值为（1.78±0.26）nmol·min^-1·mg^-1蛋白（n=3）,表观清除率Clint值为0.02mL·min^-1·mg^-1蛋白。结论利用杆状病毒/昆虫细胞系统,可获得具代谢活性的人CYP1A2重组酶,该酶可进一步用于其他底物的I相代谢研究。     

Bioactivation of Fluorinated 2-Aryl-benzothiazole Antitumor Molecules by Human Cytochrome P450s 1A1 and 2W1 and Deactivation by Cytochrome P450 2S1

Both 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) and 5-fluoro-2-(3,4-dimethoxyphenyl)-benzothiazole (GW 610) contain the benzothiazole pharmacophore and possess potent and selective in vitro antitumor properties. Prior studies suggested the involvement of cytochrome P450 (P450) 1A1 and 2W1-mediated bioactivation in the antitumor activities and P450 2S1-mediated deactivation of 5F 203 and GW 610. In the present study, the biotransformation pathways of 5F 203 and GW 610 by P450s 1A1, 2W1, and 2S1 were investigated, and the catalytic parameters of P450 1A1- and 2W1-catalyzed oxidation were determined in steady-state kinetic studies. The oxidations of 5F 203 catalyzed by P450s 1A1 and 2W1 yielded different products, and the formation of a hydroxylamine was observed for the first time in the latter process. Liquid chromatography-mass spectrometry (LC-MS) analysis with the synthetic hydroxylamine and also a P450 2W1/5F 203 incubation mixture indicated the formation of dGuo adduct via a putative nitrenium intermediate. P450 2W1-catalyzed oxidation of GW 610 was 5-fold more efficient than the P450 1A1-catalyzed reaction. GW 610 underwent a two-step oxidation process catalyzed by P450 1A1 or 2W1: a regiospecific O-demethylation and a further hydroxylation. Glutathione (GSH) conjugates of 5F 203 and GW 610, presumably through a quninoneimine and a 1,2-quinone intermediate, respectively, were detected. These results demonstrate that human P450s 1A1 and 2W1 mediate 5F 203 and GW 610 bioactivation to reactive intermediates and lead to GSH conjugates and a dGuo adduct, which may account for the antitumor activities of 5F 203 and GW 610 and also be involved in cell toxicity. P450 2S1 can catalyze the reduction of the hydroxylamine to the amine 5F 203 under anaerobic conditions and, to a lesser extent, under aerobic conditions, thus attenuating the anticancer activity.     

细胞色素P450与有害的药物相互作用

药物相互作用是引起药物不良反应的常见原因，不恰当的药物联用会造成严重的毒性反应，甚至导致死亡。细胞色素P450（CYP)介导的药物相互作用主要为诱导代谢和抑制代谢。前者致CYP的合成或活性增加，使通过这一途径消除的合用药物代谢加速．药物血浆浓度降低．延误治疗；后者使CYP受到抑制．使另一药物的代谢减少，轻者延长或加强其作用．增加不良反应，重者引发致残或致命的医疗事故。本文综述了近年来临床上由于诱导或抑制CYP而产生的有害药物相互作用，以期引起医药工作者的高度重视。     

Cytochrome P450 gene polymorphism and cancer

Human cytochrome P450 (CYP) enzymes play a key role in the metabolism of drugs and environmental chemicals. Several CYP enzymes metabolically activate procarcinogens to genotoxic intermediates. Phenotyping analyses revealed an association between CYP enzyme activity and the risk to develop several forms of cancer. Research carried out in the last decade demonstrated that several CYP enzymes are polymorphic due to single nucleotide polymorphisms, gene duplications and deletions. As genotyping procedures became available for most human CYP, an impressive number of association studies on CYP polymorphisms and cancer risk were conducted. Here we review the findings obtained in these studies regarding CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A4, CYP3A5, CYP3A7, CYP8A1 and CYP21 gene polymorphisms. Consistent evidences for association between CYP polymorphisms and lung, head and neck, and liver cancer were reported. Controversial findings suggest that colorectal and prostate cancers may be associated to CYP polymorphisms, whereas no evidences for a relevant association with breast or bladder cancers were reported. We summarize the available information related to the association of CYP polymorphisms with leukaemia, lymphomas and diverse types of cancer that were investigated only for some CYP genes, including brain, esophagus, stomach, pancreas, pituitary, cervical epithelium, melanoma, ovarian, kidney, anal and vulvar cancers. This review discusses on causes of heterogeneity in the proposed associations, controversial findings on cancer risk, and identifies topics that require further investigation. In addition, some recommendations on study design, in order to obtain more conclusive findings in further studies, are provided.     

细胞色素P450活性与癌症治疗

本文通过总结影响细胞色素P450活性的因素和抗肿瘤药的生物转化途径,以期探索细胞色素P450同工酶介导的代谢在抗癌药物体内生物转化中的作用,进而探索该酶活性与癌症患者的疗效之间的相关性。发现化疗药物的个体间药代动力学差异会引起治疗的疗效和安全性的不同结果。年龄、性别、单个基因多态性等单一因素并不能阐明个体间对药物反应的差异性,化疗方案中多个药物的相互作用在临床上非常重要。为了更好地评估细胞色素P450酶类对机体代谢的作用,药物的吸收、排泄、活化,以及代谢整个药代动力学途径涉及的酶的多态性都应进行研究。     

Cytochrome P450 in neurological disease

Advances in a multitude of disciplines support an emerging role for cytochrome P450 enzymes and their metabolic substrates and end-products in the pathogenesis and treatment of central nervous system disorders, including acute cerebrovascular injury, such as stroke, chronic neurodegenerative disease, such as Alzheimer's and Parkinson's disease, as well as epilepsy, multiple sclerosis and psychiatric disorders, including anxiety and depression. The neural tissue contains its own unique set of P450 genes that are regulated in a manner that is distinct from their molecular regulation in peripheral tissue. Furthermore, brain P450s catalyze the formation of important brain signaling molecules, such as neurosteroids and eicosanoids, and metabolize substrates as diverse as vitamins A and D, cholesterol, bile acids, as well as centrally acting drugs, anesthetics and environmental neurotoxins. These unique characteristics allow this family of proteins and their metabolites to perform such vital functions in brain as neurotrophic support, neuroprotection, control of cerebral blood flow, temperature control, neuropeptide release, maintenance of brain cholesterol homoeostasis, elimination of retinoids from CNS, regulation of neurotransmitter levels and other functions important in brain physiology, development and disease.     

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。     

细胞色素P450 1B1在上皮性卵巢癌组织中的表达

目的：检测卵巢癌组织、卵巢良性上皮性肿瘤及正常卵巢组织中细胞色素P4501B1（cytochrome P4501B1，CYP1B1）的表达，为以CYP1B1为靶点进行卵巢癌治疗提供理论基础。方法：采用免疫组化SP法检测53例上皮性卵巢癌、30例卵巢良性上皮性肿瘤及19例正常卵巢组织中CYP1B1的表达。结果：53例卵巢癌中CYP1B1阳性率92．45％，明显高于卵巢良性肿瘤组织（13．33％），差异有统计学意义（P〈0．01）。正常卵巢组织CYP1B1呈阴性表达。14例同时收集的卵巢癌转移灶组织有13例CYP1B1阳性表达，阳性率为92．86％。结论：CYP1B1可作为一个抗癌药开发及逆转化疗药耐药的新靶点。     

Cytochrome P450 monooxygenases in crustaceans

1. The hepatopancreas is the major site of cytochrome P450-dependent xenobiotic monooxygenation in crustacean species, but the presence of monooxygenase inhibitors in hepatopancreas microsomes and cytosol from many decapod species has impeded in vitro studies. Cytochrome P450 and monooxygenase activities have been reported in other crustacean organs including the antennal gland (green gland) and stomach. 2. NADPH cytochrome c reductase activity is often very low (typically less than 10 nmol cytochrome c reduced/min per mg microsomal protein) in hepatopancreas microsomes from crustacean species. NADPH cytochrome P450 reductase activity has not yet been detected in crustacean hepatopancreas microsomes. 3. The cytochrome P450 present in hepatopancreas of several crab species and the spiny lobster has been resolved into several fractions by chromatography on DEAE-cellulose. One form of cytochrome P450 from spiny lobster has been purified to 12 +/- 2 nmol/mg protein. 4. Reconstitution studies with spiny lobster hepatopancreas P450 have shown that the vertebrate sex steroids, progesterone and testosterone, are excellent substrates, whereas ecdysone--the crustacean molting hormone--is not a substrate. Activity was found with several xenobiotic substrates including benzphetamine, aminopyrine, benzo(a)pyrene, ethyl-, benzyl- and pentyl-phenoxazones and ethoxycoumarin. Highest activities (greater than 50 nmol/min per nmol P450) were found for N-demethylation of benzphetamine and aminopyrine. 5. The ability of agents which induce vertebrate cytochrome P450 to induce cytochrome P450 in crustaceans is still unclear. Some studies indicate that polycyclic aromatic hydrocarbons, but not phenobarbital-type inducers, could induce cytochrome P450 in crustaceans, whereas other studies showed no effect of either inducer type. Crustaceans are not as sensitive as fish to induction of P450 and monooxygenase activity.     

Cytochrome P450 monooxygenases in crustaceans

1. The hepatopancreas is the major site of cytochrome P450-dependent xenobiotic monooxygenation in crustacean species, but the presence of monooxygenase inhibitors in hepatopancreas microsomes and cytosol from many decapod species has impeded in vitro studies. Cytochrome P450 and monooxygenase activities have been reported in other crustacean organs including the antennal gland (green gland) and stomach.

2. NADPH cytochrome c reductase activity is often very low (typically <10nmol cytochrome c reduced/min per?mg microsomal protein) in hepatopancreas microsomes from crustacean species. NADPH cytochrome P450 reductase activity has not yet been detected in crustacean hepatopancreas microsomes.

3. The cytochrome P450 present in hepatopancreas of several crab species and the spiny lobster has been resolved into several fractions by chromatography on DEAE-cellulose. One form of cytochrome P450 from spiny lobster has been purified to 12⁺-2nmol/mg protein.

4. Reconstitution studies with spiny lobster hepatopancreas P450 have shown that the vertebrate sex steroids, progesterone and testosterone, are excellent substrates, whereas ecdysone—the crustacean molting hormone—is not a substrate. Activity was found with several xenobiotic substrates including benzphetamine, aminopyrine, benzo(a)pyrene, ethyl-, benzyl- and pentyl-phenoxazones and ethoxycoumarin. Highest activities (>50nmol/min per nmol P450) were found for N-demethylation of benzphetamine and aminopyrine.

5. The ability of agents which induce vertebrate cytochrome P450 to induce cytochrome P450 in crustaceans is still unclear. Some studies indicate that polycyclic aromatic hydrocarbons, but not phenobarbital-type inducers, could induce cytochrome P450 in crustaceans, whereas other studies showed no effect of either inducer type. Crustaceans are not as sensitive as fish to induction of P450 and monooxygenase activity.     

Cytochrome P450-dependent metabolism of gefitinib

The in vitro metabolism of [(14)C]-gefitinib (1-3 microM) was investigated using human liver microsomes and a range of expressed human cytochrome P450 enzymes, with particular focus on the formation of O-desmethyl-gefitinib (M523595), the major metabolite observed in human plasma. High-performance liquid chromatography with ultraviolet light, radiochemical and mass spectral analysis, together with the availability of authentic standards, enabled quantification and structural identification of metabolites. On incubation with pooled human liver microsomes, [(14)C]-gefitinib underwent rapid and extensive metabolism to a number of metabolites, although M523595 was only a minor microsomal product. Formation of most metabolites was markedly decreased by ketoconazole, but M523595 production was inhibited only by quinidine. Gefitinib was metabolized extensively by expressed CYP3A4, producing a similar range of metabolites to liver microsomes, but M523595 was not formed. CYP1A2, 2C9 and 2C19 produced no measurable metabolism of gefitinib, while CYP3A5 produced a range of metabolites similar to CYP3A4, but to a much lower degree. In contrast, CYP2D6 catalysed rapid and extensive metabolism of gefitinib to M523595. While formation of M523595 was CYP2D6 mediated, the overall metabolism of gefitinib was dependent primarily on CYP3A4, and this was not obviously diminished in liver microsomes from CYP2D6 poor metabolizers.