细胞色素P450酶与肿瘤的遗传易感性

细胞色素Ｐ４５０酶主要参与外来化合物进入体内后的第一阶段激活反应。Ｐ４５０酶具有催化特异性,同种Ｐ４５０酶在人群中可以表现为不同表型,这种遗传多态现象决定Ｐ４５０酶对特定的外来化合物在反应上的各异,即表现为个体对环境致癌性的不同易感性。     

细胞色素P450酶与肿瘤的遗传易感性

细胞色素Ｐ４５０酶主要参与外来化合物进入体内后的第一阶段激活反应。Ｐ４５０酶具有催化特异性，同种Ｐ４５０酶在人群中可以表现为不同表型，这种遗传多态现象决定Ｐ４５０酶对特定的外来化合物在反应上的各异，即表现为个体对环境致癌剂的不同易感性。     

细胞色素P450基因多态性与肿瘤关系研究进展

毒物代谢酶基因多态是肿瘤易感性的一个重要方面。本就细胞色素Ｐ４５０同工酶中的ＣＹＰ１Ａ１、ＣＹＰ２Ｄ６和ＣＹＰ２Ｅ１的基因多态及其与肿瘤易感性的关系作一介绍。     

细胞色素P450与肺癌关系的研究进展

细胞色素P450(CYP450)属血红蛋白类酶,是微粒体混合功能氧化酶系中最重要的一族氧化酶,分布在生物体内的各种器官组织,其作用底物非常广泛,参与机体内大部分外源性、内源性致癌物质以及抗癌药物的代谢。不同的CYP450分别代谢不同的致癌物质以及抗癌药物。现已证实CYP450家族中许多酶都具有基因多态性,其多态性在人群中的分布与多种肿瘤的易感性以及抗肿瘤药物的代谢密切相关。     

昆虫细胞色素P450异源表达

细胞色素P450酶在昆虫生长、发育及代谢外源化合物上起重要作甩，异源表达是研究昆虫P450酶的结构、功能及其表达调控的重要途径。昆虫细胞色素P450异源表达主要有三大体系：细菌、酵母、杆状病毒表达系统，本就上述三太表达体系在昆虫细胞色素P450研究中的应用作一综述。     

细胞色素P450基因多态性与药物代谢

细胞色素P450(cytochrome P450,CYP)在众多外源性和内源性物质的代谢中具有重要作用.CYP家族1-3中编码P450的基因均存在多态性,特别是CYP2C9、CYP2C19、CYP2D6和CYP3A5.超过一半的临床药物是由多态性P450介导代谢,CYP基因的多态性是造成药物反应个体差异的主要原因.近几年,许多与P450酶活性和CYP基因表达相关的等位基因已被鉴定,因此通过分型CYP基因的功能性或标签(Tag)的遗传变异,就可以获得个体的代谢表型,有助于医生及时找到正确的用药方案,有效地提高药物疗效和降低毒副作用,特别是那些治疗指数窄的药物.显然,了解CYP基因的遗传变异对于临床药物治疗和药物开发是必不可少的.基因芯片技术具有高多重水平和高通量的特点,使同时分型大量CYP基因遗传变异成为可能,是实现个性化医疗的重要技术保障.然而,DNA制备制约了预测性CYP基因分型芯片的发展,其在临床上的广泛应用尚需时日.     

广州地区汉族人群细胞色素P450 1A1和细胞色素P450 2E1基因多态性

目的 探讨广州地区汉族人群细胞色素Ｐ４５０ １Ａ１（ＣＹＰ１Ａ１）和细胞色素Ｐ４５０ ２Ｅ１（ＣＹＰ２Ｅ１）基因的多态性分布规律。方法 用ＰＣＲ－ＲＦＬＰ和等位基因特异性扩增技术,对１５０名广州地区汉族正常人的ＣＹＰ１Ａ１和ＣＹＰ２Ｅ１基因多态性进行了检测,并与其他人群进行了比较。结果 ＣＹＰ１Ａ１基因３’端非翻译区的Ｍｓｐ１多态位点ｍ１（ＭＳＰⅠ－）、ｍ２（ＭｓｐⅠ＋）等位基因频率分别为６２．３     

健康汉族人细胞色素P450 2Cl9基因的检测

目的了解广东地区汉族人细胞色素(P450 2C19)基因的分布情况. 方法应用PCR技术对正常人细胞色素(P450 2C19)基因进行扩增以SmaI进行限制性酶切图谱分析. 结果广东地区汉族人P450 2C19基因中,野生型纯合子(wt/wt) 频率是0.4454;CYP2Cl9杂合子(mt/ml) 频率是0.4091;CYP2Cl9 突变型纯合子(ml/ml)频率是0.1455.P450 2C19基因ml频率是0.3500,基因wt频率是0.6500. 结论广东地区汉族人的细胞色素CYP2C19基因频率与其它地区人群相接近.     

人细胞色素P450 前mRNA的可变剪接研究进展

Human genes typically contain multiple introns, and in many cases the exons can be joined more than one way to generate multiple rnRNAs, encoding distinct protein isoforms. This process is called alternative splicing. The article summarized the human cytochrome P450 pre-mRNA alternative splicing and their regulatory mechanism and impacts on biological functions.     

细胞色素P450氧化还原酶缺乏症的POR基因突变研究

目的 分析1例细胞色素P450氧化还原酶缺乏症患者的临床和基因突变特点,为明确患者的诊断提供依据。方法 收集甘肃省妇幼保健院1例因肾上腺皮质增生而就诊的患者的临床资料,并进行高通量测序,分析细胞色素氧化还原酶缺乏症POR基因突变与临床表型的相关性。结果 发现患者POR基因存在c.1820A>G(p.Y607C)和c.830+5G>A(splicing)复合杂合突变,其中c.830+5G>A(splicing)为国内外首次报道。结论 除了经典的PORD外,POR基因还有一些致病性较轻的突变。     

Cytochrome P450 2C19 polymorphism is associated with reduced clopidogrel response in cerebrovascular disease

Purpose

Clopidogrel is a prodrug that requires transformation into an active metabolite by cytochrome P450 (CYP) in the liver in order to irreversibly inhibit the P2Y12 adenosine diphosphate platelet receptor. CYP2C19 polymorphism has been reported to correlate with reduced antiplatelet activity of clopidogrel in coronary artery disease. We assessed the association between CYP2C19 polymorphism and clopidogrel resistance in patients with cerebrovascular disease.

Materials and Methods

We retrospectively gathered data from patients who experienced cerebrovascular disease, received clopidogrel, and were tested for clopidogrel resistance and CYP2C19 polymorphism. Clopidogrel resistance was tested by the VerifyNow P2Y12 system, and the CYP2C19 polymorphism was tested by the Seeplex CYP2C19 ACE Genotyping system. Clopidogrel resistance was expressed in P2Y12 reaction units (PRU) and percent inhibition. High PRU and low percent inhibition suggests clopidogrel resistance. CYP2C19 polymorphisms were expressed as extensive, intermediate, and poor metabolizers. Clopidogrel resistance was assessed according to the subgroup of CYP2C19 polymorphism.

Results

A total of 166 patients were evaluated. The PRU values of extensive CYP2C19 metabolizers (195.0±84.9) were significantly lower than those of intermediate and poor metabolizers (237.9±88.0, 302.2±58.9). The percent inhibition of extensive metabolizers (44.6±21.8) was significantly higher than that of intermediate and poor metabolizers (30.5±21.5, 14.0±13.4).

Conclusion

Intermediate and poor metabolizing CYP2C19 polymorphism is associated with reduced clopidogrel antiplatelet activity in patients with cerebrovascular disease. The clinical implications of this finding require further investigation.     

德国小蠊细胞色素P450 CYP4G19基因的原核表达及多克隆抗体制备

目的构建细胞色素P450 CYP4G19基因部分片段的原核表达载体并诱导其表达,纯化表达的融合蛋白并制备CYP4G19多克隆抗体。方法应用RT-PCR扩增CYP4G19基因部分片段,产物经T-A克隆、测序鉴定,亚克隆入原核表达载体pET-28a,在大肠杆菌BL21（DE3）中诱导表达,镍离子亲和层析法纯化重组蛋白后,免疫小鼠,获得多克隆抗体,ELISA及Western-blot检测多抗的效价及特异性。结果从德国小蠊cDNA中克隆出一段771bp的亲水性基因片段,在大肠杆菌中诱导表达出约32000Mr、以包涵体形式存在的P450重组蛋白。将纯化、复性的重组蛋白免疫小鼠。得到了滴度高于1：10^6的高效价多克隆抗体。Western-blot显示此多抗能与32000Mr的重组蛋白特异结合,并能识别天然的德国小蠊微粒体P450蛋白。结论利用原核表达的CYP4G19融合蛋白具有良好的免疫原性。制备出效价高、特异性强的抗德国小蠊CYP4G19多克隆抗体,为下一步关于德国小蠊CYP4G19蛋白表达特性及其抗药性功能的深入研究提供了重要的实验工具。     

Cytochrome P450IID6 recognized by LKM1 antibody is not exposed on the surface of hepatocytes.

LKM1 autoantibody, directed against P450IID6, is accepted as a marker of a particular type of autoimmune hepatitis, but its role in the pathogenesis of the disease is controversial. Localization of P450IID6 on the cell surface of rat hepatocytes was previously reported, suggesting that membrane-bound P450IID6 could be the target of LKM1 antibodies, thus allowing immune lysis of hepatocytes. The objective of the present study was to determine, using various methods, the cell localization of P450IID6 in human and rat hepatocytes. Incubation of rat and human hepatocytes with LKM1-positive serum showed slight, if any, cell membrane staining using immunofluorescence, immunoperoxidase and immunoelectron microscopic studies. No staining of the plasma membrane of human hepatocytes was observed when incubations were carried out with immunoaffinity-purified antibody directed against peptide 254-271, the main epitope of P450IID6 recognized by all LKM1 sera tested. Chinese hamster ovary cells, transfected with the complete P450IID6 cDNA and incubated with the supernatant from a B cell lymphoblastoid cell line prepared with the lymphocytes of a LKM1-positive patient, did not show any staining of the cell surface by immunofluorescence. Incubation of rat microsomal fraction vesicles with LKM1-positive serum, followed by protein A-gold immunoelectron microscopy, displayed a staining of almost all vesicles, confirming that P450IID6 is present on the cytoplasmic side of the microsomal membrane, which makes it unable to be expressed on the cell surface even if it were transported from the endoplasmic reticulum (ER). Sulpho NHS Biotin labelling of rat hepatocyte cell membranes did not show the presence of a 50-kD molecule that could have reacted with LKM1 antibody. DNA sequencing of exon 1 of the CYP2D6 gene of a patient positive for LKM1 antibody did not show any difference from that of the normal published sequence of the gene. This does not favour an alteration of the NH2 terminal sequence of the P450IID6 molecule that could explain a translocation of the molecule to the luminal side of the ER, allowing its expression on the cell surface. These results indicate that, in all likelihood, P450IID6 molecule is not present on the cell surface of normal rat and human hepatocytes. Other mechanisms than antibody-mediated cell lysis directed against membrane P450IID6 antigenic determinants must be found to account for the destruction of hepatocytes observed in this disease.     

中国苗族、布依族、土族和独龙族群体中细胞色素P450 2C19基因座遗传多态性分析

目的 研究细胞色素P450 2C19（cytochrome P450 2C19,CYP2C19）在中国4个民族群体中的基因型和基因频率。方法 采用聚合酶链反应与限制性片段长度多态性技术，分析了无血缘关系的苗族、布依族、土 和独龙族人群的基因型。结果 CYP2C19＊2突变基因在苗族、布依族、土圹和独龙族人群中的频率分别为0.292、0.329、0.315和0.349。4个群体经检验均符合Hardy-Weinberg平衡（P＞0.05）。结论 中国苗族、布族、土族和独龙族人群的CYP2C19＊2突变基因频率与欧洲、非洲人群差异较大，而与亚洲人群相近。     

Intestinal and Hepatic Expression of Cytochrome P450s and mdr1a in Rats with Indomethacin-Induced Small Intestinal Ulcers

Background: Non-steroidal anti-inflammatory drugs induce the serious side effect of small intestinal ulcerations (SIUs), but little information is available regarding the consequences to drug metabolism and absorption. Aim: We examined the existence of secondary hepatic inflammation in rats with indomethacin (INM)-induced SIUs and assessed its relationship to the cytochrome P450 (CYP) and P-glycoprotein (mdr1a), the major drug-metabolizing factors in the small intestine and the liver. Methods: Gene expression of the CYP family of enzymes and mdr1a was measured with quantitative real-time polymerase chain reaction (qPCR). Vancomycin (VCM), a poorly absorbed drug, was administered intraduodenally to rats with SIUs. Results: INM induced SIUs predominantly in the lower region of the small intestine with high expression of inflammatory markers. Liver dysfunction was also observed, which suggested a secondary inflammatory response in rats with SIUs. In the liver of rats with SIUs, the expression of CYP2C11, CYP2E1, and CYP3A1 was significantly decreased, and loss of CYP3A protein was observed. Although previous studies have shown a direct effect of INM on CYP3A activity, we could not confirm any change in hepatic CY3A4 expression (major isoform of human CYP3A) in vitro. The plasma VCM concentration was increased in rats with SIUs due to partial absorption from the mucosal injury, but not in normal mucosa. Conclusions: INM-induced SIUs had a subtle effect on intestinal CYP expression, but had an apparent action on hepatic CYP, which was influenced, at least in part, by the secondary inflammation. Furthermore, drug absorption was increased in rats with SIUs.     

Potential Positive Association between Cytochrome P450 1A1 Gene Polymorphisms and Recurrent Pregnancy Loss: a Meta‐Analysis

In order to discover the potential genetic risks associated with recurrent pregnancy loss (RPL), this meta‐analysis was conducted to assess the association between CYP1A1 gene polymorphism and RPL. Studies were retrieved from the databases PubMed, Embase, HuGENet, and CNKI. Four models were then applied. Seven studies, including three datasets for the rs1048943 and five for the rs4646903 single‐nucleotide polymorphism (SNP), were included in this analysis, involving 613 cases and 398 controls for the rs1048943; and 864 cases and 842 controls for the rs4646903 SNP. After comprehensive analysis, we found that rs4646903 was significantly associated with RPL [recessive (OR = 1.72, 95%CI: 1.13–2.61); codominant (CC vs TT; OR = 1.74, 95%CI: 1.12–2.71), (CC vs CT; OR = 1.67, 95%CI: 1.07–2.62) and allele analysis (OR = 1.27, 95%CI: 1.07–1.50)]. In the following subgroup analysis, a positive association was also discovered among people of Asian descent, especially South Asians. However, there was no obvious association between rs1048943 and RPL. In summary, our results suggest that CYP1A1 gene polymorphism (particularly for rs4646903) might be associated with RPL risk, especially among South Asians. Further studies are required to confirm this association.     

Activity of cytochrome P450 in children

The 6-hydroxycortisol/cortisol ratio was measured in 52 children aging 1.1–14.0 years. The maximum increment in this ratio occurred in the age interval of 1.1–2.0 years. During this period, the regression coefficients in the linear (r=0.57; p=0.044) and nonlinear logarithmic models (r=0.56; p=0.049) were similar. At the age of 10–14 years, the examined ratio attained 19.17±17.79.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 9, pp. 272–274, September, 2004     

花生四烯酸细胞色素P450表氧化酶转基因表达对自发性高血压大鼠血压的影响及机制探讨

目的应用重组腺相关病毒作为基因导入的载体,将CYP450表氧化酶2J2基因导入到自发性高血压大鼠(SHR)体内,观察其对SHR血压的影响。方法15只雄性SHR随机分为3组,分别予以病毒悬浮缓冲液,rAAV-GFP和rAAV-2J2尾静脉注射(1×1012pfu/只)。用尾套法监测大鼠尾动脉血压,持续6月;实验结束前采用Millar导管检测心功能。采用Western印迹法检测目的基因在大鼠体内的表达。结果2J2组的血压从第2月开始下降,并保持相对较低的水平,而对照组则缓慢上升,两者间有显著性差异。2J2组心内最大收缩压,收缩末压,dp/dtmax和dp/dtmin的绝对值与对照组相比较均显著下降。2J2组大鼠的心搏出量和心输出量与对照组相比较显著增加。结论CYP表氧化酶及其代谢产物EETs对心肌的负性肌力调节机制可能是其调节高血压的重要机制之一。     

Activity of cytochrome P450 in children

The 6β-hydroxycortisol/cortisol ratio was measured in 52 children aging 1.1–14.0 years. The maximum increment in this ratio occurred in the age interval of 1.1–2.0 years. During this period, the regression coefficients in the linear (r=0.57;p=0.044) and nonlinear logarithmic models (r=0.56;p=0.049) were similar. At the age of 10–14 years, the examined ratio attained 19.17±17.79. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 9, pp. 272–274, September, 2004