Induction of CYP1A by benzo[k]fluoranthene in human hepatocytes: CYP1A1 or CYP1A2?

While fresh human hepatocyte cultures are widely used to model hepatic cytochrome P450 (CYP) regulation and activity, their CYP1A subfamily composition induced by, e.g., polycyclic aromatic hydrocarbons is ambiguous. CYP1A1, CYP1A2, or both have been reported to be expressed, and their varied roles in chemical carcinogenesis makes resolution of which CYPs are expressed essential. We have used an immunoblot system with Bis-Tris-HCl-buffered polyacrylamide gel, which clearly resolves human CYP1A1 and CYP1A2, and polyclonal goat anti-human CYP1A1/CYP1A2 and rabbit anti-human CYP1A2 antibodies to probe the expressed CYP1A1 and CYP1A2 composition of seven individual human hepatocyte cultures induced with 5 microM benzo[k]fluoranthene (BKF) for 24 h. In six of the cultures only CYP1A1 was detected, and in the seventh both CYPs were detected. In most vehicle-treated hepatocyte cultures, neither CYP1A1 nor CYP1A2 was detected. In three additional hepatocyte cultures treated individually with BKF and 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD), the resultant induced CYP1A1/1A2 profiles were essentially not influenced by the nature of the inducing agents. To develop an activity-based assay to differentiate between CYP1A1 and CYP1A2 expression in human hepatocytes, our previously published R warfarin assay (Drug Metab. Disp. (1995) 23, 1339-1345) was applied to TCDD (10 nM)-treated hepatocyte culture. The low concentration of TCDD did not produce inhibition of the warfarin metabolism-such inhibition could confound the results. Based on the ratios of 6- to 8-hydroxywarfarin formed in two cultures, the ratios of CYP1A1/CYP1A2 expressed in these cultures were determined and they agreed with the ratios determined by immunoblot analysis. Thus each individual human hepatocyte culture must be characterized for induced CYP1A1 and CYP1A2 expression in studies of CYP1A activity. The warfarin assay provides a means of characterizing the cultures.     

Characterization of CYP1A enzyme in Adélie penguin liver

As CYP1A enzymes are induced by certain contaminants, their induction pattern has been used as a biomarker for exposure of certain pollutants. Ethoxyresorufin O-deethylase (EROD) activities are widely used in environmental assessments of polychlorinated biphenyls in many wildlife species. The EROD activity, a typical probe for CYP1A enzyme was studied in liver microsomes prepared from Adélie penguins (Pygoscelis adeliae) (n=10). Penguin liver microsomes (0.5 mg/mL) were incubated with the substrate ethoxyresorufin and NADPH at 37 degrees C for 10 min, and the reaction was terminated by addition of methanol. The formation of the metabolite resorufin was assayed by an HPLC method. EROD activity was present in all liver samples studied. Penguin liver microsomal fraction exhibits typical Michaelis-Menten kinetics in the O-deethylation of ethoxyresorufin. The data were best described by a biphasic kinetic model, which could be interpreted in terms of two populations of CYP enzyme. Mean (+/-S.D.) K(m) values for high- and low-affinity components of EROD were 51+/-109 (range: 0.16 to 358) and 872+/-703 (range: 303 to 2450) nM, respectively. The corresponding mean V(max) values for the high- and low-affinity enzyme activities were 1.8+/-1.4 (range: 0.21 to 5.1) and 9.6+/-3.7 (range: 6.0 to 18.3) pmol/min/mg. The EROD activity in penguin liver microsomes was inhibited by CYP1A inhibitors (phenacetin, 7-ethoxycoumarin and proportional variant-naphthoflavone), whereas other CYP inhibitors for CYP2C9 (tolbutamide), 2C19 (mephenytoin), 2D6 (debrisoquin) and 2E1 (diethyldithiocarbamate) had no effect. These results suggest that CYP1A-like enzymes are present in penguin livers. The activity of this enzyme may be a useful biomarker for assessing the environmental impact of pollutants on Antarctic wildlife.     

飞蝗CYP408B1和CYP409A1基因的原核表达

【目的】细胞色素P450是分布极其广泛的超家族酶,在昆虫内源及外源化合物代谢中发挥着重要的作用。本文分析了飞蝗Locusta migratoria CYP408B1和CYP409A1基因在不同组织部位的表达差异,并对两种蛋白进行原核表达,为其分子特性和生物学功能的深入研究提供基础资料。【方法】提取飞蝗5龄若虫不同组织部位的总RNA,体外反转录成c DNA,采用Real-time PCR和RT-PCR技术分析飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,构建表达载体p CW/CYP408B1、p CW/CYP409A1和p AC/CPR,将p CW/CYP408B1和p CW/CYP409A1分别与p AC/CPR在大肠杆菌Escherichia coli BL21(DE3)中进行共表达。【结果】通过PCR检测,发现CYP408B1和CYP409A1在飞蝗5龄若虫触角、脑、视叶、咽下神经节、胸神经节和附腺中均有表达,其中CYP408B1在附腺中表达量较高。原核表达结果显示,CYP409A1和CPR(NADPH细胞色素P450还原酶)均可表达,蛋白分子量分别约为58 ku和77 ku,但均为包涵体,而CYP408B1未能成功表达。【结论】本文揭示了飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,并对CYP409A1和CPR进行了原核表达,研究结果为深入探讨飞蝗细胞色素P450基因对杀虫剂的代谢解毒作用提供了实验依据和基础资料。     

飞蝗CYP408B1和CYP409A1基因的原核表达

【目的】细胞色素P450是分布极其广泛的超家族酶,在昆虫内源及外源化合物代谢中发挥着重要的作用。本文分析了飞蝗Locusta migratoria CYP408B1和CYP409A1基因在不同组织部位的表达差异,并对两种蛋白进行原核表达,为其分子特性和生物学功能的深入研究提供基础资料。【方法】提取飞蝗5龄若虫不同组织部位的总RNA,体外反转录成c DNA,采用Real-time PCR和RT-PCR技术分析飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,构建表达载体p CW/CYP408B1、p CW/CYP409A1和p AC/CPR,将p CW/CYP408B1和p CW/CYP409A1分别与p AC/CPR在大肠杆菌Escherichia coli BL21(DE3)中进行共表达。【结果】通过PCR检测,发现CYP408B1和CYP409A1在飞蝗5龄若虫触角、脑、视叶、咽下神经节、胸神经节和附腺中均有表达,其中CYP408B1在附腺中表达量较高。原核表达结果显示,CYP409A1和CPR(NADPH细胞色素P450还原酶)均可表达,蛋白分子量分别约为58 ku和77 ku,但均为包涵体,而CYP408B1未能成功表达。【结论】本文揭示了飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,并对CYP409A1和CPR进行了原核表达,研究结果为深入探讨飞蝗细胞色素P450基因对杀虫剂的代谢解毒作用提供了实验依据和基础资料。     

Regioselective hydroxylation of 17β-estradiol by mutants of CYP102A1 from Bacillus megaterium

A large set of mutants of CYP102A1 from Bacillus megaterium have human cytochrome P450-like activities and the ability to metabolize a number of marketed drugs and steroids. Here, we tested whether the CYP102A1 mutants could be used to produce hydroxylated human metabolites of 17β-estradiol (E₂). A set of the mutants, which were generated by site-directed and random mutagenesis, was used to produce hydroxylated human metabolites of E₂ in this study. Some of the tested mutants could regioselectively generate 2-OH E₂ as a major metabolite but not other hydroxylated products. These results suggest that CYP102A1 mutants would be useful for the bioconversion of steroid hormones to hydroxylated products, which can be used for industrial applications.     

Inhibition of in vitro aflatoxin B1-DNA binding in rainbow trout by CYP1A inhibitors: α-naphthoflavone, β-naphthoflavone and trout CYP1A1 peptide antibody

Rainbow trout cytochrome P450 (CYP)1A detoxifies aflatoxin B₁ (AFB₁) to aflatoxin M₁ (AFM₁), whereas CYP2K1 activates AFB₁ to AFB₁-8,9-epoxide. We report that α-naphthoflavone (ANF) and β-naphthoflavone (BNF) both strongly inhibit CYP1A-mediated ethoxyresorufin O-deethylase (EROD) activity (K_i = 9.1 ± 0.8 and 7.6 ± 1.1 nM, respectively). These inhibitors (selective for mammalian CYP1A at low concentrations), as well as rabbit polyclonal antibody to a trout CYP1A1 peptide (residues 277–294), also strongly inhibited trout microsome-catalyzed AFB₁-DNA binding and lauric acid (ω-1) hydroxylation in vitro, reactions previously established to be CYP2K1-dependent. ANF at 0.5, 5, 50 and 500 μM inhibited liver microsome-catalyzed AFB₁-DNA binding by 22, 58, 84 and 91%, respectively, whereas BNF at the same concentrations inhibited 22, 74, 78 and 81%, respectively. The CYP1A1 peptide and CYP2K1 polyclonal antibodies (10 mg IgG/mg microsomal protein) inhibited AFB₁-DNA binding by 84 and 66%, respectively, compared with pre-immune IgG. Lauric acid (ω-1) hydroxylation was inhibited 61% by 5 μM ANF, 69% by 5 μM BNF and 100% by either antibody at 12 mg IgG/mg microsomal protein. These results demonstrate that mammalian CYP1A inhibitors also inhibit trout microsomal AFB₁-DNA binding and lauric acid (ω-1) hydroxylation, catalyzed primarily by CYP2K1. In the absence of evidence that trout CYP1A can catalyze AFB₁-DNA binding, the results suggest configuration similarities at, or near, the active sites for these two fish enzymes that result in antibody crossreaction and loss of the inhibitor specificity observed with mammalian CYP1A.     

紫杉醇对食蟹猴和人CYP1A2、CYP3A4及CYP2A6酶代谢的影响

目的探讨紫杉醇对食蟹猴和人肝微粒体CYP1A2、CYP2A6和CYP3A4酶活性的影响。方法采用食蟹猴和人肝脏微粒体,分别以非那西汀、睾丸酮和香豆素分别作为CYP1A2、CYP2A6、CYP3A4的底物,建立CYP1A2、CYP2A6和CYP3A4体外代谢体系。采用不同浓度的紫杉醇分别与上述3种底物共同孵育于肝微粒体代谢体系中。用HPLC法分别测定各底物的代谢产物扑热息痛、6β-羟基睾丸酮、7-羟基香豆素的产生量,计算IC50值,以评估紫杉醇对CYP1A2、CYP2A6和CYP3A4代谢的影响。结果紫杉醇对食蟹猴肝微粒体3种酶的IC50值分别为570±5.9μmol/L、140±2.9μmol/L和无影响;紫杉醇对人肝微粒体3种酶的IC50值分别为193±6.6μmol/L、253±3.6μmol/L和24±1.6μmol/L。结论紫杉醇对食蟹猴肝微粒体CYP1A2和CYP3A4活性具有一定的抑制作用,但对CYP2A6酶的活性几乎没有影响。紫杉醇对人肝微粒体CYP1A2和CYP3A4活性的抑制作用较弱,但对CYP2A6酶的活性抑制作用较强,提示临床上紫杉醇与作为上述酶底物的药物联合用药时应慎重,以避免因中西药物相互作用所导致的不良反应发生。     

“内异消”对子宫内膜异位症大鼠CYP1A2、CYP2E1、CYP3A4活性的影响

本文主要考察"内异消"对子宫内膜异位症大鼠肝微粒体CYP1A2、CYP2E1、CYP3A4活性的影响。将16只SD大鼠随机分为空白对照组、正常给药组,16只模型SD大鼠随机分为模型对照组和模型给药组。正常给药组和模型给药组每天灌胃给予"内异消",空白对照组和模型对照组灌胃给予羧甲基纤维素钠溶液,均连续给药7 d,于第8 d给予"Cocktail"探针药物咖啡因、氯唑沙宗和硝苯地平药物,通过HPLC检测Cocktail探针药物的代谢率评价各组CYP450及CYP1A2、CYP2E1、CYP3A4活性。结果表明,与正常组比较,模型对照组和模型给药组咖啡因、氯唑沙宗的t1/2减小,硝苯地平的t1/2延长,均无显著性差异(P0.05);与正常组比较,模型对照组和模型给药组咖啡因、氯唑沙宗的AUC(0-t)显著升高(P0.05),硝苯地平的AUC(0-t)的增加无显著性。说明"内异消"对子宫内膜异位症大鼠CYP1A2、CYP2E1、CYP3A4的活性不存在显著的相互作用。     

A Systematically Combined Genotype and Functional Combination Analysis of CYP2E1, CYP2D6, CYP2C9, CYP2C19 in Different Geographic Areas of Mainland China – A Basis for Personalized Therapy

The cytochrome P450 is the major enzyme involved in drug metabolism. Single CYP genotypes and metabolic phenotypes have been widely studied, but no combination analysis has been conducted in the context of specific populations and geographical areas. This study is the first to systematically analyze the combined genotypes and functional combinations of 400 samples of major CYP genes—CYP2E1, CYP2D6, CYP2C9, and CYP2C19 in four geographical areas of mainland China. 167 different genotype combinations were identified, of which 25 had a greater than 1% frequency in the Chinese Han population. In addition, phenotypes of the four genes for each sample were in line with the predictions of previous studies of the four geographical areas. On the basis of the genotype classification, we were able to produce a systemic functional combinations analysis for the population. 25 of the combinations detected had at least two non-wild phenotypes and four showed a frequency above 1%. A bioinformatics analysis of the relationship between particular drugs and multi-genes was conducted. This is the first systematic study to analyze genotype combinations and functional combinations across whole Chinese population and could make a significant contribution in the field of personalized medicine and therapy.     

Lack of CYP1A responsiveness in species inhabiting chronically contaminated habitats: Two varieties of resistance?

Organisms chronically exposed to organic pollutants such as polychlorinated biphenyls (PCBs) can develop resistance to these chemicals, a condition associated with reduced inducibility of the biomarker enzyme cytochrome P450 1A (CYP1A). This study addresses the CYP1A response of members of the families Ictaluridae and Centrarchidae, two fish families found throughout much of the United States. We measured CYP1A expression, PCB body burdens, and conducted CYP1A challenge experiments in species from these families residing in the Town Branch/Mud River system (Logan County, KY, USA), a stream system historically contaminated with high levels of PCBs. Despite PCB concentrations in muscle tissue typically associated with elevated CYP1A (16.7 to 75.2μgPCB/g wet edible flesh), resident fish in the contaminated Town Branch/Mud River sites (yellow bullhead [Ameiurus natalis], green sunfish [Lepomis cyanellus], and spotted bass [Micropterus punctulatus]) had hepatic CYP1A activity levels similar to, rather than higher than, those in reference fish, suggesting reduced sensitivity to CYP1A induction. Lack of CYP1A expression following direct contaminant exposure has often been associated with resistance to those contaminants. To determine if CYP1A in resident populations was resistant to induction by PCBs, we exposed resident fish to a single, intraperitoneal injection with a potent CYP1A inducer, 3,4,3',4'-tetrachlorobiphenyl (PCB 77). PCB 77 treatment significantly induced hepatic CYP1A activity and protein in yellow bullhead from reference, but not contaminated, sites and had no effect on CYP1A in green sunfish from either site. The low CYP1A expression levels in resident fish with elevated PCB body burdens, together with the failure of PCB injection to induce CYP1A in certain populations, indicate an acclimatory CYP1A response in yellow bullheads and likely an inherently resistant CYP1A in green sunfish. This work demonstrates for the first time acclimation of CYP1A to PCBs in a species within the family Ictaluridae and provides further support for our previous work indicating an apparent inherent lack of CYP1A sensitivity to chlorinated inducers in Centrarchids. These traits may explain, at least in part, the common association of these families with degraded habitats and indicate Lepomis members are likely to be excellent candidates for exploring the mechanistic basis of 'inherent' CYP1A resistance. This study also underlines to the need for thorough characterization of the CYP1A responsivity of a population and/or species prior to using CYP1A as a reliable biomonitoring tool.     

Metabolism of 1α,25-dihydroxyvitamin D2 by human CYP24A1

The metabolism of 1α,25-dihydroxyvitamin D₂ (1α,25(OH)₂D₂) by human CYP24A1 was examined using the recombinant enzyme expressed in Escherichia coli cells. HPLC analysis revealed that human CYP24A1 produces at least 10 metabolites, while rat CYP24A1 produces only three metabolites, indicating a remarkable species-based difference in the CYP24A1-dependent metabolism of 1α,25(OH)₂D₂ between humans and rats. LC-MS analysis and periodate treatment of the metabolites strongly suggest that human CYP24A1 converts 1α,25(OH)₂D₂ to 1α,24,25,26(OH)₄D₂, 1α,24,25,28(OH)₄D₂, and 24-oxo-25,26,27-trinor-1α(OH)D₂ via 1α,24,25(OH)₃D₂. These results indicate that human CYP24A1 catalyzes the C₂₄-C₂₅ bond cleavage of 1α,24,25(OH)₂D₂, which is quite effective in the inactivation of the active form of vitamin D₂. The combination of hydroxylation at multiple sites and C-C bond cleavage could form a large number of metabolites. Our findings appear to be useful to predict the metabolism of vitamin D₂ and its analogs in the human body.     

CYP1A1基因单核苷酸多态性与肺癌的相关性研究

目的:探讨代谢酶CYP1A1基因MspI位点多态性与新疆汉族人群肺癌遗传易感性之间的相关性.方法:应用聚合酶链式反应(PCR)-限制性片段长度多态性(RFLP)技术检测59例新疆汉族肺癌和84例新疆汉族健康人的CYP1A1基因MspI位点多态性分布频率,并分析了CYP1A1基因MspI位点多态性与新疆汉族人群肺癌遗传易感性和患者性别之间的相关性.结果:(1)CYP1A1基因MspI位点3种多态基因型分布频率在两组间比较差异有统计学意义(χ2=6.682,P=0.035),CC基因型在病例组的分布频率显著高于正常对照组.(2)携带突变CC基因型的个体较携带TT基因型的个体患肺癌的危险性增加(OR=3.759.95%CI=1.228-11.494,P=0.035).(3)男女肺癌患者的CYP1A1基因MspI位点基因型及等位基因频率的差异均无显著性(P>0.05).结论:(1)CC突变基因型可能是新疆汉族人群的肺癌易感因素.(2)CYP1A1基因MspI位点多态性可能与新疆汉族肺癌患者的性别无关.     

氯吡格雷对大鼠肝药物酶CYP3A4 和CYP1A2 表达的影响

目的：氯吡格雷主要由CYP3A4 催化使其激活,CYP1A2 也参与氯吡格雷活化。关于氯吡格雷对肝微粒体酶的影响国内外 文献报道不多,因此本实验通过检测肝细胞色素氧化酶CYP3A4 和CYP1A2 的表达,探讨氯吡格雷对大鼠肝药物酶的影 响。方法：生理盐水为对照组,氯吡格雷设高、中、低三个剂量组（27,13.5,6.75mg/kg/d）,雄性健康大鼠连续灌胃给药7天,脱臼处 死,取肝组织,通过western blot法检测大鼠肝脏CYP3A4 和CYP1A2 蛋白表达情况。结果：1）、氯吡格雷抑制大鼠CYP3A4 蛋白 表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYP3A4 蛋白表达量降低（P<0.05）;氯吡格雷低中高剂量组间进行比较,大 鼠CYP3A4 蛋白表达量呈梯度减少（P<0.05）;2）、氯吡格雷抑制大鼠CYP1A2 蛋白表达,氯吡格雷高中低剂量组分别比生理盐水 组大鼠CYP1A2 蛋白表达量降低（P<0.05）,氯吡格雷低中高剂量组间进行比较,大鼠CYP1A2 蛋白表达量呈梯度减少（P<0.05）。 结论：氯吡格雷使肝细胞色素氧化酶CYP3A4 和CYP1A2 的表达量减少,因此氯吡格雷高、中、低3 个剂量组均不同程度的抑制 大鼠肝脏CYP3A4 和CYP1A2 的表达,提示当氯吡格雷与某些主要经CYP3A4 和CYP1A2 代谢的药物合用时,发生代谢性相关 作用的可能性大。     

应用寡核苷酸芯片并行检测CYP1A1和 GSTM1基因多态性

利用寡核苷酸芯片检测方法分析CYP1A1单核苷酸多态性 (SNP)和GSTM1缺失与否 ,实验结果证明了寡核苷酸芯片技术可并行、准确、高效地检测基因的单核苷酸多态性和其他类型的基因多态型 ,可为疾病遗传易感性及单体型的研究提供强有力的研究工具。采用该寡核苷酸芯片 ,检测了 84份正常人的血液DNA样本 ,其中GSTM1基因缺失率达到 4 7 6 % ,接近报道数值。统计分析发现 ,CYP1A1m1 m2的 3种基因型组合TT AG、TT GG和TC GG的发生频率都为 0 ,而根据实验得到的m1和m2各自基因型数据计算 ,它们的发生频率应是11 4 %、2 6 %和 3 1% ,所以推测在所检测的样本中没有T(m1位点 )和G(m2位点 )的连锁组合 ,即m1和m2位点的组合只有 3种单体型 :T A、C A和C G ,其发生频率分别是 6 9 6 %、7 7%和 2 2 6 %。     

氯吡格雷对大鼠肝药物酶CYP3A4和CYP1A2表达的影响

目的：氯吡格雷主要由CYP3A4催化使其激活,CYPlA2也参与氯吡格雷活化。关于氯吡格雷对肝微粒体酶的影响国内外文献报道不多,因此本实验通过检测肝细胞色素氧化酶CYP3A4和CYPlA2的表达,探讨氯吡格雷对大鼠肝药物酶的影响。方法：生理盐水为对照组,氯吡格雷设高、中、低三个剂量组（27,13．5,6．75mg／kg／d）,雄性健康大鼠连续灌胃给药7天,脱臼处死,取肝组织,通过westernblot法检测大鼠肝脏CYP3A4和CYPlA2蛋白表达情况。结果：1）、氯吡格雷抑制大鼠CYP3A4蛋白表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYP3A4蛋白表达量降低（P〈0．05）;氯吡格雷低中高剂量组间进行比较,大鼠CYP3A4蛋白表达量呈梯度减少（P〈0．05）;2）、氯吡格雷抑制大鼠CYPlA2蛋白表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYPlA2蛋白表达量降低（P〈0．05）,氯吡格雷低中高剂量组间进行比较,大鼠CYPlA2蛋白表达量呈梯度减少（P〈0．05）。结论：氯吡格雷使肝细胞色素氧化酶CYP3A4和CYPlA2的表达量减少,因此氯吡格雷高、中、低3个剂量组均不同程度的抑制大鼠肝脏CYP3A4和CYPlA2的表达,提示当氯吡格雷与某些主要经CYP3A4和CYPlA2代谢的药物合用时,发生代谢性相关作用的可能性大。     

应用寡核苷酸芯片并行检测CYP1A和GSTM1基因多态性

利用寡核苷酸芯片检测方法分析CYP1A单核苷酸多态性(SNP)和GSTM1缺失与否,实验结果证明了寡核苷酸芯片技术可并行、准确、高效地检测基因的单核苷酸多态性和其他类型的基因多态型,可为疾病遗传易感性及单体型的研究提供强有力的研究工具。采用该寡核苷酸芯片,检测了84份正常人的血液DNA样本,其中GSTMl基因缺失率达到47．6％,接近报道数值。统计分析发现,CYP1A m1-m2的3种基因型组合TT-AG、TT-GG和TC-GG的发生频率都为0,而根据实验得到的m1和m2各自基因型数据计算,它们的发生频率应是11．4％、2．6％和3．1％,所以推测在所检测的样本中没有T(m1位点)和G(m2位点)的连锁组合,即m1和m2位点的组合只有3种单体型：T-A、C-A和C-G,其发生频率分别是69．6％、7．7％和22．6％。     

CYP1A1, GSTM1 and GSTT1 polymorphisms and lung cancer: a pooled analysis of gene–gene interactions

Gene–environment interactions have been extensively studied in lung cancer. It is likely that several genetic polymorphisms cooperate in increasing the individual risk. Therefore, the study of gene–gene interactions might be important to identify high-susceptibility subgroups. GSEC is an initiative aimed at collecting available data sets on metabolic polymorphisms and the risks of cancer at several sites and performing pooled analyses of the original data. Authors of published papers have provided original data sets. The present paper refers to gene–gene interactions in lung cancer and considers three polymorphisms in three metabolic genes: CYP1A1, GSTM1 and GSTT1. The present analyses compare the gene–gene interactions of the CYP1A1*2A, GSTM1 and GSTT1 polymorphisms from studies on lung cancer conducted in Europe and the USA between 1991 and 2000. Only Caucasians have been included. The data set includes 1466 cases and 1488 controls. The only clear-cut association was found with CYP1A1*2A. This association remained unchanged after stratification by polymorphisms in other genes (with an odds ratio [OR] of approximately 2.5), except when interaction with GSTM1 was considered. When the OR for CYP1A1*2A was stratified according to the GSTM1 genotype, the OR was increased only among the subjects who had the null (homozygous deletion) GSTM1 genotype (OR=2.8, 95% CI=0.9–8.4). The odds ratio for the interactive term (CYP1A1*2A by GSTM1) in logistic regression was 2.7 (95% CI=0.5–15.3). An association between lung cancer and the homozygous CYP1A1*2A genotype is confirmed. An apparent and biologically plausible interaction is suggested between this genotype and GSTM1.     

西兰花CYP83A1基因的克隆及序列分析

为深入研究西兰花4-甲基亚磺酰丁基芥子油苷的合成代谢途径,对关键合成酶基因CYP83A1进行了克隆与生物信息学分析。根据前期西兰花转录组测序工作中获得的序列数据,同时参照Gen Bank数据库中拟南芥、小白菜和油菜等7种植物的CYP83A1基因CDS序列与西兰花进行比对,确定西兰花CYP83A1基因(Bo CYP83A1)的CDS序列。采用RT-PCR技术对其进行了克隆,获得Bo CYP83A1基因的CDS区序列,其全长为1 509 bp,编码502个氨基酸。预测该蛋白质的分子量为57.47 k D,理论等电点为7.1,包含2个跨膜结构域,且整个序列中不含信号肽,具有一个典型的P450结构域。氨基酸同源性分析表明,西兰花与油菜、大白菜的CYP83A1的相似性较高,均为98%。首次获得Bo CYP83A1的CDS序列,其登录号为KM111290。