吸烟和细胞色素P4501A1-MspⅠ、谷胱甘肽硫转移酶T1基因多态性与口腔癌的相关性研究

目的探讨吸烟和细胞色素P450（CYP）1A1-MspⅠ、谷胱甘肽硫转移酶（GST）T1基因多态性与口腔癌发病之间的关系。方法采用病例-对照研究的方法,以300例口腔癌患者（病例组）及300例非癌对照者（对照组）的外周血白细胞为样本,利用聚合酶链反应（PCR）技术检测Ⅰ相代谢酶CYP1A1-MspⅠ和Ⅱ相代谢酶GSTT1基因多态性,并分析吸烟和2种代谢酶基因多态性与口腔癌的相关性。结果病例组CYP1A1-MspⅠ突变纯合型（m2/m2）和GSTT1基因缺陷型[GSTT1（-）]的频率分布分别为38.33%、69.33%,而对照组的频率分布分别为21.00%、44.33%,二者差异有统计学意义（P〈0.01）。CYP1A1-MspⅠ（m2/m2）者患口腔癌的风险显著增加（OR=2.34,95%CI为1.76~4.07）。GSTT1（-）者患口腔癌的风险也显著增加（OR=2.84,95%CI为1.98~4.54）。基因突变的协同分析发现CYP1A1-MspⅠ（m2/m2）/GSTT1（-）在病例组和对照组中的分布频率分别为30.67%和6.67%,二者差异有统计学意义（P〈0.01）。CYP1A1-MspⅠ（m2/m2）/GSTT1（-）者患口腔癌的风险显著增加（OR=8.27,95%CI为3.63~11.29）。病例组的吸烟率显著高于对照组的吸烟率（OR=2.71,95%CI为1.31~4.52,P〈0.01）,CYP1A1-MspⅠ（m2/m2）及GSTT1（-）与吸烟有协同作用（OR=25.00,95%CI为11.87~35.64）。结论 CYP1A1-MspⅠ（m2/m2）和GSTT1（-）是口腔癌的易感因素,吸烟与口腔癌的易感性也有关,CYP1A1-MspⅠ（m2/m2）和GSTT1（-）与吸烟在口腔癌的发生上有相互促进的作用。

Hepatoprotective effects of S-adenosyl-L-methionine against alcohol-and cytochrome P450 2E1-induced liver injury

S-adenosyl-L-methionine (SAM) acts as a methyl donor for methylation reactions and participates in the synthesis of glutathione. SAM is also a key metabolite that regulates hepatocyte growth, differentiation and death. Hepatic SAM levels are decreased in animal models of alcohol liver injury and in patients with alcohol liver disease or viral cirrhosis. This review describes the protection by SAM against alcohol and cytochrome P450 2E1-dependent cytotoxicity both in vitro and in vivo and evaluates mechanisms for this protection.

Cytochrome P450 2E1 RsaI/PstI and DraI Polymorphisms Are Risk Factors for Lung Cancer in Mongolian and Han Population in Inner Mongolia

Objective： To explore the relationship between cytochrome P450 2E1 （CYP2E1） RsaI/PstI and DraI polymorphism and lung cancer susceptibility in Mongolian and Han population in Inner Mongolia of China. Methods： CYP2E1 RsaI/PstI and DraI polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism in 64 lung cancer patients, 150 healthy Mongolian and 150 healthy Han individuals. The distribution of genotype and allele frequencies of CYP2E1 RsaI/PstI and DraI polymorphisms were studied. Results： The risk of lung cancer was increased in individuals with CYP2E1 （cl/cl） and CYP2E1 （DD） with OR values of 2.431 （95%CI=1.082-5.460） and 2.778 （95%CI=1.358-5.683） respectively （P0.05）. When CYP2E1 RsaI/PstI and DraI polymorphisms were combined, the risk of lung cancer was reduced in individuals with CYP2E1 （cl/c2＋c2/c2 and DD＋CC） with OR values of 0.233 （95%CI=0.088-0.615, P0.05）. In smokers, the susceptibility to lung cancer was higher in the individuals with CYP2E1 （c1/c1） and CYP2E1 （DD） than in the individuals with c2 and C allele （P0.05, OR=2.643 and 4.308 respectively）. There was no significant difference in distribution of CYP2E1 genotype frequency between healthy Mongolian, Han population and lung cancer patients, healthy controls in Inner Mongolia. Conclusion： CYP2E1 （c1/c1） and CYP2E1 （DD） are predisposing factors of lung cancer in population in Inner Mongolia. CYP2E1 （c2﹢C） co-mutation may decrease the risk of lung cancer. Smoking exerts synergetic effect with CYP2E1 （c1/c1） and CYP2E1 （DD） on the occurrence of lung cancer.

Cytochrome P450 family 17 subfamily A member 1 mutation causes severe pseudohermaphroditism: A case report

BACKGROUND 17α-Hydroxylase deficiency(17-OHD)is a rare form of congenital adrenal hyperplasia,characterized by hypertension,hypokalemia,and gonadal dysplasia.However,due to the lack of a comprehensive understanding of this disease,it is prone to misdiagnosis and missed diagnosis,and there is no complete cure.CASE SUMMARY We report a female patient with 17-OHD.The patient was admitted to the Department of Neurology of our hospital due to limb weakness.During treatment,it was found that the patient’s condition was difficult to correct except for hypokalemia,and her blood pressure was difficult to control with various antihypertensive drugs.She was then transferred to our department for further treatment.On physical examination,the patient's gonadal development was found to be abnormal,and chromosome analysis demonstrated karyotype 46,XY.Considering the possibility of 17-OHD,the cytochrome P450 family 17 subfamily A member 1(CYP17A1)test was performed to confirm the diagnosis.CONCLUSION The clinical manifestations of 17-OHD are complex.Hormone determination,imaging examination,chromosome determination and CYP17A1 gene test are helpful for early diagnosis.

Influences of V5-epitope tag on the metabolic activation of AFB1 by human cytochrome P450 2A13

Objective： To explore the impact of V5-epitope tag inserted in the commercial pcDNA5/FRT/V5-His TOPO expression vector on the metabolic activation of AFB1 by human CYP2A13. Methods ： A C-terminal 6 × Histag was first introduced into CYP2A13 cDNA by PCR and subsequently transferred into the expressing vector pcDNA5/FRT. Another commercial pcDNA5/FRT/V5-His TOPO expression vector was used to develop the construct directly via PCR. Both of the constructs were then transfected into Flp-In CHO and allowed for the stable expression of CYP2A13. The mouse CYP2A5 and the vector alone were used as positive and negative control, respectively. The presence of CYP2A5 and CYP2A13 cDNA and their protein expression in the stable transfectant cells were deterrrfined by immunoblotting assay using a monoclonal antibody against 6 × Histag. The AFBl-induced cytotoxicity in these tranfected CHO cells were conducted by MTS assay and the IC50 of cell viability was used to compare the CYP enzyme metabolic activity in AFB1 metabolism among these cells. Results： In accordance with the Flp-In system working mechanism, all the transfectant cells presented same protein expression level. The CHO cells expressing CYP2A5 was more sensitive to AFB1 treatment than those cells expressing CYP2A13, there was about 30-fold ICs0 difference between the two cells （2.1 nmol/L vs 58 nmol/L）. Interestingly, CYP2A13 fused with V5-Histag had the lost of metabolic activity to AFB1 than that fused with Histag alone, the ICa, of the viability in CHO-2A13-His-V5 cells was about 20-fold less than CHO-2A13- His （〉 1 000 nmol/L vs 58 nmol/L）. However, there was no change between CYP2A5 fused with V5-Histag and Histag alone （2.4 nmol/L vs 2.1 nmol/L）. Conclusion： The results demonstrate that CYP2A13 fused with V5-epitope has a significant impact on its metabolic activation to AFB1, which indicated that it should be careful to select a new expressing vector for evaluating the enzyme activity in carcinogen metabolism.

<i>In vivo</i>effects of genistein, herbimycin a and geldanamycin on rat hepatic cytochrome P4501A

Cytochrome P4501A (the CYP1A1 and CYP1A2 enzymes) are regulated through the aryl hydrocarbon receptor (AhR)-dependent signal transduction pathway and are generally known as enzymes which metabolize anthropogenic xenobiotics such as dioxin to carcinogenic and mutagenic compounds. However, recently the facts of CYP1A activation under physiological conditions or under action of non-dioxin-like compounds appear. In the present study we show that genistein, herbimycin A and geldanamycin (the protein-tyrosine kinase inhibitors) affect in vivo to CYP1A1 activity, the CYP1A1 mRNA level and the CYP1A1 protein level. These data provide insight into the role of protein kinases in CYP1A regulation may facilitate the understanding of CYP1A regulation.

Functionalized selenium nanoparticles ameliorated acetaminophen-induced hepatotoxicity through synergistically triggering PKCδ/Nrf2 signaling pathway and inhibiting CYP 2E1

Selenium nanoparticles(SeNPs)have been demonstrated potential for use in diseases associated with oxidative stress.Functionalized SeNPs with lower toxicity and higher biocompatibility could bring better therapeutic activity and clinical application value.Herein,this work was conducted to investigate the protective effect of Pleurotus tuber-regium polysaccharide-protein complex funtionnalized SeNPs(PTR-SeNPs)against acetaminophen(APAP)-induced oxidative injure in HepG2 cells and C57BL/6J mouse liver.Further elucidation of the underlying molecular mechanism,in particular their modulation of Nrf2 signaling pathway was also performed.The results showed that PTR-SeNPs could significantly ameliorate APAP-induced oxidative injury as evidenced by a range of biochemical analysis,histopathological examination and immunoblotting study.PTR-SeNPs could hosphorylate and activate PKCδ,depress Keap1,and increase nuclear accumulation of Nrf2,resulting in upregulation of GCLC,GCLM,HO-1 and NQO-1 expression.Besides,PTR-SeNPs suppressed the biotransformation of APAP to generate intracellular ROS through CYP 2E1 inhibition,restoring the mitochondrial morphology.Furthermore,the protective effect of PTR-SeNPs against APAP induced hepatotoxicity was weakened as Nrf2 was depleted in vivo,indicating the pivotal role of Nrf2 signaling pathway in PTR-SeNPs mediated hepatoprotective efficacy.Being a potential hepatic protectant,PTR-SeNPs could serve as a new source of selenium supplement for health-promoting and biomedical applications.

Long-term modifications of blood pressure in normotensive and spontane-ously hypertensive rats by gene delivery of rAAV-mediated cytochrome P450 arachidonic acid hydroxylase

Arachidonic acid cytochrome P-450 （CYP） hydroxylase 4A isoforms, including 4A1, 4A2, 4A3 and 4A8 in the rat kidney, catalyze arachidonic acid to produce 19/20-Hydroxyeicosatetraenoic acids （20-HETE）, a biologically active metabolite, which plays an important role in the regulation of blood pressure. However, controversial results have been reported regarding the exact role of 20-HETE on blood pressure. In the present study, we used recombinant adenoassociated viral vector （rAAV） to deliver CYP 4A1 cDNA and antisense 4A1 cDNA into Sprague-Dawley （SD） rats and spontaneously hypertensive rats （SHR）, respectively, to investigate the effects of long-term modifications of blood pressure and the potential for gene therapy of hyperténsion. The mean systolic pressure increased by 14.2±2.5 mm Hg in rAAV.4A 1-treated SD rats and decreased by 13.7±2.2 mm Hg in rAAV.anti4A l-treated SHR rats 5 weeks after the injection compared with controls and these changes in blood pressure were maintained until the experiments ended at 24 weeks. In 4A1 treated animals CYP4A was overexpressed in various tissues, but preferentially in the kidney at both mRNA and protein levels. In anti-4Al-treated SHR, CYP4A mRNA in various tissues was probed, especially in kidneys, but 4A l protein expression was almost completely inhibited. These results suggest that arachidonic acid CYP hydroxylases contribute not only to the maintenance of normal blood pressure but also to the development of hypertension. rAAV-mediated anti4A administration strategy has the potential to be used as targeted gene therapy in human hypertension by blocking expression of CYP 4A in kidneys.

CYP2E1 Pst Ⅰ/Rsa Ⅰ polymorphism and colorectal cancer risk:A meta-analysis

AIM:To clarify the association between CYP2E1 PstⅠ/RsaⅠ polymorphism and susceptibility to colorectal cancer.METHODS:A meta-analysis based on 10 eligible casecontrol studies involving 4979 cases and 6012 controls was carried out to summarize the data on the association between CYP2E1 RsaⅠ/PstⅠ polymorphism and colorectal cancer risk.RESULTS:In comparison of the homozygote c2c2 and c2 carriers(c1c2 + c2c2) and the homozygous wild-type genotype(c1c1),no association was found between CYP2E1 RsaⅠ/PstⅠ polymorphism and colorectal cancer risk [odds ratio(OR)=1.24(95% CI:0.93-1.66) for c2c2;OR = 1.02(95% CI:0.88-1.19) for c2 carriers].In stratif ied analysis,Caucasians with c2c2 homozygote appeared to have an increased risk of colorectal cancer(OR=2.67,95% CI:1.03-6.89,P=0.043),no signif icant associations were found in other groups.CONCLUSION:c2c2 homozygote of CYP2E1 PstⅠ/RsaⅠ polymorphism may be associated with the increased risk of colorectal cancer in Caucasians,which needs further investigations.

CYP2C9、VKORC1基因多态性与华法林个体化用药研究进展

尽管具有治疗指数狭窄和出血并发症频繁的弊病,华法林仍是临床上应用非常广泛的口服抗凝血药物。不同患者对华法林的反应差异很大,在达到相同治疗效果的情况下,不同个体的用药剂量可能相差20倍之多。华法林的治疗剂量受多种因素影响,包括基因多态性、体重指数、年龄等及其他药物因素等,这就要求临床医师在应用华法林时需注重个体化用药及选择最优治疗方案。多种基因可影响华法林的药物代谢,其中细胞色素P450 2C9(CYP2C9)及维生素K环氧化物还原酶复合体1(VKORC1)基因多态性是目前研究的重点。本文将综述以上两个基因的基因多态性及其与华法林个体化用药相关性的研究进展。

CYP2C9及VKORC1基因多态性对心脏瓣膜置换术后华法林个体剂量差异的研究

目的研究湖北地区汉族人细胞色素P450酶2C9(CYP2C9)基因和维生素K环氧化物还原酶复合体1(VKORC1)基因多态性分布特点及其对华法林稳态剂量的影响。方法收集2012年3—8月湖北地区汉族临床使用华法林的患者108例作为华法林组,选择同期健康受试者85名为对照组。采用聚合酶链反应-限制性内切酶片段长度多态性(PCR-RFLP)技术检测CYP2C9和VKORC1基因型,并比较不同基因型华法林稳态剂量。结果两组基因型频率和等位基因频率分布比较差异无统计学意义(P>0.05)。华法林组中CYP2C9基因*1/*3型较*1/*1型华法林稳态剂量小,VKORC1基因AA型较GA型华法林稳态剂量小(P<0.05,P<0.01)。除了检测的3个多态位点,还发现了50多个变异位点。结论在湖北地区汉族人群中,存在CYP2C9和VKORC1基因多态性,且不同基因型患者间华法林稳态剂量存在差异,华法林基因相关变异位点需要进一步证实。

Detection of CYP2E1,a Genetic Biomarker of Susceptibility to Benzene Metabolism Toxicity in Immortal Human Lymphocytes Derived from the Han Chinese Population

Objective Cytochrome P450 2E1 （CYP2E1） is an important metabolizing enzyme involved in oxidative stress responses to benzene, a chemical associated with bone marrow toxicity and leukemia, We aimed to identify the CYP2E1 genetic biomarkers of susceptibility to benzene toxicity in support of environmental and occupational exposure prevention, and to test whether a model using immortal human lymphocytes might be an efficient tool for detecting genetic biomarkers. Methods Immortalized human lymphocyte cell lines with independent genotypes on four CYP2E1 SNP sites were induced with 0.01% phenol, a metabolite of benzene. CYP2E1 gene function was evaluated by mRNA expression and enzyme activity. DNA damage was measured by Single-Cell Gel Electrophoresis （SCGE）. Results Among the four SNPs, cells with rs2070673TT and rs2030920CC showed higher levels of ~YP2E1 transcription and enzymatic activity than the other genotypes in the same SNP site. Cells with higher gene expression genotypes also showed higher comet rates compared with lower gene expression genotypes. Conclusion These results suggest that CYP2E1 rs2070673 and rs2030920 might be the genetic biomarkers of susceptibility to benzene toxicity and that the immortalized human lymphocytes model might be an efficient tool for the detection of genetic biomarkers of susceptibility to chemicals.

CYP2C19 polymorphism has no influence on rabeprazole-based hybrid therapy for Helicobacter pylori eradication

AIM To evaluate the impact of cytochrome P450 2C19(CYP2C19) and interleukin-1β(IL-1β) polymorphisms on the efficacy of Helicobacter pylori(H. pylori) eradication by using rabeprazole-based hybrid therapy.METHODS A total of 88 H. pylori-infected patients were recruited to receive 14-d of hybrid therapy from March 2013 to May 2014. Three patients were excluded from analysis because of incomplete compliance. Either a follow-up endoscopy or 13 C-urea test was performed to determine the results of H. pylori eradication therapy. The genotypes of CYP2C19 and IL-1β were analyzed to investigate the impact on treatment effect. RESULTS The total eradication rate of H. pylori was 92.94%(79/85). According to the CYP2C19 genotypes, the rates of H. pylori eradication were 89.19% in extensive metabolizers(EM) and 95.83% in non-EM. The H.pylori eradication rates regarding the IL-1β genotypes were 92.59% in the normal acid secretion group and 93.10% in the low acid secretion group. After multivariable logistic regression analysis, both the genotypes of CYP2C19 and IL-1β had no significant influences on the eradication rates of H. pylori.CONCLUSION The CYP2C19 and IL-1β polymorphisms are not significantly independent factors of H.pylori eradication using rabeprazole-based hybrid therapy.

Role of CYP2E1 gene polymorphisms association with hepatitis risk in Northeast India

AIM:To investigate hepatitis virus, genetic and environmental factors, and their interactions in predisposing patients to liver diseases in Northeast India. METHODS:A total of 104 jaundice patients and 124 community controls were included. Serological analysis was performed by routine enzyme-linked immunosorbent assay, and nucleic acid testing for hepatitis viruses was done by polymerase chain reaction (PCR), followed by PCR direct sequencing for viral genotyping. Cytochrome P450 2E1 (CYP2E1) polymorphism was studied by PCR-restriction fragment length polymorphism. Nitrite and volatile nitrosamines in indigenous foods consumed routinely by the Northeast Indian ethnic population were estimated by Griess’s reagent and GC-MS, respectively.RESULTS: Hepatitis A virus (HAV) infection was predominantly prevalent (36.5%) in our cohort, followed by hepatitis B virus (HBV), hepatitis E virus (HEV) andhepatitis C virus. HBV genotype D and HEV genotype 1 were the most dominant. CYP2E1 c1/c2 genotype frequency was comparatively higher in alcoholic (P<0.0001,OR =30.5) and cryptogenic (P=0.014, OR=8.714) patients, and was associated with significantly higher hepatitis risk (P=0.0.007,OR=6.489). Mutant C allele of Cyp2E1 DraⅠ frequency was comparatively higher in HAV (P=0.006), alcoholic (P =0.003) and cryptogenic (P=0.014) cases, and was associated with overall hepatitis risk (P=0.026, OR=5.083). Indigenous foods, Gundruk, Kharoli, betel leaf and nuts were found to have the highest nitrite content. CONCLUSION: Apart from viral factors, CYP2E1 polymorphism might be associated with increased risk of liver diseases in Northeast India. Indigenous foods that contain nitrite and nitrosamine might be an associated risk factor.

Effects of ADH1C, ALDH2, and CYP2A6 Polymorphisms on Individual Risk of Tobacco-Related Lung Cancer in Male Japanese Smokers

Recent genome-wide association studies have identified several lung cancer susceptibility loci. We previously carried out a replication study in male Japanese smokers that focused on chromosome 5p15 (telomerase reverse transcriptase) and 3q28 (tumor protein p63) (Shimizu et al., Journal of Cancer Therapy, Vol. 2, No. 5, 2011, pp. 690-696). The current study was performed to confirm the association of traditional susceptibility loci [i.e., alcohol dehydrogenase 1C (ADH1C) and aldehyde dehydrogenase 2 (ALDH2)] in 1039 male Japanese smokers (573 lung cancer patients and 466 healthy control subjects) who were previously enrolled in a study to investigate the low odds ratio for lung cancer risk associated with functionally impaired and deletion polymorphisms in cytochrome P450 2A6 (CYP2A6). The minor allele frequency of rs671 in ALDH2 (0.304) was significantly higher in lung cancer cases than in controls (0.226), with an odds ratio of 1.42 [95% confidence interval (CI) of 1.12 - 1.80, p = 0.0033]. No significant association of rs698 in ADH1C with lung cancer risk was found in this population of male Japanese smokers. For light smokers categorized according to the 50th percentile Brinkman index value among the control subjects (620 daily cigarettes × years) and for the CYP2A6*1 wild-type non-carrier sub-population, significantly high odds ratios of 1.98 and 1.68 (95% CI of 1.28 - 3.06, p = 0.0022, and 1.07 - 2.66, p = 0.025), respectively, were observed for rs671 in ALDH2. The present results support the association of ALDH2 loci with lung cancers and suggest a specific effect of ALDH2 loci resulting in a higher risk of lung cancer in light smokers. CYP2A6 polymorphisms, including copy number polymorphisms, may lower the risk of heavy tobacco use-related lung cancer.

Oxidation reactivity of 1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE)by CompoundⅠmodel of cytochrome P450s

Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is needed.We have previously proved that density functional theory（DFT） is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis（2,4,6-tribromophenoxy）ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis（2,4,6-tribromophenoxy）ethanol, which may undergo hydrolysis yielding2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.

Identification of a novel cytochrome P450 CYP321B1 gene from tobacco cutworm （Spodoptera litura） and RNA interference to evaluate its role in commonly used insecticides

Insect cytochrome P450 monooxygenases （CYPs or P450s） play an important role in detoxifying insecticides leading to resistance in insect populations. A polyphagous pest, Spodoptera litura, has developed resistance to a wide range of insecticides. In the present study, a novel P450 gene, CYP321B1, was cloned from S. litura. The function of CYP321B1 was assessed using RNA interference （RNAi） and monitoring resistance levels for three commonly used insecticides, including chlorpyrifos, β-cypermethrin and methomyl. The full-length complementary DNA sequence of CYP321B1 is 1814 bp long with an open reading frame of 1 488 bp encoding 495 amino acid residues. Quantitative reverse-transcriptase polymerase chain reaction analyses during larval and pupal develop- ment indicated that CYP321B1 expression was highest in the midgut of fifth-instar larvae, followed by fat body and cuticle. The expression of CYP321B1 in the midgut was up- regulated by chlorpyrifos,β-cypermethrin and methomyl with both lethal concentration at 15% （LC15） （50, 100 and 150 μg/mL, respectively） and 50%（LC50） dosages （100,200 and 300μg/mL, respectively）. Addition of piperonyl butoxide （PBO） significantly increased the toxicity ofchlorpyrifos,β-cypermethrin and methomyl to S. litura, suggesting a marked synergism of the three insecticides with PBO and P450-mediated detoxification. RNAi- mediated silencing of CYP321B1 further increased mortality by 25.6% and 38.9% when the fifth-instar larvae were exposed to chlorpyrifos and β-cypermethrin, respectively, at the LCso dose levels. The results demonstrate that CYP321B1 might play an important role in chlorpyrifos and β-cypermethrin detoxification in S. litura.

细胞色素P450 2E1基因PstⅠ多态、腌制品与大肠癌关系的病例对照研究

目的 研究代谢酶细胞色素P4 5 0 2E1基因 (CYP2E1)PstⅠ多态性和腌制品与大肠癌易感性的关系。方法 采用人群基础的病例对照分子流行病学研究和PCR RFLP技术 ,对 12 6例大肠癌和 343名健康对照PstⅠ识别的CYP2E1基因型进行检测。结果 健康对照组CYP2E1基因野生型(C1/C1)为 6 1 8% ,杂合子 (C1/C2 )为 35 8% ,突变纯合子 (C2 /C2 )为 2 4 %。调整年龄性别后 ,结肠癌病例中突变基因型频率 5 4 9% (5 2 9%C1/C2和 2 0 %C2 /C2 )高于对照 (OR 1 979,95 %CI 1 0 90～3 5 95 ) ,但直肠癌病例与对照比较 ,无统计学意义。分层分析发现 ,突变基因型、每周 1或 2次和隔天或每天吃腌制品单因素作用的大肠癌OR值分别 1 935、2 12 2和 2 315 ,而每周 1或 2次 +突变型、隔天或每天吃 +突变型联合作用后大肠癌OR值分别为 2 2 72和 3 12 7。分别分析结、直肠癌 ,腌制品对直肠癌的危险性在食用频率为每周 1或 2次时 ,差异有统计学意义 ,野生型和突变型的OR值分别为2 6 4 6和 2 2 97,两者差异无统计学意义 ;而结肠癌危险性只有在PstⅠ突变者隔天或每天吃腌制品时才剧增 ,OR值 4 2 6 2 (1 395～ 13 0 17) ,为野生型的 2 6 9倍 ,差异有统计学意义。结论CYP2E1PstⅠG→C点突变是大肠癌的遗传易感性因素 ,与腌?

EC-SOD和CYP 1A1-MspⅠ基因多态性及吸烟与口腔癌的相关性研究

目的 探讨吸烟和细胞外超氧化物歧化酶（extracellular superoxide dismutase,EC-SOD）、细胞色素P450（cytochrom P450,CYP）1A1-MspⅠ基因多态性与口腔癌发病之间的关系。方法 采用病例-对照研究的方法,以670例口腔癌患者（病例组）及670例非癌对照者（对照组）的外周血白细胞为样本,利用聚合酶链反应（polymerase chain reaction,PCR）技术检测EC-SOD和CYP1A1-MspⅠ基因多态性,并分析吸烟和2种代谢酶基因多态性与口腔癌的相关性。结果病例组EC-SOD（C/G）和CYP1A1-MspⅠ突变纯合型（m2/m2）基因频率分布分别为39.40%、68.81%,而对照组的频率分布分别为21.34%、43.88%,二者差异均有统计学意义（P均〈0.05）;EC-SOD（C/G）者患口腔癌的风险显著增加（OR=2.40,95%CI=1.73~4.32）,CYP1A1-MspⅠ（m2/m2）者患口腔癌的风险也显著增加（OR=2.82,95%CI=1.84~4.41）;基因突变的协同分析发现EC-SOD（C/G）/CYP1A1-MspⅠ（m2/m2）在病例组和对照组中的分布频率分别为30.60%和7.16%,差异有统计学意义（P〈0.05）;EC-SOD（C/G）/CYP1A1-MspⅠ（m2/m2）者患口腔癌的风险显著增加（OR=6.87,95%CI=2.18~9.45）;病例组的吸烟率明显高于对照组（P〈0.05）,EC-SOD（C/G）/CYP1A1-MspⅠ（m2/m2）与吸烟有协同作用（OR=44.48,95%CI=17.63~62.07）,EC-SOD（C/G）/CYP1A1-MspⅠ（m2/m2）与吸烟指数（SI〉400）有协同作用（OR=248.81,95%CI=175.46~384.37）。结论 EC-SOD（C/G）和CYP1A1-MspⅠ（m2/m2）是口腔癌的易感因素,吸烟与口腔癌的易感性也有关,EC-SOD（C/G）/CYP1A1-MspⅠ（m2/m2）与吸烟在口腔癌的发生上有协同作用。

Functional reconstruction of bovine P450scc steroidogenic system in <i>Escherichia coli</i>

Mammalian cytochrome P450scc enzyme system catalyzes the initial step in steroid hormone biosynthesis—cholesterol hydroxylation followed by cleavage of the side-chain to yield pregnenolone. This system consists of three components—the cytochrome P450scc (CYP11A1), a flavoprotein (NADPH-adrenodoxin reductase, AdR) and an iron-sulfur protein (adrenodoxin, Adx). In this work, the three-component electron transport chain (AdR/Adx/CYP11A1) from bovine adrenal cortex has been implemented in Escherichia coli by co-expression of the corresponding coding sequences from a tricistronic plasmid. The cDNAs of AdR, Adx and CYP11A1 are situated in a single transcription unit and separated by ribosome binding sequences. The recombinant strain created was capable of synthesizing functional proteins identical to the bovine CYP11A1, AdR and Adx on molecular weights and immuno-specificity. The experiments in vivo showed pregnenolone production from cholesterol by the transformed bacteria. Maximal productivity of 0.42 ± 0.015 mg/l pregnenolone for 24 h has been reached for the induced cells in the presence of cholesterol solubilizing agent—methyl-β-cyclodextrin. Thus, a stable transgenic E. coli strain with the functional reconstructed bovine cholesterol side-chain cleavage system has been firstly generated in this work. The findings are of importance for studies of mammalian steroidogenic system features, and may open some perspectives for further generation of novel microbial biocatalysts.