CXCL16基因与红色荧光蛋白pDsRed2-N1融合基因表达载体的构建

目的:构建人趋化因子配体16(CXC ligand 16,CXCL16)与增强型红色荧光蛋白(red fluorescent protein,RFP)的融合基因表达载体pDsRed2-N1/CXCL16,使CXCL16-RFP融合蛋白在人293T细胞中稳定表达。方法:针对CXCL16基因设计引物,扩增人CXCL16 cDNA,退火后插入含有RFP的表达载体pDsRed2-N1。测序正确的CXCL16和RFP的融合基因表达载体pDsRed2-N1/CXCL16,经脂质体转染人293T细胞株,G418筛选获得稳定转染的细胞株。荧光显微镜观察细胞转染情况,Western blotting比较转染前后293T细胞中CXCL16蛋白的表达变化。结果:经转化细菌、抽提质粒、酶切鉴定和DNA序列分析证实,CXCL16基因已正确插入pDsRed2-N1中RFP基因的上游,获得融合基因表达载体pDsRed2-N1/CXCL16。空载体pDsRed2-N1和融合基因表达载体pDsRed2-N1/CXCL16经脂质体转染人293T细胞后,在荧光显微镜下可观察到表达RFP的细胞发出红色荧光,转染效率分别可达95%和85%。pDsRed2-N1/CXCL16转染293T细胞后,CXCL16蛋白的表达水平显著上调。结论:成功构建的pDsRed2-N1/CXCL16融合基因表达载体可在293T细胞中稳定表达CXCL16蛋白,为进一步研究CXCL16在细胞增殖调控中的作用奠定了基础。     

慢病毒介异的孕烷X受体sh-RNA稳定干扰HepG2细胞株的构建

目的： 构建慢病毒介导的人孕烷X受体(hPXR)sh-RNA干扰载体及筛选肝癌细胞稳定干扰株。方法：针对hPXR的特异性序列,设计干扰序列,构建重组克隆。转染HEK293T细胞,筛选有效干扰片段。HEK293T包装干扰病毒并转染肝癌HepG2细胞株,200 mmol/L嘌呤霉素筛选2－3周,Western blot检测PXR表达。hPXR激动剂利福平处理PXR sh-RNA稳定干扰肝癌HepG2细胞株和Scramble对照细胞,抽提RNA并鉴定hPXR靶基因细胞色素P450 3A4(CYP3A4)的表达。结果：筛选出了PXR有效干扰片段,并获得了PXR信号通路有效敲低的HepG2慢病毒稳定干扰株。结论：成功构建了慢病毒介导的PXR sh-RNA稳定干扰HepG2细胞株。     

基于3T3-L1细胞株的人类ADRB1基因稳定过表达模型的构建

目的:构建ADRB1基因稳定过表达的细胞模型。方法:将ADRB1 cDNA克隆片段和慢病毒载体连接;将重组载体与慢病毒包装质粒共转染293T细胞,收集上清液感染3T3-L1前脂肪细胞,利用GFP流式分选法筛选稳转细胞株。结果:Western blot检测证明,ADRB1过表达组的ADRB1蛋白水平显著高于mock组。结论:基于3T3-L1细胞株的ADRB1基因稳定过表达模型构建成功,为研究ADRB1在肿瘤恶病质脂肪消耗中的作用奠定了基础。     

利用GFP逆转录病毒标记肿瘤与血管内皮细胞

目的 制备携带GFP基因的逆转录病毒,以简便、快速标记活细胞。方法 将编码GFP的cDNA片段插入逆转录病毒载体pLNCX构建重组逆转录病毒载体pLNCX-GFP,借助脂质体转染单嗜性及双嗜性逆转录病毒包装细胞,G418筛选抗性克隆,然后利用荧光显微镜选出GFP表达最高的克隆。取含有毒颗粒的上清液感染NIH3T3及多种肿瘤或血管内皮细胞。结果 重组逆转录病毒载体pLNCX-GFP转染包装细胞后,包装细胞可表达GFP并产生GFP逆转录病毒。尽管GFP逆转录病毒对动物及人的肿瘤细胞或血管内皮细胞的感染能力各不相同,但由于逆转录病毒能整合进入宿主细胞基因组DNA内,经短期G418筛选后容易获得持续、稳定、高水平表达GFP的阳性细胞。表达GFP的肿瘤细胞仍可在同系动物体内生长并持续表达GFP。携带GFP基因的逆转录病毒能简便、快速介导稳定的基因转移,遗传标记多种细胞,比表达质粒等更优越。     

人肺癌细胞株L9981-nm23-H1的建立

目的 建立转染野生型nm23-H，基因的人大细胞肺癌细胞株L9981nm23-H。。方法 应用基因克隆技术构建逆转录病毒载体pLXSN-nm23H1-EGFP。脂质体法转染PA317细胞，得到逆转录病毒，并将病毒感染L9981细胞，获得L9981-nm23H1。应用PCR和Western blot检测L9981-nm23-H1细胞中nm23H1基因及其蛋白表达。结果 成功构建了逆转录病毒载体pLXSNnm23-H1-EGFP。nm23-H1 cDNA导入到L9981细胞株中，并检测到L9981-nm23-H1细胞中有nm23-H1蛋白表达。结论 nm23-H1基因在细胞株L9981-nm23-H1中能持续、稳定和高效表达。     

针对EDAG-1基因的siRNA抑制白血病细胞的生长及IL-8分泌

目的：探讨抑制胚胎发育相关基因-1（embryonic develop-associated gene1,EDAG-1）表达对白血病细胞株生长的影响及其机制。方法：将靶向EDAG-1基因的特异序列连接到逆转录病毒载体中,将脂质体介导的重组质粒转染包装产病毒细胞株PT67;收集细胞上清液转染HEL细胞株,经嘌呤霉素筛选获得稳定抑制EDAG-1基因表达的细胞株;RT-PCR法检测EDAG-1基因的抑制情况,MTT法检测转染细胞的增殖能力,同时采用RT-PCR和ELISA法检测转染后细胞中IL-8的表达水平。结果：成功构建获得靶向EDAG-1基因的反转录病毒载体,筛选获得抑制EDAG-1基因表达的HEL细胞株。EDAG-1基因被抑制的细胞株增殖速度降低,IL-8的分泌水平同时相应减低。结论：沉默EDAG-1基因的表达可以抑制白血病细胞株的增殖和IL-8的分泌,提示EDAG-1基因可能是白血病治疗的一个有效靶点。     

Notch1基因转染对人肝癌细胞Hep3B生长的影响及作用机制的研究

目的：研究逆转录病毒介导的Notch1（ICN）基因转染对人肝癌细胞生长的影响，并对其作用机制进行了探讨。方法： 采用磷酸钙沉淀法质粒共转染293T细胞，制备出表达组成性活化形式的Notch1（ICN）和/或绿色荧光蛋白（GFP）的逆转录病毒载体MSCVICN/GFP及对照逆转录病毒载体MSCVGFP，并检测病毒滴度。用逆转录病毒感染人肝癌细胞Hep3B，观察病毒的感染效率，MTT比色法测定瞬时表达Notch1（ICN）对Hep3B人肝癌细胞生长的影响，利用流式细胞仪分析细胞周期分布的变化，Western blot方法检测细胞周期调控蛋白的变化。结果：通过质粒共转染可获得具有较高滴度的重组逆转录病毒。MTT比色法显示瞬时表达Notch1（ICN）基因可以抑制人肝癌细胞Hep3B的生长，瞬时表达Notch1（ICN）基因可使Hep3B细胞周期停滞在G0/G1期并上调细胞周期调控蛋白P53的表达水平。结论：Notch1基因可通过影响细胞周期分布和P53蛋白的表达水平而抑制人肝癌细胞生长。     

特异性沉默Eca109 细胞系stat hmin 基因siRNA 表达载体的构建

 目的 构建并筛选特异性沉默stathmin基因的pSUPER-S逆转录病毒载体以及稳定表达的细胞克隆。方法 用DNA重组技术,将64nt能转录产生靶向stathmin小发夹RNA（shRNA）的寡核苷酸序列,定向克隆入逆转录病毒载体pSUPER-EGFP,应用脂质体将重组逆转录病毒载体pSUPER-S转染细胞系Eca109,G418筛选建立稳定产生逆转录病毒的细胞克隆,RT-PCR检测转染细胞stathminmR-NA的表达。结果 重组逆转录病毒载体经EcoRⅠ、HindⅢ双酶切,可见4692nt和285nt条带;测序结果表明插入序列正确;重组载体转染Eca109细胞,可表达绿色荧光蛋白（EGFP）,经G418筛选得到抗性细胞克隆,转染细胞stathmin mRNA的表达较对照组明显减弱。结论 特异性沉默stathmin基因的pSUPER-S逆转录病毒载体以及稳定表达的细胞系构建和筛选成功。     

CYP2E1基因过表达细胞株的建立及鉴定

目的： 应用分子克隆技术,构建CYP2E1基因过表达载体,转染L02肝细胞,建立CYP2E1过表达细胞株并进行鉴定,为深入研究环境和职业毒物的毒作用机制提供模型细胞。方法：根据GenBank提供的CYP2E1 基因cDNA序列设计引物,PCR扩增该基因并将其克隆到慢病毒过表达载体pLVX-acGFP1-C1中,将已经构建的慢病毒载体对293FT细胞进行转染,收集病毒上清,感染正常L02肝细胞。用嘌呤霉素进行筛选得到转染CYP2E1基因的L02细胞,通过基因测序、荧光定量PCR和Western blot对细胞株进行鉴定。结果：测序证明重组慢病毒过表达载体CYP2E1基因序列与GenBank提供的CYP2E1序列一致,荧光定量PCR检测转染CYP2E1基因的L02细胞比正常肝细胞CYP2E1 mRNA表达提高273倍,Western blot实验显示转染CYP2E1基因的L02细胞CYP2E1蛋白表达水平比正常肝细胞提高3.2倍。结论：成功构建了CYP2E1基因过表达细胞株,可应用于环境毒物和职业毒物的分子机制 研究。     

siRNA 靶向Her-2 逆转录病毒载体构建及其在SKOV3 中的表达

 目的 构建并鉴定Her-2特异性siRNA逆转录病毒载体，将其导入SKOV3卵巢癌细胞中，并初步筛选有效抑制Her-2表达的细胞株。方法 体外合成含针对Her-2特异基因序列的寡核苷酸并定向克隆入逆转录病毒载体RNAi—Ready pSIREN—RetroQ，构建的载体通过测序、酶切鉴定后，脂质体介导下转染到包装病毒细胞株PT67中，嘌呤霉素筛选并挑选细胞克隆，收获病毒上清，将病毒上清转染SKOV3中，经过嘌呤霉素筛选得到稳定抑制Her-2表达的SKOV3细胞株，并分别通过RT-PCR和免疫组化方法鉴定抑制Her-2表达的效果。结果 成功构建了重组逆转录病毒载体，转染包装病毒细胞株获得的病毒上清成功转染了SKOV3，并且抑制了Her-2的表达。结论 抑制Her-2表达的SKOV3细胞株的建立，为观察转染siRNA的逆转录病毒表达我体的肿瘤细胞恶性生物学行为变化奠定了实验基础。     

Polymorphisms in GSTM1, GSTT1 and CYP1A1 and risk of pancreatic adenocarcinoma

A prospective study of 149 unselected incident cases of pancreatic adenocarcinoma and 146 ethnically-matched controls found no associations between GSTM1 (adjusted odds ratio (AOR) 1.14), GSTT1 (AOR: 1.19) and CYP1A1 (AOR: 1.08) polymorphisms and pancreatic cancer susceptibility. Smoking and drinking status did not affect results. These polymorphisms do not appear to be important gene modifiers in pancreatic cancer.     

GSTM1, GSTT1 and GSTP1 polymorphisms and lung cancer risk

Previous studies have suggested that GST genotypes may play a role in determining susceptibility to lung cancer, though the data are often conflicting. In this study we investigated GSTM1, GSTT1 and GSTP1 status in relation to lung cancer risk in patients attending a Manchester bronchoscopy clinic. Cases were all patients (n=94) currently with, or with a history of, tumours of the lung, trachea or bronchus. The control group were all other patients (n=165) who were free of benign and malignant tumours both at the time of, or prior to, diagnosis. All patients were interviewed for information on lifestyle risk factors, and DNA extracted from bronchial lavage and blood samples was used for genotyping. GSTM1 null genotype was associated with decreased lung cancer risk (odds ratio (OR) 0.50, 95% confidence interval (CI) 0.29–0.87), particularly among men (OR 0.43, 95% CI 0.21–0.87) and those above the median age (OR 0.33, 95% CI 0.15–0.70). No difference in GSTT1 and GSTP1 genotype distribution was seen between cases and controls. The GSTM1 null genotype was associated with a decreased risk of squamous cell carcinoma: the OR, adjusted for age, sex and pack years was 0.32 (95% CI 0.12–0.82). As previous studies have reported that the GSTM1 null genotype is associated with an increased lung cancer risk, further work is required to determine whether the observed association is true, or whether it arises from bias or confounding factors.     

Polymorphisms in CYP1B1, GSTM1, GSTT1 and GSTP1, and susceptibility to breast cancer

Polymorphisms in the cytochrome P450 1B1 (CYP1B1) and glutathione S-transferase (GST) drug metabolic enzymes, which are responsible for metabolic activation/detoxification of estrogen and environmental carcinogens, were analyzed for their association with breast cancer risk in 541 cases and 635 controls from a North Carolina population. Each polymorphism, altering the catalytic function of their respective enzymes, was analyzed in Caucasian and African-American women. As reported in previous studies, individual polymorphisms did not significantly impact breast cancer risk in either Caucasian or African-American women. However, African-American women exhibited a trend towards a protective effect when they had at least one CYP1B1 119S allele (OR=0.53; 95% CI=0.20-1.40) and increased risk for those women harboring at least one CYP1B1 432V allele (OR=5.52; 95% CI=0.50-61.37). Stratified analyses demonstrated significant interactions in younger (age < or =60) Caucasian women with the CYP1B1 119SS genotype (OR=3.09; 95% CI=1.22-7.84) and younger African-American women with the GSTT1 null genotype (OR=4.07; 95% CI=1.12-14.80). A notable trend was also found in Caucasian women with a history of smoking and at least one valine allele at GSTP1 114 (OR=2.12; 95% CI=1.02-4.41). In Caucasian women, the combined GSTP1 105IV/VV and CYP1B1 119AA genotypes resulted in a near 2-fold increase in risk (OR=1.96; 95% CI=1.04-3.72) and the three way combination of GSTP1 105IV/VV, CYP1B1 119AS/SS and GSTT1 null genotypes resulted in an almost 4-fold increase in risk (OR=3.97; 95% CI=1.27-12.40). These results suggest the importance of estrogen/carcinogen metabolic enzymes in the etiology of breast cancer, especially in women before the age of 60, as well as preventative measures such as smoking cessation.     

CYP1B1 and hormone-induced cancer

Cancers in hormone-responsive tissues (e.g., breast, ovary, endometrium, prostate) occur at high incidence rates worldwide. However, their genetic basis remains poorly understood. Studies to date suggest that endogenous/exogenous oestrogen and environmental carcinogens may play a role in development and/or progression of hormone-induced cancers via oxidative oestrogen metabolism. Cytochrome P450 1B1 is a key enzyme in its oestrogen metabolism pathway, giving rise to hydroxylation and conjugation. Although CYP1B1 is expressed in many cancers, particularly high levels of expression are observed in oestrogen-mediated disease. CYP1B1 is more readily found in tumour tissue compared to normal. Given the role of CYP1B1 in pro-carcinogen and oestrogen metabolism, polymorphisms in CYP1B1 could result in modifications in its enzyme activity and subsequently lead to hormone-mediated carcinogenesis. CYP1B1 may also be involved in progression of the disease by altering the tissue response to hormones and clinical response to chemotherapy. The exact mechanism behind these events is complex and unclear. Only a few functional single nucleotide polymorphisms of CYP1B1 are known to result in amino acid substitutions and have been extensively investigated. Studies examining the contribution of different CYP1B1 alleles to hormone-mediated cancer risks are inconsistent. The main focus of this review is to appraise the available studies linking the pathogenesis of the hormone-induced cancers to various CYP1B1 polymorphisms. Additionally, we explore the role of a neuronal protein, γ-synuclein, in CYP1B1-mediated pathogenesis.     

Genetic polymorphisms of CYP1A1, GSTM1 and GSTT1 genes and lung cancer risk

Genetic polymorphisms of the genes encoding for the xenobiotic metabolizing enzymes result in individual variations in the efficiency of detoxification of environmental carcinogens, and have been extensively associated with variable risk for lung neoplasms in different ethnic and environmental backgrounds. In this study, using PCR-RFLP based assays, we investigated the distribution of genetic polymorphisms in CYP1A1, GSTM1 and GSTT1 genes in Greek lung cancer patients (N=122) and healthy controls (N=178). The frequency of CYP1A1 m1 homozygous genotype was 0.04 in patients and 0.02 in controls (detected in 4.10% of patients and in 1.69% of controls, respectively), that of GSTM1 null genotype was 0.52 in patients and 0.54 in controls, whereas those of GSTT1 null genotype was 0.17 and 0.11, in patients and controls, respectively. The GSTM1 null genotype was more frequent in adenocarcinoma, as well as in lung cancer patients with history of chronic obstructive pulmonary disease (COPD). The GSTT1 null genotype correlated with advanced age of the patients at the time of diagnosis. Three combinations of rare genotypes - in subjects carrying simultaneously deviations from the common genotype in more than one gene - were over-represented in lung cancer patients, compared to control population, and were furthermore significantly associated with history of heavy tobacco consumption in lung cancer patients. The results imply involvement of specific genotype combinations of CYP1A1, GSTM1 and GSTT1 alleles in the development of lung cancer in heavy smokers.     

Genetic polymorphisms of SULT1A1 and SULT1E1 and the risk and survival of breast cancer.

We examined whether common single nucleotide polymorphisms (SNP) in SULT1A1 (c.779G>A, *14A>G, and *85C>T) and SULT1E1 (IVS1-447C>A, IVS4-1653T>C, and *959G>A) genes influenced the risk and survival of breast cancer. Our study population consisted of 989 histologically confirmed sporadic breast cancer patients and 1,054 controls without history of cancer recruited from three teaching hospitals in Seoul. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression model. In the survival analysis for 529 breast cancer patients with completed treatments, the hazard ratios (HR) were calculated with Cox proportional hazard model. Women with the SULT1E1 *959 GA/AA genotype had a moderately decreased breast cancer risk compared with those with the GG genotypes (OR, 0.8; 95% CI, 0.70-1.00). When the haplotypes were considered, the homozygous *959 AA genotype together with the IVS4-1653 T>C base change (CTA-CCA haplotype) was associated with halved breast cancer risk (OR, 0.5; 95% CI, 0.24-0.88) compared with the wild type CTG-CTG haplotype. No other significant overall association was observed between the SULT1A1 and SULT1E1 SNPs nor haplotypes and breast cancer risk. When stratified by survival, patients with the SULT1E1 IVS4-1653 TC/CC genotypes showed a >3-fold risk of recurrence (HR, 3.2; 95% CI, 1.39-7.48) compared with those with the TT genotype. Moreover, when the haplotypes were considered, the SULT1E1 *959 G>A base change together with the IVS4-1653 T>C base change (CTG-CCA haplotype) was associated with a >4-fold risk of breast cancer (OR, 4.2; 95% CI, 1.15-15.15). These findings suggest that genetic polymorphisms of SULT1E1 are associated with increased risk and a disease free survival of breast cancer in Korean women.     

CYP1A1, GSTM1, and GSTP1 genetic polymorphisms and urinary 1-hydroxypyrene excretion in non-occupationally exposed individuals.

The CYP1A1 and glutathione S-transferase enzymes (e.g., GSTM1 and GSTP1) are involved in the activation and conjugation of polycyclic aromatic hydrocarbons (PAHs), respectively, and are controlled by genes that are polymorphic. The CYP1A1*2 allelic variant has been associated with elevated urinary 1-hydroxypyrene (1-OHP), a proposed marker for internal dose of activated PAHs, in coke-oven workers. We investigated whether this association could be observed at low exposure levels, such as those experienced by the general population. We conducted a cross-sectional study among 188 individuals (106 Japanese, 60 Caucasians, and 22 Hawaiians) who were selected as controls in a population-based case-control study and provided lifestyle information, a 12-h urine specimen, and a blood sample. 1-OHP was analyzed by high-performance liquid chromatography after enzymatic hydrolysis. Lymphocyte DNA was used for PCR-based genotyping. Smokers excreted twice as much 1-OHP (geometric mean, 0.51 nmol/12 h) as nonsmokers (geometric mean, 0.27 nmol/12 h; P = 0.006). Overall and among nonsmokers, 1-OHP urinary levels did not differ by CYP1A1, GSTM1, or GSTP1 genotypes. However, after adjusting for age, ethnicity, and number of cigarettes per day, smokers with at least one CYP1A1*2 variant allele excreted 2.0-fold more 1-OHP than smokers with the wild-type genotype (P = 0.02). Similar results were obtained for the CYP1A1*3 variant allele. The present data add to the growing evidence suggesting that individuals with the (linked) CYP1A1*2 or *3 variant alleles have a greater capacity to activate PAHs from tobacco smoke and occupational exposure and, as a result, are at greater risk for PAH-related cancers, especially certain respiratory cancers.     

Methoxyestrogens exert feedback inhibition on cytochrome P450 1A1 and 1B1

Cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1) catalyze the oxidative metabolism of 17 beta-estradiol (E2) to catechol estrogens (2-OHE2 and 4-OHE2) and estrogen quinones, which may lead to DNA damage. Catechol-O-methyltransferase catalyzes the methylation of catechol estrogens to methoxyestrogens (2-MeOE2, 2-OH-3-MeOE2, and 4-MeOE2), which simultaneously lowers the potential for DNA damage and increases the concentration of 2-MeOE2, an antiproliferative metabolite. In this study, we showed that CYP1A1 and CYP1B1 recognized as substrates both the parent hormone E2 and the methoxyestrogens. Using purified recombinant enzymes, we demonstrated that CYP1A1 and CYP1B1 O-demethylated the methoxyestrogens to catechol estrogens according to Michaelis-Menten kinetics. Both CYP1A1 and CYP1B1 demethylated 2-MeOE2 and 2-OH-3-MeOE2 to 2-OHE2, whereas CYP1B1 additionally demethylated 4-MeOE2 to 4-OHE2. Because the P450-mediated oxidation of E2 and the O-demethylation of methoxyestrogens both yielded identical catechol estrogens as products, we used deuterated E2 (E2-d4), unlabeled methoxyestrogens, and gas chromatography/mass spectrometry to examine both reactions simultaneously. Kinetic analysis revealed that methoxyestrogens acted as noncompetitive inhibitors of E2 oxidation with K(i) ranging from 27 to 153 micro M. For both enzymes, the order of inhibition by methoxyestrogens was 2-OH-3-MeOE2 > or = 2-MeOE2 > 4-MeOE2. Thus, methoxyestrogens exert feedback inhibition on CYP1A1- and CYP1B1-mediated oxidative estrogen metabolism, thereby reducing the potential for estrogen-induced DNA damage.     

谷胱苷肽S转硫酶T1、M1和P1基因多态性与结直肠癌易感性的关系

目的研究谷胱苷肽S转硫酶T1、M1和P1(GSTT1、GSTM1和GSTP1)多态性与结直肠癌易感性的关系。方法在江苏省进行了1个病例—对照研究(结直肠癌患者315例,人群对照439例),调查研究对象的生活习惯,抽取静脉血,提取白细胞DNA,以多重PCR技术检测GSTT1和GSTM1基因缺失,PCR-RFLP技术检测GSTP1基因单核苷酸多态(第104密码子A→G)。结果①在结直肠癌组和正常组GSTT1和GSTM1基因缺失频率分别为55.24%、57.31%和72.70%、73.29%、差异无显著性。②在结直肠癌组GSTP1 A/A、A/G和G/G基因型分布频度分别为57.51%、36.74%和5.75%;对照组分别为63.70%、31.05%和5.25%,2组之间差异无显著性(χ2 MH=2.993,P=0.224)。与GSTP1 A/A基因型携带者相比,G/G基因型者发生结直肠癌的危险性无显著升高,其性别、年龄、吸烟、饮酒习惯调整后的OR为1.09(95%CI:0.79~1.51)。结论GSTT1、GSTM1基因缺失型和GSTP1 G/G基因型与结直肠癌的易感性无显著相关。