核苷酸切除修复基因XPA反义RNA增强肺癌细胞对顺铂的敏感性

背景与目的：目前认为,肿瘤细胞自身核苷酸切除修复(nucleotide excision repair,NER)能力增强是肿瘤细胞产生耐药性最重要的机制之一。着色性干皮病A(xeroderma pigmentosun groupA,XPA)基因在核苷酸切除修复早期发挥核心作用。本研究拟探讨XPA基因表达与肺癌细胞株对顺铂敏感性的关系。方法：将XPA的反义RNA稳定转染人肺癌细胞株A549．用有限稀释法筛选阳性细胞克隆。分别用Northern blot和Western blot法检测阳性细胞克隆XPA mRNA和蛋白水平;MTT法检测肿瘤细胞对顺铂敏感性;宿主细胞再活化反应(host cell reactivation,HCR)检测肿瘤细胞DNA损伤修复能力。结果：筛选得到6个阳性克隆AS1～AS6,其中AS3～AS6细胞克隆的XPAmRNA和蛋白水平均明显降低。剂量依赖实验表明,顺铂对A549细胞与AS1～AS6细胞克隆的半数抑制浓度(IC50)分别为8．1、7．6、4．7、3．2、1．9、2．8、4．1~g／ml。统计学分析表明．与A549细胞相比,AS3～AS6细胞对顺铂的敏感性明显增强(F=9．75、9．14、7．39、8．91,P=0．005、0．006、0．012、0．006),而且XPA mRNA表达水平与细胞IC50值呈显著相关(r=0．927,P=0．003)。处理24、48、72h后,AS3～AS6细胞对顺铂的敏感性同样显著增强。HCR实验结果表明,AS3～AS6细胞的NER能力显著减弱,而且XPA mRNA表达水平与细胞NER能力呈显著相关(r=0．854、0．696、0．858;p=0．014、0．082、0．013)。结论：XPA反义RNA转染可明显降低肺癌细胞XPAmRNA水平,减弱细胞NER能力,继而使肺癌细胞对顺铂的敏感性增强。     

CD147反义RNA表达质粒的构建及克隆鉴定

目的　构建CD14 7反义RNA表达质粒载体。方法　用DNA重组技术将人CD14 7基因反向克隆到真核表达质粒PCD NA3.1中 ,构建成CD14 7反义RNA表达质粒PCDNAasCD14 7。用阳离子脂质体介导转染人卵巢癌细胞系 8910 ,经G4 18筛选后获得的克隆进行鉴定。结果　CD14 7反义RNA表达质粒载体PCDNAasCD14 7经限制性酶切及部分序列分析证明基因插入正确。流式细胞仪及免疫组化SP法染色均证实 :转染细胞 8910 /PCDNAasCD14 7,与亲本细胞相比 ,CD14 7的表达明显下降。结论　成功构建了CD14 7反义RNA表达质粒载体PCDNAasCD14 7,此实验结果为进一步研究CD14 7蛋白分子的生物学功能以及为卵巢癌的基因治疗研究奠定了基础。     

针对ATM基因RNA干扰质粒的构建及鉴定

目的：构建针对ATM基因的RNA干扰表达质粒pRiATM，并观察其抑制SPCA1人肺癌细胞ATM表达的效果。方法：构建针对ATM基因的短发夹状小干扰RNA真核表达载体pRiATM，并短暂转染SPCA1细胞，采用荧光定量RT—PCR和Westemblotting观察其抑制SPCA1细胞ATM表达的效果。结果：pRiATM1和pRiATM2转染SPCA1细胞后，与转染pRiG—FP非特异性对照组相比，ATMmRNA水平分别下降86．4％和77．6％（两组均P〈0．01）。与转染pRiGFP对照组相比，pRiATM1组和pRiATM2组ATM蛋白表达水平分别是对照组的4．3％和10，6％（均P〈0．01），以pRiATM1抑制ATM表达效果最显著。结论：pRiATM质粒构建成功，转染SPCA1细胞后可以明显抑制ATM基因的表达。     

核苷酸切除修复基因多态性和铂类药物耐药性关系研究进展

铂类药物广泛用于实体肿瘤的化疗,其作用机制与肿瘤细胞DNA的损伤有关,然而,机体的DNA修复机制可以将这些损伤修复.核苷酸切除修复是DNA修复中的一种,目前认为核苷酸切除修复与铂类药物的耐药相关.本文就核苷酸切除修复基因多态性和铂类药物耐药性关系研究进展作一综述.     

V型腺病毒纤维蛋白基因真核表达质粒的构建及表达

目的：构建腺病毒纤维蛋白基因的真核表达质粒,并检测其在真核细胞中的表达,为腺病毒靶向性载体构建创造条件。方法：采用限制性内切酶技术,酶切腺病毒骨架质粒pAdEasy-1,经多次亚克隆,最后完成克隆纤维蛋白基因并构建其真核表达质粒,用脂质体法将构建好的真核表达质粒瞬时转染COS-7细胞,于转染后72h,用Western blot法检测所表达的蛋白。结果：克隆成功纤维蛋白基因,并构建纤维蛋白基因真核表达质粒pcDNA/Fiber,经限制性内切酶酶切鉴定及测序证实了其正确性,Western blot结果显示,新表达蛋白在变性条件下大小为62kD,而在非变性条件下为186kD。结论：纤维蛋白基因真核表达质粒能在真核细胞中表达,产物具有三聚体结构。可用于腺病毒靶向性载体的构建。     

人肿瘤细胞核苷酸切除修复蛋白表达与抗癌药耐药的相关性

背景与目的：核苷酸切除修复（Nucleotide excision repair,NER）是真核细胞中的DNA修复多酶系统,它可能与人肿瘤细胞对抗癌药的耐药有关。本实验将探讨NER蛋白（XPA,XPB,XPD和ERCC1）的表达与人肿瘤细胞耐药的关系。方法：采用western blot检测美国国家癌症研究所（National Cancer Institute,NCI）用于抗癌药筛选的60株人肿瘤细胞的ERCC1,XPA,XPB XPD表达,并与170种抗癌药物的细胞毒试验结果进行相关性分析。结果：ERCC1,XPB和XPD的蛋白表达与抗癌药物敏感性呈负相关,在170种抗癌药物中分别有13,17和32种的耐药性与上述蛋白水平相关性显著或非常显著（P＜0．05）。而XPA的表达与药物敏感性无明显正／负相关。根据已确定的6种药物作用机理分析,肿瘤细胞XPD表达与其对烷化剂类抗癌药耐药相关性显著。结论：本实验结果肿瘤细胞的XPD蛋白表达与烷化剂类抗癌药的耐药相关,提示XPD在肿瘤细胞耐药过程中起重要作用。     

Survivin反义RNA真核表达载体的构建及鉴定

目的 为了特异封闭白血病细胞survivin的表达，抑制其功能，本实验构建了survivin反义核酸载体并导入白血病细胞系中。方法 应用RT—PCR获得survivin的cDNA片段，反向插入pcDNA3质粒载体中；经限制性酶切和测序鉴定所构建的反义核酸是否正确；采用电转染方法将重组体导入HL—60细胞中；RT—PCR技术检测转染细胞survivin表达的变化。结果 经限制性酶切和测序鉴定证明survivin反义核酸已成功构建；RT—PCR产物电泳结果显示，与转染前细胞、空质粒转染细胞相比，转染survivin反义核酸的细胞survivin mRNA水平明显降低。结论 本实验已成功建立了survivin反义核酸真核表达载体，而且在白血病细胞系中发挥了特异封闭作用，为进一步研究survivin反义核酸在白血病治疗中的作用提供了实验基础。     

核苷酸切除修复通路基因多态性与肺癌易感性研究

目的研究显示核苷酸切除修复通路在去除吸烟引起的DNA损伤中发挥着重要的作用,旨在探讨核苷酸切除修复通路单核苷酸多态性与吸烟相关性肺癌易感性的关系。方法选取1010例肺癌患者和1011例正常对照。采用基于通路的候选基因选点策略,从核苷酸切除修复通路相关的8个核心基因中筛选出40个标签SNPs进行检测和分析。结果单个位点分析发现6个SNPs（ERCC1 2个,DDB2 2个,ERCC4／XPF 1个,XPC 1个）与肺癌的易感性相关。进一步采用Logistic回归模型,调整年龄、性别、吸烟史和肿瘤家族史后,仍有3个SNPs（ERCC1 rs3212948,DDB2 rs830083,ERCC4 rs3136038）与肺癌易感性存在统计学关联。等位基因联合分析结果进一步表明肺癌的发病风险随着风险等位基因个数的增加而增加,尤其是ERCC1,ERCC2,ERCC3,ERCC5,XPA和XPC。结论本研究结果提示核苷酸切除修复通路基因多态性可能与中国汉族人群的肺癌个体易感性有关,值得进一步进行功能学探讨及大样本人群验证.     

HSU17714基因反义重组质粒的构建及其对人大肠癌细胞生长的影响

我所应用减式杂交方法筛选人大肠癌负相关基因,得到一与已知基因同源性仅50％的cDNA片段,已作为新发现的基因被NCBI收录入国际基因库,我们将此cDNA片段反向克隆至非整合型哺乳动物表达载体pREP9的多克隆位点中,构建了HSU17714基因的反义RNA表达载体,并籍脂质体将之导入人结肠癌SW1116细胞中,双层软琼脂集落培养试验、流式细胞技术分析及MTT比色法等结果分别提示转染该重组体的肠癌细胞的非锚着依赖性生长能力、增殖周期活性和细胞生长速度均受到不同程度的抑制,说明外源重组体pREP9 HSU17714(AS)对肠癌SW1116细胞的生长具有抑制作用。     

DNA repair gene polymorphisms in the nucleotide excision repair pathway and lung cancer risk: A meta-analysis

Objective: A number of studies have reported the association of "XPA", "XPC", "XPD/ERCC2" gene polymorphisms with lung cancer risk. However, the results were conflict. To clarify the impact of polymorphisms of "XPA", "XPC", "XPD/ERCC2", on lung cancer risk, a meta-analysis was performed in this study. Methods: The electronic databases PubMed and Embase were retrieved for studies included in this meta-analysis by "XPA", "XPC", "XPD/ERCC2", "lung", "cancer/neoplasm/tumor/carcinoma", "polymorphism" (An upper date limit of October, 31, 2009). A meta-analysis was performed to evaluate the relationship among XPA, XPC and XPD polymorphism and lung cancer risks. Results: A total of 31 publications retrieved from Pubmed and Embase included in this study. XPC A939C CC genotype increased lung cancer risk in total population (recessive genetic model: OR=1.23, 95% CI:1.05-1.44; homozygote comparison: OR=1.21,95%CI:1.02-1.43and CC vs. CA contrast: OR=1.25,95%CI:1.06-1.48), except in Asians. XPD A751C, 751C allele and CC genotype also increased lung cancer risk in total population and in Caucasians (recessive genetic model: Total population: OR=1.20, 95%CI:1.07-1.35). No significant correlation was found between XPD A751C and lung cancer risk in Asians and African Americans. XPD G312A AA genotype increased lung cancer risk in total population, in Asians and Caucasians(recessive genetic model: Total population: OR=1.20, 95%CI: 1.06-1.36). No significant association was found between XPA G23A, XPC C499T, XPD C156A and lung cancer risk. Conclusion: Our results suggest that the polymorphisms in XPC and XPD involve in lung cancer risks. XPA polymorphisms is less related to lung cancer risk.     

核苷酸切除修复通路基因多态性与肺癌易感性

Nucleotide excision repair (NER) pathway is one of the principal ways of the repair of DNA damage. The single nucleotide polymorphisms (SNP) of its key genes such as xeroderma pigmentosum group A (XPA) gene, excision repair cross complementing1 (ERCC1) gene and xeroderma pigmentosum group D (XPD) gene may be associated with differences in the DNA repair capacity and may influence an individual’s risk of lung cancer, because the variant genotype in those polymorphisms might destroy or alter repair function.     

反义核酸抑制靶基因表达对EB病毒转化细胞的生长控制研究

背景与目的：近年研究表明,EB病毒（Epstein-Barr virus,EBV)潜伏性膜蛋白基因（latent membrane protein gene,LMP)在鼻咽癌的发生和发展中起着重要作用。本研究着重构建体外基因反义转录系统,研究反义LMPmRNA对EBV转化细胞基因表达的抑制作用。方法：构建和制备反义核酸单链有效的体外转录系统;设计和建立反义原位示踪技术,以探测正、反义链配对互补聚合体的定位;通过对EBV转化细胞系（C1936和B95－8）的反义控制,测定细胞生长的抑制率,观测转化细胞凝集表型;通过对EBV－LMP基因表达的检测和MTT吸收活性的测试,测定转化细胞在基因转录下调之后的生存状态。结果：构建成制备反义RNA的SP6／T7双向启动子的体外基因转录系统。反义工程产物AsLMPmRNA通过胞饮作用掺入转化细胞后,经原位示踪显示,正－反义链聚合物的封闭位点主要在mRNA前体剪接加工成熟的后阶段;转化细胞增殖能力下降（生长抑制率85．5％）,细胞转化的凝集表型受抑制,MTT吸收值显著降低,显示被反义控制的C1936和B95－8细胞系的生长受到严重的抑制。应用反义原位示踪系统（antisense tracing system in situ,ATSIS)显示,AsLMPmRNA有特定靶点和抑制效应。结论：本实验所建成的体外反义转录系统所制备的RNA反义工程产物（AsLMPmRNA),有特定的选择靶点作用和高效的生物活性（特定基因LMP表达负调节）。这为反义控制转化细胞和开发反义基因工程药物提供了重要依据。     

Repair of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced DNA pyridyloxobutylation by nucleotide excision repair

The tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) forms DNA methylating and pyridyloxobutylating species. In this study, the involvement of nucleotide excision repair (NER) in the repair of pyridyloxobutyl adducts was assessed using an in vitro NER assay with pyridyloxobutylated plasmid DNA. Nuclear extracts from NER-deficient xeroderma pigmentosum (XP) cells, XPA and XPC, were less active at repairing pyridyloxobutyl adducts than were extracts from normal cells, while combining NER-deficient extracts reconstituted activity. Also, NER-deficient cells were more susceptible to NNKOAc-induced cytotoxicity than were normal cells. Results demonstrate a role for NER in the repair of NNK-induced pyridyloxobutylation.     

Current status of excision repair cross complementing-group 1 (ERCC1) in cancer

Cisplatin, carboplatin and oxaliplatin are some of the most widely used anti-cancer agents in solid tumours. The cytotoxicity of platinating agents is directly related to their ability to cause DNA intra-strand crosslinks that trigger a series of intracellular events that ultimately result in cell death. DNA intra-strand crosslinks are processed and repaired by the nucleotide excision repair pathway. It is now clear that nucleotide excision repair (NER) capacity may have a major impact on the emergence of resistance, normal tissue tolerance and patient outcomes. ERCC1 is a key player in NER. In this review, we provide an overview of mammalian NER and then focus on biochemical, structural and pre-clinical aspects of ERCC1. We then present current clinical evidence implicating ERCC1 as a predictive and prognostic marker in cancer. Early evidence also suggests that ERCC1 or the pathways involved in the regulation of ERCC1 expression may be attractive anti-cancer targets. Such agents are expected to potentiate the cytotoxicity of platinating agents and could have a major impact on cancer therapy.     

Critical DNA damage recognition functions of XPC-hHR23B and XPA-RPA in nucleotide excision repair

It has been reported that 80-90% of human cancers may result, in part, from DNA damage. Cell survival depends critically on the stability of our DNA and exquisitely sensitive DNA repair mechanisms have developed as a result. In humans, nucleotide excision repair (NER) protects the DNA against the mutagenic effects of carcinogens and ultraviolet (UV) radiation from sun exposure. By preventing mutations from forming in the DNA, the repair machinery ultimately protects us from developing cancers. DNA damage recognition is the rate-limiting step in repair, and although many details of NER have been elucidated, the mechanisms by which DNA damage is recognized remain to be fully determined. Two primary protein complexes have been proposed as the damaged DNA recognition factor in NER: xeroderma pigmentosum protein A-replication protein A (XPA-RPA) and xeroderma pigmentosum protein C-human homolog of RAD23B (XPC-hHR23B). Here we compare the evidence that supports damage detection by these protein complexes and propose a model for DNA damage recognition in NER based on the current understanding of the roles these proteins may play in the processing of DNA lesions.     

碱基切除修复基因APE和XRCC1表达与大肠癌发生相关性的探讨

目的:通过检测大肠癌、癌旁黏膜与正常黏膜中APE和XRCC1蛋白的表达,探讨大肠癌的发生机制.方法:选取大肠癌手术切除标本185例,其中32例标本取癌旁黏膜组织;正常黏膜组织36例.通过免疫组化方法检测APE和XRCC1蛋白在癌、癌旁黏膜和正常黏膜的表达.结果:大肠癌、癌旁黏膜组APE阳性表达率分别为78.9％(146/185)和81.2％(26/32),两者均明显高于正常黏膜组的61.1％(22/36),x2值分别为5.23和4.86,P值分别为0.024和0.03,但前两者APE表达差异无统计学意义.大肠癌中APE蛋白表达与患者性别、年龄、肿瘤部位、分化程度、浆膜浸润及淋巴结转移无明显相关关系.大肠癌与癌旁黏膜组XRCC1阳性表达率分别为94.6％(175/185)和87.5％(27/32),两者均明显高于正常黏膜组的27.7％(10/36),x2值分别为4.43和29.69,P值分别为0.036和0.002,但前两者间差异无统计学意义.大肠癌中XRCC1蛋白表达与患者性别、年龄、肿瘤部位、分化程度、浆膜浸润及淋巴结转移无明显相关关系.大肠癌XRCC1阳性组的APE阳性率为95.8％(136/142),显著高于大肠癌XRCC1阴性组的86.0％(37/43),XRCC1与APE两者表达呈明显正相关关系,r=0.354,P=0.02.大肠癌和癌旁黏膜组的APE和XRCC1蛋白同时表达的阳性率分别为75.8％(140/185)和65.6％(21/32),两组均明显高于正常黏膜组的16.7％(6/36),x2值分别为46.8和16.17,P值分别为0.001和0.001 5,但癌组与癌旁组间差异无统计学意义.结论:大肠癌和癌旁黏膜中存在APE和XRCC1表达上调.大肠癌发生可能与DNA复制时位点损伤及烷化剂等有毒物质损伤关系密切,同时检测大肠黏膜不同种类DNA修复基因的表达有助于大肠癌的早期诊断.