人源性大肠癌cDNA噬菌体库的构建及PCR鉴定

为构建人源性大肠癌cDNA噬菌体表达文库 ,从人大肠癌组织中提取总RNA ,纯化mRNA ,用RT PCR反转录合成cDNA第一链 ,用LD PCR合成cDNA第二链 ,除去小于 5 0 0bp的小片段 ,与λTriplEx2噬菌体连接 ,体外包装。转化E .coliXL1 blue大肠杆菌 ,滴定文库的滴度 ,用IPTG和X gal测定重组率。用PCR鉴定插入cDNA片段大小。构建成含 2 .0 7× 10 6 pfu/ml重组子的人大肠癌cDNA噬菌体表达文库 ,重组率为 94.5 % ,插入外源cDNA片段大小从 60 0bp～ 4kb ,平均约 1.4kb。文库合符要求 ,适合于大批量筛选cDNA克隆的大肠癌相关抗原基因     

SEREX方法鉴定CTCL细胞肿瘤抗原

目的 分离纯化皮肤T细胞淋巴瘤(CTCL)细胞系SeAx细胞膜蛋白并制备多克隆抗体.利用SEREX法从SeAx cDNA噬菌体表达文库中筛选肿瘤抗原.方法 培养SeAx细胞至2×1010个,用组织匀浆器匀浆后差速离心法分离细胞各组分,富集细胞膜抗原.用细胞器特异性抗体对纯化步骤中的各组分进行检测.用膜蛋白组分免疫家兔4次,每次免疫后用ELISA法测定血清抗体滴度.4次免疫后用Western blot方法测定多抗与SeAx细胞各组分蛋白反应的特异性.重组噬菌体感染大肠杆菌,将表达的重组蛋白转印到硝酸纤维素膜上,与SeAx细胞膜蛋白免疫的兔血清进行反应,阳性的克隆测定核苷酸序列,通过数据库搜索比较确定基因.结果 用差速离心法得到SeAx细胞膜蛋白,免疫家兔4次后获得了效价为1×10-5的多克隆抗体.共筛选了1×106个噬菌体克隆,得到25个阳性克隆,经核苷酸序列测定和数据库分析,其中4个cDNA片段为膜蛋白成分,分别为integrin alpha 4,ligatin,matrix metalloproteinase 24和MHC-I molecule HLA-A.结论 分离并纯化了CTCL细胞系SeAx细胞膜蛋白,成功制备了多克隆抗体,用SEREX方法从SeAx mRNA建立的cDNA噬菌体表达文库中筛选到4个肿瘤细胞膜蛋白基因,它们可以引起机体产生体液免疫反应,并可能成为潜在的免疫治疗靶点.     

大肠癌噬菌体抗体库的构建及抗CEA抗体的筛选

目的构建及初步鉴定大肠癌噬菌体抗体Fab呈现库,筛选人CEA单克隆抗体,并进行序列分析。方法分离大肠癌患者外周血淋巴细胞,提取淋巴细胞总RNA,逆转录成cDNA。用PCR扩增人全套抗体基因片段,克隆于pComb3载体,再经电穿孔转化大肠杆菌XL1-Blue菌株,形成噬菌体抗体库。以固相化CEA抗原淘筛抗体库,ELISA鉴定噬菌体抗体。其中一个阳性克隆进行测序。结果逆转录PCR分别扩增出约680bp大小的κ、λ和Fd基因。PCR产物和载体经纯化、双酶切后进行连接转化,成功地构建了人源性Fab抗体基因库,库容量达2.1×107,Fab基因重组率为50%。以单抗捕获的CEA抗原淘洗4轮,出现特异性富集,阳性克隆经直接ELISA和交叉反应ELISA实验证实具有良好的抗CEA抗原特异性。DNA测序表明该抗体重链属IgG亚类并含有一条IgL亚类的轻链。结论成功构建了大肠癌患者自然致敏抗体Fab段噬菌体呈现库,从中获得可与CEA抗原结合的噬菌体抗体,由此为大肠癌早期诊断及基因治疗提供了一种新的思路和方法。     

人前列腺癌cDNA文库的构建和筛选

目的:PC1基因是与前列腺癌相关的新基因,在雄激素非依赖和转移的前列腺癌晚期细胞系C42中高表达。为了进一步研究PC1基因的功能及作用机制,构建C42细胞的cDNA文库,寻找与前列腺癌相关基因PC1相互作用的蛋白。方法:从前列腺癌细胞系C42中提取总RNA,进而分离poly(A)+RNA,用poly(A)+RNA进行反转录并以SMARTⅢTM和CDSⅢoligo(dT)为引物进行PCR扩增,得到两端具有同源臂的PCR片段,以此同源臂为基础在酵母中实现同源重组。通过文库片段、线性化的pGADT7Rec和诱饵质粒pGBKT7PC1C共转化酵母AH109菌株,在文库构建的同时进行与PC1相互作用蛋白的筛选;或先将文库片段,线性化的pGADT7Rec转化AH109,再利用AH109和Y187两种酵母菌株的接合生殖进行筛选。最后用Far Western印迹方法进一步从体外论证了PC1蛋白可与自身相互作用形成二聚体。结果:构建了具有基因多样性和库容量足够大的人前列腺癌cDNA文库,双链cDNA片段的长度大小范围为250～5000bp。共转化的效率为4.3×105,重组效率为1.9×106,筛选的克隆数为4.3×105。接合法筛选时的接合效率为32%,筛选的克隆数为1.0×106。筛选到4个与PC1蛋白相互作用的阳性克隆。从体外证明了PC1蛋白可形成二聚体。结论:此文库的多样性和库容量均符合筛选需求。可用于前列腺癌相关基因     

抑制差减杂交筛选辐射致癌差异表达基因

目的筛选研究辐射诱发小鼠肿瘤相关差异表达基因。方法以^60Coγ射线照射诱发的小鼠白血病动物模型为研究对象，采用抑制差减杂交技术构建辐射致癌差异表达基因cDNA文库，鉴定后挑取阳性克隆测序，并与GeneBank数据库进行同源性比对分析。结果抑制差减杂交筛选得到102个阳性克隆，随机挑选30个克隆进行菌液PCR，扩增得到28个特异性插入片段，DNA测序结果经与GeneBank数据库比对发现代表了24个已知基因，其中3个为重复检出基因，暂未发现有未知序列基因。结论成功建立辐射致癌差异表达基因cDNA文库，初步筛选获得24条表达上调的差异片段，该结果将有助于充实完善辐射致癌的分子机制。     

IRM-2小鼠全长cDNA文库的构建及鉴定

目的 分离和鉴定IRM-2小鼠辐射抗性相关基因。方法 采用SMART技术构建IRM-2小鼠全长cDNA文库,提取雄性IRM-2小鼠脾脏总RNA,以此为模板,通过逆转录酶PowerScript反转录合成第1链cDNA,通过长距离PCR合成并扩增双链 cDNA。该扩增产物经纯化、Sfi Ⅰ酶切、去除小于500 bp片段后,将cDNA连接到Sfi Ⅰ消化过的PDNR-LIB质粒载体中,用电转化法将重组质粒转化到大肠杆菌DH5α,得到IRM-2小鼠cDNA原始文库并用PCR法对文库的质量进行鉴定。随机从cDNA文库挑选130个阳性克隆进行测序,与GenBank基因库进行同源性比较。结果 构建的cDNA文库的容量为2.25×10⁶个克隆,重组率达95%,平均插入片段长度约1.2 kb,全长基因比例为55%。从cDNA文库挑选的阳性克隆中有21条EST序列与小鼠已知基因不同源,在GenBank的EST数据库的注册号为DW474856~DW474876。结论 成功构建了IRM-2小鼠全长cDNA文库,21条EST提示IRM-2小鼠体内可能存在辐射抗性相关基因,为进一步分离和鉴定辐射抗性相关基因奠定了基础。     

hPer1 bHLH-PAS结构域酵母双杂交系统的构建

目的构建hPer1 bHLH-PAS结构域的酵母双杂交系统,以寻找与hPer1相互作用的新蛋白.方法构建pGBKT7-hPer1 bHLH-PAS重组诱饵质粒及pGADT7-Rec-脑cDNA文库质粒;将两种质粒顺序转染至酵母细胞AH109中,进行营养缺陷筛选阳性克隆株.结果经酶切和基因测序鉴定,证实重组诱饵质粒pGBKT7-hPer1 bHLH-PAS构建成功.脑cDNA文库转化效率为1.2×106/3 μg pGADT7-Rec.结论酵母双杂交文库筛选得到24个阳性克隆.这为寻找脑组织中与hPer1相互作用的未知蛋白奠定了基础.     

噬菌体展示技术筛选乙型肝炎病毒X抗原基因启动子DNA结合蛋白

目的筛选乙型肝炎病毒（HBV）X抗原基因启动子（Xp）DNA结合蛋白,为HBV复制机制研究探索新的途径。方法应用噬菌体展示技术,以HBV-Xp的PCR产物DNA作为固相筛选分子,对噬菌体人肝细胞cDNA文库进行4轮“吸附-洗脱-扩增”筛选,经噬斑的PCR扩增后,构建克隆载体,最后对所筛选克隆进行DNA序列分析和同源性搜索。结果噬菌体经富集后,从随机筛选的30个克隆中得到17个阳性克隆,成功构建了克隆载体。经测序分析及序列比对,最后得到5种已知基因编码蛋白（人血白蛋白、还原型烟酰胺二核甘酸脱氢酶亚型4、激肽酶原、泛素特异性蛋白酶10、睾丸增强因子转录子）和9种未知功能基因序列。结论从噬菌体人肝cDNA文库筛选得到多种具有不同生物学功能的蛋白,与HBVX抗原基因启动子具有结合作用。     

沙鼠耳蜗cDNA文库的构建

为了建立沙鼠耳蜗的cDNA文库 ,先提取沙鼠耳蜗的mRNA并经oligo(dT)引物合成cDNA第一链 ,经LD PCR法扩增合成双链cDNA后 ,克隆到λTriplex2中扩增文库。用耳蜗特异的prestin蛋白基因引物作PCR ,鉴定文库。结果显示 ,文库的库容量为 1.8× 10 6pfu ,重组率为 80 % ,用prestin蛋白基因引物可扩增出 86 3bp的prestin蛋白基因。研究表明 ,构建的文库具有较好的库容量及重组率 ,且插入片段很大 ,为从分子生物学方面研究耳蜗打下了基础     

应用抑制性消减杂交技术筛选膦甲酸钠免疫调节基因

目的 应用抑制性消减杂交(SSH)技术构建膦甲酸钠(PFA)处理的人T淋巴细胞Jurkat差异表达基因的cDNA消减文库,筛选并克隆PFA免疫调节相关基因,阐明PFA免疫调节的分子生物学机制。方法 以PFA处理Jurkat细胞,同时以生理盐水处理的相同细胞作为对照;24h后制备细胞裂解液,提取mRNA并逆转录为cDNA,经Rsa1酶切后,将实验组cDNA分成两组．分别与两种不同的接头衔接,再与对照组cDNA进行2次消减杂交及2次抑制性多聚酶链反应(PCR)扩增,将产物与T／A载体连接,构建cDNA消减文库,并转染大肠杆菌进行文库扩增,随机挑选克隆PCR扩增后进行测序及同源性分析。结果 成功构建了PFA处理淋巴细胞差异表达基因的cDNA消减文库。文库扩增后得到46个阳性克隆,进行菌落PCR分析,均得到200～1000bp插入片段。挑取含有插入片段的14个克隆进行测序,并通过生物信息学分析获得11种已知基因序列和3个未知基因。结论 应用SSH技术成功构建了PFA处理的淋巴细胞差异表达基因的cDNA消减文库,为进一步阐明PFA的免疫调节机制及深入了解PFA防治病毒性肝炎的药理作用机制提供了依据。     

大肠癌APE1的表达特点及临床意义

目的 探讨脱嘌呤／脱嘧啶核酸内切酶（APE1）在大肠癌发生、发展中的作用。方法 应用免疫组化SP法检测125例大肠癌、72例大肠腺瘤、60例癌旁大肠黏膜和40例正常大肠黏膜中APE1的表达情况,并分析APE1与大肠癌临床病理之间的关系。结果 正常大肠黏膜APE1呈胞核表达,大肠腺瘤和大肠癌组织APE1表达特征发生改变,呈胞核表达、单纯胞质表达或核浆共同表达。APE1胞质异位表达率大肠癌组织为73．6％,大肠腺瘤组织为83．3％,二者无显著性差异（P〉0．05）,但均显著高于癌旁大肠黏膜（10％）和正常大肠黏膜（0％,P〈0．01）。APE1胞质异位表达与大肠癌临床分期和淋巴结转移有关（P〈0．01,P〈0．05）。结论 APE1胞质异位表达可能在大肠癌的发生、发展中起重要作用。     

结肠癌临床、病理、X线表现与nm23-H1表达关系研究

目的：研究肿瘤转移相关基因nm23-H1在不同X线分型结肠癌中的表达及其与淋巴结转移,预后的关系。方法：应用SP免疫组化法对28例不同X线类型的结肠癌组织中的nm23-H1基因进行半定量分析。结果：在nm23-H1阳性表达组中肿块型和溃疡型结肠癌的淋巴结转移率及5年死亡率明显低于浸润型（P＜0．01）,结论：nm23-H1基因可能参与结肠癌的发生,发展,根据nm23-H1基因表达与结肠癌的X线类型联合分析有助于淋巴结转移状况的判定和预后估计。     

老年大肠癌中survivin和P53蛋白表达及与临床病理的相关性研究

目的：探讨生存素（survivin）和P53蛋白联合表达与老年大肠癌临床病理特征的关系。方法：应用免疫组织化学技术,检测90例老年大肠癌组织中survivin和P53蛋白表达。结果：90例老年大肠癌组织中survivin和P53蛋白阳性表达率分别为65.6%（59/90）和57.8%（52/90）。survivin和P53表达与老年大肠癌Dukes分期、浆膜浸润和淋巴结转移均呈正相关（P〈0.05）,P53表达与老年大肠癌组织类型相关（P〈0.05）。结论：survivin和P53表达与老年大肠癌浸润转移密切相关。联合检测其蛋白表达可作为判断老年大肠癌预后的客观指标。     

Early effects of FOLFOX treatment of colorectal tumour in an animal model: assessment of changes in gene expression and FDG kinetics

Purpose  The very early chemotherapeutic effects of the FOLFOX (fluorouracil, folinic acid, oxaliplatin) protocol were assessed in mice implanted with a human colorectal cell line. The aim of this study was to identify changes in gene expression patterns and to detect combinations of PET parameters that may be helpful in identifying treated tumours early after chemotherapy using dynamic PET studies. Methods  A human colorectal cell line (HCT 116) was used in nude mice. Dynamic PET studies were performed in untreated (n = 13) and treated (n = 12) animals. The data were assessed using compartmental and noncompartmental analysis. The removed tumour specimens were assessed by gene array analysis to obtain quantitative information on gene expression. Results  One chemotherapeutic treatment using the FOLFOX protocol resulted in an upregulation of 2,078 gene probes by more than 25%, while 2,254 probes were downregulated following treatment. The gene array data demonstrated primarily an enhancement of genes related to apoptosis. In particular, the apoptosis antigen 1 (APO-1), p21 and the G protein-coupled receptor 87 (G-87) were 2.6- to 3.3-fold upregulated as compared to the expression in untreated animals. There was a 100% separation of untreated and treated animals on the basis of these three genes. The SUV and the FDG kinetic parameters obtained by compartmental and noncompartmental fitting were not significantly different when individual parameters were compared between groups. However, classification analysis of the combination of the PET parameters VB, K1, k3, and influx revealed an overall accuracy of 84%. We were able to identify 91.7% (11/12) of the treated animals and 76.9% (10/13) of the untreated animals correctly using the classification analysis of PET data. Conclusion  Even one chemotherapeutic treatment using FOLFOX has an impact on gene expression and significantly modulates FDG kinetics. Quantitative assessment of the tracer kinetics and the application of classification analysis to the data are promising tools to identify those tumours that demonstrate a chemotherapeutic effect very early following treatment.     

遗传性非息肉病性大肠癌

目的：提高对遗传性非息肉病性大肠癌本质的认识。方法：对四个有遗传性非息肉病性大肠癌家系进行调查。结果：四家系共有14例病人,发病时平均年龄43岁。61．9％（13／21）的癌灶位于脾曲近端的大肠。大肠多原发癌占35．7％（5／14）。无结肠息肉病。四家系中之一为癌家族综合征。结论：对遗传性非息肉病性大肠癌前病人及其家系成员进行严密监测,争取疾病早诊断早治疗,提高治疗效果。     

Epidemiology of colorectal cancer

Colorectal tumors are among the most frequently encountered forms of cancer worldwide. With approximately 57,000 new cases every year, they represent the most frequent type of cancer in Germany, ranking before breast cancer (approximately 46,000) and lung cancer (approximately 37,000). Although global incidence is on the rise, in Germany it is only increasing among men, but not among women. The mortality rate (approximately 26,500 deaths annually) in Germany has declined among men for about the past 10 years and among women for about the past 20 years. The most important risk factors are familial history of colorectal and other tumors as well as lifestyle factors such as nutrition, obesity, inactivity,and smoking.Lifestyle-related risks offer a broad area for implementing primary preventive measures,which have not yet been adequately exhausted. Several proven (fecal occult blood test) and probably effective (endoscopic) methods are available for secondary prevention. Consistent encouragement of these possibilities for prevention could reduce incidence and mortality substantially and render colorectal tumors less frequent.     

Diagnosis of colorectal tumors

With the introduction of multislice CT extensive volumetric data sets can be quickly acquired in high spatial resolution.The high spatial resolution reduces partial volume effects and enables multiplanar reconstructions. Regarding the colorectum this means that the colon can be assessed if the colon is sufficiently cleaned and distended, and that transmural infiltration of colorectal carcinoma and liver metastases can be better detected. T-staging of colon cancer is less important than T-staging of rectal cancer.Based on the higher contrast MRI is superior to CT in T-staging of rectal cancer and in the differentiation between scarring tissue and recurrence of carcinoma.     

Screening for colorectal cancer

Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer deaths in the United States. Fortunately, both the incidence and mortality associated with the disease have declined during the past 2 decades. This is likely due, at least in part, to improved efforts at screening and more aggressive removal of adenomatous polyps. However, colorectal cancer screening is still generally underutilized. This article reviews the current status and future outlook for colorectal cancer screening, including a discussion of risk factors for the disease, its anatomic distribution, proposed mechanisms of development from adenomatous polyps, rationale for screening, and screening options. Published literature concerning the cost-effectiveness of colorectal cancer screening is also summarized. The article concludes with a discussion of the emerging consensus regarding the importance of and approaches to screening.