抗人KIAAO100蛋白多克隆抗体的制备

目的:制备抗人KIAA0100蛋白多克隆抗体,为今后研究人KIAA0100蛋白的结构和功能奠定基础.方法:采用生物信息学软件对人KIAA0100蛋白第1 557～2 234位氨基酸序列进行原核密码子优化,将优化后的核苷酸序列经人工合成后克隆入原核表达载体pET-30a中,构建重组质粒;采用限制性酶切分析对重组质粒进行鉴定;将正确的重组质粒转化人大肠杆菌BL21(DE3)细胞,以表达羧基末端携带6×组氨酸标签的重组蛋白;使用重组蛋白作为免疫原免疫新西兰大白兔制备抗人KIAA0100蛋白多克隆抗体;使用蛋白质印迹分析检测该多克隆抗体对人KIAA0100蛋白的识别能力.结果:限制性酶切分析显示:重组质粒被成功构建;SDS-PAGE分析结果显示:主要以包涵体形式存在的重组蛋白被成功表达;蛋白质印迹分析证实:该多克隆抗体能够高效地识别人KIAA0100蛋白.结论:成功制备了抗人KIAA0100蛋白多克隆抗体,以上研究结果为我们将来研究人KIAA0100蛋白的结构和功能奠定了基础.     

细胞周期蛋白C基因克隆与重组质粒pCMV-tag2B-CCNC的构建与鉴定

[目的]克隆人细胞周期蛋白C基因（human cvclin C，CCNC），构建真核表达载体，诱导并鉴定其表达。[方法]利用逆转录多聚酶链反应mT-PCR）法，以急性淋巴细胞性白血病细胞株6T-CEMmRNA为模板，扩增CCNC基因，将克隆获得的CCNC全长cDNA片段构建重组表达载体pCMV-tag 2B—CCNC，用脂质体Lifefectamine2000将重组质粒转染至6T-CEM细胞系，诱导其表达，Western Blot鉴定其表达。[结果]电泳获得944bp预期序列，pCMV-tag2B—CCNC经双酶切鉴定及序列分析证实为正确的有完整读码框的CCNC基因，将pCMv-tag2B_Sorcin导入6T-CEM细胞并成功表达，目的蛋白经Western blot鉴定具有生物学活性。[结论]经测序及酶切鉴定，成功克隆了CCNC的cDNA，并成功构建了CCNC真核表达质粒pCMV-tag2B—CCNC，重组质粒能表达具有生物学活性的CCNC蛋白，为研究CCNC的功能打下了基础．     

一种新的黑色素瘤相关抗原MAGE-C2的基因克隆及表达

目的:克隆人黑色素瘤相关抗原MAGE-C2的cDNA,构建真核、原核表达载体并转入相应细胞获得表达.方法:采用RT-PCR技术,从直肠癌细胞系SW480的总RNA中克隆了MAGE-C2 cDNA序列,并将开放读框分别插入质粒pEGFP-C1和pGEX-4T-3中,获得pEGFP-MAGE-C2绿色荧光蛋白(GFP)融合表达载体和pGEX-MAGE-C2谷胱甘肽转移酶(GST)融合蛋白表达载体,将pEGFP-MAGE-C2转染293T细胞,观察绿色荧光融合蛋白在细胞中的定位;将pGEX-MAGE-C2转化大肠杆菌BL21株,经IPTG诱导表达GST融合蛋白,并用谷胱甘肽亲和层析法纯化重组蛋白.结果:获得MAGE-C2开放读框并构建表达载体,测序结果与GenBank收录的序列相一致.真核表达载体转染293T细胞后显示MAGE-C2蛋白定位于细胞核;原核重组蛋白大部分以可溶性形式表达,亲和层析后,获得了较高纯度的MAGE-C2-GST融合蛋白.分析显示原核表达GST融合蛋白的相对分子质量为70 000,使用抗GST单克隆抗体进行Western blot分析证实为目的蛋白.结论:成功的获得MAGE-C2基因,构建了其表达载体并获得表达,为进一步制备MAGE-C2特异性单抗及深入探讨MAGE-C2可能参与肿瘤发生发展的机制提供了重要条件.     

人ENO1(Enolase-α)基因的原核表达、蛋白纯化及多克隆抗体的制备

目的:构建人ENO1(human Enolase-α)基因的原核表达质粒,诱导重组蛋白的表达,利用纯化后的蛋白制备具有活性的ENO1多克隆抗体.方法:用PCR方法从胃癌MKN45细胞全基因组中扩增出目的基因ENO1,将目的基因和原核表达载体pET30a(+)分别双酶切,回收酶切产物并用T4连接酶连接,获得重组质粒pET30a(+)-ENO1.将重组质粒转入大肠埃希菌菌株BL21,经异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达,用Ni-NTA亲和层析柱纯化,利用纯化的ENO1活性蛋白作为抗原免疫家兔,制备抗血清多克隆抗体,并用Western blot检测其特异性.结果:目的基因与原核表达载体经双酶切鉴定所切下的片段大小与理论值相符,测序结果表明重组人ENO1基因序列与NCBI(NM_001428.3)公布序列一致.经SDS-PAGE分析,结果显示重组蛋白的分子量约在47kDa,条带单一,无杂带出现,主要以可溶性形式存在.Western blot证实多克隆抗体制备成功.结论:成功表达、纯化了ENO1融合蛋白,制备了具有高特异性的多克隆抗体,为进一步肿瘤疫苗的研制和肿瘤标志物快速诊断的研究奠定基础.     

hnRNP A2/B1基因的蛋白表达初步探讨

目的：克隆hnRNPA2／B1基因并构建全长cDNA的原核表达载体，在大肠杆菌中进行表达。方法：以RT-PCR法从人平滑肌肌细胞总RNA中克隆hnRNPA2／B1eDNA，连接至pGEX-4T—1载体，构建重组表达质粒，转化感受态E．coli BL21进行诱导表达。结果：克隆hnRNPA2／Bl基因全长eDNA序列，经DNA测序证明与GenBank一致。进而构建重组表达载体PCEX—A2／B1，在E．coli中表达出相对分子量约63kD的融合蛋白，免疫分析证实为hnRNPA2／B1蛋白。结论：成功克隆hnRNPA2／B1基因。在E.coli获得融合表达，为进一步研究其功能及应用提供基础。     

肝癌相关抗原H2-calponin基因重组质粒的构建与表达

目的应用基因工程的方法构建H2-calponin(CNN2)基因工程表达质粒,体外表达、分离、纯化CNN2蛋白。方法以PCR扩增CNN2cDNA序列,用基因工程技术将CNN2基因重组到表达质粒pColdⅢ中,转化BL21(DE3)pLysS宿主菌,以SDS-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamideg elelectrophoresis,SDS-PAGE)检测目的蛋白的表达情况,优化表达条件,以较大体积培养基因工程菌,菌体经超声波破菌后,过Ni-NTA亲和柱纯化,Western-blot检测表达纯化的融合蛋白。结果转化有pColdⅢ-CNN2重组质粒的基因工程菌能诱导表达CNN2蛋白,表达的目的蛋白占总菌体蛋白的35%;SDS-PAGE检测发现菌体上清液和沉淀物中均有目的蛋白片段,证实部分CNN2蛋白以可溶性形式表达;Western-blot检测结果提示表达纯化的蛋白能与抗CNN2抗体发生反应。结论成功构建出表达可溶性CNN2蛋白的重组质粒,诱导表达的蛋白具有CNN2免疫原性。     

RNAi抑制H157细胞Wnt5a表达

目的 构建抑制大鼠Wnt5a基因表达的重组质粒,达到抑制H157细胞Wnt5a表达的目的。方法 根据大鼠Wnt5a的基因序列,设计合成含有发夹结构的2条寡核苷酸片段,经退火形成双链后克隆至PAVU6+27载体质粒中,对阳性重组子进行酶切和测序鉴定后转染正常H157细胞,并采用Western blot检测Wnt5a蛋白水平表达的变化。结果 重组质粒经双酶切后,有目的条带出现,提示Wnt5a干扰片断已克隆至PAVU6+27载体质粒中,DNA测序结果显示插入序列与预先设计完全一致。重组质粒转染H157细胞后经G418筛选,成功获得阳性克隆,Western blot结果显示Wnt5a的蛋白水平表达显著下降。结论 成功构建Wnt5a基因RNA干扰表达质粒,明显抑制H157细胞中Wnt5a表达,这为深入研究该基因在非小细胞肺癌发生及侵袭转移中的作用奠定了基础。     

增强型绿色荧光蛋白与MAGE-n共表达载体的构建及表达

目的构建增强型绿色荧光蛋白(enhancedgreenfluorescentprotein,EGFP)与人黑色素瘤抗原-n(melanomaantigenn,MAGE-n)真核共表达载体,并在小鼠黑色素瘤B16细胞中进行表达。方法采用酶切法从pLXSN-MAGE-n中得到MAGE-n基因片段,克隆至真核表达载体pIRES2-EGFP中,构建真核共表达质粒pIRES2-EGFP-MAGE-n。用脂质体法转染小鼠黑色素瘤B16细胞,G418筛选阳性克隆,荧光显微镜检测阳性克隆中EGFP的表达,RT-PCR、Westernblot和免疫组化分别检测阳性克隆中MAGE-nmRNA和蛋白的表达水平。结果从pLXSN-MAGE-n重组质粒中酶切获得一条约950bp的片段,成功构建了真核共表达载体pIRES2-EGFP-MAGE-n,转染B16细胞后筛选得到阳性克隆,可见到EGFP的表达,产生明亮的绿色荧光,RT-PCR检测到MAGE-nmRNA的表达,Westernblot和免疫组化检测到MAGE-n蛋白的表达。结论成功构建了共表达质粒pIRES2-EGFP-MAGE-n,获得了稳定共表达EGFP和MAGE-n的小鼠黑色素瘤B16细胞系,为进一步研究MAGE-n在肿瘤免疫治疗中的作用奠定了基础。     

癌-睾丸抗原GAGE-1基因的重组、表达及纯化

目的 为进一步研究临床应用癌-睾丸抗原GAGE-1诱导特异性抗肿瘤免疫反应,对GAGE-1基因进行克隆、体外原核重组表达及蛋白分离纯化。方法 运用RT-PCR技术从人QGY-7701肝癌细胞株中扩增GAGE-1基因片段,插入原核表达载体pGEX-6p-1中,构建重组表达质粒pGEX-6p-1-GAGE-1,并导入大肠杆菌BL21,IPTG诱导目的蛋白表达;经包涵体透析复性及GST柱亲和层析纯化目的蛋白,SDS-PAGE电泳分析鉴定。结果 扩增得到GAGE-1基因5’端251 bp片段,与GeneBank公布的序列一致,构建的PGEX-6p-1-GAGE-1原核表达质粒经IPTG诱导,在大肠杆菌中表达分子量约35.7 kD的GST-GAGE-1融合蛋白,纯化后蛋白纯度为90%以上。结论 成功构建PGEX-6p-1-GAGE-1重组表达质粒,并成功表达纯化了GST-GAGE-1融合蛋白,为进一步深入研究GAGE蛋白奠定了基础。     

重组人canstatin表达产物的抗肿瘤活性鉴定

 目的　正确构建人canstatin原核表达载体 ,诱导表达重组人canstatin融合蛋白 ,并对其活性鉴定。方法　将人canstatincDNA亚克隆入 pQE30 ,构建重组质粒 pQE30 canstatin ;转化M 15 [pREP4] 中 ,IPTG诱导表达 ,纯化回收表达产物 ,复性后用Lewis肺癌移植瘤模型对其活性鉴定。结果　成功构建人canstatincDNA表达载体 ,纯化回收 ,获得高纯度canstatin重组蛋白。纯化产物在体内能抑制Lewis肺癌移植瘤血管的生成 ,从而抑制肿瘤生长和转移 ,抑瘤率 (% )为 6 0 .0 % ,转移抑制率 (% )为 74 .3%。结论　 (1)成功构建了原核表达载体 pQE30 canstatin。 (2 )重组人canstatin融合蛋白在原核表达系统中高水平表达 ,并获得高纯度canstatin重组蛋白。 (3)重组canstatin融合蛋白可抑制Lewis肺癌移植瘤血管的生成 ,从而抑制肿瘤生长和转移活性。     

M-CSF可溶性受体在烟草中的表达及其抗M-CSF作用研究

目的:在烟草中高效表达人M-CSF可溶性受体并研究其抗M-CSF活性.方法:采用基因重组技术构建表达C端含组氨酸标签和内质网滞留信号的M-CSF可溶性受体植物表达载体,通过根瘤土壤杆菌转化烟草,获得转基因植株.PCR、蛋白印迹实验鉴定转基因植株,ELISA方法测定重组蛋白表达水平,集落形成实验测定重组蛋白活性.结果:获得50余株转基因烟草植株,PCR证实目的基因已整合到烟草基因组中,蛋白印迹实验证实转基因植株表达目的蛋白;M-CSFsR在烟草中获得高效表达,但不同转基因植株的表达水平存在差异,其中表达水平最高的一株M-CSFsR占叶片可溶性蛋白的1.92%;集落形成实验证明M-CSFsR可以抑制J6-1细胞的集落形成.结论:在烟草中高效表达有生物学活性的重组人M-CSFsR.     

Antibody against biologically active p40 subunit of porcine interleukin-12 expressed in Escherichia coli

A truncated p40 subunit of porcine interleukin-12 (pIL-12) gene without the N-terminal signal peptide sequence was amplified by PCR and cloned into prokaryotic expression vector pGEX-6P-1. The resulting recombinant plasmid pGEX-IL12-40 was transformed into host cells BL21(DE3)pLysS, and the expression of the p40 subunit was induced using isopropyl β-D-thiogalactoside (IPTG). An anti-p40 polyclonal antibody was generated by immunizing a rabbit with the purified protein. Immunoreactivities of the p40 protein and the antibody were confirmed by immunoblotting. At the same time, a recombinant plasmid expressing the entire pIL-12 consisting of p35 and p40 genes was constructed by splicing by overlap extension (SOE)-PCR and transiently transfected into BHK-21 cells. Expression of p40 subunit on the surface of the transfected cells was identified using the anti-p40 antibody. The p40 protein and the specific antibody are biologically active and can be used as detecting reagents.     

凋亡抑制蛋白Livin 两种异构体原核表达载体的构建及融合表达

 目的 构建凋亡抑制蛋白Livin两种异构体（Livinα和β）的原核细胞表达载体pET32a（＋）-livinα和pET32a（＋）-livinβ。方法 设计合成扩增Livin基因异构体全长cDNA序列的特异性PCR引物,以Hela细胞总RNA为模板,RT-PCR获得Livin基因异构体全长cDNA序列,用限制性内切酶BamHⅠ和HandⅢ双酶切取所需目的片段,并插入原核表达载体pET32a（＋）的多克隆位点,经酶切、PCR鉴定,并经过测序证实后,构建成为Livin基因异构体表达载体（pET32a（＋）-livinα、β）。将重组质粒转入表达菌株BL21,诱导表达收集菌液,超声碎菌,取其上清和沉淀分别进行SDS-PAGE电泳。结果 成功获得Livinα和β全长cDNA序列,并克隆到原核表达载体pET32a（＋）上;成功获得大小为55kd左右的融合蛋白。结论 Livin基因两种异构体原核表达载体的构建及其融合蛋白的制备,为进一步研究Livin异构体功能及在肿瘤细胞中的抗凋亡效应奠定了基础。此蛋白也可用于进一步抗体制备、免疫鉴定和诊断等研究。     

Removal of Cdk inhibitors through both sequestration and downregulation in zearalenone-treated MCF-7 breast cancer cells

Treatment of MCF 7 cells with the fungal estrogen zearalenone induced cyclin E-associated kinase activity transiently within 9-12 h; total cyclin-dependent kinase (Cdk) 2 activity was elevated for 24 h and beyond. This increased cyclin E/Cdk2 activity was associated with sequestration of the Cdk inhibitor p27 Cdk inhibitor 1B (p27(KIP1)) by newly formed cyclin D1/Cdk4 complexes and with downregulation of p27(KIP1) expression. The activation of cyclin A/Cdk2 activity corresponded with virtual elimination of p27(KIP1). The activity of cyclin E/Cdk2 complexes from zearalenone-treated lysates was inhibited in vitro by recombinant p27(KIP1), and this inhibition was relieved by the addition of recombinant cyclin D1/Cdk4 complexes. Thus, sequestration of p27(KIP1) by cyclin D1/Cdk4 resulted in activation of Cdk2 in vitro. Cdk inhibitory activity in lysates of zearalenone-treated cells was depleted by anti-p27(KIP1) and anti-Cdc2 interacting protein (p21(CIP1)) antibodies. Overexpression of the Cdk4/6-specific Cdk inhibitor of Cdk4 p16(INK4A) was associated with increased association of p27(KIP1) with Cdk2, concomitant with disruption of D cyclin/Cdk4 complexes. The proteasome inhibitor 2-leu-leu-leu-H aldehyde (MG-132) was relatively ineffective in inhibiting the initial, sequestration-dependent activation of cyclin E/Cdk2 yet was as effective as p16(INK4A) in inhibiting activation of cyclin A/Cdk2 later in G(1). Downregulation of p27(KIP1) proceeded in p16(INK4A)-expressing cells after zearalenone treatment, and G(1) arrest afforded by p16(INK4A) expression was reversible upon prolonged treatment with zearalenone. Zearalenone treatment of MCF-7 cells elicited expression of F-box protein S phase kinase-associated protein 2 (p45(SKP2)), a substrate-specific component of the ubiquitin-ligase complex that targets p27(KIP1) for degradation in the proteasome. These studies suggest that both sequestration of Cdk inhibitors by cyclin D1/Cdk4 complexes and downregulation of p27(KIP1) play major roles in the induction of Cdk2 activity and S phase entry elicited by estrogens in MCF-7 cells.     

血管生长抑制因子angiostatin在昆虫细胞中的表达及活性研究

背景与目的:抑制新生血管的形成,有助于抑制肿瘤的生长,减少和预防肿瘤转移的发生。血管抑素(angiostatin)是一种重要的内源性新生血管生成抑制剂,对血管内皮细胞增殖有较强的抑制作用。为获得具有高活性的Angiostatin表达,本研究通过杆状病毒表达系统表达重组的angiostatin,分析其在昆虫细胞中表达和生物活性。方法:用带有angiostatin的杆状病毒转移载体pBlueBacHis2B和病毒DNA共同转染Sf9细胞,构建重组病毒,蚀斑实验筛选,PCR分析确定后扩增产生大量高滴度的病毒贮存液;用SDS-PAGE电泳和Westernblot对感染不同时间后分泌的重组蛋白做时间表达分析;用ProBondTM纯化系统对表达的重组angiostatin进行纯化,分光光度计确定蛋白含量,SDS-PAGE电泳确定蛋白纯度;采用MTT法测定重组蛋白angiostatin对原代培养的人脐静脉内皮细胞(HUVEC)的抑制作用而后通过鸡胚尿囊膜实验进一步证实其抗血管形成作用。结果:成功构建了滴度为2×108pfu/ml的angiostatin重组杆状病毒,并在昆虫细胞Sf9中高效表达了分子量为53ku的angiostatin重组蛋白,纯度约为90%,重组angiostatin蛋白不仅在体外显著抑制内皮细胞的生长(IC50为2.3μg/ml),而且显著抑制鸡胚尿囊膜血管的生长。结论:此系统可制备高滴度angiostatin重组杆状病毒贮存液,并在Sf9昆虫细胞中高效表达该重组蛋白,经在体和离体细胞学实验验证其对内皮细胞的增殖具有抑制作用。     

Expression of the PreS1 peptide of hepatitis B virus and preparation of its polyclonal antibody

PreS1 is a hypothetical candidate domain of L protein for hepatitis B virus (HBV) to adhere to and invade host hepatic cells. This report deals with the expression and purification of recombinant adw2 subtype of the preS1 peptide of hepatitis B virus surface antigen in Escherichia coli. The DNA fragments of the full-length or N/C terminal sequence of preS1 synthesized by PCR were inserted into the prokaryotic expression vector pGST-MOLUC, respectively. Reconstitute plasmids (named pGST-preS1, pGST-preS1N, and pGST-preS1C) were confirmed by sequencing analysis and transferred into Escherichia coli BL21(DE3). Recombinant full-length and N/C terminal of preS1 with GST tag were expressed at high levels in soluble form after induction with IPTG. The recombinant proteins were purified by a single-step affinity chromatography method. The immune reactivity of recombinant preS1 was confirmed by Western blot and virus capture assay. Furthermore, when the purified recombinant protein was used to immunize rabbit, the specific antibody titer can reach 10(-7). Thus, our successful expression system and achievement of purified recombinant preS1 protein and its polyclonal antibody lay the foundation for better understanding of the mechanism of HBV PreS1 protein in virus endocytosis and are helpful in seeking the PreS1-related protein.     

人B细胞成熟抗原的克隆、表达及纯化

目的构建人B细胞成熟抗原（BCMA）原核表达质粒,表达BCMA融合蛋白。方法通过RT—PCR方法从人B淋巴瘤Raji总RNA中扩增BCMA的全长cDNA,并插入原核表达载体PGEX4T-1的BamHI和NotⅠ酶切位点,构建原核表达载体PGEX4T-1-BCMA,利用酶切和序列分析方法验证所构建质粒的正确性。在大肠杆菌中表达BCMA融合蛋白,并经谷胱甘肽-S-转移酶（GST）亲和柱纯化。纯化后的产物经过SDS—PAGE、Westernblot检测目的蛋白的表达情况。结果Bam HI／Notl双酶切证明重组质粒中含有目的大小的BCMA基因片段,序列分析证明重组质粒中插入片段的碱基序列均完全正确。将所构建的PGEX4T-1-BCMA质粒转染感受态DH5ct,IPTG诱导表达后超声裂解菌体,上清经GST亲和纯化,经SDS—PAGE、抗GST和BCMA抗体Westernblot分析,证实融合表达蛋白为GST—BCMA融合蛋白。结论成功构建了BCMA原核表达载体,重组质粒能够在原核表达系统中可溶性表达GST—BCMA融合蛋白,为进一步研究BCMA的生物学功能奠定了基础。     

可溶性肿瘤坏死因子相关凋亡诱导配体诱导肝癌细胞凋亡的研究

方法 采用原位杂交方法检测肝癌组织、肝癌细胞株以及正常肝组织中TRAILR的表达。采用不同浓度TRAIL蛋白处理肝癌细胞株Hep2和SMMC7721,应用流式细胞仪和原位末端标记,观察经药物处理前后该细胞株的凋亡发生率。结果 60例肝癌组织及20例正常肝组织均表达死亡受体DR5和DR4,但肝癌组织DR表达量显著强于正常肝组织。54例(90．0％)肝癌组织不表达诱捕受体DcR1,25例(41．7％)肝癌组织不表达DcR2,而20例正常肝组织均表达DcR。肝癌组织中DR的高表达及DcR的低表达,不同于正常肝组织中DR的低表达及DcR的高表达,两者间差异有显著性。两种肝癌细胞株中均可检测到DR5、DR4、DcR2的表达,但DcR1表达缺失。肝癌组织中DR的表达与肿瘤的分化、肿瘤分期有关,低分化的肿瘤DR表达减少(P＜0．01),Ⅲ、Ⅳ期肿瘤DR表达显著低于I、Ⅱ期(P＜0．05)。DR表达与患者的性别、年龄、HBsAg阳性与否、AFP水平、肿瘤大小以及是否转移无关。经TRAIL(100ng/ml)处理24h,肝癌细胞凋亡发生率约10％,而Jurkat细胞凋亡率达70％以上,胆管癌细胞QBC939凋亡发生率约50％。结论 肝细胞肝癌普遍存在TRAILR的表达,并存在受体类型的表达差异。但单一的TRAIL治疗只能有限的诱导肝癌细胞HepG2、SMMC7721发生凋亡,HCC对TRAIL诱导的凋亡存在耐药现象。     

Effect of imidazole on the solubility of a his-tagged antibody fragment

A number of studies have demonstrated the limited solubility of single-chain Fv antibody fragments and its improvement by genetic engineering. This limits the stability of recombinant protein upon storage and the efficiency of chemical modification. The RAFT3 scFv used in the present work is specific for melanoma-associated proteoglycan and an attractive candidate for clinical radioimaging studies because of its unusual radiolabelling properties. However, when expressed with a c-terminal his(6) IMAC purification tag, the recombinant protein starts to precipitate after column elution and dialysis against PBS and reaches a concentration of soluble protein of approximately 150 microg/mL within a few days upon storage at 4 degrees C. We tested several commonly used buffer modifications (addition of detergents, high salt, amino acids) to improve the solubility and stability of the protein but without any major improvement. However, we found that, when the final dialysis step was omitted and the protein left in IMAC column elution buffer (PBS containing imidazole), it remained soluble. Furthermore, several months old and precipitated protein could be redissolved in this buffer without loss of antigen binding. This observation and the largely pH-independent nature of protein solubility suggest that neither salt bridges formed by the his(6) tail nor cross-linking of his(6) tails mediated by metal ions leached from the column during elution are responsible for the limited solubility of the protein in the absence of imidazole. The presence of imidazole did not interfere with radiolabelling and in vivo tumor targeting in a mouse model. The solubilizing and stabilizing effect of imidazole could be of use for his(6) tagged and poorly soluble recombinant proteins other than scFvs.     

靶向COX-2的RNA干扰抑制胃癌细胞增殖及相关信号分子改变

目的:本研究初步探讨RNA干扰技术应用于胃癌基因治疗的特异性及作用机制。方法:设计靶向COX-2基因的siRNA,构建重组表达质粒pTZU6 1-siRNA-COX-2并导入胃癌SGC-7901细胞株,在体外诱导RNA干扰,采用RT-PCR和Western blot同时检测处理组和对照组COX-2基因表达,MTT检测细胞增殖、流式细胞仪检测细胞周期;并用Westernblot检测相关信号分子p53、PCNA及Ki67蛋白表达。结果:体外细胞实验显示,重组质粒pTZU6 1-siRNA-COX-2导入胃癌SGC-7901细胞株后,胃癌细胞生长明显被抑制;细胞周期相分布发生显著变化,G1/G0期细胞明显减少,S期细胞显著增加;与对照相比,COX-2 mRNA分别下调88.36%和86.24%,COX-2蛋白表达分别下调94.27%和91.59%。p53蛋白表达上调,PCNA及ki67蛋白表达均明显下调。对照组各指标均无明显变化。结论:siRNA明显抑制了COX-2的表达及胃癌SGC-7901细胞增殖,并引起细胞周期改变,可能与上调p53蛋白和下调PCNA及ki67蛋白表达有关。