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1.
目的:验证EpCAM分子特异性适配体对胰腺癌细胞的亲和性及对细胞凋亡的影响。方法:通过文献查询EpCAM分子特异性适配体,以流式细胞术验证适配体与胰腺癌PANC-1细胞的特异性亲和力;通过细胞免疫组化验证适配体与细胞结合的位点;通过流式细胞术检测适配体对细胞的凋亡影响。结果:选择文献报道的EpCAM分子特异性适配体EP166,在不破坏主要二级结构情况下做截断处理形成EP166s。通过流式细胞术验证发现EP166s与原适配体EP166均可以特异性识别胰腺癌PANC-1细胞,而与阴性对照的HEK293T细胞无特异性亲和力。细胞免疫荧光显示EP166s主要结合在细胞膜表面。凋亡检测结果发现EP166s在与PANC-1孵育12 h、24 h后均可促进细胞凋亡,且主要是细胞的早期凋亡,其所占百分比分别为12.2±0.20,27.13±0.36,而随机文库对照组的早期凋亡百分比分别为5.21±0.63,4.91±0.72;均值的配对T检验发现EP166s在孵育12 h和24 h后其早期凋亡所占百分数与随机文库组均有统计学差异,而且EP166s与细胞孵育12 h与24 h对凋亡的影响也有统计学差异,P≤0.01。结论:修饰后的适配体EP166s可以特异性识别胰腺癌PANC-1细胞,且结合位点位于细胞膜上;该适配体有促进PANC-1细胞凋亡的作用。  相似文献   

2.
肠球菌(Enterococcus)是内源性和外源性医院感染的第二大病原菌,检出率仅次于大肠杆菌,从分子水平上发展靶标的高亲和力分子探针对肠球菌的识别和检测具有非常重要的意义。本研究以粪肠球菌为靶标,运用全细菌指数富集的配体系统进化技术(whole-bacteria systematic evolution of ligands by exponential enrichment, whole-bacteria SELEX),从全长为79个核苷酸包含35个随机碱基序列的单链DNA文库中筛选与靶标高亲和力、高特异性结合的适配体,利用荧光分析法监控筛选过程中不同轮次所得次级文库与粪肠球菌的结合力,经12轮筛选和克隆测序,获得了39条适配体序列。进一步对筛选得到的适配体进行序列比对、二级结构分析、流式细胞分析、解离常数(Kd)测定及特异性验证,最终获得一条与粪肠球菌能特异性结合的适配体Apt 21,其Kd值为549.2 ± 147.4 nmol/L。该适配体可作为粪肠球菌检测的识别元件,为建立基于适配体的新型粪肠球菌检测方法奠定了基础。  相似文献   

3.
目的:筛选获得特异性结合磷脂酰肌醇蛋白聚糖1(GPC1)的单链DNA适配体。方法:合成全长81 nt,中间含39个随机序列的单链寡核苷酸(ss DNA)文库,运用指数富集配基系统进化(SELEX)技术筛选获得GPC1适配体;酶联免疫吸附分析法(ELISA)实验确定候选适配体与GPC1蛋白的亲和力,流式细胞术确定候选适配体与2种GPC1高表达细胞系(胰腺癌Panc-1细胞和工具细胞Luc-ZR-75-1~(GPC1))的结合特异性。结果:经过10轮SELEX筛选获得#9适配体,ELISA分析其亲和力为44±0.69 nmol/L,流式细胞术结果表明其与胰腺癌Panc-1细胞和Luc-ZR-75-1~(GPC1)细胞的阳性结合率分别为44.69%和51.44%。结论:筛选获得与GPC1蛋白有较高亲和力、与表达GPC1细胞系特异结合的ss DNA适配体。  相似文献   

4.
目的:筛选能特异性识别毒性休克综合征毒素1(TSST-1)的DNA适配体,为金黄色葡萄球菌感染的治疗奠定实验基础。方法:体外合成含有25个随机序列全长为63个碱基的单链DNA(ss DNA)文库,以TSST-1为靶标,利用指数富集的配体系统进化技术(SELEX),从ss DNA文库中筛选TSST-1适配体,利用生物信息学方法对适配体进行序列分析和结构预测,荧光定量法分析适配体的亲和力及特异性。结果:经过8轮筛选,文库的亲和力不断升高,获得了能识别TSST-1的DNA适配体T-7,它可选择性地与TSST-1结合,并测定其Kd值为103.8 nmol/L。结论:新型适配体T-7能选择性识别TSST-1,在金黄色葡萄球菌感染的治疗和诊断方面具有应用前景。  相似文献   

5.
目的:筛选能特异识别大鼠成骨细胞的单链DNA(ssDNA)适配体并对其进行鉴定。方法:利用完整细胞为靶标的消减细胞SELEX技术筛选大鼠成骨细胞特异ssDNA适配体,通过荧光显微镜、流式细胞术、基因克隆测序、MEME在线软件和RNA structure分析软件,分析适配体的一、二级结构,并对筛选得到的适配体进行鉴定。结果:经过6轮消减细胞SELEX筛选,荧光显微镜鉴定文库已富集;通过流式细胞术检测及测序分析,得到2条适配体L54和L66与大鼠成骨细胞特异结合,其平衡解离常数分别为494.4±133.3和511.4±160.7 nmol/L。结论:筛选获得特异识别大鼠成骨细胞的ssDNA适配体。  相似文献   

6.
SELEX法体外筛选胃癌细胞适配子方法的建立   总被引:1,自引:0,他引:1  
目的:建立SELEX技术筛选胃癌细胞SGC-7901适配子的方法,并初步鉴定获得的SGC-790 1细胞适配子.方法:体外合成全长88bp中间含52bp随机序列的ssDNA文库 ,通过优化PCR扩 增条件,利用地高辛-抗地高辛抗体-碱性磷酸酶系统测定亲和力,经SELEX反复筛选获得胃 癌SGC-7901细胞的特异性适配子.将最后一轮筛选产物克隆、测序并用相关软件分析适配子 序列的一级结构和二级结构.结果:经12轮SELEX筛选,ssDNA文库与SGC- 7901细胞的亲和力由0.16上升至1.14,表明特异性适配子得到逐步富集.22个克隆子测序, 有4个序列完全一致,二级结构预测茎环可能是适配子与胃癌细胞作用的结构基础.结论:成功建立了SELEX技术体外筛选胃癌细胞SGC-7901高亲和性适配子的方法.  相似文献   

7.
人中性粒细胞FcγRI(即CD64),Ig G Fc高亲和力受体之一,是早期诊断脓毒血症和系统性细菌感染的一个灵敏和特异的新标志物;目前,采用流式细胞计量术测定,难以在一般实验室开展。本研究旨在应用新型的体外筛选技术——指数富集配基的系统进化(systematic evolution of ligands by exponential enrichment,SELEX)技术——从体外合成的随机寡核苷酸文库中筛选人FcγRI的高亲和力和高特异性的核酸适配体(aptamer)。本文以人FcγRI为靶标,将其固定在羧基活化磁珠上,进行SELEX筛选。经过8轮筛选,共获得3个重点研究的单克隆适配体。生物信息学分析结果显示,人FcγRI适配体的模拟二级结构以茎-环和G-四聚体为主,可能是FcγRI与适配体的作用位点,G-T错配常见。流式细胞计量术和荧光显微镜分析显示,筛选出的典型单克隆适配体解离常数(the dissociation constant,Kd)均达到纳摩尔水平,而且适配体只与脓毒血症中性粒细胞结合,具有良好的亲和力和特异性。本研究表明,通过SELEX技术,成功获取了人FcγRI特异性核酸适配体,为以此适配体为分子探针,进一步建立用于脓毒血症早期诊断的新方法奠定了基础。  相似文献   

8.
核酸适配体(aptamer)是在体外采用指数富集的配基系统进化技术(systematic evolution of ligands by exponential enrichment, SELEX)从人工合成的随机寡核苷酸文库中筛选得到的一段寡核苷酸序列(RNA或DNA),能折叠成特定的三维空间结构同靶物质进行高特异性与高亲和性的结合。近年来,以全细胞为靶标筛选(cell-SELEX)获得的核酸适配体在疾病相关的领域有很大的应用潜力,尤其在细胞分子的识别、生物标志物的发现等方面,但cell-SELEX的过程复杂、难度大及获得的核酸适配体性能不佳等问题仍然制约着细胞特异性核酸适配体的进一步发展,如何高效地筛选获得核酸适配体是其应用的关键。本文总结了目前在cell-SELEX技术基础上发展起来的新方法、新策略及核酸适配体在肿瘤研究中的应用,望为相关科研人员的研究提供参考。  相似文献   

9.
核酸适配体以其类似抗体的功能及诸多优于抗体的特点引起人们的广泛关注,如何利用指数富集的配基系统进化技术(SELEX技术)来高效地筛选核酸适配体是其应用的关键。结合近些年核酸适配体的研究进展,为提高筛选效率及核酸适配体性能,针对适配体筛选三大不同环节所做的尝试及改良进行相关的阐述,包括初始随机寡核苷酸文库的设计与修饰、筛选过程所用方法及次级文库的制备、筛选过程后(Post-SELEX)核酸适配体性能的优化等;特别比较了筛选方法包括毛细管电泳SELEX、细胞SELEX、磁珠SELEX、加尾SELEX、微流控SELEX、微阵列SELEX和高通量SELEX,以及次级文库的制备方法诸如不对称PCR法、λ核酸外切酶法、磁珠法、不等长PCR法、综合性方法等;对核酸适配体发展面临的问题及发展前景进行探讨,以期为相关科研人员的研究提供参考。  相似文献   

10.
目的:筛选能特异识别vasorin(VASN)蛋白的单链DNA(ss DNA)适配体并对其进行鉴定。方法:利用SPRSELEX技术筛选VASN蛋白特异ss DNA适配体,通过基因克隆测序、MEME在线软件和RNA structure软件分析富集文库序列并挑选出候选适配体序列,利用EMSA、ELISA、流式细胞术对候选适配体进行特异性与亲和力鉴定。结果:经过5轮SELEX筛选,获得了与VASN蛋白特异结合的ss DNA适配体富集文库,合成候选适配体,经EMSA和ELISA检测分析,证实适配体V4-2能与VASN蛋白特异结合,而不与无关对照牛血清白蛋白结合,其平衡解离常数为281.3±103.7 nmol/L;流式细胞术证实V4-2能够特异识别高表达VASN蛋白的Hep G2细胞。结论:筛选获得特异识别VASN蛋白的ss DNA适配体V4-2。  相似文献   

11.
Systemic lupus erythematosus (SLE) is the most common autoimmune disease in China. B cell activating factor (BAFF) is an important target for the treatment and detection of SLE. It is of great significance to develop novel molecular recognition elements with high affinity for BAFF. In this study, artificial nucleic acid aptamers against BAFF were screened from a 78 nt single-stranded DNA random library by systematic evolution of ligands exponential enrichment (SELEX) in vitro based on several selection and amplification steps. Through ten rounds of selection, the aptamers with high specificity and affinity for BAFF were identified. After high-throughput sequencing, several aptamers were selected and further examined for binding affinity and specificity. The investigation by dot blotting, Eastern blotting analyses and enzyme-linked oligonucleotide assay (ELONA) showed that the aptamers Apt 7 and Apt 12 with dissociation constants of 241.00±19.75 nmol/L and 413.51±46.94 nmol/L were able to recognize BAFF specifically. After molecular docking analysis, Apt 7 was truncated to Apt 7~1, and the dissociation constant was 192.10±28.61 nmol/L. A sandwich ELONA using Apt 7~1 and BAFF antibodies was established to detect BAFF. The detection limit was estimated to be 0.227 nmol/L. This study provides new molecular recognition elements for the detection of BAFF and the study of antagonists.  相似文献   

12.
Graham JC  Zarbl H 《PloS one》2012,7(4):e36103

Background

Disease-specific biomarkers are an important tool for the timely and effective management of pathological conditions, including determination of susceptibility, diagnosis, and monitoring efficacy of preventive or therapeutic strategies. Aptamers, comprising single-stranded or double-stranded DNA or RNA, can serve as biomarkers of disease or biological states. Aptamers can bind to specific epitopes on macromolecules by virtue of their three dimensional structures and, much like antibodies, aptamers can be used to target specific epitopes on the basis of their molecular shape. The Systematic Evolution of Ligands by EXponential enrichment (SELEX) is the approach used to select high affinity aptamers for specific macromolecular targets from among the >1013 oligomers comprising typical random oligomer libraries. In the present study, we used live cell-based SELEX to identify DNA aptamers which recognize cell surface differences between HPV-transformed cervical carcinoma cancer cells and isogenic, nontumorigenic, revertant cell lines.

Methodology/Principal Findings

Whole-cell SELEX methodology was adapted for use with adherent cell lines (which we termed Adherent Cell-SELEX (AC-SELEX)). Using this approach, we identified high affinity aptamers (nanomolar range Kd) to epitopes specific to the cell surface of two nontumorigenic, nontumorigenic revertants derived from the human cervical cancer HeLa cell line, and demonstrated the loss of these epitopes in another human papillomavirus transformed cervical cancer cell line (SiHa). We also performed preliminary investigation of the aptamer epitopes and their binding characteristics.

Conclusions/Significance

Using AC-SELEX we have generated several aptamers that have high affinity and specificity to the nontumorigenic, revertant of HPV-transformed cervical cancer cells. These aptamers can be used to identify new biomarkers that are related to carcinogenesis. Panels of aptamers, such as these may be useful in predicting the tumorigenic potential and properties of cancer biopsies and aid in the effective management of pathological conditions (diagnosis, predicted outcome, and treatment options).  相似文献   

13.

Background

Cell-SELEX is now widely used for the selection of aptamers against cell surface biomarkers. However, despite negative selection steps using mock cells, this method sometimes results in aptamers against undesirable targets that are expressed both on mock and targeted cells. Studying these junk aptamers might be useful for further applications than those originally envisaged.

Methodology/Principal Findings

Cell-SELEX was performed to identify aptamers against CHO-K1 cells expressing human Endothelin type B receptor (ETBR). CHO-K1 cells were used for negative selection of aptamers. Several aptamers were identified but no one could discriminate between both cell lines. We decided to study one of these aptamers, named ACE4, and we identified that it binds to the Annexin A2, a protein overexpressed in many cancers. Radioactive binding assays and flow cytometry demonstrated that the aptamer was able to bind several cancer cell lines from different origins, particularly the MCF-7 cells. Fluorescence microscopy revealed it could be completely internalized in cells in 2 hours. Finally, the tumor targeting of the aptamer was evaluated in vivo in nude mice xenograft with MCF-7 cells using fluorescence diffuse optical tomography (fDOT) imaging. Three hours after intravenous injection, the aptamer demonstrated a significantly higher uptake in the tumor compared to a scramble sequence.

Conclusions/Significance

Although aptamers could be selected during cell-SELEX against other targets than those initially intended, they represent a potential source of ligands for basic research, diagnoses and therapy. Here, studying such aptamers, we identify one with high affinity for Annexin A2 that could be a promising tool for biomedical application.  相似文献   

14.

Background

Ovarian cancer is the most lethal gynecological malignancy, and the ovarian clear cell carcinoma subtype (OCCA) demonstrates a particularly poor response to standard treatment. Improvements in ovarian cancer outcomes, especially for OCCA, could be expected from a clearer understanding of the molecular pathology that might guide strategies for earlier diagnosis and more effective treatment.

Methodology/Principal Findings

Cell-SELEX technology was employed to develop new molecular probes for ovarian cancer cell surface markers. A total of thirteen aptamers with Kd''s to ovarian cancer cells in the pico- to nanomolar range were obtained. Preliminary investigation of the targets of these aptamers and their binding characteristics was also performed.

Conclusions/Significance

We have selected a series of aptamers that bind to different types of ovarian cancer, but not cervical cancer. Though binding to other cancer cell lines was observed, these aptamers could lead to identification of biomarkers that are related to cancer.  相似文献   

15.
Pancreatic cancer is one of the most aggressive human malignancies with extremely poor prognosis. The moderate activity of the current standard gemcitabine and gemcitabine-based regimens was due to pre-existing or acquired chemo-resistance of pancreatic cancer cells. In this study, we explored the potential role of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) in gemcitabine resistance, and studied the underlying mechanisms. We found that NU-7026 and NU-7441, two DNA-PKcs inhibitors, enhanced gemcitabine-induced cytotoxicity and apoptosis in PANC-1 pancreatic cancer cells. Meanwhile, PANC-1 cells with siRNA-knockdown of DNA-PKcs were more sensitive to gemcitabine than control PANC-1 cells. Through the co-immunoprecipitation (Co-IP) assay, we found that DNA-PKcs formed a complex with SIN1, the latter is an indispensable component of mammalian target of rapamycin (mTOR) complex 2 (mTORC2). DNA-PKcs–SIN1 complexation was required for Akt activation in PANC-1 cells, while inhibition of this complex by siRNA knockdown of DNA-PKcs/SIN1, or by DNA-PKcs inhibitors, prevented Akt phosphorylation in PANC-1 cells. Further, SIN1 siRNA-knockdown also facilitated gemcitabine-induced apoptosis in PANC-1 cells. Finally, DNA-PKcs and p-Akt expression was significantly higher in human pancreatic cancer tissues than surrounding normal tissues. Together, these results show that DNA-PKcs is important for Akt activation and gemcitabine resistance in PANC-1 pancreatic cancer cells.  相似文献   

16.
Breast cancer is the most common female cancer. However, the known effective specific biomarkers for breast cancer are still scarce. Abnormal membrane proteins serve as ideal biomarkers for disease diagnoses, therapeutics and prognosis. Thus aptamers (single-stranded oligonucleotide molecules) with molecular recognition properties can be used as efficient tools to sort cells based on differences in cell surface architecture between normal and tumor cells. In this study, we aimed to screen specific aptamer against MCF-7 human breast cancer cells. Cell-SELEX process was performed to isolate aptamers from a combinatorial single-stranded nucleic acid library that selectively targeting surface proteins of MCF-7 cells in contrast with MCF-10A human mammary epithelial cells. The process was repeated until the pool was enriched for sequences that specifically recognizing MCF-7 cells in monitoring by flow cytometry. Subsequently, the enriched pool was cloned into bacteria, and positive clones were sequenced to obtain individual sequences. Representative sequences were chemically synthesized and evaluated their binding affinities to MCF-7 cells. As a result, an aptamer S1 was finally identified to have high binding affinity with equilibrium dissociation constant (Kd) value of 29.9 ± 6.0 nM. FAM-labeled aptamer S1 induced fluorescence shift in MCF-7 cells but not in MCF-10A human mammary epithelial cells, or MDA-MB-453 and MDA-MB-231 human breast cancer cells. Furthermore, result of cell imaging observed from laser confocal fluorescence microscope showed that MCF-7 cells exhibited stronger fluorescence signal resulted from Cy5-labeled aptamer S1 than MCF-10A cells. The above findings suggested that S1 may be a specificity and selectivity aptamer for MCF-7 cells and useful for the breast cancer detection and diagnosis.  相似文献   

17.
Epidemiologic and animal studies have linked pancreatic cancer growth with fat intake, especially unsaturated fats. Arachidonic acid release from membrane phospholipids is essential for tumor cell proliferation. Lipoxygenases (LOX) constitute one pathway for arachidonate metabolism. We previously reported that 5-LOX and 12-LOX are upregulated in human pancreatic cancer cells and that blockade of these enzymes abolishes pancreatic cancer cell growth. The present study was aimed at evaluating the effect of LOX inhibition on differentiation and apoptosis in pancreatic cancer cells in parallel with growth inhibition. Four human pancreatic cancer cell lines, PANC-1, MiaPaca2, Capan2, and HPAF, were used. Apoptosis was evaluated by three separate methods, including DNA propidium iodide staining, DNA fragmentation, and the TUNEL assay. Morphological changes and carbonic anhydrase activity were used to determine the effect of LOX inhibitors on differentiation. The general LOX inhibitor NDGA, the 5-LOX inhibitor Rev5901, and the 12-LOX inhibitor baicalein all induced apoptosis in all four pancreatic cancer cell lines, as confirmed by all three methods, suggesting that both the 5-LOX and 12-LOX pathways are important for survival of these cells. Furthermore, NDGA, Rev5901, or baicalein resulted in marked cellular morphological changes in parallel with increased intracellular carbonic anhydrase activity, indicating that LOX blockade induced a more differentiated phenotype in human pancreatic cancer cells. Together with our previous findings, this study suggests that perturbations of LOX activity affect pancreatic cancer cell proliferation and survival. Blockade of LOX enzymes may be valuable for the treatment of human pancreatic cancer.  相似文献   

18.
白明华  马一楠  王宝峰  黄珊  贾辉 《生物磁学》2013,(25):4851-4853
目的:胰腺癌恶性程度高、进展快、预后差,姜黄素对于抑制恶性肿瘤的发生和进程具有广泛的生物学效应。但姜黄素能否诱导人胰腺癌细胞凋亡,其具体作用机制如何?目前仍无报道。本研究拟观察姜黄素对人胰腺癌PANC.1细胞凋亡的影响,探讨姜黄素诱导PANC.1细胞凋亡的机制。方法:不同浓度姜黄素处理人胰腺癌PANC-1细胞,流式细胞仪检测PANC-1细胞凋亡率,并分析Caspase-9和Caspase-3活性的变化,同时通过RT—PCR和Westemblot分析PANC-1细胞中P53表达的变化。结果:PANC-1细胞经不同浓度的姜黄素处理后,可以显著诱导细胞凋亡,并呈现一定的剂量依赖性,提示姜黄素具有一定抗肿瘤活性。姜黄素能够同时增加Caspase-9和Caspase-3的活性,并呈现一定的剂量依赖性,提示姜黄素可能通过Caspase-9和Caspase-3途径来诱导PANC.1细胞凋亡的发生。RT—PCR和westernblot结果显示,姜黄素可以显著增加PANC-1细胞中P53蛋白表达水平。结论:姜黄素可以显著诱导PANC-1细胞凋亡的发生,提高Caspase-9和Caspase-3的活性,同时增加的P53表达,并呈现一定的剂量依赖性,提示姜黄素诱导PANC-1细胞凋亡的过程可能与增加细胞中Caspase-9,Caspase-3以及P53的表达有关。本研究探讨了姜黄素诱导PANC-1细胞凋亡的分子机制,为姜黄素的进一步应用提供了新的思路和理论支持,在人胰腺癌的临床治疗中具有一定的潜在应用价值。  相似文献   

19.
Oncogenic KRAS, an important target for antitumor therapy, contributes to pancreatic cancer tumorigenesis, progression and maintenance. However, intracellular compensation regulation can help cells to resist the targeted therapy. Gene knockdown method such as RNAi may help to understand this intracellular regulatory system and discover novel therapeutic approach. In this study, two stable transfected cell lines were constructed through lentivirus-mediated shRNA targeting KRAS of PANC-1 cells, to investigate cell response to the knockdown of KRAS. Human whole genome microarray was then used to compare the gene expression profile. As a result, ribosomal proteins L26 and L29 (RPL26 and RPL29) were dramatically upregulated by KRAS-shRNA specifically. To identify whether RPL26 or RPL29 was critical for PANC-1 cells, siRNAs against RPL26 and RPL29 were designed and transfected in vitro. The results showed that knockdown of RPL26 or RPL29 expression significantly suppressed cell proliferation, induced cell arrest at G0/G1 phase and enhanced cell apoptosis. Reactive oxygen species (ROS) assay indicated that silencing of RPL26 or RPL29 markedly decreased the intracellular ROS generation. Our findings imply that siRNA interference against RPL26 and RPL29 is of potential value for intervention of pancreatic cancer.  相似文献   

20.
Series of 2-pyridineformamide thiosemicarbazones were synthesized. Their preferential cytotoxicity in nutrient deprived medium (NDM) was evaluated using PANC-1 human pancreatic cancer cells by employing an antiausterity strategy. 2-Pyridineformamide thiosemicarbazones induced apoptosis and exhibited preferential cytotoxic activity toward PANC-1 cells in NDM, with potencies in the submicromolar range. These compounds are potential candidates for the development of therapeutics against pancreatic cancer.  相似文献   

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