噬菌体多肽peptide 20抗胃癌细胞肝转移作用的实验研究

目的:探讨噬菌体多肽peptide 20对胃癌肝高转移潜能细胞XGC9811-L肝转移能力的影响。方法:细胞体外生长实验观察噬菌体多肽peptide 20是否可影响胃癌肝高转移潜能细胞XGC9811-L的生长能力;侵袭、运动实验检测peptide 20对XGC9811-L细胞的侵袭和运动能力的影响;体外黏附试验检测peptide 20是否可抑制XGC9811-L对不同细胞外基质的黏附能力。结果:噬菌体多肽peptide 20对细胞的生长无影响,但可减弱XGC9811-L的侵袭、运动、及对collagen Ⅳ的黏附能力。结论:噬菌体多肽peptide 20可抑制胃癌肝高转移潜能细胞的侵袭、运动和对collagen Ⅳ的黏附能力。     

胃癌腹膜高转移细胞特异性结合噬菌体多肽的筛选及鉴定

目的寻找能够与胃癌腹膜高转移细胞GC9811-P特异性结合的噬菌体多肽,探索治疗胃癌腹膜转移的新方法。方法运用噬菌体呈现肽技术,先后用胃癌的腹膜高转移细胞系GC9811-P和其亲本细胞GC9811对噬菌体12肽库进行消减性的全细胞淘洗．经过3轮筛选,随机挑选40个噬菌体单克隆C1～G40。用ELISA法选取能够与GC9811-P特异性结合的单克隆。将选出的单克隆分别注入裸鼠腹腔,采用免疫组化法排除与正常组织亦高结合的阳性单克隆。对筛选出的噬菌体克隆进行DNA序列测定,并推导其外源性氨基酸序列,进行同源性分析。结果经过3轮淘洗,噬菌体克隆得到理想富集。C9、C18、C23、C29、C34和C37可与GC9811-P特异性结合,经免疫组化证实,这6个单克隆均不与裸鼠腹腔内正常组织结合。测序结果大致展示了两种外源性多肽,即TLNINRLIIPRT和SMSIxSPYIxxx。结论筛选出6个可与GC9811-P细胞特异性结合的噬菌体多肽;这两个肽序列能否阻断GC9811-P细胞向腹膜转移尚待进一步确定。     

胃癌细胞特异性结合肽的筛选及鉴定

目的 筛选与胃癌细胞特异性结合的多肽。方法 以正常细胞为吸附细胞,胃癌细胞为筛选靶细胞对噬菌体随机12肽库进行消减筛,用细胞酶联免疫吸附试验（ELISA）、免疫细胞和组织化学法及裸鼠正常组织结合实验鉴定阳性克隆并进行DNA测序。结果 经三轮筛选,利用ELISA从随机挑选的24个噬菌体克隆中得到8个与胃癌细胞具有高结合力的噬菌体阳性克隆,经免疫细胞化学及裸鼠正常组织结合试验鉴定,发现第20、24两个克隆能与胃癌细胞特异性结合,而不与正常细胞和裸鼠组织结合,噬菌体阳性克隆氨基酸序列无同源性。结论 得到两个序列不同的特异性结合胃癌细胞的噬菌体克隆,这可为进一步的研究提供实验依据。     

环7肽库筛选胃癌耐药细胞特异性结合短肽

目的获得与胃癌耐药细胞株SGC7901/VCR特异结合的抑制耐药短肽,作为提高胃癌化疗效果的先导化合物。方法以SGC7901/VCR细胞为靶细胞,胃粘膜永生化上皮细胞GES,胃癌药敏细胞SGC7901为吸附细胞对噬菌体7肽库进行消减筛选,用细胞ELISA鉴定阳性噬菌体克隆并测序,利用竞争抑制试验确定阳性克隆的结合部位是否为外源性肽段。结果经4轮筛选,从随机挑选的30个噬菌体克隆中得到14个能特异性与SGC7901/VCR结合而不与胃癌药敏细胞结合的阳性克隆,确定其氨基酸序列分别为SY1和SY2(筛选所得安基酸序列正在专利申请中),含SY1为阳性克隆。结论用噬菌体环7肽库成功筛选到能特异性结合胃癌耐药细胞株的短肽,为肿瘤治疗或药物靶向治疗奠定基础。     

MDA-MB-231乳腺癌细胞特异性多肽的初步筛选

目的 利用噬菌体展示技术,从噬菌体随机十二肽库中筛选出能够特异性结合MDA-MB-231乳腺癌细胞的噬菌体克隆.方法 以人正常乳腺细胞为减性筛选细胞、MDA-MB-231乳腺癌细胞为靶细胞,对噬菌体随机十二肽库进行筛选,挑取富集后的阳性单克隆噬菌体,酶联免疫吸附试验（ELISA）及DAB染色鉴定阳性噬菌体的特异性及亲和力.结果 经过3轮筛选,噬菌体得到约113倍的富集,随机挑选11株单克隆噬菌体,ELISA显示8号噬菌体单克隆对乳腺癌细胞的亲和力是对照的6.5倍,DAB鉴定亦显示其对乳腺癌细胞的特异性及亲和力最高,命名为LK-8.结论 利用噬菌体筛选技术成功筛选出能够特异性结合MDA-MB-231乳腺癌细胞的特异性噬菌体单克隆LK-8,可为进一步合成特异性多肽用于早期诊断和靶向治疗乳腺癌奠定基础.     

筛选与KDR有结合活性的小肽

目的：从噬菌体12肽库和环7肽库中,筛选能够与KDR分子有特异结合活性的小肽。方法：以KDR/IgGFc为靶分子筛选噬菌体12和肽7肽库,经过3轮筛选和竞争性洗脱后,由ELISA、细胞-ELISA和竞争结合实验,鉴定阳性噬菌体克隆并测序。结果：从40个噬菌体克隆中得到12个能特异性与靶分子结合的阳性克隆,其中,6个噬菌体克隆与靶分子有较强的结合力,6个结合力较弱。结论：测序结果表明,12条小肽的一级结构中没有发现共同模式。特异性与KDR结合的活性小肽,有望在临床上作为放化疗药物的导向肽,以提高药物的选择性和降低其毒副作用。     

应用随机多肽文库分析BAC5单抗相关的抗原表位

目的　鉴定能被BAC5单抗识别的定位于鼻咽癌细胞表面的抗原表位。方法　应用BAC5单抗作为靶抗体对噬菌体呈现的随机 12肽文库进行 3轮生物淘洗 ,用抗体捕获和竞争试验的夹心ELISA方法选择和鉴定阳性噬菌体克隆 ,对阳性和阴性噬菌体的外源性DNA片段进行序列分析 ,推导和比较由这些噬菌体所呈现的多肽氨基酸序列。结果　通过 3轮生物淘洗能被抗体捕获的噬菌体克隆为 77% ( 35 /45 )。用竞争试验从所捕获的克隆中测得 8个阳性克隆。来自这 8个克隆的噬菌体呈现三种外源多肽 ,即$CH Q S H Y P Y P V V S L ( 4/8)$CQ N Q A W F S Q P P V R M ( 3/8)和 T Q A Y K G F P V L P S ( 1/8) ,与来自阴性克隆的多肽序列 N H Q S T F W Q K W T A ( 6 /6 )比较 ,前 3个序列在靠近肽的N端都具有相同的脯氨酸 (P)和缬氨酸 (V)结构 ( P V )。结论　BAC5单抗能识别近N端含有脯氨酸和缬氨酸结构的多肽。这些多肽可能模拟存在于鼻咽癌细胞表面并与BAC5单抗相关的抗原表位的构象。     

人表皮生长因子受体2模拟表位的筛选

目的:从噬菌体12肽库中筛选出人表皮生长因子受体2（Her2）的抗原模拟表位。方法:以曲妥珠单抗为靶分子,在噬菌体12肽库中进行3轮淘选,以ELISA方法及竞争抑制实验鉴定阳性克隆,并对阳性克隆株进行测序。结果:经过3轮淘选,与曲妥珠单抗结合的噬菌体得到了有效富集,回收率从（2.00×10-8）%增加到（2.87×10-5）%,ELISA显示20个克隆中筛选获得了18个与曲妥珠单抗具有较高亲和性的阳性噬菌体,对阳性克隆测序获得两种氨基酸序列:HTSSLWHLFRST、VHWDFRQWWQPS。结论:噬菌体展示技术可成功筛选到表皮生长因子2模拟表位,为探索乳腺癌的防治研究创造了条件。     

宫颈癌HeLa细胞特异性结合肽的筛选及鉴定

背景与目的:宫颈癌的分子靶向治疗具有很好的疗效,同时可以显著减少抗癌药物对人体自身的损伤,因此备受关注。本研究利用噬菌体体内展示技术筛选及鉴定宫颈癌特异性结合肽,将有可能成为化疗药物的靶向载体,为宫颈癌靶向药物治疗奠定基础。方法:体外培养宫颈癌HeLa细胞接种裸鼠,建立肿瘤动物模型。将随机肽库尾静脉注入裸鼠体内,循环15 min,心脏灌注后回收肿瘤组织噬菌体扩增、纯化并以此作为起始物进行第2轮的筛选,如此进行3轮体内筛选后挑取噬菌体克隆,进行免疫组化及ELISA实验,初步鉴定噬菌体克隆对宫颈癌细胞的亲和力及特异性,并将具有强亲和力的克隆进行测序。结果:ELISA结果显示,随机挑选10个噬菌体单克隆中8个克隆对HeLa细胞具有很强的亲和力,将这8个克隆进行测序,获得相同短肽序列LLRSTGF。结论:利用噬菌体展示技术筛选出与宫颈癌细胞HeLa特异性结合的短肽,进一步与化疗药物结合,为宫颈癌靶向治疗提供新的方法。     

鼻咽癌患者血清抗体相关抗原优势表位的筛选

背景与目的：EB病毒与鼻咽癌(nasopharyngeal carcinoma,NPC)密切相关。可应用多种血清学方法检测鼻咽癌患者血清EBV抗体,本研究利用鼻咽癌患者血清中纯化的EB病毒相关多抗,从噬菌体展示的随机肽库中筛选相关的优势抗原表位,在表位水平为鼻咽癌患者血清抗体的检测寻找新的检测抗原。方法：以B95-8细胞EBV蛋白为抗原,从鼻咽癌患者血清中洗脱EB病毒相关多抗,对噬菌体展示的随机12肽库进行三轮生物淘洗。用夹心ELISA法和竞争抑制实验筛选阳性克隆,对这些阳性克隆进行测序,并将其展示的外源多肽与EB病毒蛋白的抗原性区域进行同源序列比对分析。结果：从第三轮的淘洗洗脱液中随机挑取64个噬菌体克隆,用夹心ELISA法筛选到25个阳性克隆,阳性率为39．06％,选取其中13个克隆进行竞争ELISA实验,有11个克隆出现抑制现象,抑制率在18．09％～65．94％之问。选取吸光度(A)值和抑制率均较高的5个克隆为阳性克隆,它们所展示的外源多肽序列分别为-A-T-S-H-L-H-V-R-L-P-W-T-(d15／d18)、-G-S-T-H-K-H-N-H-F-N-K-T-(d19)、-K-P-I-H-E-H-P-H-R-F-K-S-(e8)、-H-T-H-K一1-K-I-P-LP-I-Q-(e23)。这些多肽序列分别与EB病毒膜蛋白(d15／d18)、EB病毒胸苷激酶(d19)、EB病毒主要壳蛋白(e8,e23)抗原区域的氨基酸存在序列相似性。结论：利用鼻咽癌患者血清中的特异多抗可以从噬菌体展示的随机肽库中筛选到EB病毒相关抗原表位。     

Screening and Identification of a peptide specifically targeted to NCI-H1299 from a phage display peptide library

In this study, a NCI-H1299 (Non-Small Cell Lung Cancer, NSCLC) and a normal lung cell line (Small Airway Epithelial Cells, SAEC) were used for the subtractive screening in vitro with a phage display-12 peptide library. After three rounds of panning, there was an obvious enrichment for the phages specifically binding to the NCI-H1299 cells, and the output/input ratio of phages increased about 875-fold (from 0.4 × 10⁴ to 3.5 × 10⁶). A group of peptides being capable of binding specifically to the NCI-H1299 cells were obtained, and the affinity of these peptides to bind to the targeted cells and tissues was studied. Through a cell-based ELISA, immunocytochemical staining, immunohistochemical staining, and immunofluorescence, a M13 phage isolated and identified from the above screenings, and a synthetic peptide ZS-1 (sequence EHMALTYPFRPP) corresponded to the sequence of the surface protein of the M13 phage were demonstrated to be capable of binding to the tumor cell surfaces of NCI-H1299 and A549 cell lines and biopsy specimens, but not to normal lungs tissue samples, other different cancer cells, or nontumor surrounding lung tissues. In conclusion, the peptide ZS-1 may be a potential candidate of biomarker ligands used for targeted drug delivery in therapy of lung cancer.     

体内噬菌体展示技术筛选人髓样乳腺癌Bcap-37细胞特异性结合肽及其性质、结合效果研究

目的探讨体内噬菌体展示技术筛选的人髓样乳腺癌Bcap-37细胞特异性结合肽的性质和结合效果,为乳腺癌早期诊断提供分子靶向探针。方法制备人髓样乳腺癌Bcap-37细胞荷瘤裸鼠模型,采用噬菌体环七肽库进行3轮体内筛选。免疫组织化学法检测筛选的噬菌体在肿瘤及正常组织中的分布情况。酶联免疫吸附试验(ELISA)鉴定单克隆噬菌体对Bcap-37细胞的亲合力。提取阳性单克隆噬菌体DNA并测序,选取重复率高的序列合成多肽,制备光学分子探针,应用荧光分子成像验证合成的多肽在荷瘤小鼠体内对乳腺移植瘤的特异性和靶向性。结果第3轮体内筛选的噬菌体回收率为第1轮的107.2倍。免疫组织化学结果显示,随筛选轮次增加,肿瘤组织中结合的噬菌体依次增加;肿瘤组织结合的噬菌体多于正常组织(肺脏、骨骼肌、肝脏、肾脏),肿瘤组织切片扫描图像的吸光度(A)值均较正常组织高,差异均有统计学意义(均P<0.05)。ELISA结果显示,随机选取的50个单克隆噬菌体中,22个为阳性(亲合力≥2)。阳性单克隆噬菌体DNA测序分析后,得到4条有重复的氨基酸序列,选择重复率最高的氨基酸序列CSPLNTRFC,化学合成异硫氰酸荧光素(FITC)标记的CSPLNTRFC多肽。Bcap-37细胞荷瘤裸鼠模型体内验证实验显示,FITC-CSPLNTRFC多肽能明显富集在乳腺移植瘤组织。结论利用体内噬菌体展示技术能够筛选出可与人髓样乳腺癌Bcap-37细胞特异性结合的多肽CSPLNTRFC,有助于进行乳腺癌早期诊断的体外研究。     

Neuroblastoma tumor cell-binding peptides identified through random peptide phage display

Random peptide phage display libraries have been employed widely to identify protein-protein interactions, using as targets either purified proteins, intact cells, or organs. To isolate peptides that bind to human neuroblastoma cells, we have used a phage display approach with the neuroblastoma cell line WAC 2 as the target. In particular, two bacteriophages, t147 and t160, displaying peptides p147 and p160, respectively, were isolated by repeated display cycles. Binding of t147 and t160 to WAC 2 cells was abrogated by pretreatment with the peptides p147 and p160, respectively, which strongly support that cellular binding of both phages is dictated by their displayed peptides. Immunofluorescence analysis by confocal light microscopy revealed that the major proportion of t147 remains on the surface of WAC 2 cells and that only a fraction is taken up into the cells. In contrast, the vast majority of t160 is internalized. K(+) depletion reduced the number of the phages internalized by the cells to approximately 20% for t160 and to 10% for t147, indicating that the phage internalization was through receptor-mediated endocytosis. Phage t147 appears to bind to a range of tumor cell lines, including neuroblastoma, breast cancer, glioblastoma and C-cell carcinoma, but less so to non-tumor lines, such as erythrocytes, lymphocytes, monocytes and epithelial cells. Phage t160 bound to a range of neuroblastoma cell lines and a breast cancer cell line, but not to other tested cell lines. While neither of the displayed peptides conferred a narrow tissue specific binding ability, they do provide a basis for targeted drug delivery in selected experimental or natural tumor systems.     

胃癌耐药细胞特异性结合小肽对多药耐药的影响

目的 研究环九肽（SY1）与胃癌耐药细胞（SGC7901／VCR）的结合特性及其对胃癌耐药性的逆转作用。方法 将细胞分为SGC7901和SGC7901／VCR2组培养。以无关噬菌体、阴性噬菌体为对照组,用免疫荧光技术检测含有SY1的阳性噬菌体与SGC7901／VCR的结合特性;通过体外药敏试验（MTT）分析含有SY1的阳性噬菌体和化学合成的SY1对SGC7901／VCR耐药性的改变;应用流式细胞仪检测在SY1作用下SGC7901／VCR细胞内阿霉素（ADM）的蓄积和储留。结果 （1）免疫荧光分析的结果显示,含有SY1的阳性噬菌体能够结合于SGC7901／VCR的膜表面,而不与亲本细胞SGC7901结合,无关噬菌体和阴性噬菌体均不与SGC7901／VCR结合,表明SY1可与SGC7901／VCR特异性结合。（2）MTT试验结果显示,在含有SY1的阳性噬菌体及化学合成的SY1的作用下,SGC7901／VCR的存活率显著降低（P〈0．05）,其对长春新碱的耐药性降低。（3）在化学合成的SY1作用下,SGC7901／VCR细胞内ADM的储留蓄积高于对照组（P〈0．05）。结论 利用环七肽库差减筛选得到的环九肽SY1不仅能与SGC7901／VCR特异性结合,而且可部分逆转其对长春新碱的耐药性。这可能为胃癌多药耐药的逆转提供新思路。     

Screening and identification of a renal carcinoma specific peptide from a phage display peptide library

Background

Specific peptide ligands to cell surface receptors have been extensively used in tumor research and clinical applications. Phage display technology is a powerful tool for the isolation of cell-specific peptide ligands. To screen and identify novel markers for renal cell carcinoma, we evaluated a peptide that had been identified by phage display technology.

Methods

A renal carcinoma cell line A498 and a normal renal cell line HK-2 were used to carry out subtractive screening in vitro with a phage display peptide library. After three rounds of panning, there was an obvious enrichment for the phages specifically binding to the A498 cells, and the output/input ratio of phages increased about 100 fold. A group of peptides capable of binding specifically to the renal carcinoma cells were obtained, and the affinity of these peptides to the targeting cells and tissues was studied.

Results

Through a cell-based ELISA, immunocytochemical staining, immunohistochemical staining, and immunofluorescence, the Phage ZT-2 and synthetic peptide ZT-2 were shown to specifically bind to the tumor cell surfaces of A498 and incision specimens, but not to normal renal tissue samples.

Conclusion

A peptide ZT-2, which binds specifically to the renal carcinoma cell line A498 was selected from phage display peptide libraries. Therefore, it provides a potential tool for early diagnosis of renal carcinoma or targeted drug delivery in chemotherapy.     

Tumor cell-targeting by phage-displayed peptides

We isolated cancer cell-specific phages by subtracting and selecting complex peptide display phage libraries on cultured human cancer cells. The best candidate was selected by performing three rounds of subtraction before each of five selections on the human colorectal WiDr cell line. The phage showed more than 1000-fold higher binding efficiency for WiDr cells when compared to five other human cancer cell lines, including two of colorectal origin, and when compared to wild-type M13 phage. Fifty-fold higher binding efficiency was also seen for a human breast cancer cell line. We show that the WiDr cell binding of the selected phage was efficiently competed by the synthetic peptide HEWSYLAPYPWF, predicted from the phage sequence. This confirms that the specificity of the peptide is independent of the display by the phage coat proteins. The identified peptide may target biomarkers linked to colorectal cancer, and thus be useful for designing gene transfer vectors as well as diagnostic and prognostic tools for this disease.