Tumor is a serious threat to human health. At present, surgical resection, chemoradiotherapy, targeted therapy and immunotherapy are the main therapeutic strategies. Monoclonal antibody has gradually become an indispensable drug type in the clinical treatment of cancer due to its high efficiency and low toxicity. Phage antibody library technology (PALT) is a novel monoclonal antibody preparation technique. The recombinant immunoglobulin variable region of heavy chain (VH)/variable region of light chain (VL) gene is integrated into the phage vector, and the antibody is expressed on the phage surface in the form of fusion protein to obtain a diverse antibody library. Through the process of adsorption-elution-amplification, the antibody library can be screened to obtain the antibody molecule with specific binding antigen as well as its gene sequence. PALT has the advantages of short antibody production cycle, strong plasticity of antibody structure, large antibody yield, high diversity and direct production of humanized antibodies. It has been used in screening tumor markers and preparation of antibody drugs for breast cancer, gastric cancer, lung cancer and liver cancer. This article reviews the recent progress and the application of PALT in tumor therapy.
Humans ; Bacteriophages/genetics* ; Immunoglobulin Variable Region/genetics* ; Gene Library ; Antibodies, Monoclonal/therapeutic use* ; Immunotherapy ; Peptide Library

Single chain antibody fragment (scFv) is a small molecule composed of a variable region of heavy chain (VH) and a variable region of light chain (VL) of an antibody, and these two chains are connected by a flexible short peptide. scFv is the smallest functional fragment with complete antigen-binding activity, which contains both the antibody-recognizing site and the antigen-binding site. Compared with other antibodies, scFv has the advantages of small molecular weight, strong penetration, low immunogenicity, and easy expression. Currently, the most commonly used display systems for scFv mainly include the phage display system, ribosome display system, mRNA display system, yeast cell surface display system and mammalian cell display system. In recent years, with the development of scFv in the field of medicine, biology, and food safety, they have also attracted much attention in the sectors of biosynthesis and applied research. This review summarizes the advances of scFv display systems in recent years in order to facilitate scFv screening and application.
Animals ; Immunoglobulin Variable Region/genetics* ; Immunoglobulin Fragments/metabolism* ; Single-Chain Antibodies/metabolism* ; Peptide Library ; Mammals/genetics*

OBJECTIVE: To establish a new method for synthesizing Lewis blood group antigens, that is, the mimotopes of Lewis blood group antigens were screened by using an alpaca phage display nanobody library. METHODS: We selected mimotopes of the Lewis a (le^a) antigen by affinity panning of an alpaca phage display nanobody library using a monoclonal anti-le^a antibody. Enzyme-linked immunosorbent assay (ELISA) was used to test the affinity of the positive clones for the monoclonal anti-le^a antibody, and the high-affinity positive clones were selected for sequencing and synthesis. Finally, the sensitivity, specificity and reactivity of the synthesized le^a mimotope in clinical samples were verified by ELISA. RESULTS: A total of 96 phage clones were randomly selected, and 24 were positive. Fourteen positive clones with the highest affinity were selected for sequencing. The result showed that there were 5 different sequences, among which 3 sequences with the highest frequency, largest difference and highest affinity were selected for expression and synthesis. The sensitivity and specificity of le^a mimic antigen by ELISA showed that, the minimum detection limit of gel microcolumn assay (GMA) and ELISA method were 25 times different, and the le^a mimic antigen had no cross reacted with the other five unrelated monoclonal antibodies(P<0.001). Finally, 30 clinical plasma samples were analyzed. The mean absorbance of the 15 positive plasma samples was significantly higher than that of the 15 negative plasma samples (P=0.02). However, the positive signal values of the clinical samples were much lower than those of the monoclonal antibodies. CONCLUSION A new method of screening le^a mimic antigen by using alpaca phage nanoantibody library has been established, which is expected to realize the screening of le^a mimotopes, thus realizing the application of high-sensitivity detection methods such as ELISA and chemiluminescence in blood group antibody identification.
Animals ; Antibodies, Monoclonal ; Antineoplastic Agents, Immunological ; Bacteriophages ; Blood Group Antigens ; Camelids, New World ; Enzyme-Linked Immunosorbent Assay/methods* ; Epitopes ; Humans ; Lewis Blood Group Antigens ; Peptide Library

PURPOSE: This study was carried out to identify a peptide that selectively binds to kidney injury molecule-1 (KIM-1) by screening a phage-displayed peptide library and to use the peptide for the detection of KIM-1overexpressing tumors in vivo. MATERIALS AND METHODS: Biopanning of a phage-displayed peptide library was performed on KIM-1–coated plates. The binding of phage clones, peptides, and a peptide multimer to the KIM-1 protein and KIM-1–overexpressing and KIM-1–low expressing cells was examined by enzyme-linked immunosorbent assay, fluorometry, and flow cytometry. A biotin-peptide multimer was generated using NeutrAvidin. In vivo homing of the peptide to KIM-1–overexpressing and KIM1–low expressing tumors in mice was examined by whole-body fluorescence imaging. RESULTS: A phage clone displaying the CNWMINKEC peptide showed higher binding affinity to KIM-1 and KIM-1–overexpressing 769-P renal tumor cells compared to other phage clones selected after biopanning. The CNWMINKEC peptide and a NeutrAvidin/biotin-CNWMINKEC multimer selectively bound to KIM-1 over albumin and to KIM-1–overexpressing 769-P cells and A549 lung tumor cells compared to KIM-1–low expressing HEK293 normal cells. Co-localization and competition assays using an anti–KIM-1 antibody demonstrated that the binding of the CNWMINKEC peptide to 769-P cells was specifically mediated by KIM-1. The CNWMINKEC peptide was not cytotoxic to cells and was stable for up to 24 hours in the presence of serum. Whole-body fluorescence imaging demonstrated selective homing of the CNWM-INKEC peptide to KIM-1–overexpressing A498 renal tumor compared to KIM1–low expressing HepG2 liver tumor in mice. CONCLUSION: The CNWMINKEC peptide is a promising probe for in vivo imaging and detection of KIM-1‒overexpressing tumors.
Animals ; Bacteriophages ; Clone Cells ; Enzyme-Linked Immunosorbent Assay ; Flow Cytometry ; Fluorometry ; Kidney Neoplasms ; Kidney ; Liver ; Lung ; Mass Screening ; Mice ; Optical Imaging ; Peptide Library ; Peptides

To screen the specific anti-human intercellular adhesion molecule-1 (ICAM-1) single chain fragment variable (scFv) using phage display library technology and to identify its biological activity. P1 peptide was used as antigen, and the phage antibodies against human ICAM-1 antigen were panned by four binding-eluting-amplifying cycles using Tomlinson I+J phage display library. After four rounds of selective enrichment screening, the positive clones were determined by PCR, enzyme linked immunosorbent assay (ELISA)-based antigenic cross reaction and Dot blotting. Then the binding specificity and biological activity of purified scFv were identified by Western blotting, competitive ELISA and cell adhesion inhibition assay respectively. Furthermore, four positive clones were first panned through P1 peptide coated-ELISA assay, and then J-A1 was obtained and identified by PCR, ELISA-based antigenic cross reaction and Dot blotting, which could show a specific binding between P1 peptide and human ICAM-1 protein antigen. Subsequently, the purified scFv showed a satisfactory specificity and anti-adhesive activity in competitive ELISA and the cell adhesion inhibition assay. The specific anti-human ICAM-1 scFv was prepared successfully from Tomlinson I+J phage display library, which pave the way for further application of anti-human ICAM-1 scFv for inflammation diseases therapeutics.
Antibodies ; Enzyme-Linked Immunosorbent Assay ; Humans ; Immunoglobulin Variable Region ; Intercellular Adhesion Molecule-1 ; immunology ; Peptide Library ; Single-Chain Antibodies

OBJECTIVE: Vascular endothelial growth factor (VEGF) interaction with its receptor, VEGFR-3/Flt-4, regulates lymphangiogenesis. VEGFR-3/Flt-4 expression in cancer cells has been correlated with clinical stage, lymph node metastasis, and lymphatic invasion. The objective of this study is to identify a VEGFR-3/Flt-4-interacting peptide that could be used to inhibit VEGFR-3 for ovarian cancer therapy. METHODS: The extracellular fragment of recombinant human VEGFR-3/Flt-4 (rhVEGFR-3/Flt-4) fused with coat protein pIII was screened against a phage-displayed random peptide library. Using affinity enrichment and enzyme-linked immunosorbent assay (ELISA) screening, positive clones of phages were amplified. Three phage clones were selected after four rounds of biopanning, and the specific binding of the peptides to rhVEGFR-3 was detected by ELISA and compared with that of VEGF-D. Immunohistochemistry and immunofluorescence analyses of ovarian cancer tissue sections was undertaken to demonstrate the specificity of the peptides. RESULTS: After four rounds of biopanning, ELISA confirmed the specificity of the enriched bound phage clones for rhVEGFR-3. Sequencing and translation identified three different peptides. Non-competitive ELISA revealed that peptides I, II, and III had binding affinities for VEGFR-3 with Kaff (affinity constant) of 16.4+/-8.6 microg/mL (n=3), 9.2+/-2.1 microg/mL (n=3), and 174.8+/-31.1 microg/mL (n=3), respectively. In ovarian carcinoma tissue sections, peptide III (WHWLPNLRHYAS), which had the greatest binding affinity, also co-localized with VEGFR-3 in endothelial cells lining lymphatic vessels; its labeling of ovarian tumors in vivo was also confirmed. CONCLUSION: These finding showed that peptide III has high specificity and activity and, therefore, may represent a potential therapeutic approach to target VEGF-VEGFR-3 signaling for the treatment or diagnosis of ovarian cancer.
Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Ovarian Neoplasms/*therapy ; *Peptide Library ; Sequence Analysis, DNA ; Signal Transduction/physiology ; Vascular Endothelial Growth Factor A/metabolism ; Vascular Endothelial Growth Factor Receptor-3/antagonists & inhibitors/*metabolism

Membrane type-1 matrix metalloproteinase (MT1-MMP or MMP14) plays the pivotal role in tumor development and metastasis, so it is a promising drug target in malignancy. To acquire MT1-MMP specific binding peptides, we first analyzed MMPs sequences to find the divergent and specific sequence of MT1-MMP by bioinformatics approach, then set the specific sequence as the sense peptide target and designed antisense peptide library. Finally, by means of molecular docking, molecular dynamics simulation and in vitro cell assays, we screened the antisense peptide library against MT1-MMP and further studied the obtained specific peptides. Here, we identified the divergent and specific sequence of AYIREGHE (Named MT1-loop) located in MT1-MMP loop by multiple sequence alignment and established the antisense peptides library with capacity of 1 536 sequences. After two rounds of virtual screening, we obtained five antisense peptides with Rerankscores in the top for further screening. They all interacted with MT1-MMP, and docked well at the active site composed of MT1-loop sequence. Analysis of the affinities of these five antisense peptides to other MMPs (MMP1-3, MMP7-13, MMP14 HPX, MMP16) revealed that the peptide FVTFPYIR was more specific to MT1-MMP. Molecular dynamics simulation showed that the peptide FVTFPYIR might affect the stability of MT1-MMP and thus have effects on its activities. Meanwhile, the peptide FVTFPYIR could specifically inhibit the growth of MG63 and MDA-MB-231 tumor cells both of which expressed MT1-MMP. The work provides a new insight and way for the development of antitumor lead peptides targeting MT1-MMP.
Amino Acid Sequence ; Humans ; Matrix Metalloproteinase 14 ; chemistry ; Molecular Dynamics Simulation ; Neoplasms ; Peptide Library ; Peptides ; chemistry

BACKGROUNDMultiple myeloma (MM) is a malignant tumor, which takes the second place in malignant blood disease. The clinical symptoms are complicated that make more difficult to diagnose and therapy. Lots of researches focus on the proteins about MM in order to solve those problems. We used proteomic methods to find potential biomarkers in MM patients.

METHODSWe applied the peptide ligand library beads (PLLBs) to deplete high abundance proteins in serum for finding potential pathogenic factors and biomarkers of MM. Using 1D-Gel-liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified 789 and 849 unique serum proteins in MM patients and in healthy controls, respectively.

RESULTSTwenty-two proteins were found differentially expressed between the two groups including serum amyloid A protein, vitamin D-binding protein isoform-1 precursor, plasma kallikrein, and apolipoprotein A-I. Changes of integrin alpha-11 and isoform-1 of multimerin-1 were validated with Western blotting. The linkage of the differentially expressed proteins and the pathogenesis pathways of MM were discussed.

CONCLUSIONSPLLB combined with 1D-gel-LC-MS/MS analysis is an efficient method to identify differentially expressed proteins in serum from patients with MM.

Biomarkers ; blood ; Biomarkers, Tumor ; blood ; Humans ; Multiple Myeloma ; blood ; Peptide Library ; Proteomics ; methods ; Tandem Mass Spectrometry

OBJECTIVETo obtain the C7C peptide ligands of Mycobacterium tuberculosis by affinity screening based on the phage-displayed random C7C peptide library, and preliminarily identify the binding capacity of the peptide to Mycobacterium.

METHODSInactive Mycobacterium tuberculosis reference strain H37Rv was used as the target molecule to screen the Ph. D.-C7C peptide library, and Mycobacterium bovis, BCG was used for reverse screening. After 4 rounds of affinity screening, single phages eluted by H37Rv and BCG were selected for DNA sequencing. ELISA was used to detect the binding affinities of different single phage clones. The cyclic peptides displayed by the phage clones showing the highest appetency were synthesized in vitro with fluorescent markers. Fluorescence microscopy and flow cytometer was used to detect the binding affinities of synthesized cyclic peptides, comparing with linear binding peptides obtained before.

RESULTSAfter 4 rounds of biopanning, phages that could bind with target molecules were remarkable enriched. 16 common sequences were obtained by sequencing analysis of single phages. With ELISA, phage SB1, SB5, SB8 and SB26 all showed higher affinity with H37Rv and BCG, the ratio to negative control of which were ≥ 2.1, but could not bind to the 3 nonmycobacteria, which were identified as the positive clones. Based on the results of flow cytometer detection, the affinities to H37Rv of 4 cyclic peptides SB1, SB5, SB24, SB26 were (73.2 ± 6.3)%, (63.2 ± 5.3)%, (32.9 ± 3.1)%, (89.4 ± 7.0)%, and to BCG were (65.6 ± 6.1)%, (48.6 ± 4.5)%, (10.3 ± 1.8)%, (86.6 ± 7.9)%, separately, which were all higher than H8 ((4.0 ± 1.0)%, (5.5 ± 1.2)%) . From the results of fluorescence microscopy observation, all of the fluorescent labeled cyclic peptides SB1, SB5, SB24, SB26 could bind to H37Rv and showed higher fluorescence intensities, which also had certain affinities to other 18 mycobacteria, but the fluorescence intensities were lower than H37Rv, and didn't bind to 3 non-mycobacteria.

CONCLUSIONBased on the replacement of linear 7 peptide library with C7C peptide library, new ligands of Mycobacterium tuberculosis were achieved successfully, which showed significantly higher binding affinities to mycobacteria.

Base Sequence ; Enzyme-Linked Immunosorbent Assay ; Ligands ; Mycobacterium tuberculosis ; Peptide Library ; Peptides

A positional scanning synthetic peptide combinatorial library (PS-SCL) was screened in order to identify antimicrobial peptides against the cariogenic oral bacteria, Streptococcus mutans. Activity against Streptococcus gordonii and Aggregatibacter actinomycetemcomitans was also examined. The library was comprised of six sub-libraries with the format O(1-6)XXXXX-NH2, where O represents one of 19 amino acids (excluding cysteine) and X represents equimolar mixture of these. Each sub-library was tested for antimicrobial activity against S. mutans and evaluated for antimicrobial activity against S. gordonii and A. actinomycetemcomitans. The effect of peptides was observed using transmission electron microscopy (TEM). Two semi-mixture peptides, RXXXXN-NH2 (pep-1) and WXXXXN-NH2 (pep-2), and one positioned peptide, RRRWRN-NH2 (pep-3), were identified. Pep-1 and pep-2 showed significant antimicrobial activity against Gram positive bacteria (S. mutans and S. gordonii), but not against Gram negative bacteria (A. actinomycetemcomitans). However, pep-3 showed very low antimicrobial activity against all three bacteria. Pep-3 did not form an amphiphilic alpha-helix, which is a required structure for most antimicrobial peptides. Pep-1 and pep-2 were able to disrupt the membrane of S. mutans. Small libraries of biochemically-constrained peptides can be used to generate antimicrobial peptides against S. mutans and other oral microbes. Peptides derived from such libraries may be candidate antimicrobial agents for the treatment of oral microorganisms.
Aggregatibacter actinomycetemcomitans ; Amino Acids ; Anti-Infective Agents ; Bacteria ; Gram-Negative Bacteria ; Gram-Positive Bacteria ; Mass Screening* ; Membranes ; Microscopy, Electron, Transmission ; Peptide Library* ; Peptides ; Streptococcus gordonii ; Streptococcus mutans