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Phage Clones (phage + clone)
Selected AbstractsIdentification of oligopeptides binding to peritoneal tumors of gastric cancerCANCER SCIENCE, Issue 10 2006Noriyuki Akita This is a report of in vivo intraperitoneal biopanning, and we successfully identified a novel peptide to target the multiple peritoneal tumors of gastric cancer. A phage display library was injected directly into the abdominal cavity of mice bearing peritoneal tumors of human gastric cancer, and phages associated with the tumors were subsequently reclaimed from isolated samples. The tumor-associated phages were amplified and the biopanning cycle was repeated five times to enrich for high affinity tumor-selective binding peptides. Finally, a tri-peptide motif, KLP, which showed homology with laminin 5 (a ligand for ,3,1 integrin), was identified as a binding peptide for peritoneal tumors of gastric cancer. Phage clones displaying the sequence KLP showed 64-fold higher binding to peritoneal tumors than control phage and were preferentially distributed in tumors rather than in normal organs after intraperitoneal injection into mice. In addition, the KLP phages were more likely to bind to cancer cells in malignant ascites derived from a patient with recurrent gastric cancer. Synthesized peptide containing the motif KLP (SWKLPPS) also showed a strong binding activity to peritoneal tumors without cancer growth effect. Liposomes conjugated with SWKLPPS peptide appeared significantly more often in tumors than control liposomes after intraperitoneal injection into mice. Furthermore, modification of liposomes with SWKLPPS peptide enhanced the antitumor activity of adriamycin on gastric cancer cells. The peptide motif KLP seems a potential targeting ligand for the treatment of peritoneal metastasis of gastric cancer. (Cancer Sci 2006; 97: 1075,1081) [source] Characterization of prostate-specific antigen binding peptides selected by phage display technologyJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2006Catherine Ferrieu-Weisbuch Abstract Prostate-specific antigen (PSA) is an important marker for the diagnosis and management of prostate cancer. Free PSA has been shown to be more extensively cleaved in sera from benign prostatic hyperplasia patients than in sera from prostate cancer patients. Moreover, the presence of enzymatically activatable PSA was characterized previously in sera from patients with prostate cancer by the use of the specific anti-free PSA monoclonal antibody (mAb) 5D3D11. As an attempt to obtain ligands for the specific recognition of different PSA forms including active PSA, phage-displayed linear and cyclic peptide libraries were screened with PSA coated directly into microplate wells or presented by two different anti-total PSA mAbs. Four different phage clones were selected for their ability to recognize PSA and the inserted peptides were produced as synthetic peptides. These peptides were found to capture and to detect specifically free PSA, even in complex biological media such as sera or tumour cell culture supernatants. Alanine scanning of peptide sequences showed the involvement of aromatic and hydrophobic residues in the interaction of the peptides with PSA whereas Spotscan analysis of overlapping peptides covering the PSA sequence identified a peptide binding to the kallikrein loop at residues 82,87, suggesting that the peptides could recognize a non-clipped form of PSA. Moreover, the PSA-specific peptides enhance the enzymatic activity of PSA immobilized into microplate wells whereas the capture of PSA by the peptides inhibited totally its enzymatic activity while the peptide binding to PSA had no effect in solution. These PSA-specific peptides could be potential tools for the recognition of PSA forms more specifically associated to prostate cancer. Copyright © 2005 John Wiley & Sons, Ltd. [source] Phage display identifies novel peptides that bind extracellular-regulated protein kinase 2 to compete with transcription factor binding,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 6-7 2004Mark A. Rainey Abstract Extracellular-regulated protein kinase 2 (ERK2) is a serine/threonine-specific protein kinase capable of phosphorylating multiple protein substrates within a cell. In an attempt to identify novel peptides that bind and inhibit the function of an active form of ERK2, phage display was carried out using a disulfide-constrained peptide library (X2CX14CX2). Several phage clones were identified by an enzyme-linked immunosorbent assay (ELISA) that competed with both a protein substrate and adenosine triphosphate (ATP) for immobilized ERK2. A chemically synthesized peptide derived from these experiments, NH2 -KKKIRCIRGWTKDIRTLADSCQY-COOH, inhibited ERK2 phosphorylation of the protein substrate Ets,138, exhibiting competitive and mixed inhibition towards Ets,138 and MgATP2,, respectively. Surprisingly, the same peptide displayed equally potent inhibition towards the phosphorylation of ATF2 by p38 MAPK,, another MAP kinase that has ,46% sequence similarity to ERK2. This study indicates that active ERK2 can be targeted by phage display to find novel antagonists to kinase function and suggests that protein-binding sites within the MAPK family may contain conserved features that render them susceptible to ligand binding. Copyright © 2004 John Wiley & Sons, Ltd. [source] Function-modulating human monoclonal antibodies against platelet-membrane receptors isolated from a phage-display libraryJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2003Y. Hagay Summary., Monoclonal antibodies to platelet membrane receptors have been used extensively for analysis of receptor structure and function. Function-blocking human antibodies are being used for the development of antiplatelet drugs. We isolated human monoclonal antibodies from a library of single-chain Fv (scFv) antibodies displayed on the surface of filamentous phage, by selection on whole platelets. Eight different platelet-binding clones were isolated, of which three bound to the platelet-membrane glycoprotein (GP) GPIb in an ELISA assay. Specific elution with a recombinant polypeptide of von Willebrand factor (VWF) spanning the GPIb, binding site, yielded the same three phage clones. Two of the three anti-GPIb clones could be purified as scFv monoclonal antibodies, and they competed with each other for binding to intact platelets, suggesting that they bind at or near the same site on GPIb. Their binding affinities differed, however, and the clone with higher affinity inhibited ristocetin-induced platelet aggregation. These data indicate that selection from a phage display library of human scFvs using whole platelets can be applied for the isolation of functional antiplatelet-GPIb antibodies useful for the development of new therapeutic and diagnostic strategies. [source] Cloning, expression, and identification of anti-carbofuran single chain Fv geneBIOTECHNOLOGY PROGRESS, Issue 4 2009Hong Wang Abstract Phage display method was used to clone anti-carbofuran (CBF) single chain Fv (scFv) gene. The heavy chain and light chain variable region genes were amplified by the polymerase chain reaction from the CBF-specific hybridoma cell lines 5D3 and assembled as a scFv DNA fragment with linker peptide (Gly4Ser)3. The scFv DNA fragment was cloned into M13 phagemid vector pCANTAB5E and the anti-CBF antibody libraries were then constructed. After one round of panning with CBF-ovalbumin (CBF-OVA) as a conjugate, antigen-binding positive recombinant phage clones were successfully selected by enzyme-linked immunosorbent assay (ELISA). The positive phages were used to infect Escherichia coli HB2151 cells and the expression of the soluble scFv antibodies was then induced by IPTG. The scFv antibody was about 31 kDa by SDS-PAGE and showed HRP-anti-E-tag antibody-recognized activity by Western blotting. The indirect competitive ELISA (icELISA) showed that the recombinant scFv antibody could competitively combine with CBF, with the IC50 value of 1.07 ng/mL. The cross reactivity studies showed that the anti-CBF scFv antibody, similar to the parent monoclonal antibody, poses high specificity to CBF and has little reactivity to the analogs. Taken together, these findings suggest that the recombinant scFv antibody can be used for further developing immunoassay method for CBF. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Seroreactivity against MAGE-A and LAGE-1 proteins in melanoma patientsBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2003D. Usener Summary Background Cancer-testis antigens exemplify a growing number of tumour antigens which are expressed in a variety of malignancies, but not in normal tissues other than germ cells, primarily those of the testis. Objectives To investigate the humoral response to known cancer-testis antigens in melanoma patients. Methods We used phage clones coding for seven different melanoma antigens MAGE-A or LAGE-1A proteins. These clones were isolated using the newly developed DNA hybridization analysis of recombinantly expressed cDNA libraries (HYREX) approach. HYREX combines the advantage of a nonradioactive library screening method with the possibility of subsequently analysing the serological response to the recombinant proteins. We isolated clones coding for MAGE-A1, -A3, -A4b, -A6, -A9 and -A12, as well as LAGE-1A. Additionally, we correlated gene expression and seroreactivity. Results Between 13% and 27% of sera (n = 15) were reactive against individual tumour antigens. We found the presence of specific antibodies was, with only two exceptions, generally correlated with mRNA expression of the antigen within cell lines derived from the same patient. While cross-reactivity of patients' IgG might play a role in these cases, antibodies from patients' sera were able to distinguish even the closely related MAGE-A3 and -A6. In general, the mRNA expression frequency was higher than the detected IgG responses. Conclusions Antibody recognition of specific tumour antigens by patients' sera may be used for evaluating the possible immunogenicity of new antigens; serological tests could be used for tumour monitoring purposes. [source] | |||||||||||||