title: A novel peptide isolated from a phage display peptide library with trastuzumab can mimic antigen epitope of HER-2.
abstract: Trastuzumab, a humanized antibody to HER-2, has been shown to be effective in the treatment of breast cancer in which HER-2 overexpression and metastasis occurs. In our search for an effective mimic epitope of HER-2 binding with trastuzumab and to develop HER-2 peptide vaccine, we screened a phage display 12-mer peptide library with trastuzumab as the target. A mimetic peptide (mimotope) H98 (LLGPYELWELSH) that could specifically recognize trastuzumab was isolated. The DNA encoding peptide H98 was cloned and expressed as the fusion protein GST-H98 in Escherichia coli BL21. The purified GST-H98 could specifically bind to trastuzumab and block the binding of trastuzumab to HER-2 protein. Moreover, H98 could significantly block the function of trastuzumab inhibiting the growth of cancer cells. Mice that were immunized with GST-H98 made specific antibody to H98 as well as to HER-2. In addition, T-cell proliferation occurred in mice immunized with GST-H98. Although no sequence homology was found between H98 and HER-2, through the use of structure analysis we were able to determine that peptide H98 contributed to a conformational epitope of HER-2. Furthermore, we determined that the last two amino acids at the C terminus, and the third together with the fourth amino acid at the N terminus of peptide H98 are critical to the binding of H98 to trastuzumab. As a result, we conclude that peptide H98 has potential for being developed as a HER-2 vaccine for biotherapy of cancer with HER-2 overexpression.
authors.affiliation: Department of Biochemistry and Molecular Biology, Beijing Institute for Cancer Research and Peking University School of Oncology, Beijing 100034, China.
authors.forename: Beihai
authors.initials: B
authors.lastname: Jiang
authors.forename: Wenbin
authors.initials: W
authors.lastname: Liu
authors.forename: Hong
authors.initials: H
authors.lastname: Qu
authors.forename: Lin
authors.initials: L
authors.lastname: Meng
authors.forename: Shumei
authors.initials: S
authors.lastname: Song
authors.forename: Tao
authors.initials: T
authors.lastname: Ouyang
authors.forename: Chengchao
authors.initials: C
authors.lastname: Shou
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000941:Antigens / Q000737:chemistry; D000970:Antineoplastic Agents / Q000494:pharmacology; D001667:Binding, Competitive; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004396:Coloring Agents / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D009154:Mutation; D041681:NIH 3T3 Cells; D009369:Neoplasms / Q000628:therapy; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D013154:Spleen / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000941:Antigens; D000970:Antineoplastic Agents; D004396:Coloring Agents; D004247:DNA; D000939:Epitopes; D005982:Glutathione Transferase; D007074:Immunoglobulin G; D019151:Peptide Library; D010455:Peptides; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D013778:Tetrazolium Salts; D013844:Thiazoles; D000068878:Trastuzumab; C022616:thiazolyl blue