title: Identification and characterization of ErbB-3-binding protein-1 as a target for immunotherapy.
abstract: Based on immune reactivity in response to a whole-cell colon tumor vaccine and using serological identification of Ags by recombinant cDNA expression cloning, we here describe the molecular and functional identification of a novel human tumor Ag. By screening a cDNA expression library derived from the coloncarcinoma cell line HT-29 with pooled colorectal cancer patients' sera, 26 clones reactive with IgG Abs could be identified. Characterization of these cDNA clones by sequence analysis and alignment, and detailed serological analysis revealed cancer-related immunoreactivity for the ErbB-3-binding protein-1 (Ebp1). Immunohistochemical staining of colorectal tumors and neighboring normal colon tissue indicated the observed cancer-related immunogenicity of Ebp1 to be related to overexpression. Via reverse immunology, five potential HLA-A2-restricted T cell epitopes were identified, of which two (Ebp1(45-54) and Ebp1(59-67)) bound HLA-A2 with intermediate and high affinity, respectively. Analysis of their immunogenicity in vitro indicated that only the high-affinity Ebp1(59) epitope gave rise to CD8(+) T cells capable of recognizing both exogenously loaded Ebp1 peptide and endogenously expressed Ebp1 on target cells. In addition, in vivo CD8(+) T cell responsiveness against the Ebp1(59) epitope could be detected in two of nine and three of six cancer patients PBMC and tumor draining lymph nodes, respectively, but not in nine of nine healthy donors tested. These data confirm that Ebp1 is an immunogenic protein, capable of eliciting CD8-mediated responses in vivo and in vitro, providing a rationale for further exploration of Ebp1 as a possible target for anticancer immunotherapy.
authors.affiliation: Department of Pathology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
authors.forename: Saskia J A M
authors.initials: SJ
authors.lastname: Santegoets
authors.forename: Marco W J
authors.initials: MW
authors.lastname: Schreurs
authors.forename: Anneke W
authors.initials: AW
authors.lastname: Reurs
authors.forename: Jelle J
authors.initials: JJ
authors.lastname: Lindenberg
authors.forename: Esther W M
authors.initials: EW
authors.lastname: Kueter
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: van den Eertwegh
authors.forename: Erik
authors.initials: E
authors.lastname: Hooijberg
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Brandwijk
authors.forename: Simon E
authors.initials: SE
authors.lastname: Hufton
authors.forename: Hennie R
authors.initials: HR
authors.lastname: Hoogenboom
authors.forename: Rik J
authors.initials: RJ
authors.lastname: Scheper
authors.forename: Veerle A
authors.initials: VA
authors.lastname: Somers
authors.forename: Tanja D
authors.initials: TD
authors.lastname: de Gruijl
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D001943:Breast Neoplasms / Q000276:immunology / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D003601:Cytotoxicity Tests, Immunologic; D018076:DNA, Complementary / Q000096:biosynthesis; D016503:Drug Delivery Systems; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D015723:Gene Library; D015789:HLA-A2 Antigen / Q000276:immunology; D019073:HT29 Cells; D006801:Humans; D007116:Immunization, Passive / Q000379:methods; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D020893:Receptor, ErbB-3 / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000951:Antigens, Neoplasm; D018076:DNA, Complementary; D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; C101633:PA2G4 protein, human; D016601:RNA-Binding Proteins; D020893:Receptor, ErbB-3