title: T cells recognize PD(N/T)R motif common in a variable number of tandem repeat and degenerate repeat sequences of MUC1.
abstract: The tumor-associated antigen MUC1 is a transmembrane glycoprotein, which is overexpressed in human carcinomas. Peptide epitopes, containing the PDTR fragment from the variable number of tandem repeat (VNTR) domains of MUC1 have been found to be immunodominant in T-cell and B-cell responses. However, little is known about the immunogenicity and specificity of T-cell epitopes from other regions of MUC1 that may also participate in immune responses against tumors. In this study, the combination of immunoinformatics, molecular modeling and a vaccine adjuvant strategy were used to predict and describe a novel T-cell epitope, SAPDNRPAL, located within the degenerate tandem repeat of MUC1. This peptide possesses structural similarity to both VNTR-derived SAPDTRPAP and Sendai virus peptide FAPGNYPAL, which are known to induce cytotoxic T lymphocytes (CTL). We found that SAPDNRPAL had a higher affinity for mouse H-D(b), H-2K(b) and human HLA-A2 molecules than SAPDTRPAP. A chimeric peptide (CP) containing SAPDNRPAL and an adjuvant C5a-derived decapeptide induced epitope-specific type 1 T cells in human MUC1 transgenic mice (ELISPOT). Mice that received dendritic cells (DC) pulsed with the CP or a 25-mer peptide containing the SAPDNRPAL sequence showed increased frequencies of SAPDNRPAL- and SAPDTRPAP-specific interferon-gamma producing T cells. PDTR-specific antibody 214D4 reacted with both SAPDNRPAL and SAPDTRPAP (ELISA). Altogether, our data suggest that the degenerate MUC1 repeat sequence contains the immunogenic T-cell epitope SAPDNRPAL, which is cross-reactive with the VNTR-derived peptide SAPDTRPAP. We suggest that the use of immunogenic PDNR-containing epitope(s) in vaccine strategies could be beneficial for developing increased, PD(N/T)R motif-specific T-cell responses against tumors expressing MUC1.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA.
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Pisarev
authors.forename: Leo
authors.initials: L
authors.lastname: Kinarsky
authors.forename: Thomas
authors.initials: T
authors.lastname: Caffrey
authors.forename: Franz-George
authors.initials: FG
authors.lastname: Hanisch
authors.forename: Sam
authors.initials: S
authors.lastname: Sanderson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hollingsworth
authors.forename: Simon
authors.initials: S
authors.lastname: Sherman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001666:Binding Sites, Antibody / Q000276:immunology; D019496:Cancer Vaccines / Q000276:immunology; D002460:Cell Line; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D005805:Genes, MHC Class I / Q000276:immunology; D006183:H-2 Antigens / Q000276:immunology; D015789:HLA-A2 Antigen / Q000276:immunology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008958:Models, Molecular; D018396:Mucin-1 / Q000235:genetics / Q000276:immunology*; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D020080:Tandem Repeat Sequences / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D006183:H-2 Antigens; D015789:HLA-A2 Antigen; C116055:MUC1 tandem repeat peptide; D018396:Mucin-1; D010446:Peptide Fragments