title: Identification of natural antigenic peptides of a human gastric signet ring cell carcinoma recognized by HLA-A31-restricted cytotoxic T lymphocytes.
abstract: Peptides of human melanomas recognized by CD8+ CTLs have been identified, but the nature of those of nonmelanoma tumors remains to be elucidated. Previously, we established a gastric signet ring cell carcinoma HST-2 and HLA-A31 (A*31012)-restricted autologous CTL clone, TcHST-2. In the present study, we determined the natural antigenic peptides of HST-2 cells. The purified preparation of acid-extracted Ags was submitted to the peptide sequencer, and one peptide, designated F4.2 (Tyr-Ser-Trp-Met-Asp-Ile-Ser-Cys-Trp-Ile), appeared to be immunogenic. To confirm the antigenicity of F4.2 further, we constructed an expression minigene vector (pF4.2ss) coding adenovirus E3, a 19-kDa protein signal sequence plus F4.2. An introduction of pF4.2ss minigene to HST-2 and HLA-A31(+) allogeneic tumor cells clearly enhanced and induced the TcHST-2 reactivity, respectively. Furthermore, when synthetic peptides of F4.2 C-terminal-deleted peptides were pulsed to HST-2 cells, F4.2-9 (nonamers), but not F4.2-8 or F4.2-7 (octamer or heptamer, respectively), enhanced the reactivity of TcHST-2, suggesting that the N-terminal ninth Trp might be a T cell epitope. This was confirmed by lack of antigenicity when using synthetic substituted peptides as well as minigenes coding F4.2 variant peptides with Ala or Arg at the ninth position of F4.2. Meanwhile, it was indicated that the sixth position Ile was critically important for the binding to HLA-A31 molecules. Thus, our data indicate that F4.2 may work as an HLA-A31-restricted natural antigenic peptide recognized by CTLs.
authors.affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Sahara
authors.forename: Y
authors.initials: Y
authors.lastname: Okada
authors.forename: T
authors.initials: T
authors.lastname: Yasoshima
authors.forename: Y
authors.initials: Y
authors.lastname: Hirohashi
authors.forename: Y
authors.initials: Y
authors.lastname: Nabeta
authors.forename: I
authors.initials: I
authors.lastname: Hirai
authors.forename: T
authors.initials: T
authors.lastname: Torigoe
authors.forename: S
authors.initials: S
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Matsuura
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: J
authors.initials: J
authors.lastname: Hamuro
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.forename: K
authors.initials: K
authors.lastname: Hirata
authors.forename: K
authors.initials: K
authors.lastname: Kikuchi
authors.forename: N
authors.initials: N
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D001483:Base Sequence; D018279:Carcinoma, Signet Ring Cell / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D002999:Clone Cells; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry; D015234:HLA-A Antigens / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D014162:Transfection; D014269:Trifluoroacetic Acid; D014407:Tumor Cells, Cultured
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens; C069527:HLA-A31 antigen; D010446:Peptide Fragments; D014269:Trifluoroacetic Acid