title: Identification of two new HLA-A*0201-restricted cytotoxic T lymphocyte epitopes from colorectal carcinoma-associated antigen PLAC1/CP1.
abstract: BACKGROUND
  To explore the potential application of placenta-specific PLAC1/Cancer Placenta (CP) 1 antigen for immunotherapy in CRC patients, further identification of the cytotoxic T lymphocyte epitopes from this antigen is necessary.
  
  
  METHODS
  We assessed the protein expression of PLAC1/CP1 using a tissue chip and immunochemistry staining in CRC samples. Simultaneously, we predicted four PLAC1/CP1-derived HLA-A*0201-restricted peptides by using reverse immunology methods. Peptide-specific CD8(+) T cell responses were assessed by an IFN-γ release ELISPOT assay. Effector CD8(+) T cells lyse HLA-A*0201 CRC cell line SW620 was detected in a granzyme-B release ELISPOT cytotoxicity assay.
  
  
  RESULTS
  Our results indicated that PLAC1/CP1 was highly expressed in 56.7 % (55/97) of adenocarcinomas. PLAC1/CP1 protein expression was associated with CRC tumor differentiation, the tumor/node/metastasis stage, and lymph node metastasis. Two of four peptides showed high affinities in an HLA-A2 binding assay. In 66.7 % (6/9) of peripheral blood mononuclear cells of CRC samples with PLAC1/CP1 protein-positive expression, these two peptides, PLAC1/CP1 p41-50 (FMLNNDVCV) and PLAC1/CP1 p69-77 (HAYQFTYRV), were immunogenic in the induction of peptide-specific CD8(+) T cell responses as assessed by an IFN-γ release ELISPOT assay. Furthermore, the generated effector CD8(+) T cells could specifically lyse the PLAC1/CP1 HLA-A*0201 CRC cell line SW620 in a granzyme-B release ELISPOT cytotoxicity assay.
  
  
  CONCLUSIONS
  These results show that the PLAC1/CP1 antigen is a possible prognostic marker of CRC and that PLAC1/CP1 p41-50 and PLAC1/CP1 p69-77 are novel HLA-A*0201-restricted CD8(+) T cell epitopes and potential targets for peptide-based immunotherapy in CRC patients.
authors.affiliation: Department of Pathology, Peking University People's Hospital, Beijing, 100044, People's Republic of China, liufangfang@pkuph.edu.cn.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Liu
authors.forename: Henghui
authors.initials: H
authors.lastname: Zhang
authors.forename: Danhua
authors.initials: D
authors.lastname: Shen
authors.forename: Shan
authors.initials: S
authors.lastname: Wang
authors.forename: Yingjiang
authors.initials: Y
authors.lastname: Ye
authors.forename: Hongsong
authors.initials: H
authors.lastname: Chen
authors.forename: Xuewen
authors.initials: X
authors.lastname: Pang
authors.forename: Qiujing
authors.initials: Q
authors.lastname: Song
authors.forename: Peiying
authors.initials: P
authors.lastname: He
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000276:immunology; D014408:Biomarkers, Tumor / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D058501:Enzyme-Linked Immunospot Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D015789:HLA-A2 Antigen / Q000276:immunology*; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011257:Pregnancy Proteins / Q000276:immunology*; D011379:Prognosis; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D018984:Epitopes, T-Lymphocyte; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; C415583:PLAC1 protein, human; D011257:Pregnancy Proteins