title: The specific immune response to tumor antigen CP1 and its correlation with improved survival in colon cancer patients.
abstract: OBJECTIVE
  The present study was undertaken to determine the expression of a newly identified tumor antigen cancer-placenta 1 (CP1) in colorectal carcinoma (CRC) and explore the CP1-specific immune response in CRC patients and its correlation with patient survival.
  
  
  METHODS
  CP1 expression was determined by reverse-transcription polymerase chain reaction, immunohistochemistry, and Western blot analysis. Serum antibodies against CP1 were detected by enzyme-linked immunosorbent assay, and T-cell response was measured by interferon-gamma/granzyme-B release enzyme-linked immunospot assays. The HLA-A2-restricted epitopes in CP1 were predicted by bioinformatics and then experimentally validated by enzyme-linked immunospot assay.
  
  
  RESULTS
  CP1 expression was detected in a significant number of CRC tissues, reaching 47.6% at the messenger RNA (mRNA) level and 28.6% at the protein level. Of patients with CP1 mRNA(+) tumors, more than 50% had CP1-responsive CD4(+) and CD8(+) T cells and 30% spontaneous-occurring antibodies against CP1. Further studies revealed 2 dominant HLA-A2-restricted epitopes in the CP1 antigen: p31-39 and p58-66. In a follow-up study up to 33 months after surgery, 9 of the 10 patients with CP1-specific CD8 T-cell response survived, whereas 6 of the 8 nonresponders died. Kaplan-Meier analysis indicated a significant correlation between T-cell response and patient survival.
  
  
  CONCLUSIONS
  CP1 represents a new class of tumor-specific shared antigen. Its high expression in CRC tissues, prevalence of CP1-specific immune responses in CP1 mRNA(+) CRC patients, and positive correlation with survival suggest that the antigen may be a useful target for cancer immunotherapy.
authors.affiliation: Department of Gastroenterological Surgery, Surgical Oncology Laboratory, Peking University People's Hospital, Beijing, China.
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Liu
authors.forename: Xue-Yuan
authors.initials: XY
authors.lastname: Dong
authors.forename: Xue-Wen
authors.initials: XW
authors.lastname: Pang
authors.forename: Qiao
authors.initials: Q
authors.lastname: Xing
authors.forename: Hong-Cheng
authors.initials: HC
authors.lastname: Wang
authors.forename: Hua-Gang
authors.initials: HG
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: Yin
authors.forename: Michael
authors.initials: M
authors.lastname: Fant
authors.forename: Ying-Jiang
authors.initials: YJ
authors.lastname: Ye
authors.forename: Dan-Hua
authors.initials: DH
authors.lastname: Shen
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Wang
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000235:genetics* / Q000276:immunology*; D015153:Blotting, Western; D016516:CD4-CD8 Ratio; D002681:China / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000235:genetics / Q000276:immunology* / Q000401:mortality; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012334:RNA, Neoplasm / Q000235:genetics*; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D015996:Survival Rate; D013601:T-Lymphocytes / Q000276:immunology*; D016335:Zinc Fingers
chemical_list: D000951:Antigens, Neoplasm; D012334:RNA, Neoplasm