title: A novel DNA/peptide combined vaccine induces PSCA-specific cytotoxic T-lymphocyte responses and suppresses tumor growth in experimental prostate cancer.
abstract: OBJECTIVE
  To develop a completely novel DNA peptide-combined vaccine and determine whether it can efficiently improve tumor-specific cytotoxic T lymphocyte (CTL) responses and inhibit tumor progression in experimental prostate cancer models.
  
  
  METHODS
  The DNA/peptide combined vaccine was prepared by the self-assembly of a cationic peptide ([K]18P9) containing 18 lysines and a CTL epitope peptide, prostate stem cell antigen (PSCA (14-22)) (HLA-A2 restricted) with a recombinant plasmid encoding human full-length PSCA gene (pcDNA3.1(+)-PSCA) through electrostatic interactions. The formation of a DNA/peptide complex was examined by DNA retardation assay, DNase I protection assay, and transmission electron microscopy. The efficacy of vaccination using this complex was demonstrated in terms of the PSCA-specific CTL activity and antitumor immunity to PSCA(+) tumors in a murine model.
  
  
  RESULTS
  This form of DNA/peptide complex could efficiently transfer the plasmid encoding full-length PSCA gene into mammalian cells and induced potent CTLs cytotoxicity against a human prostate carcinoma cell line established from the left supraclavicular lymph node metastasis from a 50-year-old man with prostate carcinoma in 1977. Expressing PSCA compared with pcDNA3.1(+)-PSCA, [K]18P9 peptide, or pcDNA3.1(+). Moreover, the vaccination of mice with this complex induced a potent antitumor immunity to prostate carcinomas in a xenograft tumor model in nude mice.
  
  
  CONCLUSIONS
  This study suggests that a specific antitumor immune response can be induced by this DNA/peptide combined vaccine, which represents a new strategy for use in the immunotherapy of prostate cancer.
authors.affiliation: Department of Urology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China. zhkq2004@163.com
authors.forename: Ke-qin
authors.initials: KQ
authors.lastname: Zhang
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.forename: Jin
authors.initials: J
authors.lastname: Ye
authors.forename: Man
authors.initials: M
authors.lastname: Jiang
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Feng-shuo
authors.initials: FS
authors.lastname: Jin
authors.forename: Yu-zhang
authors.initials: YZ
authors.lastname: Wu
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000187:drug effects; D019496:Cancer Vaccines / Q000627:therapeutic use*; D003850:Deoxyribonuclease I; D058851:GPI-Linked Proteins / Q000187:drug effects; D018014:Gene Transfer Techniques; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D009363:Neoplasm Proteins / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000628:therapy*; D060888:Real-Time Polymerase Chain Reaction; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects*; D019444:Vaccines, DNA / Q000627:therapeutic use*
chemical_list: D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D058851:GPI-Linked Proteins; D009363:Neoplasm Proteins; C110843:PSCA protein, human; D019444:Vaccines, DNA; D003850:Deoxyribonuclease I