title: Prostate stem cell antigen: Identification of immunogenic peptides and assessment of reactive CD8+ T cells in prostate cancer patients.
abstract: Identification of TAAs recognized by CD8(+) CTLs paved the way for new concepts in cancer therapy. In view of the heterogeneity of tumors and their diverse escape mechanisms, CTL-based cancer therapy largely depends on an appropriate number of TAAs. In prostate cancer, the number of antigens defined as suitable targets of CTLs remains rather limited. PSCA is widely distributed in prostate cancer. In this report, we define immunogenic peptides of PSCA which are recognized by circulating CD8(+) T cells from prostate cancer patients and able to activate CTLs in vitro. Screening the amino acid sequence of PSCA for peptides containing a binding motif for HLA-A*0201 resulted in 8 candidate peptides. Specificity and affinity of peptide binding were verified in a competition assay. Frequencies of CD8(+) T lymphocytes reactive against selected epitopes were determined in the blood of prostate cancer patients using the ELISPOT assay. Increased frequencies were revealed for CD8(+) T cells recognizing the peptides ALQPGTALL and AILALLPAL. CTLs from prostate cancer patients were raised against these 2 peptides in vitro when presented by autologous DCs. They specifically recognized peptide-pulsed T2 target cells and prostate cancer cells that were HLA-A*0201- and PSCA-positive, indicating that these peptides were naturally generated by tumor cells. These data suggest that PSCA is a promising target for the immunotherapy of prostate cancer.
authors.affiliation: Institute of Immunology, Medical Faculty, Technical University of Dresden, Dresden, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kiessling
authors.forename: Marc
authors.initials: M
authors.lastname: Schmitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Stevanovic
authors.forename: Bernd
authors.initials: B
authors.lastname: Weigle
authors.forename: Kristina
authors.initials: K
authors.lastname: Hölig
authors.forename: Monika
authors.initials: M
authors.lastname: Füssel
authors.forename: Susanne
authors.initials: S
authors.lastname: Füssel
authors.forename: Axel
authors.initials: A
authors.lastname: Meye
authors.forename: Manfred P
authors.initials: MP
authors.lastname: Wirth
authors.forename: Ernst Peter
authors.initials: EP
authors.lastname: Rieber
mesh_terms: D000368:Aged; D000951:Antigens, Neoplasm / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019496:Cancer Vaccines / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D058851:GPI-Linked Proteins; D015234:HLA-A Antigens / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology*; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000276:immunology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured
chemical_list: D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D058851:GPI-Linked Proteins; D015234:HLA-A Antigens; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C110843:PSCA protein, human; D010446:Peptide Fragments; D012333:RNA, Messenger