title: Effects of oxygen on the antigenic landscape of prostate cancer cells.
abstract: BACKGROUND
  Use of allogeneic cancer cells-based immunotherapy for treatment of established prostate cancer (PCa) has only been marginally effective. One reason for failure could stem from the mismatch of antigenic signatures of vaccine cells and cancer in situ. Hence, it is possible that vaccine cells expressed antigens differently than tumor cells in situ. We hypothesized that cells grown in vitro at low oxygen tension (pO2) provide a better antigen match to tumors in situ and could reveal a more relevant antigenic landscape than cells grown in atmospheric pO2.
  
  
  METHODS
  We tested this hypothesis by comparing PCa cells propagated at pO2 = 2 kPa and 20 kPa. To identify potential tumor-associated antigens (TAAs), we prepared PCa cell lysates, resolved them by two-dimensional electrophoresis and immunoblotting using spontaneous antibodies from plasma derived from PCa patients and control subjects. Antibody-labeled spots were analyzed by MALDI-TOF mass spectrometry and validated by ELISA. We selected hypoxia-regulated HSP70 and hnRNP L and hypoxia-independent HSP60 and determined the frequency of plasma samples reacting with these molecules.
  
  
  RESULTS
  Frequency of HSP60-reactive plasma was low in healthy controls [1.3 % (1/76)], while it was elevated in PCa patients [13.0 % (7/54); p < 0.05]. These data suggest a humoral immune response to HSP60 in PCa. Levels of autoantibodies to HSP70 did not differ from healthy controls [3.7 % (2/54)] in PCa patients [5.3 % (2/38)]. Similarly, hnRNP L autoantibodies did no differ between healthy controls [6.1 % (3/49)] and PCa patients [5.3 % (2/38)].
  
  
  CONCLUSIONS
  Overall our results suggest the value of hypoxia as a modifier of the cellular and antigenic landscape of PCa cells. By modifying the immune reactivity of PCa cells in culture, manipulation of pO2 can be proposed as a new avenue for improving diagnosis, prognosis and immunotherapy for PCa.
authors.affiliation: Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. tma224@hotmail.com.
authors.forename: Tangeng
authors.initials: T
authors.lastname: Ma
authors.affiliation: Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. Schreiber.Claire@mayo.edu.
authors.forename: Claire A
authors.initials: CA
authors.lastname: Schreiber
authors.affiliation: Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. Knutson.Gaylord@mayo.edu.
authors.forename: Gaylord J
authors.initials: GJ
authors.lastname: Knutson
authors.affiliation: Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. aek768@gmail.com.
authors.forename: Abdelouahid El
authors.initials: AE
authors.lastname: Khattouti
authors.affiliation: Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. msakiyama@umc.edu.|Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. msakiyama@umc.edu.
authors.forename: Marcelo J
authors.initials: MJ
authors.lastname: Sakiyama
authors.affiliation: Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. mhassan@umc.edu.|Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. mhassan@umc.edu.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hassan
authors.affiliation: Proteomics Research Center, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. charlesworth.cristine@mayo.edu.
authors.forename: Mary Christine
authors.initials: MC
authors.lastname: Charlesworth
authors.affiliation: Proteomics Research Center, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. madden.benjamin@mayo.edu.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Madden
authors.affiliation: Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. xzhou@umc.edu.
authors.forename: Xinchun
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. vuk@mayo.edu.|Division of Hematology, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. vuk@mayo.edu.|Division of Preventive and Occupational Medicine, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. vuk@mayo.edu.
authors.forename: Stanimir
authors.initials: S
authors.lastname: Vuk-Pavlović
authors.affiliation: Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. crgomez@umc.edu.|Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. crgomez@umc.edu.|Department of Radiation Oncology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. crgomez@umc.edu.|Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. crgomez@umc.edu.|Division of Hematology, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. crgomez@umc.edu.|Division of Preventive and Occupational Medicine, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. crgomez@umc.edu.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Gomez
mesh_terms: D000368:Aged; D000951:Antigens, Neoplasm / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D014408:Biomarkers, Tumor / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D018834:Chaperonin 60 / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004797:Enzyme-Linked Immunosorbent Assay; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology / Q000378:metabolism; D034664:Heterogeneous-Nuclear Ribonucleoprotein L / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000276:immunology* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014407:Tumor Cells, Cultured
chemical_list: D000951:Antigens, Neoplasm; D001323:Autoantibodies; D014408:Biomarkers, Tumor; D018834:Chaperonin 60; D016207:Cytokines; D018840:HSP70 Heat-Shock Proteins; D034664:Heterogeneous-Nuclear Ribonucleoprotein L; D010100:Oxygen