title: Immunoseroproteomic Profiling in African American Men with Prostate Cancer: Evidence for an Autoantibody Response to Glycolysis and Plasminogen-Associated Proteins.
abstract: African American (AA) men suffer from a disproportionately high incidence and mortality of prostate cancer (PCa) compared with other racial/ethnic groups. Despite these disparities, African American men are underrepresented in clinical trials and in studies on PCa biology and biomarker discovery. We used immunoseroproteomics to profile antitumor autoantibody responses in AA and European American (EA) men with PCa, and explored differences in these responses. This minimally invasive approach detects autoantibodies to tumor-associated antigens that could serve as clinical biomarkers and immunotherapeutic agents. Sera from AA and EA men with PCa were probed by immunoblotting against PC3 cell proteins, with AA sera showing stronger immunoreactivity. Mass spectrometry analysis of immunoreactive protein spots revealed that several AA sera contained autoantibodies to a number of proteins associated with both the glycolysis and plasminogen pathways, particularly to alpha-enolase (ENO1). The proteomic data is deposited in ProteomeXchange with identifier PXD003968. Analysis of sera from 340 racially diverse men by enzyme-linked immunosorbent assays (ELISA) showed higher frequency of anti-ENO1 autoantibodies in PCa sera compared with control sera. We observed differences between AA-PCa and EA-PCa patients in their immunoreactivity against ENO1. Although EA-PCa sera reacted with higher frequency against purified ENO1 in ELISA and recognized by immunoblotting the endogenous cellular ENO1 across a panel of prostate cell lines, AA-PCa sera reacted weakly against this protein by ELISA but recognized it by immunoblotting preferentially in metastatic cell lines. These race-related differences in immunoreactivity to ENO1 could not be accounted by differential autoantibody recognition of phosphoepitopes within this antigen. Proteomic analysis revealed differences in the posttranslational modification profiles of ENO1 variants differentially recognized by AA-PCa and EA-PCa sera. These intriguing results suggest the possibility of race-related differences in the antitumor autoantibody response in PCa, and have implications for defining novel biological determinants of PCa health disparities.
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350; tsanchez@llu.edu.
authors.forename: Tino W
authors.initials: TW
authors.lastname: Sanchez
authors.affiliation: ¶Mass Spectrometry Core Facility, Division of Biochemistry, LLU School of Medicine, Loma Linda, California 92350.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Zhang
authors.affiliation: §Department of Biological Sciences, University of Texas, El Paso, Texas 79968.
authors.forename: Jitian
authors.initials: J
authors.lastname: Li
authors.affiliation: §Department of Biological Sciences, University of Texas, El Paso, Texas 79968.
authors.forename: Liping
authors.initials: L
authors.lastname: Dai
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350.|‖LLU Cancer Center Biospecimen Laboratory, Loma Linda, California 92350.
authors.forename: Saied
authors.initials: S
authors.lastname: Mirshahidi
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350.
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Wall
authors.affiliation: ‡‡Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee Alabama 36088.
authors.forename: Clayton
authors.initials: C
authors.lastname: Yates
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350.|**LLU School of Behavioral Health, Loma Linda, California 92350.
authors.forename: Colwick
authors.initials: C
authors.lastname: Wilson
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350.|**LLU School of Behavioral Health, Loma Linda, California 92350.
authors.forename: Susanne
authors.initials: S
authors.lastname: Montgomery
authors.affiliation: §Department of Biological Sciences, University of Texas, El Paso, Texas 79968.
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Zhang
authors.affiliation: From the ‡Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California 92350.|§§Department of Medicine, Division of Rheumatology, LLU School of Medicine, Loma Linda, California 92350.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Casiano
mesh_terms: D001741:Black or African American; D000368:Aged; D000912:Antibodies, Neoplasm / Q000097:blood; D000951:Antigens, Neoplasm / Q000097:blood; D001323:Autoantibodies / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood / Q000276:immunology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000276:immunology; D006019:Glycolysis; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D010751:Phosphopyruvate Hydratase / Q000276:immunology; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000208:ethnology / Q000276:immunology*; D040901:Proteomics / Q000379:methods*; D025521:Tumor Suppressor Proteins / Q000276:immunology
chemical_list: D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D001323:Autoantibodies; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; C095157:ENO1 protein, human; D010751:Phosphopyruvate Hydratase