title: Identification of prostate-enriched proteins by in-depth proteomic analyses of expressed prostatic secretions in urine.
abstract: Urinary expressed prostatic secretion or "EPS-urine" is proximal tissue fluid that is collected after a digital rectal exam (DRE). EPS-urine is a rich source of prostate-derived proteins that can be used for biomarker discovery for prostate cancer (PCa) and other prostatic diseases. We previously conducted a comprehensive proteome analysis of direct expressed prostatic secretions (EPS). In the current study, we defined the proteome of EPS-urine employing Multidimensional Protein Identification Technology (MudPIT) and providing a comprehensive catalogue of this body fluid for future biomarker studies. We identified 1022 unique proteins in a heterogeneous cohort of 11 EPS-urines derived from biopsy negative noncancer diagnoses with some benign prostatic diseases (BPH) and low-grade PCa, representative of secreted prostate and immune system-derived proteins in a urine background. We further applied MudPIT-based proteomics to generate and compare the differential proteome from a subset of pooled urines (pre-DRE) and EPS-urines (post-DRE) from noncancer and PCa patients. The direct proteomic comparison of these highly controlled patient sample pools enabled us to define a list of prostate-enriched proteins detectable in EPS-urine and distinguishable from a complex urine protein background. A combinatorial analysis of both proteomics data sets and systematic integration with publicly available proteomics data of related body fluids, human tissue transcriptomic data, and immunohistochemistry images from the Human Protein Atlas database allowed us to demarcate a robust panel of 49 prostate-derived proteins in EPS-urine. Finally, we validated the expression of seven of these proteins using Western blotting, supporting the likelihood that they originate from the prostate. The definition of these prostatic proteins in EPS-urine samples provides a reference for future investigations for prostatic-disease biomarker studies.
authors.affiliation: Ontario Cancer Institute, University Health Network, Toronto, Canada.
authors.forename: Simona
authors.initials: S
authors.lastname: Principe
authors.forename: Yunee
authors.initials: Y
authors.lastname: Kim
authors.forename: Simona
authors.initials: S
authors.lastname: Fontana
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ignatchenko
authors.forename: Julius O
authors.initials: JO
authors.lastname: Nyalwidhe
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Lance
authors.forename: Dean A
authors.initials: DA
authors.lastname: Troyer
authors.forename: Riccardo
authors.initials: R
authors.lastname: Alessandro
authors.forename: O John
authors.initials: OJ
authors.lastname: Semmes
authors.forename: Thomas
authors.initials: T
authors.lastname: Kislinger
authors.forename: Richard R
authors.initials: RR
authors.lastname: Drake
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Medin
mesh_terms: D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D030562:Databases, Protein; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D011467:Prostate / Q000737:chemistry* / Q000378:metabolism; D011469:Prostatic Diseases / Q000378:metabolism / Q000652:urine; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000652:urine; D029584:Prostatic Secretory Proteins / Q000737:chemistry / Q000378:metabolism / Q000652:urine*; D020543:Proteome / Q000032:analysis* / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D029584:Prostatic Secretory Proteins; D020543:Proteome