Ontario Cancer Institute, University Health Network, Toronto, Canada.
J Proteome Res. 2012 Apr 6;11(4):2386-96. doi: 10.1021/pr2011236. Epub 2012 Feb 29.
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.
尿前列腺分泌物或“EPS-尿”是经直肠指检（DRE）后收集的近端组织液。EPS-尿是前列腺衍生蛋白的丰富来源，可用于前列腺癌（PCa）和其他前列腺疾病的生物标志物发现。我们之前对直接表达的前列腺分泌物（EPS）进行了全面的蛋白质组分析。在当前的研究中，我们采用多维蛋白质鉴定技术（MudPIT）定义了 EPS-尿的蛋白质组，并为未来的生物标志物研究提供了这种体液的综合目录。我们从活检阴性的非癌诊断中鉴定了 11 个 EPS-尿中的 1022 个独特蛋白，其中一些患有良性前列腺疾病（BPH）和低级别 PCa，代表了尿液背景下分泌的前列腺和免疫系统衍生蛋白。我们进一步应用基于 MudPIT 的蛋白质组学来生成和比较来自非癌症和 PCa 患者的一组混合尿液（pre-DRE）和 EPS-尿（post-DRE）的差异蛋白质组。这些高度受控的患者样本池的直接蛋白质组比较使我们能够定义可在 EPS-尿中检测到并与复杂的尿液蛋白背景区分开的一组前列腺丰富蛋白。对这两个蛋白质组数据集的组合分析以及与相关体液的公开蛋白质组学数据、人类组织转录组数据和人类蛋白质图谱数据库中的免疫组织化学图像的系统整合，使我们能够在 EPS-尿中确定一组 49 个稳健的前列腺衍生蛋白。最后，我们使用 Western blot 验证了其中七种蛋白质的表达，支持它们源自前列腺的可能性。这些在 EPS-尿样本中前列腺蛋白的定义为未来的前列腺疾病生物标志物研究提供了参考。
