Leiden University Medical Center , Center for Proteomics and Metabolomics , 2300 RC Leiden , The Netherlands.
Academic Medical Center , University of Amsterdam , 1105 AZ Amsterdam , The Netherlands.
Anal Chem. 2018 Apr 3;90(7):4414-4421. doi: 10.1021/acs.analchem.7b04281. Epub 2018 Mar 14.
The concentration of prostate-specific antigen (PSA) in serum is used as an early detection method of prostate cancer (PCa); however, it shows low sensitivity, specificity, and a poor predictive value. Initial studies suggested the glycosylation of PSA to be a promising marker for a more specific yet noninvasive PCa diagnosis. Recent studies on the molecular features of PSA glycosylation (such as antenna modification and core fucosylation) were not successful in demonstrating its potential for an improved PCa diagnosis, probably due to the lack of analytical sensitivity and specificity of the applied assays. In this study, we established for the first time a high-performance PSA Glycomics Assay (PGA), allowing differentiation of α2,6- and α2,3-sialylated isomers, the latter one being suggested to be a hallmark of aggressive types of cancer. After affinity purification from urine and tryptic digestion, PSA samples were analyzed by CE-ESI-MS (capillary electrophoresis-electrospray ionization coupled to mass spectrometry). Based on positive controls, an average interday relative standard deviation of 14% for 41 N-glycopeptides was found. The assay was further verified by analyzing PSA captured from patients' urine samples. A total of 67 N-glycopeptides were identified from the PSA pooled from the patients. In summary, the first PGA successfully established in this study allows an in-depth relative quantitation of PSA glycoforms from urine. The PGA is a promising tool for the determination of potential glycomic biomarkers for the differentiation between aggressive PCa, indolent PCa, and benign prostate hyperplasia in larger cohort studies.
血清中前列腺特异性抗原（PSA）的浓度被用作前列腺癌（PCa）的早期检测方法；然而，它的灵敏度、特异性和预测值都较低。最初的研究表明 PSA 的糖基化是一种更具特异性但非侵入性的 PCa 诊断的有前途的标志物。最近对 PSA 糖基化的分子特征（如天线修饰和核心岩藻糖基化）的研究未能证明其在改善 PCa 诊断方面的潜力，这可能是由于所应用的分析方法缺乏分析灵敏度和特异性。在这项研究中，我们首次建立了一种高性能 PSA 糖组学分析（PGA），能够区分α2,6-和α2,3-唾液酸化异构体，后者被认为是侵袭性癌症的标志。在尿液中进行亲和纯化和胰蛋白酶消化后，通过毛细管电泳-电喷雾电离耦合质谱（CE-ESI-MS）分析 PSA 样品。基于阳性对照，发现 41 种 N-糖肽的平均日内相对标准偏差为 14%。该测定法通过分析来自患者尿液样本的 PSA 进一步得到验证。从患者的 PSA 中总共鉴定出 67 种 N-糖肽。总之，本研究首次成功建立的 PGA 允许对尿液中的 PSA 糖型进行深入的相对定量。PGA 是在更大的队列研究中确定侵袭性 PCa、惰性 PCa 和良性前列腺增生之间潜在糖基生物标志物的有前途的工具。
