Department of Pathology, Johns Hopkins University, Baltimore, Maryland 21231, United States.
Anal Chem. 2011 Sep 15;83(18):7013-9. doi: 10.1021/ac200815q. Epub 2011 Aug 18.
Prostate cancer is the most common malignancy in men in the United States, and one in seven men with prostate cancer dies of the disease. A major issue of prostate diagnosis is that there is no good method to reliably distinguish aggressive prostate cancer from nonaggressive prostate cancer. This leads to significant unnecessary suffering among prostate cancer patients and massive unnecessary health care expenditures. In this study, we aim to identify glycoproteins associated with aggressive prostate cancer using optimal cutting temperature (OCT)-embedded frozen tissues obtained from patients with known clinical outcome. To eliminate the interference of mass spectrometric analysis by the compounds in OCT and identify extracellular proteins that are likely to serve as biomarkers in body fluids, we employed glycoproteomic analysis using solid-phase extraction of glycopeptides, which allowed the immobilization of glycopeptides to solid support and removal of OCT from sample proteins before releasing the glycopeptides from the solid support for mass spectrometry analysis. Tumor tissues were cryostat microdissected from four cases of aggressive and four cases of nonaggressive prostate tumors, and glycopeptides were isolated and labeled with iTRAQ reagents before the samples were analyzed with LTQ Orbitrap Velos. From the aggressive prostate cancer tissues, we identified the overexpression of three glycoproteins involved in an extracellular matrix remodeling and further examined two glycoproteins, cathepsin L and periostin, using Western blot and immunohistochemistry analyses. This is the first proteomic study to identify proteins potentially associated with aggressive prostate cancer using OCT-embedded frozen tissues. Further study of these proteins will be needed to understand the roles of extracellular matrix proteins in cancer progression and their potential clinical utility in improving diagnosis of aggressive prostate cancer.
前列腺癌是美国男性中最常见的恶性肿瘤，每七名前列腺癌患者中就有一人死于该病。前列腺诊断的一个主要问题是，没有很好的方法来可靠地区分侵袭性前列腺癌和非侵袭性前列腺癌。这导致前列腺癌患者承受了巨大的不必要的痛苦，并导致大量不必要的医疗支出。在这项研究中，我们旨在使用来自具有已知临床结果的患者的 OCT 包埋冷冻组织，通过最佳切割温度（OCT）来识别与侵袭性前列腺癌相关的糖蛋白。为了消除 OCT 化合物对质谱分析的干扰，并鉴定可能作为体液生物标志物的细胞外蛋白质，我们采用了固相提取糖肽的糖蛋白质组学分析，该方法允许糖肽固定在固相上，并在将糖肽从固相上释放出来进行质谱分析之前，从样品蛋白质中去除 OCT。从 4 例侵袭性和 4 例非侵袭性前列腺肿瘤中对肿瘤组织进行 cryostat 显微解剖，分离糖肽并用 iTRAQ 试剂标记，然后用 LTQ Orbitrap Velos 分析样品。从侵袭性前列腺癌组织中，我们鉴定出三种参与细胞外基质重塑的糖蛋白的过表达，并进一步使用 Western blot 和免疫组织化学分析检查了两种糖蛋白，组织蛋白酶 L 和 periostin。这是使用 OCT 包埋冷冻组织鉴定潜在与侵袭性前列腺癌相关的蛋白质的首次蛋白质组学研究。需要进一步研究这些蛋白质，以了解细胞外基质蛋白在癌症进展中的作用及其在改善侵袭性前列腺癌诊断方面的潜在临床应用。
