Chemistry Department of Indiana University, Bloomington, Indiana 47405, USA.
Mol Cell Proteomics. 2012 Jul;11(7):M111.015792. doi: 10.1074/mcp.M111.015792. Epub 2012 Mar 5.
Pancreatic cancer is now the fourth leading cause of cancer deaths in the United States, and it is associated with an alarmingly low 5-year survival rate of 5%. However, a patient's prognosis is considerably improved when the malignant lesions are identified at an early stage of the disease and removed by surgical resection. Unfortunately, the absence of a practical screening strategy and clinical diagnostic test for identifying premalignant lesions within the pancreas often prevents early detection of pancreatic cancer. To aid in the development of a molecular screening system for early detection of the disease, we have performed glycomic and glycoproteomic profiling experiments on 21 pancreatic cyst fluid samples, including fluids from mucinous cystic neoplasms and intraductal papillary mucinous neoplasms, two types of mucinous cysts that are considered high risk to undergo malignant transformation. A total of 80 asparagine-linked (N-linked) glycans, including high mannose and complex structures, were identified. Of special interest was a series of complex N-linked glycans containing two to six fucose residues, located predominantly as substituents on β-lactosamine extensions. Following the observation of these "hyperfucosylated" glycans, bottom-up proteomics experiments utilizing a label-free quantitative approach were applied to the investigation of two sets of tryptically digested proteins derived from the cyst fluids: 1) all soluble proteins in the raw samples and 2) a subproteome of the soluble cyst fluid proteins that were selectively enriched for fucosylation through the use of surface-immobilized Aleuria aurantia lectin. A comparative analysis of these two proteomic data sets identified glycoproteins that were significantly enriched by lectin affinity. Several candidate glycoproteins that appear hyperfucosylated were identified, including triacylglycerol lipase and pancreatic α-amylase, which were 20- and 22-fold more abundant, respectively, following A. aurantia lectin enrichment.
胰腺癌现已成为美国第四大癌症死因，其 5 年生存率仅为 5%，令人震惊。然而，如果在疾病早期发现恶性病变并通过手术切除，患者的预后会得到显著改善。不幸的是，由于缺乏实用的筛查策略和临床诊断测试来识别胰腺内的癌前病变，通常无法早期发现胰腺癌。为了帮助开发用于早期检测该疾病的分子筛查系统，我们对 21 份胰腺囊液样本进行了糖组学和糖蛋白质组学分析，其中包括黏液性囊腺瘤和导管内乳头状黏液性肿瘤的囊液，这两种黏液性囊肿被认为有很高的恶变风险。共鉴定出 80 种天冬酰胺连接（N-连接）聚糖，包括高甘露糖和复杂结构。特别引人关注的是一系列含有 2 至 6 个岩藻糖残基的复杂 N-连接聚糖，主要作为β-乳糖胺延伸的取代基。观察到这些“高岩藻糖基化”聚糖后，我们采用无标记定量方法进行了基于 Bottom-up 的蛋白质组学实验，以研究源自囊液的两组胰蛋白酶消化蛋白：1）原始样本中的所有可溶性蛋白和 2）通过使用表面固定化的Aleuria aurantia 凝集素选择性富集岩藻糖基化的可溶性囊液蛋白的亚蛋白质组。对这两个蛋白质组学数据集进行比较分析，鉴定出通过凝集素亲和力显著富集的糖蛋白。鉴定出几种候选糖蛋白似乎过度岩藻糖基化，包括三酰基甘油脂肪酶和胰腺α-淀粉酶，它们在经过 A. aurantia 凝集素富集后分别增加了 20 倍和 22 倍。
