Department of Chemistry and Biomolecular Sciences, Macquarie University , North Ryde, NSW 2109, Australia.
Barnett Institute and Department of Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States.
Acc Chem Res. 2016 Oct 18;49(10):2099-2106. doi: 10.1021/acs.accounts.6b00193. Epub 2016 Sep 21.
Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Delineating biological markers (biomarkers) for early detection, when treatment is most effective, is key to prevention and long-term survival of patients. Development of reliable biomarkers requires an increased understanding of the CRC biology and the underlying molecular and cellular mechanisms of the disease. With recent advances in new technologies and approaches, tremendous efforts have been put in proteomics and genomics fields to deliver detailed analysis of the two major biomolecules, genes and proteins, to gain a more complete understanding of cellular systems at both genomic and proteomic levels, allowing a mechanistic understanding of the human diseases, including cancer, and opening avenues for identification of novel gene and protein based prognostic and therapeutic markers. Although the importance of glycosylation in modulating protein function has long been appreciated, glycan analysis has been complicated by the diversity of the glycan structures and the large number of potential glycosylation combinations. Driven by recent technological advances, LC-MS/MS based glycomics is gaining momentum in cancer research and holds considerable potential to deliver new glycan-based markers. In our laboratory, we investigated alterations in N-glycosylation associated with CRC malignancy in a panel of CRC cell lines and CRC patient tissues. In an initial study, LC-MS/MS-based N-glycomics were utilized to map the N-glycome landscape associated with a panel of CRC cell lines (LIM1215, LIM1899, and LIM2405). These studies were subsequently extended to paired tumor and nontumorigenic CRC tissues to validate the findings in the cell line. Our studies in both CRC cell lines and tissues identified a strong representation of high mannose and α2,6-linked sialylated complex N-glycans, which corroborate findings from previous studies in CRC and other cancers. In addition, certain unique glycan determinants such as bisecting β1,4-GlcNAcylation and α2,3-sialylation, identified in the metastatic (LIM1215) and aggressive (LIM2405) CRC cell lines, respectively, were shown to be associated with epidermal growth factor receptor (EGFR) expression status. In this Account, we will describe the mass spectrometry based N-glycomics approach utilized in our laboratory to accurately profile the cell- and tissue-specific N-glycomes associated with CRC. We will highlight altered N-glycosylation observed by our studies, consistent with findings from other cancer studies, and discuss how the observed alterations can provide insights into CRC pathogenesis, opening new avenues to identify novel disease-associated glycan markers.
结直肠癌（CRC）是全球最常见的癌症之一。鉴定用于早期检测的生物标志物（biomarkers）对于预防和患者长期生存至关重要，因为早期检测时治疗效果最佳。开发可靠的生物标志物需要深入了解 CRC 生物学以及疾病潜在的分子和细胞机制。随着新技术和方法的最新进展，蛋白质组学和基因组学领域投入了大量精力，对两种主要生物分子（基因和蛋白质）进行详细分析，以在基因组和蛋白质组水平上更全面地了解细胞系统，从而深入了解人类疾病（包括癌症）的发病机制，并为鉴定新的基于基因和蛋白质的预后和治疗标志物开辟途径。尽管糖基化在调节蛋白质功能方面的重要性早已被人们所认识，但由于聚糖结构的多样性和潜在的糖基化组合数量庞大，聚糖分析一直很复杂。受最近技术进步的推动，基于 LC-MS/MS 的糖组学在癌症研究中势头强劲，具有提供新的基于聚糖的标志物的巨大潜力。在我们的实验室中，我们研究了一组 CRC 细胞系和 CRC 患者组织中与 CRC 恶性程度相关的 N-糖基化改变。在最初的研究中，基于 LC-MS/MS 的 N-糖组学用于绘制与一组 CRC 细胞系（LIM1215、LIM1899 和 LIM2405）相关的 N-聚糖图谱。这些研究随后扩展到配对的肿瘤和非肿瘤性 CRC 组织，以验证细胞系中的发现。我们在 CRC 细胞系和组织中的研究发现，高甘露糖和α2,6 连接唾液酸化的复杂 N-聚糖具有强烈的代表性，这与 CRC 和其他癌症中的先前研究结果一致。此外，在转移性（LIM1215）和侵袭性（LIM2405）CRC 细胞系中分别鉴定出的某些独特的聚糖决定因素，如双分支β1,4-GlcNAcylation 和α2,3 唾液酸化，与表皮生长因子受体（EGFR）表达状态相关。在本报告中，我们将描述我们实验室中用于准确分析与 CRC 相关的细胞和组织特异性 N-聚糖组的基于质谱的 N-糖组学方法。我们将重点介绍我们的研究中观察到的改变的 N-糖基化，这些改变与其他癌症研究的结果一致，并讨论观察到的改变如何为 CRC 发病机制提供新的见解，为鉴定新的疾病相关聚糖标志物开辟新途径。
