Biomolecular Mass Spectrometry Unit, Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
Mol Cell Proteomics. 2012 Sep;11(9):571-85. doi: 10.1074/mcp.M111.011601. Epub 2012 May 9.
Colorectal cancer is the third most common cancer worldwide with an annual incidence of ~1 million cases and an annual mortality rate of ~655,000 individuals. There is an urgent need for identifying novel targets to develop more sensitive, reliable, and specific tests for early stage detection of colon cancer. Post-translational modifications are known to play an important role in cancer progression and immune surveillance of tumors. In the present study, we compared the N-glycan profiles from 13 colorectal cancer tumor tissues and corresponding control colon tissues. The N-glycans were enzymatically released, purified, and labeled with 2-aminobenzoic acid. Aliquots were profiled by hydrophilic interaction liquid chromatography (HILIC-HPLC) with fluorescence detection and by negative mode MALDI-TOF-MS. Using partial least squares discriminant analysis to investigate the N-glycosylation changes in colorectal cancer, an excellent separation and prediction ability were observed for both HILIC-HPLC and MALDI-TOF-MS data. For structure elucidation, information from positive mode ESI-ion trap-MS/MS and negative mode MALDI-TOF/TOF-MS was combined. Among the features with a high separation power, structures containing a bisecting GlcNAc were found to be decreased in the tumor, whereas sulfated glycans, paucimannosidic glycans, and glycans containing a sialylated Lewis type epitope were shown to be increased in tumor tissues. In addition, core-fucosylated high mannose N-glycans were detected in tumor samples. In conclusion, the combination of HILIC and MALDI-TOF-MS profiling of N-glycans with multivariate statistical analysis demonstrated its potential for identifying N-glycosylation changes in colorectal cancer tissues and provided new leads that might be used as candidate biomarkers.
结直肠癌是全球第三大常见癌症，年发病率约为 100 万例，年死亡率约为 65.5 万例。因此，迫切需要确定新的靶点，以开发更敏感、可靠和特异的用于早期结肠癌检测的方法。翻译后修饰被认为在癌症的进展和肿瘤的免疫监视中起着重要作用。在本研究中，我们比较了 13 例结直肠癌肿瘤组织和相应对照结肠组织的 N-糖基化谱。N-糖基通过酶解释放、纯化并用 2-氨基苯甲酸标记。用亲水相互作用液相色谱（HILIC-HPLC）与荧光检测和负离子模式 MALDI-TOF-MS 对样品进行分析。使用偏最小二乘判别分析（PLS-DA）研究结直肠癌中的 N-糖基化变化，发现 HILIC-HPLC 和 MALDI-TOF-MS 数据均具有极好的分离和预测能力。为了进行结构解析，结合了正离子模式 ESI 离子阱-MS/MS 和负离子模式 MALDI-TOF/TOF-MS 的信息。在具有高分离能力的特征中，发现含有双触角 GlcNAc 的结构在肿瘤中减少，而硫酸化聚糖、少甘露糖型聚糖和含有唾液酸化 Lewis 型表位的聚糖在肿瘤组织中增加。此外，还在肿瘤样本中检测到核心岩藻糖基化高甘露糖型 N-聚糖。总之，HILIC 和 MALDI-TOF-MS 联合分析 N-糖基化图谱与多元统计分析相结合，证明了其在鉴定结直肠癌组织中 N-糖基化变化方面的潜力，并为可能作为候选生物标志物的新靶点提供了依据。
