Aberrant glycosylation is considered to be a hallmark of colorectal cancer (CRC), as demonstrated by various studies. While the N-glycosylation of cell lines and serum has been widely examined, the analysis of cancer-associated N-glycans from tissues has been hampered by the heterogeneity of tumors and the complexity of N-glycan structures. To overcome these obstacles, we present a study using laser capture microdissection that makes it possible to largely deconvolute distinct N-glycomic signatures originating from different regions of heterogeneous tissues including cancerous, stromal, and healthy mucosa cells. N-glycan alditols were analyzed by means of porous graphitized carbon liquid chromatography-electrospray ionization tandem mass spectrometry, enabling the differentiation and structural characterization of isomeric species. In total, 116 N-glycans were identified that showed profound differences in expression among cancer, stroma, and normal mucosa. In comparison with healthy mucosa, the cancer cells showed an increase in α2-6 sialylation and monoantennary N-glycans, as well as a decrease in bisected N-glycans. Moreover, specific sialylated and (sialyl-)Lewis^A/X antigen-carrying N-glycans were exclusively expressed in cancers. In comparison with cancer, the stroma showed lower levels of oligomannosidic and monoantennary N-glycans, Lewis^A/X epitopes, and sulfation, as well as increased expression of (core-)fucosylation and α2-3 sialylation. Our study reveals the distinct N-glycomic profiles of different cell types in CRC and control tissues, proving the necessity of their separate analysis for the discovery of cancer-associated glycans.

多项研究表明，异常糖基化被认为是结直肠癌 (CRC) 的标志。虽然细胞系和血清的 N-糖基化已被广泛检查，但来自组织的癌症相关N-聚糖的分析受到肿瘤的异质性和N-聚糖结构的复杂性的阻碍。为了克服这些障碍，我们提出了一项使用激光捕获显微切割的研究，该研究可以在很大程度上解卷积源自异质组织不同区域（包括癌性、间质和健康粘膜细胞）的不同 N 糖组特征。氮通过多孔石墨化碳液相色谱-电喷雾电离串联质谱法对β-聚糖糖醇进行分析，从而能够区分异构体并进行结构表征。总共鉴定出116 个N-聚糖，它们在癌症、基质和正常粘膜之间的表达存在显着差异。与健康粘膜相比，癌细胞表现出α2-6唾液酸化和单触角N-聚糖的增加，以及二等分N-聚糖的减少。此外，特异性唾液酸化和（唾液酸-）Lewis ^A/X抗原携带N-聚糖仅在癌症中表达。与癌症相比，基质显示出较低水平的寡甘露糖苷和单触角N-聚糖、Lewis ^A/X表位和硫酸化，以及（核心）岩藻糖基化和α2-3唾液酸化的表达增加。我们的研究揭示了 CRC 和对照组织中不同细胞类型的独特 N 糖组谱，证明了对它们进行单独分析以发现癌症相关聚糖的必要性。