Institute of Anatomy & Experimental Morphology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
Institute of Anatomy I, University Hospital Jena, Teichgraben 7, 07743 Jena, Germany.
Glycobiology. 2023 Oct 6;33(8):637-650. doi: 10.1093/glycob/cwad061.
One critical step of metastasis formation is the extravasation of circulating tumor cells from the bloodstream. This process requires the dynamic interaction of cell adhesion molecules like E-selectin on endothelial cells with carbohydrate ligands on tumor cells. To characterize these glycans in a comprehensible approach, the rolling, tethering, and firm adhesion of nine human tumor cell lines on human umbilical vein endothelial cells was analyzed using laminar flow adhesion assays. The tumor cell lines were grouped into three subsets by their canonical E-selectin ligand status (sialyl-Lewis A and X +/+, -/+, -/-) and their adhesiveness was compared after enzymatic, pharmacologic, chemical treatment or antibody blockade of the tumor cells or endothelial cells, respectively. Tumor cells were also screened regarding their glycosyltransferase expression profile. We found that although E-selectin and terminal α2,3-sialic acid largely determined firm adhesion, adhesive events did not exclusively depend on the presence of sialyl-Lewis A and/or sialyl-Lewis X. Nevertheless, two of the three sialyl-Lewis A/X-/- tumor cells additionally or fully depended on vascular cell adhesion molecule-1 for firm adhesion. The significance of O-GalNAc- and N-glycans for adhesion varied remarkably among the tumor cells. The sialyl-Lewis A/X+/+ subset showed glycoprotein-independent adhesion, suggesting a role of glycolipids as well. All sialyl-Lewis A/X-/- tumor cells lacked FUT3 and FUT7 expression as opposed to sialyl-Lewis A/X+/+ or -/+ cell lines. In summary, the glycans on tumor cells mediating endothelial adhesion are not as much restricted to sialyl-Lewis A /X as previously assumed. The present study specifically suggests α2,3-linked sialic acid, O-GalNAc glycans, glycosphingolipids, and FUT3/FUT7 products as promising targets for future studies.
肿瘤细胞从血液中渗出是转移形成的关键步骤之一。这一过程需要细胞黏附分子（如内皮细胞上的 E-选择素）与肿瘤细胞上的碳水化合物配体之间的动态相互作用。为了以一种易于理解的方式描述这些糖链，我们使用层流黏附实验分析了 9 个人类肿瘤细胞系在人脐静脉内皮细胞上的滚动、锚定和牢固黏附。根据其经典的 E-选择素配体状态（唾液酸化 Lewis A 和 X +/+, -/+, -/-），将肿瘤细胞系分为三组，并分别对其在肿瘤细胞或内皮细胞经酶、药物、化学处理或抗体阻断后的黏附性进行了比较。此外，还对肿瘤细胞的糖基转移酶表达谱进行了筛选。我们发现，尽管 E-选择素和末端α2,3-唾液酸在很大程度上决定了牢固黏附，但黏附事件并不完全依赖于唾液酸化 Lewis A 和/或 Lewis X 的存在。然而，三个唾液酸化 Lewis A/X-/-肿瘤细胞中的两个还额外或完全依赖血管细胞黏附分子-1 进行牢固黏附。O-GalNAc 和 N-聚糖对黏附的重要性在肿瘤细胞之间差异显著。唾液酸化 Lewis A/X+/+亚组表现出糖蛋白非依赖性黏附，这表明糖脂也可能发挥作用。所有的唾液酸化 Lewis A/X-/-肿瘤细胞均缺乏 FUT3 和 FUT7 表达，而唾液酸化 Lewis A/X+/+或 -/+细胞系则有表达。综上所述，介导内皮黏附的肿瘤细胞上的聚糖并不像以前假设的那样局限于唾液酸化 Lewis A /X。本研究特别表明α2,3 连接的唾液酸、O-GalNAc 聚糖、糖鞘脂和 FUT3/FUT7 产物是未来研究的有前途的靶点。
