Department of Chemical and Biomolecular Engineering, Ohio University, Athens, OH 45701, United States.
Biochem Biophys Res Commun. 2011 Mar 18;406(3):423-9. doi: 10.1016/j.bbrc.2011.02.061. Epub 2011 Feb 15.
Cancer cell adhesion to vascular endothelium is a critical process in hematogenous metastasis. We hypothesized that breast cancer cells express ligands that bind under blood flow conditions to E-selectin expressed by endothelial cells. At a hemodynamic wall shear rate, BT-20 and MDA-MB-468 breast cancer cells adhered to cytokine-activated human umbilical cord vein endothelial cells (HUVECs) but not to anti-E-selectin monoclonal antibody treated HUVECs, demonstrating that adhesion was specifically mediated by E-selectin. Characterization of glycans expressed on breast cancer cells by a panel of antibodies revealed that BT-20 cells expressed sialyl Lewis X (sLe(x)) and sialyl Lewis A (sLe(a)) but MDA-MB-468 cells did not, suggesting that the former possess classical glycans involved in E-selectin mediated adhesion while the latter have novel binding epitopes. Protease treatment of the breast cancer cells failed to significantly alter the carbohydrate expression profiles, binding to soluble E-selectin-Ig chimera, or the ability of the cells to tether and roll on E-selectin expressed by HUVECs, indicating that glycosphingolipids are functional E-selectin ligands on these cells. Furthermore, extracted breast cancer cell gangliosides supported binding of E-selectin-Ig chimera and adhesion of E-selectin transfected cells under physiological flow conditions. In summary, our results demonstrate that breast cancer cells express sialylated glycosphingolipids (gangliosides) as E-selectin ligands that may be targeted for prevention of metastasis.
癌细胞与血管内皮的黏附是血行转移的关键过程。我们假设乳腺癌细胞表达配体，这些配体在血流条件下与内皮细胞表达的 E-选择素结合。在血流切变率下，BT-20 和 MDA-MB-468 乳腺癌细胞黏附于细胞因子激活的人脐静脉内皮细胞（HUVEC），但不黏附于用抗 E-选择素单克隆抗体处理的 HUVEC，表明黏附是由 E-选择素特异性介导的。用一组抗体对乳腺癌细胞表达的聚糖进行表征，结果表明 BT-20 细胞表达唾液酸化路易斯 X（sLe(x)）和唾液酸化路易斯 A（sLe(a）），而 MDA-MB-468 细胞不表达，这表明前者具有参与 E-选择素介导黏附的经典糖结合表位，而后者具有新的结合表位。用蛋白酶处理乳腺癌细胞，未能显著改变糖的表达谱、与可溶性 E-选择素-Ig 嵌合体的结合，或细胞在 HUVEC 上与 E-选择素的连接和滚动能力，这表明糖脂是这些细胞上功能性的 E-选择素配体。此外，提取的乳腺癌细胞神经节苷脂支持 E-选择素-Ig 嵌合体的结合以及 E-选择素转染细胞在生理流动条件下的黏附。总之，我们的结果表明，乳腺癌细胞表达唾液酸化糖脂（神经节苷脂）作为 E-选择素配体，可能成为预防转移的靶点。
