Cheresh D A
Scripps Clinic and Research Foundation, La Jolla, California 92037.
Prog Clin Biol Res. 1989;288:3-24.
The disialogangliosides GD2 and GD3 play a major role in the ability of human melanoma cells to attach to Arg-Gly-Asp-containing substrates such as fibronectin and vitronectin, since pretreatment of these cells with monoclonal antibodies to the oligosaccharide of GD2 and GD3 can inhibit their attachment and spreading on such adhesive proteins. This report demonstrates that human melanoma cells (M21) synthesize and express a glycoprotein receptor that shares antigenic epitopes with the vitronectin receptor on human fibroblasts and is capable of specifically recognizing the Gly-Arg-Gly-Asp-Ser-Pro sequence. Biochemical evidence is presented indicating that the vitronectin receptor on M21 human melanoma cells contains associated calcium and GD2. This ganglioside copurified with the glycoprotein receptor for vitronectin on affinity columns containing either an Arg-Gly-Asp-containing peptide, Concanavalin A, or lentil lectin. This major Arg-Gly-Asp-directed receptor on M21 cells could be metabolically labeled with 45Ca++. Chelation of this ion with EDTA caused the dissociation of GD2 from the receptor and rendered the remaining glycoprotein incapable of binding to an Arg-Gly-Asp containing peptide. Reconstitution experiments demonstrated a requirement for calcium and not magnesium for receptor binding to Arg-Gly-Asp and indicated that addition of ganglioside can enhance this interaction.
双唾液酸神经节苷脂GD2和GD3在人类黑色素瘤细胞附着于含精氨酸-甘氨酸-天冬氨酸的底物（如纤连蛋白和玻连蛋白）的能力中起主要作用，因为用针对GD2和GD3寡糖的单克隆抗体对这些细胞进行预处理可抑制它们在此类黏附蛋白上的附着和铺展。本报告表明，人类黑色素瘤细胞（M21）合成并表达一种糖蛋白受体，该受体与人成纤维细胞上的玻连蛋白受体具有共同的抗原表位，并且能够特异性识别甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸-脯氨酸序列。文中提供了生化证据，表明M21人类黑色素瘤细胞上的玻连蛋白受体含有相关的钙和GD2。在含有含精氨酸-甘氨酸-天冬氨酸的肽、伴刀豆球蛋白A或扁豆凝集素的亲和柱上，这种神经节苷脂与玻连蛋白的糖蛋白受体共纯化。M21细胞上这种主要的精氨酸-甘氨酸-天冬氨酸导向受体可用45Ca++进行代谢标记。用乙二胺四乙酸螯合该离子会导致GD2从受体上解离，使剩余的糖蛋白无法与含精氨酸-甘氨酸-天冬氨酸的肽结合。重组实验表明，受体与精氨酸-甘氨酸-天冬氨酸结合需要钙而非镁，并且添加神经节苷脂可增强这种相互作用。
