Importance of carbohydrates in platelets-mediated cell adhesion

小鼠结肠癌（结肠26）细胞仅在富血小板血浆（PRP）存在的情况下才能附着在培养的肝窦内皮细胞上。大多数肿瘤细胞不是直接附着在内皮细胞上，而是通过聚集的血小板附着在内皮细胞上。此外，几乎所有粘附在内皮细胞上的肿瘤细胞都显示ECA （Erythrina crystagalli凝集素）阳性，而粘附前近一半的细胞ECA结合阴性。当eca阳性细胞与eca阴性细胞分离时，与eca阴性细胞相比，显示出较强的肝脏转移能力。从结肠26细胞粗膜部分提取eca阳性物质，发现其能抑制血小板粘附。这些结果表明，结肠26细胞表面的eca阳性糖链可能介导了结肠26细胞与血小板的结合和肿瘤细胞对内皮的附着。上述诱导的结肠癌细胞与肝窦细胞的附着可能引起肿瘤转移的一系列事件。

Mouse colon carcinoma (colon 26) cells were shown to attach to cultured hepatic sinusoidal endothelial cells only in the presence of PRP (platelet-rich-plasma). Most of tumor cells firstly attached to the endothelial cells not directly but via aggregated platelets. In addition, almost all of the tumor cells that were attached to the endothelial cells showed positive staining with ECA (Erythrina crystagalli agglutinin), whereas nearly half of the cells before adhesion were negative for ECA binding. ECA-positive cells, when separated from ECA-negative ones, revealed strong potency for metastasis to the liver compared with ECA-negative ones. ECA-positive materials were extracted from the crude membrane fraction of colon 26 cells and were found to suppress the platelet adhesion. These results indicate that the ECA-positive sugar chains on the surface of colon 26 cells should mediate the binding between colon 26 cells and platelets and the attachment of tumor cells to the endothelium. The attachment of colon carcinoma cells to hepatic sinusoidal cells induced as above may cause the successive events in establishing cancer metastasis.