STRUCTURE AND BIOSYNTHESIS OF SELECTIN LIGANDS

本提案的主要目的是阐明结构和 选择素配体的生物合成，以及选择素-碳水化合物的作用 肿瘤细胞粘附和转移相互作用。 在过去的几年里， 我们在这一领域取得了重要进展。 首先，我们发现， 转移性结肠癌细胞比转移性结肠癌细胞更强地粘附E-选择素， 低转移性对应物。 第二，这种肿瘤细胞粘附可以是 被含唾液酸化LeX的重组糖蛋白抑制。 三是 证明了整体转移唾液酸LeX寡糖转移 在细胞表面上的粘附导致与E-选择素的粘附。 另外我们 克隆了核心2和I β-16-N-乙酰葡糖胺基转移酶， 多聚唾液酸转移酶，在表达克隆方面获得重要的专业知识。 根据这些调查结果，提出以下三个主要领域： 1. 小鼠中选择素配体的阐明和选择素的调节 通过基因转移配体。 我们将阐明小鼠中性粒细胞 寡糖，因此是小鼠选择素配体。 此外，调制 通过糖基转移酶基因转移形成唾液酸LeX和唾液酸莱亚， 与E-和P-选择素的粘附相关。 2. L-选择素配体的分子鉴定。 我们将确定是否 磺基唾液酸LeX实现L-选择素介导的粘附。 我们还将克隆 编码形成磺基唾液酸LeX的磺基转移酶的cDNA， 选择素配体 3. 糖类在肿瘤转移中的作用。 我们将确定唾液酸是否 LeX（和唾液酸化莱亚）在血液传播的肿瘤转移中起主要作用。 这些研究还将扩展到确定低聚糖是否 结构在肿瘤转移中起关键作用。 这些研究将使我们能够了解的结构和生物合成的 选择素配体及其在肿瘤中的作用 转移

The primary objective of this proposal is to elucidate the structures and biosynthesis of selectin ligands, and the roles of selectin-carbohydrate interaction in tumor cell adhesion and metastasis. In the past few years, we have made critical progress in this field. First, we found that highly metastatic colonic carcinoma cells adhere more strongly to E-selectin than low metastatic counterparts. Second, such tumor cell adhesion can be inhibited by sialyl LeX-containing recombinant glycoproteins. Third, we demonstrated that en bloc transfer sialyl LeX oligosaccharide transferred on the cell surface results in adhesion to E-selectin. In addition, we have cloned the core 2 and I beta-16-N-acetylglucosaminyltransferases and polysialyltransferase, gaining significant expertise in expression cloning. Based on these findings, three major areas are proposed as follows: 1. Elucidation of selectin ligands in mice and modulation of selectin ligand by gene transfer. We will elucidate the mouse neutrophil oligosaccharides, thus mouse selectin ligands. In addition, modulation of sialyl LeX and sialyl Lea formation by glycosyltransferase gene transfer is correlated with adhesion to E- and P-selectin. 2. Molecular Identification of L-selectin ligands. We will determine if sulfo sialyl LeX achieves L-selectin-mediated adhesion. We will also clone cDNA encoding a sulfotransferase that forms sulfo sialyl LeX, a putative L- selectin ligand. 3. Roles of carbohydrates in tumor metastasis. We will determne if sialyl LeX (and sialyl Lea plays a major role in blood-borne tumor metastasis. The studies will also be extended to determine if oligosaccharide structures play a critical role in tumor metastasis. These studies will allow us to understand the structure and biosynthesis of selectin ligands and the roles selectin-mediated adhesion in tumor metastasis.