糖链对肿瘤细胞生物学行为的影响及机制研究年度报告

张嘉宁 张延 燕秋 贾莉 汪淑晶

摘 要：该研究其主要目的是利用糖基转移酶酶学活性检测法，筛选替代糖基转移酶天然糖苷供体底物的糖探针，建立体外糖基化修饰蛋白、标记糖链的方法，高通量筛选发现肿瘤相关糖基转移酶对应的靶蛋白和糖链结构，并发现肿瘤特征性糖基转移酶抑制剂。并且，观察了一系列糖基转移酶及相关特征糖链在肿瘤中的表达及结构特点。得到如下结论：关于糖基转移酶抑制剂发现的相关工作已达该领域领先水平。发现的高通量筛选方法可以推动糖基转移酶抑制剂的发现工作。同时，已发现的ppGlaNAc-T抑制剂可以作为分子探针工具研究此类酶的生物学功能，并为肿瘤等疾病提供基于糖靶标的治疗药物先导物。此外，该研究还揭示了唾液酰基转移酶ST6Gal-I的表达调控规律。发现了α5-integrin的α2，6唾液酸化修饰与肝癌细胞粘附呈正相关。提示，Cav-1上调ST6Gal-I表达及α2，6连接唾液酸水平是促进肝癌细胞转移的早期事件，而Cav-1、ST6Gal-I及ECM黏附的顺序调控有可能为转移性肝癌的早期治疗提供新的靶点和思路。提出了糖蛋白N-糖链作为预测白血病耐药标志物的可能性。即N-糖链、糖基因的差异表达的确与白血病耐药具有相关性，是潜在的白血病耐药相关标志物。

关键词：糖基转移酶 探针 肿瘤 耐药

Annual Report-Effect and Mechanism of Sugar Chains on the Biological Behavior

of Tumor Cells

Zhang Jianing1 Zhang Yan2 Yan Qiu1 Jia Li1 Wang Shujing1

（1.Dalian Medical University；2.Shanghai Jiao Tong University）

Abstract：This study suggests that the new Y subfamily of ppGalNAc-Ts plays an important role in protein glycosylation； characterizing their functions will provide new insight into the role of ppGalNAc-Ts. Disulfide- and terminal alkyne-modified magnetic silica particles （DA-MSPs） were synthesized and used to covalently capture and reductively release azido glycopeptides via click chemistry and dithiothreitol treatment. Using DA-MSPs， an efficient and specific enrichment method for separating azido glycopeptides has been developed. The alterations of integrin glycosylation play a crucial role in tumor metastasis. Our previous studies indicated that caveolin-1 promoted the expression of the key a2，6-sialytransferase ST6Gal-I and fibronectin-mediated adhesion of mouse hepatocarcinoma cell. Herein， we investigated the role of a2，6-sialylated a5-integrin in the adhesion of mouse hepatocarcinoma H22 cell. We demonstrated that caveolin-1 up-regulated cell surface a2，6-linked sialic acid via stimulating ST6Gal-I transcription. Cell surface a2，6-sialylation was required for integrin a5b1-dependent cell adhesion to fibronectin， and an increase in a2，6-linked sialic acid on a5-subunit facilitated fibronectin-mediated focal adhesion kinase phosphorylations， suggesting that a2，6-sialylated a5-subunit promoted integrin a5b1-dependent cell adhesion. B4GALT family consists of seven members， which encode corresponding enzymes known as type II membrane-bound glycoproteins. These enzymes catalyze the biosynthesis of different glycoconjugates and saccharide structures， and have been recognized to be involved in various diseases. In this study， we sought to determine the expressional profiles of B4GALT family in four pairs of parental and chemoresistant human leukemia cell lines and in bone marrow mononuclear cells （BMMC） of leukemia patients with multidrug resistance （MDR）. The results revealed that B4GALT1 and B4GALT5 were highly expressed in four MDR cells and patients， altered levels of B4GALT1 and B4GALT5 were responsible for changed drug-resistant phenotype of HL60 and HL60/adriamycin-resistant cells. Thus， we propose that B4GALT1 and B4GALT5， two members of B4GALT gene family， are involved in the development of MDR of human leukemia cells， probably by regulating the activity of Hh signaling and the expression of P-gp and MRP1.

Key Words：Glycotransferases； Probe； Tumor； Resistance

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