蛴螬多糖以半乳凝素-1为靶点抑制肿瘤血管生成的结构基础与构效关系

项目名称： 蛴螬多糖以半乳凝素-1为靶点抑制肿瘤血管生成的结构基础与构效关系

项目编号： No.81473329

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 医药、卫生

项目作者： 曹蔚

作者单位： 西北农林科技大学

项目金额： 73万元

中文摘要： 多糖是中药重要的水溶性成分，对肿瘤有显著的治疗作用，但结构复杂，构效研究缓慢，是亟待解决的制约多糖应用与发展的科学问题。近年，具有糖结合活性的半乳凝素-1（Gal-1）调控肿瘤血管生成关键作用的发现，为多糖构效研究提供了新思路。我们前期研究发现：多糖是中药蛴螬抗肿瘤的主要药效物质，其活性与结构密切相关；且多种蛴螬均一性多糖中的2种可与Gal-1特异结合，显著抑制肿瘤血管生成。提示：蛴螬多糖糖链中存在活性结构域，可特异性拮抗Gal-1而产生抗肿瘤作用。基于此，本研究拟采用化学和波谱法解析蛴螬多糖的一级结构；酶法降解获得多糖片段，表面等离子体共振及固相结合法筛选结合Gal-1的多糖片段，进而综合评价其抑制血管生成的作用，解析活性片段结构；通过N-H-HSQC分析和分子动力学模拟研究多糖阻断Gal-1抑制肿瘤血管生成的构效关系。为揭示蛴螬抗肿瘤作用的物质基础，丰富活性多糖结构数据库提供科学依据。

中文关键词： 蛴螬；多糖；结构；抗肿瘤；血管生成

英文摘要： The efficacy of polysaccharides, as an important water-soluble components of Chinese medicine, on the treatment of cancer and other diseases has been proved over the last three decades. However, because of the complexity of the structures and mechanisms of polysaccharides, the relationship between structures and anti-tumor activities remains unclear. Recent studies showed that some kinds of saccharides regulated the tumor angiogenesis by inhibiting Galectin-1 (Gal-1), which attracted our great attention. These results may help to find the effective polysaccharides from traditional Chinese medicine. Our previous studies showed that the polysaccharides are the main anti-tumor substances of Holotrichia diomphalia Bates. We had isolated five homo-polysaccharides from Holotrichia diomphalia larvae and found that the anti-tumor activities were closely related to their structures. Among these homo-polysaccharides, two acidic polysaccharides could significantly combine to Gal-1 and down-regulate the expression of Gal-1, and further inhibit the tumor angiogenesis. These results suggest that there are some important recognition units for Gal-1 in the polysaccharides isolated from H. diomphalia. To elucidate anti-tumor structure-activity relationship, and further to demonstrate the Gal-1 binding domain of H. diomphalia polysaccharide, we will analysis the primary structures of the polysaccharides from H. diomphalia Bates using a combination of instrumental and chemical analysis, including methylation analysis, GC-MS, IR, 2D NMR spectroscopy (C-H COSY, HSQC, HMBC, TOCSY and NOESY), etc. After the polysaccharides are degraded by specific enzymes and purified by gel columns, their affinities to Gal-1 will be measured using the solid phase binding assay and surface plasmon resonance analysis. Anti-angiogenesis effects will be determined using the tube formation assay and migration assay in vitro, and in nude mice xenografted cancer cells. The structure of anti-tumor polysaccharide fragments will be investigated using the chemical and instrumental methods as mentioned above. In addition, the binding constants between polysaccharide fragments and Gal-1 will be determined using 15N-1H-HSQC NMR and calculated with molecular dynamics simulation. From above, we will elucidate the anti-tumor structure-activity relationship of the H. diomphalia polysaccharides. These results might be helpful in understanding the anti-tumor mechanism of polysaccharides, and developing a novel anti-tumor agent.

英文关键词： Holotrichia diomphalia;polysaccharide;structure;anti-tumor;angiogenesis