基于非天然唾液酸的肿瘤表面糖萼结构与免疫性能的调控与应用

Mammalian cell surfaces are anchored with glycoconjugates termed glycocalyx which is involved in cell-cell and cell-environment interactions, such as attachment, migration and immunological clearance. Immuno-systems destroy “non-self” cells and save “self” cells by sensing of certain biomarkers. However, “non-self” cancer cells could evade immunological surveillance. Current immunotherapy relies on programming host immuno-systems to re-target cancer cells. In contrast, in vivo tumor engineering to trigger immunological clearance has been largely unexplored.. We recently reported in vivo tumor imaging with sialic acid bearing hydrophobic substitutions at C-9 where the unnatural sialic acids are preferentially endocytosized by tumor cells. Sialic acid is a 9-carbon monosaccharide typically located at termini of cell surface glycoconjugates. Herein, we wish to develop new approaches to manipulate tumor immunogenecity by altering tumor sialylation. Sialic acid with abiotic hydrophobic entities will be used to target cancers in vivo and then incorporated into tumor glycocalyx by tumor sialylation pathway. The abiotic groups displayed on tumor surface will alter immunological signature of tumors and thus modulate tumor interactions with immunological cells. Specifically, 1) sialic acid with 2, 4-dinitrophenyl group (DNP) will be used to engineer tumors in mice. We will examine in vivo recruitment of anti-DNP IgG by tumor surface DNP and the resulting anti-tumor effects；2）3-F-sialic acid with hydrophobic groups will be used for in vivo inhibition of tumor sialylation to decrease surface sialic acid and elicit immunological killing of tumors; 3) unnatural sialic acids with varied affinity to Siglec-1 and Siglec-7 will be installed into tumor glycocalyx to modulate tumor affinity with macrophages or NK cells. The effects on tumor viability will be determined. . In summary, we will explore a small molecule-based approach for in vivo engineering of tumor glycocalyx via the use of tumor-targeting unnatural sialic acids. The aim is to modulate tumor surface structure and immunological signature for biological studies or biomedical applications, such as immunotherapy.

细胞糖萼调控细胞之间或细胞-环境相互作用。免疫系统清除体内有害“非我”细胞，保留“自我”细胞。癌细胞能避免免疫识别，肿瘤免疫学研究主流是调节免疫系统，使其识别癌细胞。少有研究来改变体内肿瘤结构，触发免疫杀死。我们发现C-9含疏水基唾液酸被小鼠肿瘤有效摄取。在此基础上，拟合成将含不同取代基的唾液酸，用于选择性导入肿瘤糖萼，改变肿瘤免疫特性，调控肿瘤免疫识别。研究内容：1）在唾液酸上连接2，4-二硝基苯抗原，探索在活体内抗原导入肿瘤糖萼引发免疫杀灭效率；2）基于含氟唾液酸抑制细胞唾液酸化的报道，将在含氟唾液酸上连接疏水基团，用于体内肿瘤的靶向性富集，降低肿瘤唾液酸丰度，将肿瘤由“我”转化为“非我”，便于免疫清除；3）在癌细胞糖萼引入非天然唾液酸，提高或降低肿瘤与巨噬细胞或NK细胞的结合力，表征相关免疫效果。本课题利用非天然唾液酸调控肿瘤糖萼结构与免疫识别，是免疫疗法的一种新视角。

发展基于细胞糖合成代谢，将非天然唾液酸以共价键形式表达炎癌细胞糖萼上，抑制肿瘤生长与炎症反应。这为全新炎癌免疫调控新方法。发展基于细胞糖分选通路的应激细胞器稳定成像全新策略。这为相关细胞生物学研究提供了全新方案；由此发展了细胞器内生物正交反应，分析信号传导过程细胞器动态变化。最后，利用功能探针研究细胞糖分解代谢通路， 研究糖苷酶与炎症、衰老的关联。