基于纳米抗体的光交联新技术研究CD38在肿瘤发生中的作用机制

CD38 is highly expressed on several hematological malignant tumor cells and immunomodulatory Treg cells, while at relatively low levels on normal lymphoid and myeloid cells, and in some tissues of non-hematopoietic origin. As a transmembrane glycoprotein, CD38 possesses ecto-enzymatic activity, and also functions as a receptor and adhesion molecule. Therefore, this has triggered the development of several CD38 antibodies to treat CD38+ hematologic malignancies such as multiple myeloma (MM), acute lymphoblastic leukemia, NK/T cell lymphoma, and acute myeloid leukemia. Through Fc-mediated direct effects and also immunomodulatory effects, these antibodies showed strong anti-tumor effects. Since the signaling pathway mediated by CD38 in these processes remains unclear, we aim to investigate the receptor functions of CD38 in tumor cells by the following strategy. Firstly, we will develop a new method for studying the extracellular interactome of membrane proteins based on nanobodies and trifunctional crosslinkers. Secondly, the new method will be applied to profile CD38 interatome in different cells. Last but not least, we will study the functions of CD38 and its interactors in tumorigenesis, which might shed light on the molecular mechanism of CD38 signaling pathway and give clues for the development of new therapies.

CD38在多种恶性肿瘤细胞以及调节性T细胞上高表达，然而在正常淋巴细胞、骨髓细胞以及一些非造血细胞组织中蛋白丰度相对很低。CD38作为一个跨膜的糖蛋白，具有胞外酶活性，也能够作为表面受体和黏附分子发挥功能。基于这些特点，目前一系列CD38抗体被开发用于治疗多发性骨髓瘤。虽然这些抗体获得了理想的抗肿瘤效果，然而对于CD38在肿瘤细胞中的具体生物学功能以及参与的信号通路还不清楚。在上述观点基础上，本项目拟研究在相关肿瘤发生过程中CD38的受体功能及机制：首先，基于纳米抗体和三功能交联剂开发特异、灵敏的膜蛋白互作组鉴定技术；其次，将新技术应用于CD38+肿瘤细胞中，寻找CD38的蛋白互作组；最后，通过对CD38与其互作蛋白的生物学功能研究，为人们理解CD38在肿瘤发生与免疫调节中的作用机制提供理论依据，并为新药的开发提供思路。

CD38在多种恶性肿瘤细胞以及调节性T细胞上高表达，然而在正常淋巴细胞、骨髓细胞以及一些非造血细胞组织中蛋白丰度相对很低。CD38作为一个跨膜的糖蛋白，具有胞外酶活性，也能够作为表面受体和黏附分子发挥功能。基于这些特点，目前一系列CD38抗体被开发用于治疗多发性骨髓瘤。虽然这些抗体获得了理想的抗肿瘤效果，然而对于CD38在肿瘤细胞中的具体生物学功能以及参与的信号通路还不清楚。本项目首先基于CD38纳米抗体和三功能交联剂开发特异、灵敏的膜蛋白互作组鉴定技术；其次，将该技术应用于CD38+肿瘤细胞中，鉴定了CD38的蛋白互作蛋白CD71，并证明了细胞内钙信使cADPR主要由III型CD38，而非II型CD38合成的；再次，利用CD38的纳米抗体构建了immunoPET，用于多发性骨髓瘤的在体诊断；再在CD38纳米抗体的基础上开发了新型纳米抗体药物偶联物，实现了对多发性骨髓瘤的高效杀伤；最后利用纳米抗体技术解析了另一个NAD信号酶SARM1的激活机制。