补体膜调控蛋白参与肿瘤抗体治疗耐药的分子机制

The immune surveillance and clearance are the important roles of complement system, however in which the molecular mechanisms of the immune response and host defense of autologous cells, further immune evasion and resistance development of cancer cells remains largely unknown. It is recognized that the up-regulations of membrane complement regulatory proteins (mCRPs) may be crucial during the above process. However, its molecular regulation mechanisms still remains elusive. The applicant has recently revealed the regulation mechanisms and the key signaling molecules for mCPR CD59 transcription, i.e. Sp1 modulates the constitutive expression of CD59, while NF-kB together with CREB modulates the inducible expression of CD59. In this proposal, we plan to extend our study for CD59 to the remaining mCRPs CD46 and CD55. Using GeneRacer, ChIP, EMSA, complement activation and xenografted nude mice, we will dissect their regulation mechanisms and further the key signaling molecules during the process of host defense in the levels of molecule, cell and animal. Moreover, the development of non-responsiveness and resistance to cancer antibody-based therapy will be exemplified in this study. We will dedicate to understand their underlying mechanisms and further find the key signaling molecules as the potential drug targets. In the end, we project to screen the druggable molecules for these targets; therefore, this study is hopeful to provide new insight into facilitating cancer antibody-based therapy.

免疫监视和免疫清除是补体系统的重要功能，但此过程中宿主细胞如何应答和防御，进一步肿瘤细胞如何逃避补体杀伤并形成耐药的分子机制仍然是一个未知的重要科学问题，尽管补体膜调控蛋白（mCRPs）表达的上调可能是其中的关键因素，但对其分子调控机制还知之甚少。申请人最近首次系统地揭示了mCRPs分子CD59在转录水平上的分子调控机制及关键信号分子，即Sp1调节组成型CD59的表达，而NF-kB与CREB相互作用调节诱导型CD59的表达。本项目拟进一步研究其余两种mCRPs 分子CD46与CD55，利用GeneRacer、ChIP、EMSA、补体激活和裸鼠成瘤等实验手段，在分子、细胞及整体水平全面地阐述所有mCRPs参与宿主防御的调控网络及关键节点分子。然后以肿瘤抗体治疗的无应答与耐药形成为模型，探讨其中mCRPs的调控分子机制，发现潜在药物治疗靶点并筛选干预药物，为增敏肿瘤抗体治疗提供新思路新方法。

淋巴瘤发病率与死亡率均位于十大肿瘤之列，R（RIT, 美罗华）-C（CTX, 环磷酰胺）H（ADM, 阿霉素）O（VCR, 长春新碱）P（Pre, 强的松）是主要类型淋巴瘤的一线治疗方案，但仍有约1/4的患者耐药复发而最终死亡，因此研究耐药机制并筛选逆转耐药药物至关重要。我们选取主要淋巴瘤亚型的弥漫大B淋巴瘤（包括GCB与ABC分型）R-CHOP耐药作为研究对象，通过转录组学、蛋白质组学和其他常规的生化分子生物学技术，在分子、细胞与整体（动物与临床样本）水平揭示了R-CHOP耐药的机制，并筛选获得体内外可完全逆转R-CHOP耐药的药物，该药物已处于临床III期或进入临床使用，因此该研究结果对淋巴瘤的治疗将产生重要影响。另外，我们还揭示了淋巴瘤R治疗耐药的重要原因为药物靶点CD20的下调与补体膜调控蛋白CD59的上调，进一步阐明了CD59在生理、炎症与肿瘤细胞/肿瘤干细胞条件下对细胞的保护作用与调控机制，提供了机体不同细胞不同条件下逃避补体免疫监视的理论基础。