RAB7A调控内吞和自噬在多发性骨髓瘤发病和进展中的作用机制研究

Multiple myeloma (MM) is a currently incurable plasma malignancy and the incidence goes up annually. There is one of feasible methods to explore new targets and strategy for the treatment of MM from the regulation of differentiation and survival of plasma cells. RAB7A is an important protein that regulates the integration of intracellular vesicles with lysosomes and participates in basic life activities such as endocytosis and autophagy.Our previous research has shown that knockout of MM cell line U266 RAB7A gene could block CXCR4 endocytosis and affect autophagy lead to increased LC3-II. Based on the previous work, the further study will focus on the role of RAB7A in MM cell proliferation and apoptosis , the related key signal pathway and the possible mechanisms on the genomic stability of MM cells from the transcription and signal transduction level using myeloma cell lines, immunodeficient mouse tumor model .The project deadline helps to deepen the understanding of the pathogenesis of MM, and also can offer new potential targets and strategy for prevention and control of MM.

多发性骨髓瘤（multiple myeloma，MM）系浆细胞恶性克隆性疾病，目前发病率逐年增高且仍不可治愈。RAB7A是调控胞内囊泡与溶酶体融合的重要蛋白，参与受体内吞和自噬等基本生命活动过程。本课题组前期研究结果显示，敲除MM细胞株U266 RAB7A基因能阻断CXCR4的内吞和影响自噬导致LC3-II增加。本研究拟前期工作基础上，通过MM细胞株、免疫缺陷小鼠荷瘤模型进一步研究RAB7A在MM细胞增殖与凋亡中的作用，及相关的关键信号模块改变，探索RAB7A对MM细胞基因组稳定性的影响及可能的机制，从转录调控和信号转导水平深入揭示RAB7A调控骨髓瘤细胞的机制。课题如期完成有助于加深对骨髓瘤发病机制的理解，也能为多发性骨髓瘤防治提供新的潜在靶点和策略。

RAB7A属于小G蛋白家族，参与胞内囊泡结构与溶酶体融合降解过程的控制，可能与受体内吞和自噬小体的溶酶体途径降解有关。RAB7A在多发性骨髓瘤发病和进展中的作用迄今所知甚少，值得深入研究。通过本项目资助我们发现，通过CRISPR-Cas9敲除骨髓瘤细胞RBA7A促进骨髓瘤细胞增殖、减少骨髓瘤细胞自发凋亡及增加药物抗性。我们发现RAB7A缺陷可以通过增加ERK、P38和JUK磷酸化水平在骨髓瘤细胞中发挥促增殖抗和凋亡的作用。进一步研究发现RAB7A敲除后骨髓瘤细胞CXCR4、P62和LC3II累积，提示受体内吞和autophagy flux受损。RAB7A敲除骨髓瘤细胞MitoTracker和DCFH-DA染色荧光强度均增高，彗星试验显示拖尾增加，提示RAB7A敲除导致线粒体ROS水平增高，继而增加基因组不稳定性。RAB7A敲除骨髓瘤细胞在NSG小鼠荷瘤模型上具有加快骨髓瘤进展的作用。本研究初步揭示了RAB7A在骨髓瘤发病中的作用，并基本确认了其作用机制，有助于加深对骨髓瘤发病机制的理解。在原定计划之外，本课题组还探索了CAR-T联合靶向CD19和BCMA抗骨髓瘤的临床试验，观察到CD19和BCMA双靶向是骨髓瘤治疗的优选方案，有助于提高骨髓瘤的临床疗效。