Blimp-1调控内质网稳态在多发性骨髓瘤发病中的作用和机制研究

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. Blimp-1 is the key transcription factor to regulate differentiation and survival of plasma cells, but very little involved in MM. Our previous research has shown that myeloma cells highly expressed Blimp-1 and RNA interference silencing Blimp-1 expression damaged endoplasmic reticulum steady-state, inhibited myeloma cells proliferation and induced its apoptosis by inhibition of the UPR (unfolded protein response). Based on the previous work, the further study will focus on the influence of endoplasmic reticulum homeostasis and the pathogenesis of myeloma through regulating UPR reaction by Blimp-1 and deeply reveal the mechanism of Blimp-1 regulating myeloma cells from the transcription and signal transduction level using Blimp-1 knockout mice model, myeloma cell lines and primary cells. 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。从浆细胞分化和存活调控入手，探索多发性骨髓瘤治疗的新靶点和新策略是一可行手段。Blimp-1是调控浆细胞分化和存活的关键转录因子，但对其在多发性骨髓瘤中的作用尚少有涉及。本课题组前期研究显示，骨髓瘤细胞高表达Blimp-1，RNA干扰沉默Blimp-1表达可通过抑制未折叠蛋白反应（unfolded protein response，UPR）破坏内质网稳态抑制骨髓瘤细胞增殖并诱导其凋亡。本研究拟在前期工作基础上通过基因敲除小鼠模型、骨髓瘤细胞株和原代细胞进一步研究Blimp-1调控UPR反应影响内质网稳态的作用及其对骨髓瘤发病的调控作用；并从转录调控和信号转导水平深入揭示Blimp-1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。

Blimp-1是B细胞终末分化为浆细胞的关键调控者，但其在浆细胞来源肿瘤-多发性骨髓瘤中作用不清，亟待澄清。通过敲基因小鼠模型，我们发现Blimp-1缺失阻断了浆细胞生成和免疫球蛋白分泌，但同时会导致B细胞分化阻滞产生弥漫大B淋巴瘤样表现。我们在NCI-H929细胞下调Blimp-1表达后发现细胞增殖和甲基纤维素半固体培养克隆形成受抑，凋亡率增加。我们进一步研究发现，下调Blimp-1可以通过影响UPR中Xbp-1为代表的适应性模块和CHOP - Caspase 12为代表的促凋亡模块在NCI-H929骨髓瘤细胞中发挥促增殖抗凋亡的作用。沉默Blimp-1可延长骨髓瘤荷瘤NSG小鼠生存期，提示Blimp-1是骨髓瘤治疗的一个潜在靶点。在原定计划之外，本课题组还发现诱导凋亡不是高浓度维生素C杀伤K-ras突变骨髓瘤细胞的主要机制，在此基础上解释了NADPH耗竭所致的Ferroptosis样改变才是细胞的真正死因。由于快速诱导耐受，大剂量维生素C虽然安全且毒性低微，但用于K-ras突变肿瘤效果存疑。我们结果提示Ras突变骨髓瘤细胞快速适应维生素C的主要机制是由于磷酸戊糖途径产生大量NADPH，抑制磷酸戊糖途径关键酶G6PD可以极大的增加维生素C对Ras突变骨髓瘤细胞的杀伤能力，有望以此发现为基础开发高效低毒的治疗K-ras突变骨髓瘤及其他肿瘤的新策略。