Ezrin蛋白介导的BTK促急性淋巴细胞白血病细胞迁移、侵袭的作用机制研究

Recently, many studies have shown that aberrant expression of BTK play a pivotal role in the incidence and progress of B cell malignancies. It is reported that activated BTK was accompanied by activation of PI3K and Rho in the process of BTK distribution in cell membrane, and regulate B cell function by controlling the F-actin dynamic changes. Our previous studies have confirmed that the activation of cytoskeleton regulatory protein Ezrin mediated by Rho family play an important role in cancer cell growth, migration and drug resistance. Preliminary experiments showed that both BTK and Ezrin highly expressed in early and recurrence B-cell acute lymphoblastic leukemia (B-ALL), which participates in the migration of B-ALL, blocking BTK can decrease the expression of Ezrin and the co-localization with F-actin. We speculate that the activation of BTK participate in B-ALL migration through changing reconstruction and distribution of skeleton protein by affecting interaction with Ezrin. We therefore intend to investigate the mechanism of cytoskeleton reorganization and activation of Ezrin proteins induced by BTK involved in migration and invasion of B-ALL cell lines and B-ALL clinical samples by employing RNAi, Western blot, Transwell and co-immunoprecipitation techniques. Our research will provide a theoretical foundation for treatment of B-ALL with extramedullary infiltration.

近年研究表明Bruton酪氨酸激酶（BTK）的异常活性与B细胞恶性肿瘤的发病及进展密切相关，活化的BTK在重新分布于胞膜过程中伴随PI3K和Rho的激活，并通过调控骨架蛋白F-actin动态变化调节B细胞功能。我们前期研究证实由Rho介导活化的细胞骨架调节蛋白Ezrin在癌细胞生长、迁移及耐药中发挥重要作用。预实验发现BTK和Ezrin在初、复发B急淋(B-ALL)细胞中表达升高，并参与B-ALL迁移，阻断BTK可降低Ezrin表达并减弱其与F-actin的共定位，由此推测活化的BTK可能通过与Ezrin相互作用导致骨架蛋白的构象和分布发生改变参与B-ALL的侵袭迁移。本研究拟以急淋细胞系及临床样本为研究对象，通过RNAi、免疫共沉淀等技术，探讨活化的BTK诱导细胞骨架重组和Ezrin蛋白活化参与B-ALL细胞侵袭迁移的分子机制，为治疗B-ALL细胞髓外浸润提供科学理论依据。

白血病的发病率有逐年递增的趋势，尤其是白血病的髓外浸润导致的疾病复发，对人类的健康造成严重危害。因此阐明白血病细胞转移的规律及机制，寻找有效的抑制白血病细胞转移的新靶标，对白血病的治疗具有重要的指导意义。.本研究从临床角度出发，结合前期工作基础，首先通过公共数据库以及临床样本和芯片分析发现BTK和Ezrin的表达与临床病人的预后以及疾病的进展具有相关性。进一步以急淋细胞系SUB-P15和RS4；11细胞为模型，运用QRT-PCR、Western blot、transwell、等实验技术，通过体内、体外实验证实了BTK参与急淋细胞的迁移，同时发现BTK的表达变化影响细胞的表型；证明了磷酸化ezrin是BTK介导的急淋细胞迁移中的关键分子，其活化受Vav、ROCK等的调控；通过免疫荧光、免疫共沉淀阐明了BTK与p-Ezrin以及F-actin之间的相互作用以及分子在细胞内的再分布在细胞运动中起着重要作用。本研究为明确B细胞血液肿瘤的髓外侵犯提供了理论依据，为治疗髓外侵犯的B细胞血液肿瘤奠定了理论基础。