Racl在基质细胞衍生因子1诱导人脑胶质瘤细胞系U251迁移和侵袭中的作用

Role of Racl in the SDF-l-induced migration and invasion of human glioma cell line U251

目的通过特异性的Racl活性抑制剂下调Racl的活性，探讨Racl在基质细胞衍生因子1（SDF-1）诱导的人恶性胶质瘤U251细胞迁移和侵袭中的作用。方法SDF-1和（或）NSC23766处理取人脑胶质瘤细胞系U251；通过细胞迁移实验和Transwell细胞侵袭实验评价不同处理组U251细胞的迁移和侵袭能力；Racl活性实验和Western印迹分别检测不同处理组U251细胞中GTP．Racl和总Racl蛋白的表达水平；免疫荧光法检测不同处理组U251细胞中Racl的表达及细胞内定位。结果SDF-1处理组细胞迁移和侵袭能力（处理组迁移数与侵袭数分别为115．44±3．3，51．04±2．5）明显强于对照组（迁移数与侵袭数分别为64．8±2．3，28．0±2．2），P〈0．05；SDF-1对细胞内Racl活化有明显的刺激作用（P〈0．05），并且细胞运动前端的胞膜下可见Racl蛋白聚集。Racl抑制剂NSC23766对SDF-1诱导的细胞迁移和侵袭有显著的抑制作用（P〈0．05）；与SDF-1处理组比较，NSC23766预处理组细胞内Racl活性明显降低（P〈0．05），且细胞运动前端的胞膜下未见Racl蛋白聚集。3组中总Racl蛋白的表达水平没有明显变化（P〉0．05）。结论Racl对SDF-1诱导的人恶性胶质瘤细胞系U251迁移和侵袭具有调控作用，抑制Racl活化可能成为治疗恶性胶质瘤的新的治疗策略。

Objective To explore the role of Racl in the SDF-l-induced migration and invasion of glioma cells with a specific Racl inhibitor. Methods Human glioma cell lines U251 treated with SDF-1 or/ and specific Racl inhibitor were used. The migration and invasion capacities of cells in 2D cell migration/3D invasion assay were assessed. Western blot was employed to detect the levels of Racl and GAPDH in cell lysates and the Racl activity measured by Racl activation assays. Immunofluorescence was used to identify the expression and intraeellular location of Rael in U251 cells. Results SDF-1 significantly increased the migration and invasion capacities of U251 cells （P 〈 0. 05 ）. The stimulation of SDF-1 boosted the activity of Racl versus the unstimulated cells （P 〈 O. 05 ）. And Racl was recruited to protruding edge in SDF-1- stimulated cells. Inhibition of Racl with specific Racl inhibitor decreased the migration and invasion capacities of SDF-1-induced U251 cells（ P 〈 0. 05 ）. In comparison with the SDF-1 treated group, the activity of Racl significantly decreased （ P 〈 0. 05 ） and the recruitment of Racl to protruding edge significantly decreased in the NSC23766 pre-treated group. Conclusions This study provides novel evidence that Racl modulates the SDF-l-induced migration and invasion of glioma cells. It suggests that the inhibition of Racl activation may be a new therapeutic target for glioma.