Rac1介导E-cadherin下调引起的白血病细胞行为改变

目的:确定上皮-钙黏蛋白(E-cadherin)表达下调或缺失在白血病细胞恶性行为中的作用及分子机制,最终阐明骨髓微环境与造血细胞相互作用改变在白血病发生中的作用。方法:通过RNA干扰白血病细胞(Raji细胞)及基质细胞(293T细胞)中E-cadherin的表达;细胞黏附实验测定E-cadherin表达沉默后2种细胞间的黏附能力改变;MTT法测定干扰后293T细胞上Raji细胞的增殖能力;Westernblotting方法确定干扰后Rho家族小GTP酶Rac1的表达。结果:RNA干扰E-cadherin表达后,Raji细胞对293T细胞的黏附能力显著降低,在293T细胞上的增殖能力显著增强,同时Rac1的表达升高。结论:白血病细胞中E-cadherin表达丧失,引起细胞黏附降低,增殖能力增强,表明E-cadherin表达缺失与白血病细胞恶性行为的获得有关,Rac1可能介导了E-cadherin表达缺失引起的细胞行为改变。

Rac1 mediates behaviors of leukemic cells in response to down-regulation of E-cadherin expression

AIM: To investigate the effect of E-cadherin down-regulation on the behaviors of leukemic cells and its molecular mechanism, and to further determine the role of abnormal interactions between hematopoietic progenitor and bone marrow microenvironment in leukogenesis. METHODS: E-cadherin was silenced via small RNA interference in Raji leukemic cells and 293T stroma cells. The ability of cell-cell adhesion was determined by cell adhesion assay after E-cadherin was knockdown. Adhesion associated proliferation was examined by MTT assay after plating Raji cells onto 293T cells. The expression of Rho GTPase Rac1 was determined by Western blotting. RESULTS: After E-cadherin was silenced in Raji and 293T cells, the ability of cell-cell homophilic adhesion was reduced significantly and the proliferation of Raji cells cultured on 293T cells was promoted significantly. Additionally, siRNA mediated silencing of E-cadherin in Raji cells resulted in up-regulation of Rac1 protein. CONCLUSION: Silencing the expression of E-cadherin in leukemic cells results in decreased adhesion and enhanced proliferation of leukemic cells. Inhibition of E-cadherin expression is responsible for the malignant behaviors of leukemia cells, which may be mediated by Rac1 GTPase.