中文摘要：

目的 探讨酪氨酸激酶受体EphA2和其配体EphrinAl表达与脑胶质瘤恶性表型的关系，为发现恶性脑胶质瘤治疗新靶点提供理论依据。方法 构建针对EphA2的RNAi载体pSilencer－EphA2－SR质粒并转染U251、U87和SHG44细胞，应用Westem blotting检测转染后细胞EphA2、EphrinAl的表达，MTT法和软琼脂克隆形成实验检测细胞增殖能力的变化，体外侵袭实验和流式细胞仪分别检测细胞侵袭和凋亡的变化；建立U251、U87和SHG44细胞的裸鼠胶质瘤移植模型，分别于瘤内注射脂质体＋pSilencer空载体或脂质体＋pSilencer-EphA2－SR质粒，30d后比较移植瘤的平均体积和质量，免疫组化染色检测移植瘤组织EphA2和EphrinAl的表达。结果 成功构建EphA2 RNAi载体pSilencer－EphA2－SR质粒。转染pSilencer－EphA2－SR后48h Western blotting结果显示3种细胞EphA2表达水平均降低，而EphrinAl表达水平升高；MTT、软琼脂克隆形成实验、体外侵袭实验结果显示3种细胞的4值、克隆形成率、侵袭率均低于转染pSilencer空载体者。差异有统计学意义（P＜0．05）；而流式细胞仪检测显示3种细胞的凋亡率均高于转染pSilencer空载体者，差异有统计学意义（P＜0．05）。瘤内注射脂质体＋pSilencer—EphA2－SR质粒后移植瘤的体积和重量均低于注射脂质体＋pSilencer空载体者，差异有统计学意义（P＜0．05）。免疫组化染色显示瘤内注射脂质体＋pSilencer-EphA2－SR质粒后EphA2表达降低，EphrinAl表达水平升高，瘤内注射脂质体＋pSilencer空载体后二者的表达无明显变化。结论 EphA2、EphrinAl是脑胶质瘤恶性表型的重要调控分子，干扰EphA2分子可显著上调EphrinAl表达、部分逆转胶质瘤细胞恶性表型，提示EphA2、EphrinAl有望成为脑胶质瘤治疗新靶点。

英文摘要：

Objective To investigate the relation between altered expressions of EphA2 receptor tyrosine kinase and its ligand EphrinA1 and malignant phenotype of glioma cells, and explore the new targeting molecule for treating malignant gliomas. Methods The RNAi vector （plasmid pSilencer-EphA2-SR） against EphA2 was constructed and transfected into the malignant glioma cells （U251, U87 and SHG44）. Forty-eight h after the transfection, the expressions of EphA2 and EphrinA1 were detected by Western blotting; the viability and anchorage independence of the glioma cells were observed by MTT assay and colony formation assay; the invasion viability and apoptosis of glioma cells were observed by modified Boyden chamber assay and flow cytometry. Glioma xenograft models were established in nude mice; plasmid pSilencer-EphA2-SR or pSilencer-null mixed with lipofectamine was intratumorally injected. The average tumor volume and weight of the transplanted gliomas were measured and compared; the expressions of EphA2 and EphrinA1 were detected by immunohistochemical staining. Results The RNAi plasmid against EphA2 was successfully constructed. After the transfection of plasmid pSilencer-EphA2-SR, the expression of endogenous EphA2 was suppressed, which consequently resulted in increased EphrinA1 level. As compared with cells of the plasmid pSilencer-null group, cells of the plasmid pSilencer-EphA2-SR group showed obviously decreased cell viability, anchorage independence rate and in vitro invasion ability, but significantly increased cell apoptosis rate （P〈0.05）. Furthermore, suppression of EphA2 resulted in delayed tumor growth and increased EphrinA1 expression in mice xenografts. Conclusion EphA2 and EphrinA1 may be key coupled-regulators for malignant phenotype of glioma cells. EphA2 suppression partially reverses the malignant phenotype of aggressive gliomas, possibly through up-regulating the EphrinA1 expression, which indicates that EphA2 and EphrinA1 might become the new targeting molecule for treatment of gliomas.