Oct4及其翻译后修饰对脑胶质瘤细胞增殖和致瘤性的调控机制研究

Oct4是维持多潜能干细胞多能性和自我更新至关重要的转录因子。虽在一些肿瘤细胞系和肿瘤组织中检测到Oct4的mRNA或蛋白，但其功能与作用机制都不清楚。我们的前期工作表明Oct4的T235位点可被蛋白激酶Akt磷酸化，该位点的磷酸化修饰可显著促进胚胎癌细胞和脑胶质瘤细胞的自我更新和致瘤性。本项目拟在该基础上，通过质谱技术等全面系统地探明脑胶质瘤细胞中Oct4的关键翻译后修饰（磷酸化、O-糖基化、甲基化）位点，监测脑胶质瘤细胞微球形成和裸鼠移植瘤形成过程中Oct4翻译后修饰谱的动态变化；解析关键位点的翻译后修饰对Oct4蛋白稳定性、胞内定位、蛋白互作和靶基因转录等的调节作用，以及对脑胶质瘤细胞增殖、凋亡和致瘤性等的影响；进一步研究脑胶质瘤患者样本中Oct4翻译后修饰谱与疾病发生发展、预后和耐药的相关性，评价其作为相应生物标志物的可行性，为针对脑胶质瘤的诊治提供新靶标和新策略。

Oct4 is a transcription factor encoded by POU5F1 that plays an indispensible role in maintaining the pluripotency and self-renewal of pluripotent stem cells. Increasing evidence indicated the presence of Oct4 in some tumor tissues and cancer cell lines but the mechanism of action remains unclear. Our previous work showed that Oct4 can be phosphorylated by Akt at T235 which promotes the self-renewal and tumorigenicity of embroynal carcinoma cells and glioblastoma cells. Building upon this foundation, in current project, we plan to systematically identify all the key post-translational modification (PTM) sites in Oct4 in glioblastoma cells and to determine the dynamic changes of the Oct4 PTM profiles during the formation of glioblastoma cell-derived neurospheres and xenografts. The roles of specific PTM sites in regulating the protein stability, intracellular localization, protein-protein interaction and transcriptional activity of Oct4, and their roles in regulating the proliferation, apoptosis and tumorigenicity of glioblastoma cells will all be assessed. The Oct4 PTM profiles will also be determined in the tissues from glioblastoma patients to evaluate the feasibility of using specific Oct4 PTM profiles as a biomarker for prognosis and drug-resistant status.