EGFRvIII/HOTAIR/NFκB转录调控ALDH1A3参与胶质瘤干细胞间质表型转化的机制研究

Glioma stem cell is the main reason for tumor recurrence, progression and chemoresistance. In our previous studies, mesenchymal phenotype of gliomas was characterized by ALDH1A3 high expression, which was also the dominant isoform for ALDH enzyme activity of glioma stem cells. Furthermore, the expression level of ALDH1A3 was associated with glioma cell migration and invasion, EGFRvIII mutation, and patient clinical prognosis. Here, we propose a hypothesis that EGFRvIII/HOTAIR/NFκB signaling pathway could regulate ALDH1A3 in the mesenchymal phenotype transformation of glioma stem cells. To verify the above hypothesis, on the basis of Chinese Giloma Genome Atlas (CGGA), we will analyze the transcriptional regulation relationships between EGFRvIII mutation and ALDH1A3 expression through HOTAIR and its target genes and NFκB signaling pathway, and explore their functional roles in mesenchymal phenotype transformation of glioma stem cells via a series of molecular biology avenues in vitro and in vivo. In summary, the present study aims to investigate the regulatory mechanisms of EGFRvIII and ALDH1A3 in stemness maintenance and phenotype transformation of glioma stem cells, and evaluate its significance in glioma molecular diagnosis, prognosis estimation and targeted therapy.

胶质瘤干细胞是脑胶质瘤复发、进展和产生耐药性的根源。我们前期研究发现ALDH1A3作为间质型胶质瘤的特征性标记物，也是决定胶质瘤干细胞ALDH酶的主要亚型，可促进胶质瘤细胞的迁移和侵袭，并且与EGFRvIII突变及患者生存预后显著相关。为此，我们提出假说：EGFRvIII/HOTAIR/NFκB转录调控ALDH1A3参与胶质瘤干细胞的间质表型转化。为了验证这一假说，本项目将依托已经建立的中国脑胶质瘤基因组学数据库，利用体外细胞系和动物成瘤模型，分析EGFRvIII突变通过HOTAIR作用于靶基因进而影响NFκB信号通路，实现对胶质瘤干细胞关键分子ALDH1A3的调控作用，深入解析EGFRvIII与ALDH1A3联合调控胶质瘤干细胞分子表型转化的分子机制。本研究将从间质表型转化这个新视点揭示胶质瘤干细胞的分子调控机制，为脑胶质瘤的分子诊断、预后判断及靶向治疗提供全新思路。

胶质瘤干细胞是脑胶质瘤复发、进展和产生耐药性的根源。我们前期研究发现ALDH1A3作为间质型胶质瘤的特征性标记物，也是决定胶质瘤干细胞ALDH酶的主要亚型，可促进胶质瘤细胞的迁移和侵袭，并且与EGFRvIII突变及患者生存预后显著相关。为探索胶质瘤干细胞EGFRvIII如何调控ALDH1A3表达进而影响胶质瘤化疗耐药性。我们构建了EGFRvIII 过表达的脑胶质瘤细胞系与脑胶质瘤干细胞系，在转录组水平与蛋白水平证实 EGFRvIII 对 ALDH1A3 的表达调控；证明了ALDH1A3 表达的改变调控脑胶质瘤细胞与脑胶质瘤干细胞的间质表型转化，改变肿瘤间质表型相关的肿瘤生物学行为并通过激活 NFκB 信号通路促进了化疗耐药性产生；构建了以 ALDH1A3 为核心的脑胶质瘤间质表型相关基因的预后预测模型，预测脑胶质瘤的化疗敏感性。此外，在研究中我们还发现，ALDH1A3作为关键基因引起脑胶质瘤干细胞的代谢组改变，通过对相关细胞的代谢组学检测，发现磷酸戊糖途径（PPP）在胶质瘤干细胞干性特征维持过程中可能扮演重要角色，另外还发现ALDH1A3可能通过调控CXXC4表达影响基因组甲基化状态，从而导致替莫唑胺耐药性的改变。上述结论为更进一步探索与逆转ALDH1A3引起的脑胶质瘤干细胞化疗耐药提供了新的突破口。