细胞骨架蛋白Coronin3在胶质母细胞瘤上皮－间质转化中的作用及其分子机制

Since the tumor cells the great capabilities for invasive growth that helps them escape the radiotherapy or/and chemotherapy, glioblastoma (GBM) has become the most common neural tumor with highest malignancy as well as the strongest migration and metastatic recurrence. Therefore, to understand the mechanisms of GBM invasive growing should be of great significance for improving the prognosis of this disease. It has been suggested that the biological process of epithelial to mesenchymal transition (EMT) participates in tumor invasion, in which actin cytoskeleton remodeling is involved as a critical step. Meantime, Coronin 3, a member in the conserved actin-associated proteins, has been described to be overexpressed in GBM and is closely related to its invasion and migration. However, whether Coronin 3 is involved in EMT of glioblastoma as well as its molecular mechanism has not been reported yet. Based on our previous study of the relationship between coronin and actin cytoskeleton, our current study is to confirm the involvement of Coronin 3 in GBM of glioblastoma by the cell experiment. We further try to explore the functions of Coronin 3 in changes of cell polarity, formation of tumor invasion structures, as well as effects of cell migration and invasion. We also try to identify the involved signaling pathway during Coronin 3 participates in EMT. Finally, the animal model of nude rice should be employed to validate the experimental results above. Collectively, our investigation here can reveal the roles of Coronin 3 involved in GBM invasion and migration as well as its related molecular mechanisms, supplying the new idea and therapeutic target for GBM.

胶质母细胞瘤GBM是最常见、恶性程度最高、转移复发能力最强的一种神经胶质肿瘤。其肿瘤细胞具有很强侵袭能力，可逃避放疗、化疗的治疗作用，也是手术治疗预后差的主要原因，故研究GBM侵袭生长相关机制，对改善该疾病的预后有重要意义。前人的研究提示，上皮－间质转化（EMT）参与上皮肿瘤的侵袭过程，但肌动蛋白骨架重塑是EMT的关键环节。Coronin3是一种在GBM中高表达的肌动蛋白结合蛋白，并与肿瘤细胞侵袭生长密切相关，但它是否参与肿瘤EMT过程尚无报道。因此本项目拟在前期工作基础上，通过体外细胞实验探明Coronin 3是否参与GBM进程；明确它对细胞极性改变、侵袭结构形成、和细胞运动能力的影响；鉴定它在EMT中的信号途径；并最终在裸鼠动物模型中验证上述结果。本研究可阐明Coronin3在GBM中的作用及其机制，揭示肌动蛋白骨架在胶质瘤EMT中的分子途径，也为胶质瘤的临床治疗提供新靶点和新思路。

证据表明Coronin3在各种癌症中异常表达，与癌症的发生和发展有关，然而目前对Coronin3细胞骨架蛋白的研究大多集中在肝癌、肺癌、胃癌、食管癌和乳腺癌等方面，胶质瘤中对于Coronin3的研究也有报道，但深入机制无最新进展，而且这些研究中并未涉及到上皮-间质转化（epithelial to mesenchymal transition，EMT）过程。我们团队旨在探讨Coronin3在胶质母细胞瘤（GBM）中的生物学功能和调控机制，揭示肌动蛋白骨架在胶质瘤EMT中所需的分子途径。通过shRNA和siRNA敲低策略评估了GBM细胞系T98G细胞的肿瘤特征。验证了调控EMT进程的ZEB2蛋白在这一进程中的作用。结果显示：与野生T98G细胞株相比，Coronin3蛋白的敲低显著抑制了EMT进程中间质相关蛋白的表达（包括N-cadherin蛋白和vimentin蛋白），提高了EMT进程中上皮相关蛋白的表达（E-cadherin蛋白）。同时，敲低Coronin3的表达后也明显抑制了体外神经胶质瘤细胞的增殖、迁移和侵袭能力，细胞形态也由椭圆形变成了长梭形。而通过细胞免疫荧光的方法检测细胞极性标志物定位改变时发现细胞极性标志物GM130蛋白和MUC蛋白的位置和表达量并未随Coronin3表达量的变化而发生改变。此外，在后续的研究中我们还发现，调控EMT的关键蛋白ZEB2与Coronin3蛋白密切正相关，这或许可以成为探明Coronin3蛋白影响胶质瘤细胞EMT进程具体通路的关键突破点。通过以上研究，阐明了Coronin3在胶质瘤中的作用，揭示了肌动蛋白骨架在胶质瘤EMT中所产生的影响，也为胶质瘤的分子治疗提供了新靶点和新思路。