内向整流钾离子通道Kir2.1在髓母细胞瘤干细胞侵袭转移中的作用及其机制研究

侵袭转移是髓母细胞瘤（髓母）患者最重要的死亡原因，但其分子机制不清。我们前期分离鉴定出髓母干细胞，发现其具有高侵袭转移特性。经基因表达谱芯片分析发现，内向整流钾离子通道Kir2.1在髓母干细胞中高表达，且与髓母干细胞干性特征及侵袭转移特性密切相关，但不依赖其离子通道功能。生物信息学分析表明Kir2.1可能与CASK相互作用，后者可促进Reelin的表达，而Reelin能激活PI3K/Akt信号通路。因此，我们推测Kir2.1可能通过与CASK相互作用而促进Reelin的表达，继而激活PI3K/Akt信号通路而最终促进髓母的侵袭和转移。本项目拟用髓母干细胞及临床标本为材料，采用qPCR、RNAi、Western blot、Co-IP、流式细胞术和免疫组化等方法技术，实施一系列体内、外实验证明这一假设，有望丰富和加深对髓母侵袭转移机制的认识，并为髓母的治疗提供新思路和新靶标。

The invasion and metastasis are the most important causes of death in medulloblastoma (MB) patients, but the underlying molecular mechanisms are unclear. Previously, we isolated and characterized MB stem cells, and found that the cells possess high ability of invasion and metastasis. By using the gene expression microarray, we found that the inward rectifier potassium channel Kir2.1 is highly expressed in MB stem cells compared with differentiated cells. The expression level of Kir2.1 was associated with stem-like features and abilities of invasion and metastasis in an ion channel-independent manner. Bioinformatics revealed that PDZ-binding motif of Kir2.1 may interact with CASK. CASK can target and enhance the expression of Reelin, an activator of PI3K/Akt signaling pathway. Therefore, we hypothesize that Kir2.1 expressed in MB can interact with CASK and enhance the expression of Reelin. Reelin further activates the PI3K/Akt pathway which promotes the invasion and metastasis of MB. In this study, we plan to demonstrate this hypothesis by employing MB stem cells and clinical samples as materials, and using a series of methods, such as qPCR, RNAi, Western blotting, Co-IP, flow cytometry and performing a series of experiments in vitro and in vivo. It would contribute to understanding the mechanism of invasion and metastasis of MB and could provide new targets for treatment of MB.