ZEB2通过miR-637靶向Akt及HMGA1促进胶质瘤细胞生长及抑制凋亡的分子机制

Our previous preliminary investigation suggested that ZEB2 protein was highly expressed in glioma samples than normal brain tissues using immunohistochemical staining, and the expression level of ZEB2 was positively correlated with the status of pathology classification. Furthermore, down-regulation of ZEB2 inhibits glioma cell proliferation, migration, invasion and induced cell cycle arrest at G1/S phase and apoptosis. Further, miRNA array and real-time PCR were used to diffenentially expressed miRNAs in knocking down the expression of ZEB2 in glioma cells, and miR-637 were shown to be upregulated. Based on the bioinformatic analyses and preliminary experiments, we proposed a novel regulatory mechanism of ZEB2: miR-637 is direct transcriptional targets of ZEB2 which binds to 5'-CACCT of miR-637, thereby regulates cell cycle and/or cell apoptotic pathways by targeting Akt and HMGA1 in glioma. Therefore, further studies will be performed as follow: 1) Confirming the role of tumor promotor of ZEB2 in glioma. 2) Validating ZEB2 as a transcription factor to control the expression of miR-637 through directly regulating their promoter. 3) Confirming miR-637 can directly regulate target gene Akt and HMGA1 that mediating cell cycle and/or cell apoptotic pathways. If the project is carried out, we will find a new pathway to elucidate the molecular mechanism of glioma, These findings will provide a potential candidates for targeted therapeutic intervention of glioma.

前期我们初步鉴定ZEB2在胶质瘤中系高表达，并与WHO分级呈正相关，同时，ZEB2能促进胶质瘤细胞侵袭转移、促进细胞周期进展及抑制细胞凋亡。根据miRNAs芯片、生物信息学分析及预实验结果，我们提出一个新的ZEB2调控机制：ZEB2作为转录因子调控miR-637启动子区域的5'-CACCT ( G) 序列，进而调控miR-637靶基因HMGA1及Akt，而HMGA1又可激活PI3K/Akt通路从而抑制胶质瘤细胞生长及促进细胞凋亡。进一步研究将从如下几个方面开展工作：1）确证ZEB2在胶质瘤中发挥癌基因的功能；2）验证ZEB2作为转录因子可以通过直接调节miR-637启动子从而影响其转录；3）明确miR-637直接靶向调节Akt或通过靶向HMGA1激活PI3K/Akt通路参与细胞周期和细胞凋亡过程。如本项目顺利开展，将揭示一个新的ZEB2表达调控机制，为临床治疗复发胶质瘤提供新的基因靶点。

本项目共执行4年，各项工作按照研究计划有序进行，并取得了较好的成果。在项目执行期间，培养了多名中青年科研技术骨干和数名神经外科硕、博士。研究内容具体如下：.1.我们前期发现ZEB2在胶质瘤中高表达，且与肿瘤的进展正相关，ZEB2可以促进胶质瘤细胞的增殖、迁移与侵袭。.2.我们通过miRNA芯片测序，生物信息学分析以及相关分子生物学实验，发现ZEB2可以结合到miR-637的启动子区，进而下调miR-637的表达。该部分结果尚未发表.3.我们发现miR-637的下调可以促进胶质瘤细胞的增殖、迁移与侵袭，这与我们的前期结果相吻合。.4.通过生物信息学分析及相应的分子生物学实验，我们发现miR-637可以直接结合Akt1的mRNA进而下调其表达，说明miR-637在胶质瘤中发挥了抑癌作用，同时也可能是一个诊断胶质瘤的标志及治疗胶质瘤的有效靶点。.5.我们同时发现miR-637可以结合HMGA1的mRNA进而下调其表达从而影响PI3K/Akt通路，这有可能是miR-637发挥作用的另外一条信号通路。.6.同时，我们在本项目的资助下，也对胶质瘤手术切除范围对病人的预后影响做了大量临床研究。