肿瘤DNA异常甲基化受甲基化酶、组氨酸和核小体等多因素调控(Cell Reports 2012),它是促进恶性胶质瘤发生发展的重要原因。PTEN或miR-149的甲基化失活可激活胶质瘤的关键信号通路PI3K-AKT，但其下游途径则有待深入探索。在恶性胶质瘤中，申请人的前期研究发现PTEN或miR-149甲基化能使EZH2发生AKT依赖性磷酸化；磷酸化的EZH2则进一步与NFKB分子结合。这高度提示EZH2可连接PI3K-AKT和NFKB通路，从而形成AKT-EZH2-NFKB轴。因此，申请人将用免疫沉淀和信号阻断等方法证明该轴在恶性胶质瘤中是否存在；并在原代细胞和荷瘤裸鼠中观察该轴对肿瘤生长的影响；再结合临床资料，分析EZH2磷酸化与肿瘤分级和患者预后的关系。由此可明确PTEN或miR-149的甲基化，是否经AKT-EZH2-NFKB轴而促进胶质瘤的恶性生长，从而为其治疗提供有效的新策略。

Aberrant DNA methylation of tumors, regulated by multiple factors including DNA methyltransferases, histone modifications and nucleosome structure (Cell Reports 2012), plays a very important role in the initiation and development of malignant glioma. The PI3K-AKT pathway, one of the core signaling pathways in glioma, may be activated by epigenetic silencing of PTEN or miR-149. It is, however, not clear what is the downstream of PI3K-AKT pathway when PTEN or miR-149 is inactivated via promoter hypermethylation. In malignant glioma, the applicants of this proposal found that DNA methylation of the PTEN or miR-149 gene induced phosphorylation of EZH2 protein in an AKT-dependant manner, and that the phosphorylated EZH2 physically interacted with RelA: the key subunit of the nuclear factor-κB (NFKB) molecule. These results indicate that EZH2 might link PI3K-AKT and NFKB pathways, which can induce the formation of an AKT-EZH2-NFKB axis in this type of tumor. Based on these findings, the applicants will first investigate whether there exists the AKT-EZH2-NFKB axis in malignant glioma through completion of multiple experiments such as immunoprecipitation and signaling blockade.Furthermore,the applicants will test whether the axis is essential for the malignant growth of primary tumor cells in vitro and in xenografting nude mice. Lastly, the applicants will exam the relationship between activation of the AKT-EZH2-NFKB axis and pathological grading of tumors or prognosis of patients through clinical analysis. Therefore, elucidation of the activation of the AKT-EZH2-NFKB axis initiated by epigenetic selincing of PTEN or miR-149 may provide a novel and effective strategy for the treatment of malignant glioma.