Nrf2-TET1交互对话调控化疗诱导的胶质瘤焦亡的机制研究

The prognosis of glioma is severely affected by chemoresistance. Nrf2 is stablely overexpressed in glioma and protects tumor as an important protectin. But the mechanism under Nrf2 overexpression in glioma and its role in chmoresistance still need further research. Our previous results indicate that Nrf2 regulates proliferation, apoptosis, migration, angiogenesis and stem cell differentiation of glioma. And the results of preliminary experiment indicate that Nrf2 plays an important role in chemoresistance of glioma. Silencing Nrf2 promoted pyroptosis induced by chemotherapy in glioma. Also expression of TET1 and Nrf2 was enhanced in glioma, which may be regulated by each other. Based on our previous results and reviews over pertinent literature, the complicated relationship among Nrf2 and TET catch our attention. We presume that the crosstalk between Nrf2 and TET1 may exist in glioma and induce persistent high level expression of Nrf2, which further lead to chemoresistance. So the hypothesis is that Nrf2 and TET1 crosstalk may regulate pyroptosis induced by chemotherapy in glioma. Based on preliminary study, the relationship of Nrf2 and TET1 in glioma and its role in glioma prognosis would be further studied by molecular biological, methylation detection and transgenes technique in vivo and in vitro. This study is source of innovation. And the results will reveal the mechanism of glioma chemoresistance, which will provide new thread for effective therapy and new target for drug development.

化疗耐药严重影响胶质瘤患者的预后，Nrf2作为重要的保护因子在胶质瘤内持续高表达并保护肿瘤细胞，但其持续高表达的机制尚不清楚。申请人的前期研究首次证实Nrf2调控胶质瘤的增殖、凋亡、迁移、血管生成及分化，预实验结果提示沉默Nrf2可促进化疗诱导的胶质瘤焦亡，Nrf2与TET1在胶质瘤内表达增高并存在相互调节。基于1)Nrf2、TET1存在调控关系；2)Nrf2、TET1在胶质瘤内表达增高，推测可能存在Nrf2-TET1之间的交互对话导致两者持续性激活，从而导致肿瘤恶性表型增加，并提出“Nrf2-TET1交互对话影响化疗诱导的胶质瘤焦亡”的假说。本项目基于前期研究基础，通过体内外实验及分子生物学、转基因、表观遗传相关技术，进一步验证胶质瘤内Nrf2与TET1的相互关系及两者与胶质瘤预后的关系，明确Nrf2持续高表达机制及调控该对话机制对预后的影响。本研究属源头创新，可为临床治疗提供新的方向。

胶质瘤化疗耐药是胶质瘤患者预后不良的重要影响因素。课题组既往研究发现Nrf2、TET1在胶质瘤内高表达，并基于文献提出Nrf2-TET1交互对话影响化疗诱导的胶质瘤焦亡。研究内容如下：.第一部分：胶质瘤组织与细胞内Nrf2、TET1表达水平增高，且Nrf2启动子甲基化水平处于低位。过表达载体分别上调胶质瘤内Nrf2、TET1表达水平，发现Nrf2表达升高可以通过下调miR-29b而促进TET1表达，TET1升高通过降低Nrf2启动子甲基化水平而促进Nrf2表达，存在Nrf2-TET1交互对话机制。.第二部分：体外实验利用耐药胶质瘤细胞系及亲本细胞系，发现耐药细胞内TET1表达水平升高，Nrf2启动子甲基化水平下降。且TMZ可诱导TET1表达水平、活性增高。化疗诱导的TET1增高进一步促进Nrf2启动子去甲基化从而诱导Nrf2-ARE通路基因活化，成为胶质瘤细胞耐药的重要机制。.第三部分：体内体外实验发现，慢病毒载体分别抑制胶质瘤细胞内Nrf2、TET1表达，细胞增殖能力下降，化疗诱导焦亡水平增加，焦亡相关蛋白表达升高。移植瘤体积明显缩小。提示Nrf2-TET1对话机制在化疗诱导的细胞焦亡中其重要作用。