自噬在电离辐射诱发重编程中的作用及串话调控机制研究

The radiotherapy has been challenged by the radiation-induced reprogramming (RIR) occurring in the differentiated cancer cells, which finally induces the tumor recurrence due to the cells dedifferentiating toward a stem-like state. However, the mechanism of RIR still remains elusive. Our previous data showed that accompany by the induction of RIR, autophagy was greatly inhibited during the switch of the differentiated glioma cells to the induced-cancer stem cells (iCSCs). Further, wsing thioridazine (TDZ) to induce the autophagy in differentiated glioma cells after 3Gy γ-rays exposure, the number of glioma stem-like cells greatly reduced. However, is the inhibition of autophagy necessary for the RIR initiation? Also, how the dedifferentiating cells finish the reshaping (mitochondrial remodelling and cell size reduction) under the inhibition of autophagy? .There are three specific aims in this study: Aim 1, to detect and confirm the trends of RIR and autophagy after glioma cells exposure to sub-toxic radiation; Aim 2, to test the cross-talk regulation of RIR and autophagy in irradiated glioma cells; and Aim 3, to examine the molecular network and mechanism of TCTP-mTORC1 in the regulation of RIR and autophagy, also, by using the TCTP inhibitors and autophagy activators in the animal experiments, to detect the potential drugs in devastating RIR and sensitizing glioma cells to radiation.The new regulation network and molecular mechanism in RIR, if identified, will provide novel insights of setting up new clinical strategies to restrain the tumor recurrence after radiotherapy.

辐射诱导重编程（RIR）是放射领域的新挑战,已分化肿瘤细胞重获“干性”将导致复发和治疗失败，但RIR的调控机制尚未揭示。研究表明，自噬调控“正常细胞→iPSCs”的重编程进程，mTORC1是介导重编程-自噬串话的关键分子。自噬是辐照后胶质瘤细胞的主要死亡方式，我们的前期研究却发现：胶质瘤细胞RIR的启动和高峰阶段伴随自噬抑制，激活自噬可有效破坏RIR。然而，自噬受抑是否是RIR启动的必要因素？自噬受抑状态下如何完成重编程的细胞和线粒体重塑？成为疑问。我们和其他团队已证实，TCTP是启动重编程的“开关”分子，其抑制剂TDZ可激活自噬并破坏重编程。尽管TCTP-mTORC1存在多种交互调控关系，但在RIR-自噬调控中的作用却一无所知。本课题拟在前期基础上，以胶质瘤细胞为对象，围绕TCTP-mTORC1深入探讨自噬与RIR的串话调控规律及机制，为寻找新型放疗增敏剂和抗肿瘤复发药物提供重要依据。

已分化胶质瘤细胞重获“干性”是导致脑胶质瘤放疗后复发和治疗失败的重要原因，但其机制尚不明确。前期课题组发现胶质瘤细胞辐射诱导的重编程（RIR）的启动和高峰阶段伴随自噬抑制，激活自噬可有效破坏RIR，鉴于TCTP是启动重编程的“开关”分子，且其抑制剂具有激活自噬的作用，本课题在前期基础上，以胶质瘤细胞为对象，围绕多能转录因子-TCTP和辐射诱导的自噬-重编程间的交互调控作用进行深入研究，并开展靶向TCTP药物筛选研究。项目组相继明确受照胶质瘤细胞自噬和重编程发生的时程规律，揭示TCTP蛋白与转录因子Oct4和Nanog在蛋白和启动子水平均存在相互调控和影响线粒体分裂，参与受照GBM细胞线粒体重塑的作用；同时阐明了TCTP通过调控Beclin 1和mTORC1复合物抑制受照GBM细胞自噬发生的分子机制，并证实自噬和重编程在受照GBM细胞中存在交互抑制的作用；此外，我们证实TCTP参与胶质瘤细胞干性特征维持，并与胶质瘤细胞放疗抵抗和预后密切相关，最后通过离体及在体实验筛选出可有效靶向TCTP提高胶质瘤细胞放疗敏感性的药物（双氢青蒿素DHA）。研究结果有望为阐明辐射诱导肿瘤细胞重编程为肿瘤干细胞提供新的理论依据，同时明确了TCTP高表达作为胶质瘤放化疗抵抗的相关机制，为解决临床胶质瘤放疗抵抗问题提供新的靶点，筛选出的抑制剂有望为胶质瘤患者带来福音。

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