肿瘤干细胞标志物CD133与DNA甲基化酶DNMT1相互作用的功能和机制

CD133, a widely known marker of cancer stem cell, plays critical roles in tumor initiation, invasion, migration and drug-fast. Thus, CD133 has been considered as a new target for cancer therapy. However, CD133-mediaed signaling pathways remain largely known. Our previous study showed that CD133 was located in the nuclear of glioma stem cell. The nuclear localization of CD133 was correlated with histopathological grade and glioma recurrence. Furthermore, CD133 physically interacted with DNA methyltransferase 1 (DNMT1) and regulated the transcription and promoter methylation of DNMT1 target gene p21. CD133 regulates glioma stem cell self-renewal through up-regulation of p21 transcription. Increasing evidence show that p21 promotes genomic stability in cancer stem cells and maintains the self-renewal capacity of cancer stem cells. Thus, we speculate that the interaction between nuclear CD133 and DNMT1 might regulate the self-renewal of glioma stem cell through regulation p21 promoter methylation. In this project, we intend to uncover the molecular mechanism and biological function of the interaction between CD133 and DNMT1 in glioma stem cell self-renewal, quiescence, drug-fast and tumor initiation. Through these efforts, firstly, we hope to illuminate nuclear CD133-DNMT1-p21 signaling axis, thus exploring the mechanism and function of CD133 nuclear localization. Second, this project will uncover the mechanism maintain glioma stem cell self-renewal, thus providing clues to target glioma stem cell.

肿瘤干细胞标志物CD133在肿瘤启动、耐药、侵袭中发挥着重要的功能，有望成为肿瘤治疗的新靶点。然而CD133 直接介导的信号通路不明，成为其在肿瘤干细胞分选、功能研究和临床应用的瓶颈之一。我们前期研究发现:(1)CD133能定位于胶质瘤干细胞细胞核;(2)核定位CD133能与DNA甲基化酶DNMT1相互作用，继而抑制肿瘤干细胞自我更新维持基因p21的启动子甲基化;(3)CD133籍此激活p21转录，从而促进胶质瘤干细胞自我更新。鉴于此，本项目拟利用人胶质瘤标本、胶质瘤干细胞模型和小鼠胶质瘤原位模型，阐释CD133和DNMT1相互作用的机制、调控因素及其在胶质瘤干细胞自我更新、成瘤、耐药中的功能和机制，有望首次揭示出维持胶质瘤干细胞自我更新的核CD133-DNMT1-p21信号轴，发现不同于膜定位CD133的信号通路，为了解胶质瘤干细胞自我更新的分子机制、开展肿瘤干细胞的靶向治疗提供新思路。

肿瘤干细胞标志物CD133在肿瘤启动、耐药、侵袭中发挥着重要的功能，有望成为肿瘤治疗的新靶点。然而CD133 直接介导的信号通路不明，成为其在肿瘤干细胞分选、功能研究和临床应用的瓶颈之一。本项目利用人胶质瘤标本、胶质瘤干细胞模型和小鼠胶质瘤原位模型，阐释CD133和DNMT1相互作用的机制、调控因素及其在胶质瘤干细胞自我更新、成瘤、耐药中的功能和机制。研究发现：CD133能与DNA甲基化酶DNMT1相互作用，继而抑制肿瘤干细胞自我更新维持基因p21的启动子甲基化，CD133籍此激活p21转录，从而促进胶质瘤干细胞自我更新； CD133的单泛素化修饰通过和TSG101相互作用促进其分泌，CD133糖基化调控其分泌； CD133的糖链合成酶β1,4-半乳糖基转移酶Ⅴ可以催化Notch1的beta1,4半乳糖基化修饰，半乳凝素3和Notch1的半乳糖基化修饰相互作用可以抑制Notch1的降解，β1,4-半乳糖基转移酶Ⅴ藉次促进胶质瘤启始细胞的成瘤和向血管内皮细胞分化； OGT酶通过对EIF4E的糖基化修饰促进CD133+肿瘤细胞中的自我更新；CD133 与 Src 的相互作用为 Src 提供了结合位点，促进了 Src 激酶活化，促进了 Src 对 FAK 的磷酸化，活化的 Src 和 FAK 可能形成复合物作用于下游的底物，促进细胞骨架蛋白的重塑和细胞迁移。研究成果发表J Biol Chem2篇、Mol Cell Biol1篇等5篇论文；申请2项专利。培养博士研究生3名;参加国内学术会议3次。