甲基转移酶DOT1L调控膀胱癌干细胞自我更新的作用及分子机制研究

Histone methylation plays an important role in the occurrence and development of tumor. So far, however, little is known about the function and mechanism of histone methylation modification in bladder cancer stem cells. Therefore, this project is aiming to explore the self-renewal regulation mechanism of disruptor of telomeric silencing-1 like (DOT1L) in bladder cancer stem cells, which is a histone methyltransferase. Bladder cancer stem cells were successfully isolated from the previous study. By the expression spectrum microarray and bioinformatics analyses, differential genes were identified, which were closely related to the maintenance of bladder cancer stem cells. We found DOT1L was overexpressed in bladder cancer tissues and bladder cancer stem cells. Knockdown of DOT1L caused smaller numbers of bladder cancer cell spheres, and inhibited the ability of bladder cancer stem cells into tumor. We also found that DOT1L regulated the expression and activation of STAT3 in bladder cancer stem cells. Based on those results, this study will further investigate the self-renewal roles and mechanisms of DOT1L in bladder cancer stem cells, elucidation of the molecular mechanism of DOT1L regulating the expression of STAT3 and regulating the self-renewal of bladder cancer stem cells. This study is expected to clarify the clinical significance of DOT1L as a new target for bladder cancer, and to provide theoretical basis for clinical intervention of bladder cancer.

组蛋白甲基化修饰在肿瘤发生发展中发挥着重要作用，但在膀胱癌干细胞自我更新的维持中知之甚少。因此，本课题将深入研究组蛋白甲基转移酶DOT1L对膀胱癌干细胞自我更新的调控作用及分子机制。我们前期成功分离了膀胱癌干细胞，通过表达谱差异分析，鉴定了一批与膀胱癌干细胞干性维持密切相关的基因。其中，DOT1L在膀胱癌组织和膀胱癌干细胞中显著高表达，其缺失表达导致干细胞小球的数量显著减少，并抑制膀胱癌干细胞成瘤能力。我们还发现在膀胱癌干细胞中DOT1L调控STAT3的表达和活化。在此基础上，我们将探讨DOT1L 在膀胱癌干细胞自我更新中的作用，阐明DOT1L 调控STAT3 转录表达的分子机制，揭示DOT1L 通过调控STAT3进而调节膀胱癌干细胞自我更新的机理，从而明确DOT1L作为膀胱癌干预新靶点的临床意义，为膀胱癌的临床干预提供理论基础。

通过该项目的实施，证实了DOT1L在膀胱癌干细胞及膀胱癌组织中高表达，发现了DOT1L缺失抑制膀胱癌干细胞的自我更新。当DOT1L缺失后，GATA3启动子区域的甲基化减弱，GATA3表达上调，从而抑制了STAT3的表达，实现了对膀胱癌干细胞的抑制。在膀胱癌干细胞中高表达的基因DOT1L和STAT3，可作为膀胱癌干细胞治疗的潜在靶点。同时，我们分析了多个表达谱芯片的分析，发现了LncHand2和LncHDAC2在肝癌和肝癌干细胞中高表达。通过体内体外大量的实验，证明了LncHand2和LncHDAC2与肝癌的起始和进展有密切关系，并阐明了其调控肝癌发生的分子机制。该项目的实施，在肿瘤干细胞自我更新调控机制领域取得了重要的研究成果，为肿瘤干细胞的靶向干预提供了重要的理论依据，已发表该项目标注的研究论文3篇，期间获得2018年北京市科技进步一等奖。通过该项目资助，培养了2名博士毕业。