外泌体介导的miR-151a序贯调控DNA双链断裂修复途径的胶质瘤替莫唑胺耐药机理研究

As key vehicles of intercellular communication, exosomes have been implicated in tumorigenesis and recognized as biomarkers of disease and delivery vehicles for clinical application. In our study, we found that miR-151a expression was lower in TMZ-resistant cells and derived exosomes. Upregulation of miR-151a in glioma cells blocked the emergence of acquired TMZ resistance through targeting XRCC4 and ATM. TMZ-resistant cells derived exosomes were delivered to nearby cells, and then disseminated TMZ resistance. Here, we propose a hypothesis that miR-151a may regulate acquisition of TMZ resistance via sequentially modulating Non Homologous End Joining (NHEJ) and Homologous recombination (HR) DNA repair pathway. Now we aim to validate the functional role of miR-151a in targeting of XRCC4-mediated Non Homologous End Joining (NHEJ) and ATM-mediated Homologous Recombination (HR) DNA repair pathway, analyze how intercellular transfer of miR-151a by exosomes disseminates TMZ resistance, and explore the clinical application of circulating and exosomal miR-151a. In summary, our results may provide novel targets and optimize treatment strategies for molecular targeted therapy to overcome TMZ resistance, enhancing the clinical benefits of TMZ therapy in glioma patients.

外泌体作为细胞间通讯的关键介质，为肿瘤耐药研究提供了新的模式，也有望成为新型诊断标志物和治疗工具。我们前期发现：微小RNA，miR-151a在胶质瘤替莫唑胺耐药细胞及其外泌体中低表达；携带低表达miR-151a的耐药细胞外泌体进入受体细胞，可能通过miR-151a对XRCC4与ATM蛋白的靶向作用，促使受体细胞耐药表型增强。为此本课题拟明确miR-151a靶向 XRCC4和ATM蛋白调控DNA双链断裂修复途径NHEJ和HR通路的过程，解析外泌体介导的miR-151a调控替莫唑胺耐药机制，探索包裹miR-151a的外泌体逆转替莫唑胺耐药的作用，分析循环中外泌体相关miR-151a临床价值。本研究可确立胶质瘤耐药细胞外泌体传递miR-151a通过序贯调控受体细胞中DNA双链断裂修复途径（NHEJ和HR通路）来介导替莫唑胺耐药的机理，为胶质瘤耐药理论提供有益补充，为寻找新治疗靶点提供参考依据。

胶质瘤是最常见的颅内恶性肿瘤，目前治疗方案主要依赖手术及术后放化疗。TMZ是目前胶质瘤一线化疗药化疗，但化疗耐药严重削弱了替莫唑胺(TMZ)对胶质母细胞瘤(GBM)的治疗作用，然而目前耐药机制尚不明确。作为肿瘤微环境中的关键性媒介，外泌体可参与肿瘤多个生物学进程。然而，外泌体能否调控胶质瘤化疗耐药仍有待确定。在本研究中，我们发现miR-151a在TMZ耐受的GBM临床样本和细胞系中表达水平显著下调。敲低miR-151a可促胶质瘤化疗耐药，而过表达miR-151a可通过靶向抑制 XRCC4介导的DNA修复恢复增加胶质瘤细胞对TMZ敏感性。此外，外泌体可通过介导miR-151a在细胞间传递调控胶质瘤TMZ耐药。回复表达耐药细胞外泌体中miR-151a可抑制外泌体介导的耐药性传递。最后，我们发现脑脊液中外泌体miR-151a表达水平可提示患者TMZ敏感性。外泌体miR-151a表达水平不仅可作为生物标记物，还可以作为治疗复发GBM新的潜在治疗靶点。