放射诱导应激颗粒阻隔RFX-1/RBM47抑制焦亡导致鼻咽癌放射抵抗的机制

放射抵抗是鼻咽癌治疗失败的主要原因，阐明其机制并鉴定关键靶点至关重要。前期我们首次发现GSDME依赖的焦亡是鼻咽癌细胞受照射后重要的死亡方式，其发生率与放射敏感性正相关；此外，射线可诱导鼻咽癌细胞产生由eIF2α磷酸化启动组装的应激颗粒，其数量与焦亡发生率负相关；且应激颗粒内含RFX-1和RBM47蛋白，敲减RFX-1或RBM47均下调GSDME mRNA和蛋白表达致放射抵抗；进一步发现RFX-1激活GSDME转录，RBM47结合并稳定GSDME mRNA。由此提出科学假说：射线诱导鼻咽癌细胞内ROS升高，使eIF2α磷酸化激活应激颗粒组装，在空间上阻隔RFX-1和RBM47从多层面下调GSDME表达，从而抑制焦亡导致鼻咽癌放射抵抗。本项目将明确应激颗粒及焦亡在鼻咽癌放射抵抗中的作用，阐明应激颗粒阻隔RFX-1和RBM47发挥功能、抑制焦亡致放射抵抗的机制，为逆转鼻咽癌放射抵抗提供新靶点。

Radiotherapy is the standard of care for nasopharyngeal carcinoma (NPC) and the radioresistance is the main cause for treatment failure, which shows significant importance to clarify its mechanism and identify the key targets. We firstly found that except apoptosis, GSDME-dependent pyroptosis occurred broadly among NPC cell lines after receiving radiation, which was positively correlated with radiosensitivity. Besides, we also found considerable stress granules (SGs) initiated by eIF2α phosphorylation in the NPC cell cytoplasm after radiation, which was negatively correlated with the GSDME-dependent pyroptosis. Further studies indicated that SGs sequestered RFX-1 and RBM47, and knocking down either of them could inhibit GSDME transcription and expression inducing radioresistance; More importantly, we found that the RFX-1 could activate GSDME transcription by binding to its promoter region, and the RBM47 could stabilize GSDME mRNA when binding together. Therefore, we put forward the following scientific hypothesis: radiation could increase ROS to induce eIF2α phosphorylation, then initiate the assembly of SGs, which down-regulate GSDME expression from different levels through sequestering RFX-1 and RBM47 in space, inhibiting the pyroptosis and leading to NPC radioresistance. This project will furtherly investigate the detailed mechanisms underlying how SGs sequester RFX-1 and RBM47 and what are the detailed binding sites of RFX-1 and RBM47 to GSDME, which probably supply novel biomarkers and targets for promoting NPC’s radiosensitivity.