Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou 730000, China.
Int J Mol Sci. 2023 Jun 26;24(13):10658. doi: 10.3390/ijms241310658.
Radioresistance remains a critical obstacle in the clinical management of glioblastoma (GBM) by radiotherapy. Therefore, it is necessary to explore the molecular mechanisms underlying radioresistance to improve patient response to radiotherapy and increase the treatment efficacy. The present study aimed to elucidate the role of specificity protein 1 (Sp1) in the radioresistance of GBM cells. Different human GBM cell lines and tumor-bearing mice were exposed to ionizing radiation (IR). Cell survival was determined by the colony formation assay. The expression of genes and proteins in the cells and tissues was analyzed by RT-PCR and western blotting, respectively. The γ-H2AX, p-Sp1 and dependent protein kinase catalytic subunit (DNA-PKcs phospho S2056) foci were analyzed by immunofluorescence. Apoptotic rates were measured by flow cytometry. Sp1 was upregulated after IR in vitro and in vivo and knocking down Sp1-sensitized GBM cells to IR. Sp1 activated the DNA-PKcs promoter and increased its expression and activity. Furthermore, the loss of Sp1 delayed double-strand breaks (DSB) repair and increased IR-induced apoptosis of GBM cells. Taken together, IR upregulates Sp1 expression in GBM cells, enhancing the activity of DNA-PKcs and promoting IR-induced DSB repair, thereby leading to increased radioresistance.
放射抗拒性仍然是胶质母细胞瘤（GBM）放射治疗临床管理的一个关键障碍。因此，有必要探索放射抗拒性的分子机制，以提高患者对放射治疗的反应，增加治疗效果。本研究旨在阐明特异性蛋白 1（Sp1）在 GBM 细胞放射抗拒性中的作用。将不同的人 GBM 细胞系和荷瘤小鼠暴露于电离辐射（IR）下。通过集落形成实验测定细胞存活率。分别通过 RT-PCR 和 Western blot 分析细胞和组织中基因和蛋白的表达。通过免疫荧光分析 γ-H2AX、p-Sp1 和依赖蛋白激酶催化亚基（DNA-PKcs 磷酸化 S2056）焦点。通过流式细胞术测量细胞凋亡率。IR 在体外和体内均上调 Sp1，敲低 Sp1 可使 GBM 细胞对 IR 敏感。Sp1 激活了 DNA-PKcs 启动子，增加了其表达和活性。此外，Sp1 的缺失延迟了双链断裂（DSB）修复，并增加了 IR 诱导的 GBM 细胞凋亡。综上所述，IR 上调了 GBM 细胞中的 Sp1 表达，增强了 DNA-PKcs 的活性，促进了 IR 诱导的 DSB 修复，从而导致放射抗拒性增加。
