Abstract：
Radioresistance is an inevitable obstacle in the clinical treatment of inoperable patients with non-small cell lung cancer (NSCLC). Combining treatment with radiosensitizers may improve the efficacy of radiotherapy. Previously, the quinoline derivative 10E as new exporter of Nur77 has shown superior antitumor activity in hepatocellular carcinoma. Here, we aimed to investigate the radiosensitizing activity and acting mechanisms of 10E. In vitro, A549 and H460 cells were treated with control, ionizing radiation (IR), 10E, and 10E + IR. Cell viability, apoptosis, and cycle were examined using CCK-8 and flow cytometry assays. Protein expression and localization were examined using western blotting and immunofluorescence. Tumor xenograft models were established to evaluate the radiosensitizing effect of 10E in vivo. 10E significantly inhibited cell proliferation and increased their radiosensitivity while reducing level of p-BCRA1, p-DNA-PKs, and 53BP1 involved in the DNA damage repair pathway, indicating that its radiosensitizing activity is closely associated with repressing DNA damage repair. A549 cells showed low level of Nur77 and a low response to IR but 10E-treated A549 cells showed high level of Nur77 indicating that Nur77 is a core radiosensitivity factor and 10E restores the expression of Nur77. Nur77 and Ku80 extranuclear co-localization in the 10E-treated A549 cells suggested that 10E-modulated Nur77 nuclear exportation inhibits DNA damage repair pathways and increases IR-triggered apoptosis. The combination of 10E and IR significantly inhibits tumor growth in a tumor xenograft model. Our findings suggest that 10E acts as a radiosensitizer and that combining 10E with radiotherapy may be a potential strategy for NSCLC treatment.
摘要：
在不能手术的非小细胞肺癌（NSCLC）患者的临床治疗中，辐射抵抗是不可避免的障碍。与放射增敏剂联合治疗可以提高放疗的疗效。以前,喹啉衍生物10E作为Nur77的新出口国在肝细胞癌中显示出优越的抗肿瘤活性。这里,我们旨在研究10E的放射增敏活性和作用机制。体外，A549和H460细胞用对照处理，电离辐射(IR),10E,和10E+IR。细胞活力，凋亡，并使用CCK-8和流式细胞术检测周期。使用蛋白质印迹和免疫荧光检查蛋白质表达和定位。建立肿瘤异种移植模型以评估10E的体内放射增敏作用。10E显着抑制细胞增殖并增加其放射敏感性，同时降低p-BCRA1，p-DNA-PKs的水平，53BP1参与DNA损伤修复途径，表明其放射增敏活性与抑制DNA损伤修复密切相关。A549细胞显示出低水平的Nur77和对IR的低反应，但10E处理的A549细胞显示出高水平的Nur77，表明Nur77是核心放射敏感性因子，10E恢复了Nur77的表达。Nur77和Ku80在10E处理的A549细胞中的核外共定位表明10E调节的Nur77核输出抑制DNA损伤修复途径并增加IR触发的凋亡。10E和IR的组合显著抑制肿瘤异种移植模型中的肿瘤生长。我们的发现表明10E作为放射增敏剂，将10E与放疗结合可能是NSCLC治疗的潜在策略。
