Radioresistance is a major challenge that largely limits the efficacy of radiotherapy in lung cancer. Gold nanoparticles (AuNPs) are emerging as novel radiosensitizers for cancer patients. Therefore, this study was designed to explore the radiosensitizing effect and mechanism of AuNPs loaded with small interfering RNA (siRNA)-SP1 (AuNPs-si-SP1) on lung cancer. AuNPs-si-SP1 was prepared by the noncovalent binding between AuNPs and siRNA-SP1. The adsorption capacity of AuNPs to siRNA-SP1 was analyzed by gel electrophoresis. The cell uptake of AuNPs-si-SP1 was observed under a laser confocal microscopy. Silencing efficacy of AuNPs-si-SP1 was validated by RT-qPCR and Western blot analysis. Cell viability was determined by CCK-8 assay, radiosensitization by plate colony formation assay, cell apoptosis and cell cycle by flow cytometry, and DNA double strand breaks by immunofluorescence in the presence or absence of AuNPs-si-SP1 or GZMB. The downstream mechanism of SP1 was predicted by bioinformatics analysis, followed by verification by Western blot analysis. Subcutaneous tumorigenesis in nude mice was established to verify the radiosensitization of AuNPs-si-SP1 and GZMB in vivo. AuNPs-si-SP1 effectively absorbed SP1 siRNA and was highly internalized by A549 cells to reduce SP1 protein expression. AuNPs-si-SP1 or GZMB overexpression promoted cells to G2/M phase, DNA double strand breaks, and enhanced radiosensitivity. SP1 could repress GZMB expression in lung cancer cells. In vivo experiments manifested that AuNPs-si-SP1 could inhibit the growth of solid tumor in nude mice to achieve radiosensitization by inhibiting SP1 to upregulate GZMB. AuNPs-si-SP1 might increase the radiosensitivity of lung cancer by inhibiting SP1 to upregulate GZMB.

放射抗性是一个主要挑战，在很大程度上限制了放疗在肺癌中的疗效。金纳米粒子 (AuNPs) 正在成为癌症患者的新型放射增敏剂。因此，本研究旨在探讨负载小干扰RNA（siRNA）-SP1（AuNPs-si-SP1）的AuNPs对肺癌的放射增敏作用及其机制。AuNPs-si-SP1 是通过 AuNPs 和 siRNA-SP1 之间的非共价结合制备的。通过凝胶电泳分析 AuNPs 对 siRNA-SP1 的吸附能力。在激光共聚焦显微镜下观察 AuNPs-si-SP1 的细胞摄取。通过 RT-qPCR 和蛋白质印迹分析验证了 AuNPs-si-SP1 的沉默功效。通过CCK-8测定法测定细胞活力，通过平板集落形成测定法测定放射增敏作用，通过流式细胞术测定细胞凋亡和细胞周期，在 AuNPs-si-SP1 或 GZMB 存在或不存在的情况下，通过免疫荧光使 DNA 双链断裂。通过生物信息学分析预测 SP1 的下游机制，然后通过蛋白质印迹分析进行验证。建立裸鼠皮下致瘤以验证AuNPs-si-SP1和GZMB的放射增敏作用体内。AuNPs-si-SP1 有效吸收 SP1 siRNA 并被 A549 细胞高度内化以降低 SP1 蛋白表达。AuNPs-si-SP1 或 GZMB 过表达促进细胞进入 G2/M 期、DNA 双链断裂并增强放射敏感性。SP1 可以抑制肺癌细胞中 GZMB 的表达。体内实验表明，AuNPs-si-SP1可以通过抑制SP1上调GZMB来抑制裸鼠实体瘤的生长，从而达到放射增敏作用。AuNPs-si-SP1 可能通过抑制 SP1 上调 GZMB 来增加肺癌的放射敏感性。