School of Medicine, Southeast University, Nanjing 210009, People's Republic of China.
Radiotherapy Department, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, People's Republic of China.
Nanotechnology. 2021 Apr 2;32(14):145102. doi: 10.1088/1361-6528/abd20a.
Radioresistance significantly decreases the efficacy of radiotherapy, which can ultimately lead to tumor recurrence and metastasis. As a novel type of nano-radiosensitizer, silver nanoparticles (AgNPs) have shown promising radiosensitizing properties in the radiotherapy of glioma, but their ability to efficiently enter and accumulate in tumor cells needs to be improved. In the current study, AS1411 and verapamil (VRP) conjugated bovine serum albumin (BSA) coated AgNPs (AgNPs@BSA-AS-VRP) were synthesized and characterized. Dark-field imaging and inductively coupled plasma mass spectrometry were applied to investigate the accumulation of AgNPs@BSA-AS and AgNPs@BSA-AS-VRP mixed in different ratios in U251 glioma cells. To assess the influences of 19:1 mixed AgNPs@BSA-AS and AgNPs@BSA-AS-VRP on the P-glycoprotein (P-gp) efflux activity, rhodamine 123 accumulation assay was carried out. Colony formation assay and tumor-bearing nude mice model were employed to examine the radiosensitizing potential of 19:1 mixed AgNPs@BSA-AS and AgNPs@BSA-AS-VRP. Thioredoxin Reductase (TrxR) Assay Kit was used to detect the TrxR activity in cells treated with different functionally modified AgNPs. Characterization results revealed that AgNPs@BSA-AS-VRP were successfully constructed. When AgNPs@BSA-AS and AgNPs@BSA-AS-VRP were mixed in a ratio of 19:1, the amount of intracellular nanoparticles increased greatly through AS1411-mediated active targeting and inhibition of P-gp activity. In vitro and in vivo experiments clearly showed that the radiosensitization efficacy of 19:1 mixed AgNPs@BSA-AS and AgNPs@BSA-AS-VRP was much stronger than that of AgNPs@BSA and AgNPs@BSA-AS. It was also found that 19:1 mixed AgNPs@BSA-AS and AgNPs@BSA-AS-VRP significantly inhibited intracellular TrxR activity. These results indicate that 19:1 mixed AgNPs@BSA-AS and AgNPs@BSA-AS-VRP can effectively accumulate in tumor cells and have great potential as high-efficiency nano-radiosensitizers in the radiotherapy of glioma.
放射抗性显著降低了放射治疗的疗效，最终导致肿瘤复发和转移。作为一种新型的纳米增敏剂，银纳米粒子（AgNPs）在胶质母细胞瘤的放射治疗中显示出有前途的放射增敏特性，但它们有效进入和积累在肿瘤细胞中的能力需要提高。在本研究中，合成并表征了 AS1411 和维拉帕米（VRP）偶联牛血清白蛋白（BSA）包裹的 AgNPs（AgNPs@BSA-AS-VRP）。暗场成像和电感耦合等离子体质谱法用于研究不同比例混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 在 U251 神经胶质瘤细胞中的积累。为了评估 19:1 混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 对 P-糖蛋白（P-gp）外排活性的影响，进行了罗丹明 123 积累测定。集落形成实验和荷瘤裸鼠模型用于检测 19:1 混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 的放射增敏潜力。使用硫氧还蛋白还原酶（TrxR）试剂盒检测用不同功能修饰的 AgNPs 处理的细胞中的 TrxR 活性。表征结果表明成功构建了 AgNPs@BSA-AS-VRP。当 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 以 19:1 的比例混合时，通过 AS1411 介导的主动靶向和抑制 P-gp 活性，细胞内纳米颗粒的数量大大增加。体外和体内实验清楚地表明，19:1 混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 的放射增敏效果明显强于 AgNPs@BSA 和 AgNPs@BSA-AS。还发现 19:1 混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 显著抑制了细胞内 TrxR 活性。这些结果表明，19:1 混合的 AgNPs@BSA-AS 和 AgNPs@BSA-AS-VRP 可以有效地积累在肿瘤细胞中，并且作为胶质母细胞瘤放射治疗的高效纳米增敏剂具有很大的潜力。
