Molecular Tumorbiology, Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
Nanoscale. 2015 May 21;7(19):8931-8. doi: 10.1039/c5nr01167a.
The potential toxicity of nanoparticles has currently provoked public and scientific discussions, and attempts to develop generally accepted handling procedures for nanoparticles are under way. The investigation of the impact of nanoparticles on human health is overdue and reliable test systems accounting for the special properties of nanomaterials must be developed. Nanoparticular zinc oxide (ZnO) may be internalised through ambient air or the topical application of cosmetics, only to name a few, with unpredictable health effects. Therefore, we analysed the determinants of ZnO nanoparticle (NP) genotoxicity. ZnO NPs (15-18 nm in diameter) were investigated at concentrations of 0.1, 10 and 100 μg mL(-1) using the cell line A549. Internalised NPs were only infrequently detectable by TEM, but strongly increased Zn(2+) levels in the cytoplasm and even more in the nuclear fraction, as measured by atom absorption spectroscopy, indicative of an internalised zinc and nuclear accumulation. We observed a time and dosage dependent reduction of cellular viability after ZnO NP exposure. ZnCl2 exposure to cells induced similar impairments of cellular viability. Complexation of Zn(2+) with diethylene triamine pentaacetic acid (DTPA) resulted in the loss of toxicity of NPs, indicating the relevant role of Zn(2+) for ZnO NP toxicity. Foci analyses showed the induction of DNA double strand breaks (DSBs) by ZnO NPs and increased intracellular reactive oxygen species (ROS) levels. Treatment of the cells with the ROS scavenger N-acetyl-l-cysteine (NAC) resulted in strongly decreased intracellular ROS levels and reduced DNA damage. However, a slow increase of ROS after ZnO NP exposure and reduced but not quashed DSBs after NAC-treatment suggest that Zn(2+) may exert genotoxic activities without the necessity of preceding ROS-induction. Our data indicate that ZnO NP toxicity is a result of cellular Zn(2+) intake. Subsequently increased ROS-levels cause DNA damage. However, we found evidence for the assumption that DNA-DSBs could be caused by Zn(2+) without the involvement of ROS.
纳米粒子的潜在毒性目前引起了公众和科学界的讨论，并且正在努力制定普遍接受的纳米粒子处理程序。对纳米粒子对人类健康的影响的研究已经滞后，必须开发考虑到纳米材料特殊性质的可靠测试系统。纳米氧化锌（ZnO）可能通过环境空气或化妆品的局部应用等途径被人体吸收，其健康影响难以预测。因此，我们分析了 ZnO 纳米粒子（NP）遗传毒性的决定因素。我们使用 A549 细胞系，研究了直径为 15-18nm 的 ZnO NPs，浓度分别为 0.1、10 和 100μg/ml。通过 TEM 仅偶尔能检测到内吞的 NPs，但原子吸收光谱法测量到细胞质中，甚至核部分中 Zn（2+）水平明显升高，表明内吞锌和核积累。我们观察到 ZnO NP 暴露后细胞活力呈时间和剂量依赖性降低。ZnCl2 暴露于细胞也会导致细胞活力相似的损伤。用二乙三胺五乙酸（DTPA）络合 Zn（2+）导致 NP 的毒性丧失，表明 Zn（2+）对 ZnO NP 毒性的重要作用。焦点分析表明 ZnO NPs 可诱导 DNA 双链断裂（DSBs）并增加细胞内活性氧（ROS）水平。用 ROS 清除剂 N-乙酰-L-半胱氨酸（NAC）处理细胞可导致细胞内 ROS 水平显著降低和 DNA 损伤减少。然而，ZnO NP 暴露后 ROS 缓慢增加，NAC 处理后 DSBs 减少但未完全抑制，表明 Zn（2+）可能在不需要 ROS 诱导的情况下发挥遗传毒性作用。我们的数据表明，ZnO NP 的毒性是细胞摄取 Zn（2+）的结果。随后增加的 ROS 水平会导致 DNA 损伤。但是，我们发现了一个证据，表明 DNA-DSBs 可能是由 Zn（2+）引起的，而不涉及 ROS。
