ZnO nanoparticles induce apoptosis in human dermal fibroblasts via p53 and p38 pathways.

The production of engineered nanoparticles is growing rapidly as the field of nanotechnology continues to expand. Zinc oxide nanoparticles (ZnO NPs) are used in various applications, including catalysis, electronics, biosensors, medicine, paints, sunscreens and cosmetics, thus it is important to understand the biological effects and risks of ZnO NPs. This study was designed to investigate the apoptosis induction by ZnO NPs via mitogen-activated protein kinase p38 and cell cycle checkpoint protein p53 pathways in human dermal fibroblasts. MTT-based cell viability assay showed a significant decrease in cell survivorship after ZnO NP exposure, and phase contrast images revealed that ZnO NP treated cells had lower density and a rounded morphology. Apoptosis induction was confirmed by the annexin V assay and Western blot analysis showed the up-regulation of p53 and phospho-p38 proteins. Furthermore, in ZnO NP exposed cells, p53 protein was phosphorylated at Ser33 and Ser46 sites known to be phosphorylated by p38. Our results suggest that ZnO NPs have the potential to induce apoptosis in human dermal fibroblasts via p53-p38 pathways.

Meyer K ，Rajanahalli P ，Ahamed M ，Rowe JJ ，Hong Y ... -  《-》

ZnO nanoparticles induce TNF-α expression via ROS-ERK-Egr-1 pathway in human keratinocytes.

The area of nanotechnology continues to expand rapidly and zinc oxide (ZnO) nanoparticles (NPs) are widely being used in cosmetics and sunscreens. Although ZnO-NPs are considered materials that can potentially cause skin inflammation, the underlying mechanisms remain elusive. The aim of this study was to investigate the signaling pathways of a cutaneous inflammatory response induced by ZnO-NPs. ZnO-NPs increased the early growth response-1 (Egr-1) expression, promoter activity and its nuclear translocation in HaCaT cells. HaCaT cells and primary keratinocytes were exposed to ZnO NPs over a range of doses and time course. Protein levels and mRNA levels of Egr-1 and mitogen-activated protein kinase (MAPK) were measured by Western blot and ELISA, respectively. As an in vivo study, ZnO-NPs were applicated on mouse skin, and immunohistochemical stain with TNF-α and Egr-1 was done. ZnO-NPs activated extracellular signal-regulated kinase (ERK) of MAPK pathways. The up-regulation of Egr-1 expression by ZnO-NPs stimulation was found to be inhibited by an ERK inhibitor, but by neither c-Jun-N-terminal kinase (JNK) nor p38 inhibitor. Antioxidative N-acetyl-cysteine (NAC) strongly inhibited the level of Egr-1 and phosphorylated ERK expression in ZnO-NPs treated cells. ZnO NPs also increased tumor necrosis factor (TNF)-α expression and secretion, which were inhibited by the blockade of Egr-1 expression. The present study demonstrated that ZnO-NPs might induce inflammatory response via ROS-ERK-Egr-1 pathway in human keratinocytes.

Jeong SH ，Kim HJ ，Ryu HJ ，Ryu WI ，Park YH ，Bae HC ，Jang YS ，Son SW ... -  《-》

Zinc oxide nanoparticles induce oxidative DNA damage and ROS-triggered mitochondria mediated apoptosis in human liver cells (HepG2).

Sharma V ，Anderson D ，Dhawan A 《-》

Repetitive exposure to zinc oxide nanoparticles induces dna damage in human nasal mucosa mini organ cultures.

Data on the toxicological properties of zinc oxide nanoparticles (ZnO-NPs) is incomplete. ZnO-NPs may enter humans via inhalation or ingestion. The aim of the current study was to evaluate ZnO-NP-induced genotoxicity in three-dimensional (3D) mini organ cultures (MOCs) of human nasal mucosa following repeated exposure to ZnO-NP and regeneration. Nasal MOCs of 10 patients and ZnO-NPs were cultivated for one week and then characterized by electron microscopy. Nasal MOCs were partially covered by ciliated epithelium after one week of cultivation. ZnO-NPs were distributed to the cytoplasm and the nucleus. MOCs were exposed once, twice, or three times to 0.1 or 5 μg/ml of ZnO-NPs for 1 hr per exposure and were then evaluated for cytotoxicity and genotoxicity. MOCs were cultivated for 24 hr after the triple ZnO-NP exposure to allow for regeneration. ZnO-NP exposure did not result in significant cytotoxicity or apoptosis, as determined by trypan blue exclusion and caspase-3 activity, respectively. A significant increase in DNA damage was detected following repetitive exposure compared to single exposure to ZnO-NPs at 5 μg/ml, but not 0.1 μg/ml ZnO-NPs. At both concentrations of ZnO-NP, DNA fragmentation increased after 24 hr of regeneration. In contrast, DNA damage which was induced by the positive control, methyl methanesulfonate, was significantly reduced after 24-hr regeneration. Thus, our results suggest that repetitive exposure to low concentrations of ZnO-NPs results in persistent or ongoing DNA damage.

Hackenberg S ，Zimmermann FZ ，Scherzed A ，Friehs G ，Froelich K ，Ginzkey C ，Koehler C ，Burghartz M ，Hagen R ，Kleinsasser N ... -  《-》

The role of the tumor suppressor p53 pathway in the cellular DNA damage response to zinc oxide nanoparticles.

In this paper, we explored how ZnO nanoparticles cross-interact with a critical tumor suppressive pathway centered around p53, which is one of the most important known tumor suppressors that protects cells from developing cancer phenotypes through its control over major pathways like apoptosis, senescence and cell cycle progression. We showed that the p53 pathway was activated in BJ cells (skin fibroblasts) upon ZnO nanoparticles treatment with a concomitant decrease in cell numbers. This suggests that cellular responses like apoptosis in the presence of ZnO nanoparticles require p53 as the molecular master switch towards programmed cell death. This also suggests that in cells without robust p53, protective response can be tipped towards carcinogenesis when stimulated by DNA damage inducing agents like ZnO nanoparticles. We observed this precarious tendency in the same BJ cells with p53 knocked down using endogeneous expressing shRNA. These p53 knocked down BJ cells became more resistant to ZnO nanoparticles induced cell death and increased cell progression. Collectively, our results suggest that cellular response towards specific nanoparticle induced cell toxicity and carcinogenesis is not only dependent on specific nanoparticle properties but also (perhaps more importantly) the endogenous genetic, transcriptomic and proteomic landscape of the target cells.

Ng KW ，Khoo SP ，Heng BC ，Setyawati MI ，Tan EC ，Zhao X ，Xiong S ，Fang W ，Leong DT ，Loo JS ... -  《-》