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.