"Iron free" zinc oxide nanoparticles with ion-leaking properties disrupt intracellular ROS and iron homeostasis to induce ferroptosis

Exposure to nanomaterials (NMs) is an emerging threat to human health, and the understanding of their intracellular behavior and related toxic effects is urgently needed. Ferroptosis is a newly discovered, iron-mediated cell death that is distinctive from Apoptosis or other cell-death pathways. No evidence currently exists for the effect of "iron free" engineered NMs on Ferroptosis. We showed by several approaches that (1) zinc oxide nanoparticles (ZnO NPs)-induced cell death involves ferroptosis; (2) ZnO NPs-triggered Ferroptosis is associated with elevation of Reactive Oxygen Species (ROS) and lipid peroxidation, along with depletion of glutathione (GSH) and downregulation of Glutathione Peroxidase 4 (GPx4); (3) ZnO NPs disrupt intracellular iron homeostasis by orchestrating iron uptake, storage and export; (4) p53 largely participates in ZnO NPs-induced ferroptosis; and (5) ZnO particle remnants and dissolved zinc ion both contribute to Ferroptosis. In conclusion, our data provide a new mechanistic rationale for Ferroptosis as a novel cell-death phenotype induced by engineered NMs.