Zn²⁺-induced cell death is mediated by the induction of intracellular ROS in ARPE-19 cells

Purpose. Recent studies have shown that Zn²⁺ induced cell death in retinal pigment epithelial cells. Here we sought to investigate the mode of Zn²⁺-induced cell death and the role of reactive oxygen species (ROS) in human retinal pigment epithelial cell line, ARPE-19 cells. Methods. Cell viability was measured by MTT assay. Cell death of ARPE-19 cells was measured by annexin V-fluorescein isothiocyanate (FITC) binding assay, TUNEL assay. The formation of intracellular ROS was measured using 2′,7′- dichlorofluorescein diacetate (DCFH-DA). The activation of mitogen-activated protein kinase (MAPK) was examined by Western blot analysis. Results. This study demonstrated that Zn²⁺ treatment induced both necrosis and apoptosis in ARPE-19 cells. Exposure of ARPE-19 cells to Zn²⁺ led to the activation of ERK1/2, JNK1/2/3, and p38 MAPKs. The activation of these MAPKs was blocked by treatment with the antioxidant, N-acetylcystein (NAC). More importantly, inhibition of ROS production by NAC completely prevented Zn²⁺-induced cell death in RPE cells. Conclusions. This study suggests that Zn²⁺ induces both apoptosis and necrosis in ARPE-19 cells and that its cytotoxicity may depend on the induction of intracellular ROS.