Effects of ZnO nanoparticles on proliferation and apoptosis of human lung epithelial BEAS-2B cells

Abstract

To investigate the effects of ZnO nanoparticles (ZnO NPs) on proliferation and apoptosis of human lung epithelial cells BEAS-2B and its molecular mechanisms. BEAS-2B cells were treated with ZnO NPs at concentrations of 3, 6 and 12 μg/ml for 12 h and 24 h, the control group was not treated with ZnO NPs, each with 3 replicate wells. Cell viability was detected by CCK-8 method, and the half lethal concentration (IC50) was analyzed. Then, the BEAS-2B cells were treated with ZnO NPs at selected concentrations of 3 and 6 μg/ml for 24 h respectively,each group was set with 3 replicate. Cell morphology was observed under inverted microscope. The morphology of cell nuclei was observed by Hochest33342 staining. The morphology of apoptosis was observed by AO staining and scanning electron microscopy. Cell cycle progression, cell apoptosis rate and the level of reactive oxygen species(ROS)were detected by flow cytometry. Western blot was used to detect the expression levels of Bcl-2 and Bax protein. Compared with the control group, the cell viability of cells treated with ZnO NPs were decreased significantly(P＜0.01), and the IC50 was 6.13 μg/ml at 24 h of drug treatment. After the cells were treated with ZnO NPs for 24 h, the levels of ROS were increased significantly(P＜0.05, P＜0.01)in 3 μg/ml, 6 μg/ml groups. The cell cycle was arrested at G2/M phase, chromatin condensation and apoptotic bodies were induced, apoptosis rate was increased significantly(P＜0.01) in 6 μg/ml group. The expression of Bcl-2 was decreased(P＜0.05), and the expression of Bax was increased (P＜0.05) in cells treated with 6 μg/ml ZnO NPs for 24 h. ZnO NPs induced ROS accumulation, blocked progress of cell cycle and induced cell apoptosis in BEAS-2B cells.