Effect of Iodide Excess on Human Thyroid Cells(Nthy-ori 3-1) Apoptosis

Objective To explore the damage effect of iodide excess on the human thyroid cells(Nthy-ori 3-1) and the mechanism.Methods Nthy-ori 3-1 cells were treated with different concentrations of potassium iodide(KI) in vitro.After 24 hours of culture,the MTT assay and lactate dehydrogenase(LDH) assay were used to measure the cell viabilities and the LDH leakage rate.The reactive oxygen species(ROS) level,the constituent ratio of the cell cycle and the apoptosis rate were measured by using flow cytometry.Results Compared with the control group,the cell viabilities in 50 mmol/L iodide-treated group decreased(P0.05) and LDH leakage rate increased significantly(P0.05).No significant difference was seen for ROS level among four groups(P0.05).The percentage of G0/G1 phase cells in 50 mmol/L iodide-treated group was higher than the control group and the percentage of apoptosis was significantly increased in 50 mmol/L iodide-treated group(P0.05).Conclusion Iodide excess can decrease the cell viabilities,increase the LDH leakage rate,block the cells in G0/G1 phase and induce cell apoptosis.These results indicate that cell cycle arrest may be related to the thyroid cells damage induced by iodide excess.