The proteomic analysis of human lung epithelial cells exposed with or without radon

Human lung epithelial A549 cells were exposed to radon 1,000 Bq/m3 for 30 min, repeated daily for seven days. The control cells were cultured under the same conditions but without radon exposure. Cells were washed three times with ice-cold 1x phosphate buffer saline supplemented with protease inhibitor, followed lysed by lysis buffer (50 mM Tris pH 8.0, 150 mM NaCl, 1% NP40, and 0.5% Sodium deoxycholate) at room temperature for 15 min with a shaker (EYELA CM-1000, Tokyo Rikakikai Co. Ltd., Tokyo, Japan). The lysates were then stored at -80°C. The proteins were identified using LC-MS/MS and the spectra were searched against the A549 cell protein database using ProteinPilot software. The resulting file was imported into PeakView as a library, and peaks from SWATH-MS runs were extracted with a false discovery rate of less than 1%. The data were then exported to the MarkerView software program, and the peak area of each protein was normalized relative to the total peak areas for all detected proteins. Differential protein expression was analyzed to determine the relative abundances of proteins in A549 cells exposed with and without radon.