Abstract: ObjectiveTo explore the apoptosis and the mRNA expression of Bcl-2 and Bax gene during malignant transformation of human bronchial epithelial cells(16HBE cells) induced by cadmium.MethodsReal-time fluorescent quantitative reverse transcriptase polymerase chain reaction(QPCR) was used to detect the level of bal-2 and bax mRNA in 16HBE cells and cell apoptosis of different generations after cadmium chloride exposure(the 5th,15th,35th generation of the cells,and neoplasmed cells from nude mice’s tumor tissue).Flow cytometric analysis was used to analyze cell apoptosis.ResultsThe apoptosis rates of cadmium chloride exposed 16HBE cells and their 5th,15th,35th generation,and neoplasmed cells from nude mice’s tumor tissue were 0.65%,1.14%,1.87%,3.78%,and 4.93%.The relative expression values o f bal-2 mRNA in the 16HBE cells and their 5th,15th,35th generation,and neoplasmed cells from nude mice’s tumor tissue were 9.067±0.155,8.183 ±0.206,5.971±0.015,and 4.533±0.030,4.863±0.066,and the relative expression values o f bax mRNA in those cells were 5.973±0.026,6.012±0.112,6.659±0.028,7.032±0.045,and 7.519±0.022,respectively.With the increment of transformed generations of 16HBE cells treated with cadmium chloride,the mRNA expression of Bal-2 gene were decreased gradually,while the mRNA expression of Bax gene was increased gradually(P<0.05).ConclusionCadmium chloride could induce apoptosis in malignant transformation of human bronchial epithelial cells and down-regulate the expression of bal-2 gene and up-regulate the expression of bax gene.