Apoptosis induced by cadmium chloride during the early stage of transformation of Balb/c 3T3 cells

Objective To study the effects of cadmium chloride(CdCl_2) on the apoptosis of Balb/c 3T3 cells during the tumor-promoting phase of two-stage cell transformation test,and to elucidate the involved gene expression changes.Methods Balb/c 3T3 cells were treated with N-methyl-N′-nitro-N-nitrosoguanidine(MNNG) as initiator and CdCl_2 as promoter to generate the two-stage cell transformation model.The cytotoxicity of CdCl_2 was measured by trypan blue exclusion assay,and the cellular apoptosis was detected by Annexin V-FITC/PI staining and flow cytometry.The gene expression changes induced by CdCl_2 during the tumor-promoting phase were determined by mouse toxicology gene chip analysis.Results After 1 mg/L MNNG initiated,324 μg/L CdCl_2 could promote the transformation of Balb/c 3T3 cells.The cell viability was decreased and the percentage of apoptotic cells was increased significantly after CdCl_2 treatment for 2 days.Additionally,in all differentially expressed genes induced by CdCl_2,11 genes were related to apoptosis and 10 genes were related to antioxidation.Conclusion CdCl_2 can induce apoptosis in Balb/c 3T3 cells during the tumor-promoting phase,and change the transcriptional expression of some genes related to apoptosis or antioxidation.