Abstract: BACKGROUND ＆ AIM： To explore the molecular mechanisms potentially responsible for carcinogensis due to cadmium chloride by evaluating changes of the translation enlongation factor 1δ p31(TEF_1δ p31) expression in the malignant transformation of human bronchial epithelial cell lines(16HBE) induced by cadmium chloride(CdCl2). MATERIALS AND METHODS: The changes of TEF_1δ p31 mRNA in semi_transformed cells, transformed cells and tumorigenic cells induced by CdCl2 solution were assessed with both RT_PCR and Taqman fluorescent quantitative PCR assay. RESULTS: ①Compared with non_transformed human bronchial epithelial cells , the fluorescent quantitative PCR assay showed that the semi_transformed cells, transformed cells and tumorigenic cells all expressed higher levels of TEF_1δ p31 mRNA(P<0.01 or P<0.05). As compared with control cells, the TEF_1δ p31 expressions during the 3 different stages of malignant transformation were 3.4 times, 5.2 times and 6.9 times, respectively, in low concentration of CdCl2(5 μmol/L); 4.1 times, 6.9 times and 6.3 times, respectively, in moderate concentration of CdCl2 (10 μmol/L); 1.4 times,2.9 times and 8.4 times, respectively, in high concentration of CdCl2(15 μmol/ L). These results showed a positive correlation(r>0.799,P<0.01) between overexpression levels of TEF_1δ p31 mRNA and malignant degree of the cells, but no correlation to the concentration of cadmium. ② There was a close relationship(F=7.128，P=0.001)between abnormal expression of TEF_1δ p31 in different stages of 16HBE cells induced and transformed by different concentrations of CdCl2. CONCLUSION: There was marked overexpression of TEF_1δ p31 gene during malignant transformation of human bronchial epithelial cell lines induced by cadmium chloride ,and the TEF_1δ p31 expression was associated with malignant degree of the cells and concentration of CdCl2 . This may be one molecular mechanisms potentially responsible for carcinogensis caused by cadmium.

Key words: cadmium chloride(CdCl2), human bronchial epithelial cell, malignant transformation, translation elongation factor TEF_1δ p31, Taqman fluorescent quantitative PCR