[The effects of the cadmium chloride on the DNA damage and the expression level of gadd gene in HepG2 cell line]. 
To investigate the effects of the cadmium chloride on the DNA damage and the expression of the gadd153 and gadd45beta promoter and mRNA in HepG2 cells.  DNA damage induced by cadmium chloride was detected by comet assay.  The plasmids (pGADD153-Luc and pG45-Luc) containing DNA damage and repair inducible gene 153 and 45 (gadd153 and gadd45beta) promoter and luciferase and gadd45beta reporter gene were constructed.  The activity of gadd153 and gadd45beta promoter were represented by the luciferase activity, the inducible luciferase activities was detected by bioluminescence.  The expression of gadd153 and gadd45beta mRNA was detected by RT-PCR.  The results of comet assay indicated that Olive Tail Moment induced by the cadmium chloride increased significantly at the dose of 100, 300 micromol/L, compared with the control (P < 0.05).  The luciferase activity analysis showed that the expression levels of gadd153 promoter increased significantly in 1, 5, 10 micromol/L treatment group, compared with the control (P < 0.05).  The expression levels of gadd45beta promoter in 5, 10 micromol/L treatment group were significantly higher than that in control group (P < 0.05).  The expression levels of gadd153 mRNA induced by cadmium chloride at the doses of 1, 5, 10 micromol/L and the expression levels of gadd45beta mRNA induced at the doses of 5, 10 micromol/L were significantly higher than thoae in control group (P < 0.05).  The cadmium chloride can induce the DNA damage and increase the expression levels of the gadd153 and gadd45beta promoters in HepG2 cells.