Abstract
Cadmium is a potential carcinogenic environmental and occupational pollutant. A wide variety of mutagens have been shown to cause DNA damage, but it is not yet clear whether the DNA damage is relative to inducement of mutations. DNA damage and the formation of mutations at the hypoxanthine guanine phosphoribosyl trans ferase (HPRT) induced by cadmium chloride (CdCl2) were investigated with rat lymphocytes and V79 Chinese hamster lung cells. The hprt mutant frequency (MF) assay was used as the method to measure gene mutation in the rat lymphocytes and V79 cells exposed to CdCl2, and comet assay analysis was performed to detect DNA lesion and repair in CdCl2-induced V79 cells. The results showed that CdCl2 treatment caused a strong genotoxic effect and a marginal effect on the frequency of gene mutations. The hprt mutant frequencies in the rat lymphocytes and V79 cells exposed to CdCl2 were statistically higher than those of the negative control. There was statistical significance in TL, TD and percentage of comet cell with tails. CdCl2 treatment can induce DNA single-strand breaks. There was a dose-dependent increase between CdCl2 and DNA lesion. After cells were treated with CdCl2 and hydrogen peroxide (H2O2), the TL and TD declined with repair time increasing, which indicated that DNA damages were repaired gradually. However, DNA repair with treatment of CdCl2 was slower than that of H2O2 in V79 cells, which suggests that CdCl2 affected DNA repair of damaged cells. The study also showed that the hprt MF and comet assay can be used for genotoxicity testing of heavy metals. DNA damage detected with the comet assay may be relative to mutagenesis.
