OBJECTIVETo explore the DNA damage and the expression of oncogenic protein induced by cadmium in vitro (human cells) and in vivo in rats.

METHODSThe colony formation assay and the MTT assay were employed to determine the cytotoxicity of cadmium. The DNA damage and the cell cycle were measured by the comet assay and the flow cytometry, respectively. The western bolt and the X-Gal staining were also used to determine the change of oncogenic protein and the senescent marker.

RESULTSThe cadmium inhibited the proliferation of cells and induced DNA damage significantly not only in human cultured cells but also in vivo animal cells. The comet rate increased from 6.1% in the control group to 23.2% in 200 microM cadmium treatment group (P < 0.01). The comet rate increased in all organs of male rats with the increase of dosage, and there were significant difference between treatment the groups and the control group in kidney and ventral prostate (P < 0.05). Furthermore, the cadmium blocked the cell cycle progression. At the same time, the expression of c-myc, c-Jun and beta-Gal were increased by cadmium.

CONCLUSIONThe cadmium could induce DNA damage and block the cell cycle, and further cause senescence, and death. However, the cadmium induced the DNA damage and the oncogenic protein expression may be the important factors to cause cancer.