Joint effects of cadmium and mercury on DNA damage and apoptosis in human embryo hepatocytes

Objective To study the effects of cadmium and mercury alone and in combination on DNA damage and apoptosis in human embryo hepatocytes(L02 cells).Methods L02 cells were exposed to 0.01-100 μmol/L of cadmium chloride(CdCl2),mercury chloride(HgCl2) and their mixtures(CdCl2+HgCl2) for 24 hours.MTT method was used to measure the survival of L02 cells,and then the joint effects of these mixtures were judged depending on the Finney law.Single cell gel electrophoresis(SCGE) and flow cytometry(FCM) were used to measure the DNA damage and apoptosis of L02 cells respectively.Results 0.01 μmol/L of cadmium,mercury and their mixtures could stimulate the growth of L02 cells,but when the concentration of cadmium,mercury and their mixtures were more than 1 μmol/L,they could significantly inhibit the growth of L02 cells,and the joint effects of cadmium and mercury were additive action.The rates of DNA damage and the percentages of apoptosis were significantly higher than the control group after exposure to cadmium,mercury and their mixtures for 24 hours,and the rate of DNA damage and the percentage of apoptosis showed an ascendant trend with the increase of individual dose.Conclusion The joint exposure of cadmium and mercury may has synergistic toxic effect,which may be due to the oxidative stress induced by cadmium and mercury.