Effect of DNA single strand breaks and 8-OHd G production on cadmium-induced toxicity on human embryonic kidney epithelial cells / 中国职业医学

ABSTRACT

OBJECTIVE: To explore the effects of cadmium chloride( CdCl_2) on DNA single strand breaks and the production of 8-hydroxy-2'-deoxyguanosine( 8-OHdG) in human embryonic kidney epithelial cells( HEK cells). METHODS: HEK cells in logarithm growth phase were divided into 5 groups and incubated with the different concentrations of CdCl_2( 0. 0,2. 5,5. 0,10. 0 and 20. 0 μmol/L) for 24,48 and 72 hours in vitro. After harvesting the cells,DNA single strand breaks was tested by single cell gel electrophoresis,and the level of 8-OHdG was measured using the enzyme linked immunosorbent assay. RESULTS: The Olive tail moment was statistically significant in the main effect of CdCl_2 exposed HEK cells( P < 0. 01). Among them,when HEK cells were exposed to 5. 0 μmol / L of CdCl_2,the Olive tail moment began to have a statistical significant increasing trend compared with the 0. 0 μmol / L group( P < 0. 05); when CdCl_2 concentration was 2. 5-10. 0 μmol / L,the Olive tail moment lengthened with the increasing dose of cadmium exposure,showing a doseeffect relationship( P < 0. 05). The tail DNA% was statistically significant in the interaction between exposure treatment and exposure time in HEK cells( P < 0. 01). Among them,when CdCl_2 concentration was at 2. 5-10. 0 μmol / L at 24 hours time point and 5. 0-20. 0 μmol / L at 48 hours time point,the tail DNA% raised with the increasing dose of cadmium exposure,showing a dose-effect relationship( P < 0. 05). The tail DNA% at 3 time points of 24,48 and 72 hours after exposure to 20. 0 μmol / L of CdCl_2 in HEK cells increased with the increasing time of cadmium exposure,showing a timeeffect relationship( P < 0. 05). The level of 8-OHdG had statistical significance in the main effect of CdCl_2 exposure treatment in HEK cells( P < 0. 05). Among them,the level of 8-OHdG was first significantly increased only after exposure to 10. 0 μmol / L CdCl_2 compared with the 0. 0 μmol / L group( P < 0. 05). After treatment with Ca Cl2,there was no doseeffect relationship and time-effect relationship found between the cadmium chloride exposure and tail length as well as the tail / head length ratio and 8-OHdG level. CONCLUSION: To a certain extent,CdCl_2 exposure may cause both DNA single strand breaks and 8-OHdG production in HEK cells. Compared with 8-OHdG,the DNA single strand breaks show more significant change with a lower dose of cadmium treatment,which may be related to its higher sensitivity to cadmium toxicity than 8-OHdG.