EFFECT OF ARSENIC AND CADMIUM ON THE PERSISTENCE OF MUTAGEN-INDUCED DNA LESIONS IN HUMAN-CELLS

The alkaline single cell gel electrophoresis (SCG test or comet assay) was used to characterize the influence of sodium arsenite (NaAsO2) an d cadmium sulphate (CdSO4) on the persistence of mutagen-induced DNA l esions. Human blood and SV40-transformed fibroblasts (MRC5CV1) were tr eated for 2 hr with methyl methanesulphonate (MMS) or benzo(a)pyrene ( BaP). MMS induced concentration-related DNA damage in white blood cell s (WBC) and fibroblasts in similar concentrations. For the induction o f DNA damage by BaP, higher concentrations had to be applied to WBC th an to the fibroblast cell line. To study the influence of metal ions o n the persistence of DNA lesions, treated cells were further incubated for 2 hr in the absence (postincubation) or presence (posttreatment) of NaAsO2 or CdSO4. After postincubation, MMS- and BaP-induced DNA eff ects were reduced in both cell types, indicating that repair of DNA le sions had token place. When the cells were posttreated with NaAsO2 or CdSO4, BaP- and MMS-induced DNA lesions persisted in both cell types, indicating on inhibition of DNA repair by these metals. The results su ggest a strong interaction of arsenic and cadmium with BaP- and MMS-in duced DNA repair processes. (C) 1996 Wiley-Liss, Inc.