FIGURE 3.
Inhibition of PARP-1 increases UVR-induced oxidative DNA damage. A, HaCaT cells were incubated with 2 μm arsenite or 3 mm 3-AB in serum-free medium for 24 h and then exposed to 8 J/cm2 UV radiation on ice. After UVR exposure, cells were rinsed and incubated with serum-free medium for 20 min, and PARP-1 activity was detected as described in the legend to Fig. 2A. Results are representative of at least three experiments. B, HaCaT cells were incubated with 2 mm 3-AB in serum-free medium for 24 h and then exposed to 8 J/cm2 UV radiation on ice. 8-OHdG was detected by immunoperoxidase staining (upper panel) 120 min after UVR exposure and quantified using image analysis software (lower panel). The experiment was repeated at least three times. *, p < 0.05 compared with UVR alone. C, same as B, but 8-OHdG was measured by HPLC-EC. Bars represent the mean of three independent experiments ±S.D.; *, p < 0.05 compared with UVR alone.