ROLE OF ULTRAVIOLET A-INDUCED OXIDATIVE DNA-DAMAGE APOPTOSIS VIA LOSSOF MITOCHONDRIAL-MEMBRANE POTENTIAL AND CASPASE-3 ACTIVATION

UVA has been implicated in multistage photocarcinogenesis. HPLC analys is revealed that the 7,8-dihydro-8-oxo-2'-deoxyguanosine content of DN A in HL-60 cells increased immediately after WA irradiation. Pulsed fi eld gel electrophoresis showed that cellular DNA strand breakage was i nduced at 1 h after WA irradiation, Flow cytometry showed that mitocho ndrial membrane potential (Delta Psi m) decreased time-dependently in cells exposed to WA. The activity of caspase-3 and DNA ladder formatio n increased at 2 h after WA irradiation. These results suggest that WA irradiation induces oxidative DNA damage, followed by the loss of Del ta Psi m and subsequent activation of caspase-3, resulting in apoptosi s. (C) 1998 Academic Press.