Role of ultraviolet A-induced oxidative DNA damage apoptosis via loss of mitochondrial membrane potential and caspase-3 activation

UVA has been implicated in multistage photocarcinogenesis. HPLC analysis revealed that the 7,8-dihydro-8-oxo-2'-deoxyguanosine content of DNA in HL-60 cells increased immediately after WA irradiation. Pulsed field gel electrophoresis showed that cellular DNA strand breakage was induced at 1 h after WA irradiation, Flow cytometry showed that mitochondrial membrane potential (Delta Psi m) decreased time-dependently in cells exposed to WA. The activity of caspase-3 and DNA ladder formation increased at 2 h after WA irradiation. These results suggest that WA irradiation induces oxidative DNA damage, followed by the loss of Delta Psi m and subsequent activation of caspase-3, resulting in apoptosis. (C) 1998 Academic Press.