Hydrogen peroxide causes greater oxidation in cellular RNA than in DNA

Human A549 lung epithelial cells were challenged with O-18-labeled hydrogen peroxide ([O-18]-H2O2), the total RNA and DNA extracted in parallel, and analyzed for O-18-labeled 8-oxo-7,8-dihydroguanosine ([O-18]-8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine ([O-18]-8-oxodGuo) respectively, using high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-MS/MS). [O-18]-H2O2 exposure resulted in dose-response formation of both [O-18]-8-oxoGuo, and [O-18]-8-oxodGuo and O-18-labeling of guanine in RNA was 14-25 times more common than in DNA. Kinetics of formation and subsequent removal of oxidized nucleic acids adducts were also monitored up to 24 h. The A549 showed slow turnover rates of adducts in RNA and DNA giving half-lives of approximately 12.5 h for [O-18]-8-oxoGuo in RNA and 20.7 h for [O-18]-8-oxodGuo in DNA, respectively.