Oxidative stress mediates neuronal DNA damage and apoptosis in response tocytosine arabinoside

Cytosine arabinoside (AraC) is a nucleoside analog that produces significan t neurotoxicity in cancer patients. The mechanism by which AraC causes neur onal death is a matter of some debate because the conventional understandin g of AraC toxicity requires incorporation into newly synthesized DNA. Here we demonstrate that AraC-induced apoptosis of cultured cerebral cortical ne urons is mediated by oxidative stress. AraC-induced cell death was reduced by treatment with several different free-radical scavengers (N-acetyl-L-cys teine, dipyridamole, uric acid, and vitamin E) and was increased following depletion of cellular glutathione stores. AraC induced the formation of rea ctive oxygen species in neurons as measured by an increase in the fluoresce nce of the dye 5-(6)-carboxy-2 ' ,7 ' -dichlorodihydrofluorescein diacetate . AraC produced DNA single-strand breaks as measured by single-cell gel ele ctrophoresis and the level of DNA strand breakage was reduced by treatment with the free radical scavengers. These data support a model in which AraC induces neuronal apoptosis by provoking the generation of reactive oxygen s pecies, causing oxidative DNA damage and initiating the p53-dependent apopt otic program. These observations suggest the use of antioxidant therapies t o reduce neurotoxicity in AraC chemotherapeutic regimens.