Relevance of reactive oxygen species in the induction of 8-oxo-2'-deoxyguanosine in HaCaT keratinocytes

Abstract

There is growing evidence that solar radiation-induced oxidative DNA damage may play an important role in carcinogenesis of the skin. One substantial modification in this context is the oxidation of the guanine base to 8-oxo-2'-deoxyguanosine. Using HaCaT keratinocytes, measurement of the 8-oxo-2'-deoxyguanosine content in this study was performed by flow cytometry on whole cells. Hydrogen peroxide and hydroxyl radicals seem not to be involved in the process of this DNA alteration. However, our results demonstrate that ultraviolet A can cause DNA damage at guanine sites primarily via photosensitized reactions. Although singlet oxygen can also lead to 8-oxo-2'-deoxyguanosine, the major mechanism seems to be based on formation of the guanylcation radical through excited riboflavin and can therefore proceed without the involvement of reactive oxygen species.