Direct monitoring of UV-induced free radical generation in HaCaT keratinocytes

Background. Ultraviolet radiation (UVR) is one of the most important aetiological factors in the development of skin cancer, with an estimated 100 000 new cases of nonmelanoma skin cancer (NMSC) diagnosed each year in the UK. To date, little work has been carried out to investigate the role of UVR in the increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) following exposure of skin cells to simulated solar UVR. Aim. To monitor directly the effects of simulated solar UVR on ROS and RNS generation in HaCaT keratinocytes. Methods. This study reports the use of electrochemical monitoring techniques for the direct, real- time detection of two highly reactive free radical species, superoxide (O-2(-)) and nitric oxide (NO), from HaCaT keratinocyte cells that had been exposed to a source of UVR designed to simulate the doses of UVA and UVB found in solar light. Results. An increase in both O-2(-) and NO generation was observed in HaCaT cells that had been exposed to UVR. No detectable increase in either species was observed in cells that had not been exposed to UVR. The specificity of the electrochemical methods for O-2(-) or NO was confirmed through the scavenging or inhibition of these species. Conclusion. The findings of this study demonstrated that exposure of HaCaT cells to relatively low doses of UVR resulted in the immediate generation of both O-2(-) and NO, therefore potentially leading to the downstream generation of highly damaging metabolites and the development of a number of pathologies, including cancer.