Cell-density-dependent changes in mitochondrial membrane potential and reactive oxygen species production in human skin cells post sunlight exposure
Solar ultraviolet radiation (UVR) is the principal etiological factor in skin carcinogenesis. In vivo and in vitro studies have demonstrated previously that oxidative DNA damage, mitochondrial mass and mitochondrial membrane potential (MMP) changes are associated with skin cell response to UVR stress. Methods:
Spontaneously immortalized human skin keratinocytes were irradiated with increasing sub-lethal doses of simulated sunlight irradiation (SSI) using a Q-Sun solar simulator. The effects of SSI on reactive oxygen species (ROS) formation, mitochondrial mass and MMP were then determined. Results:
SSI induced mitochondrial mass increase post low SSI (0.25–2.5 J/cm2), whereas higher SSI doses (5.0 and 7.5 J/cm2) decreased mitochondrial mass. Mitochondrial mass increased with time post 5.0 J/cm2 irradiation and all changes in mass were independent of cell density status. Changes in ROS and MMP were cell density dependent. Additionally, an inverted dose-dependent decrease in ROS formation was observed 3 h post SSI with the lower SSI dose (0.25 J/cm2). Conclusions:
Observations from the present study suggest that changes in the cell's microenvironment (modeled through varying cell density) influence changes in MMP and ROS detoxifying responses in sun-exposed skin cells.
Document Type: Research Article
Affiliations: 1: Radiation and Environmental Science Centre, Focas Institute 2: School of Physics, Dublin Institute of Technology, Dublin, Ireland 3: Mitochondrial Biology & Radiation Research, School of Science, Institute of Technology Sligo, Ash Lane, Sligo, Ireland
Publication date: December 1, 2010