Human keratinocyte radiosensitivity is linked to redox modulation
Résumé
Background: Ionising radiation-induced reactive oxygen species (ROS) overproduction induces keratinocyte alterations and constitutes one of the most common effects after therapeutic γ-irradiation. ROS production is controlled by a complex enzymatic system. Objective: The aim of our study is to analyse the role of radiation-induced oxidative stress in keratinocytes death by apoptosis. We hypothesized that keratinocyte capacity to hamper radiation-induced ROS generation may control their radiosensitivity. Methods: For this purpose, an original human skin explant model was developed and two types of human epidermal cells were used: primary keratinocytes NHEK and spontaneous non-tumourigenic cell line HaCaT. Results: cDNA-arrays analysis was performed 24 h after a 20 Gy γ-radiation and revealed down-regulation of genes involved in oxidative stress control and the apoptosis process. This was confirmed by alterations in catalase, GPx and SOD enzymatic activities. This redox modulation was concomitant to the down-regulation of anti-apoptotic genes and up-regulation of some pro-apoptotic genes (caspase 10, ubiquitin C). Interestingly TUNEL labelling revealed an increase in the number of apoptotic cells. We also demonstrated a differential inducibility of the cell antioxidant network in two keratinocyte lines, which results in a differential cellular level of ROS, explaining their different radiosensitivities. Conclusion: Keratinocytes apoptosis is partly dependent on ROS production after exposure to γ-rays. In addition, the differential radiosensitivity of keratinocytes is linked to different oxidative stress responses. © 2005 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.
Mots clés
catalase
complementary DNA
glutathione peroxidase
reactive oxygen metabolite
superoxide dismutase
apoptosis
article
cell line
controlled study
DNA determination
down regulation
enzyme activity
epidermis cell
gamma radiation
human
human cell
keratinocyte
nick end labeling
nucleotide sequence
oxidation reduction reaction
oxidative stress
priority journal
radiation dose
radiosensitivity
Adult
Apoptosis
Catalase
Cell Line
Transformed
Epidermis
Female
Gene Expression Profiling
Glutathione Peroxidase
Humans
Keratinocytes
Oxidation-Reduction
Oxidative Stress
Radiation
Ionizing
Reactive Oxygen Species
Superoxide Dismutase