Human keratinocyte radiosensitivity is linked to redox modulation.
BACKGROUND
Ionising radiation-induced reactive oxygen species (ROS) overproduction induces keratinocyte alterations and constitutes one of the most common effects after therapeutic gamma-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 24h after a 20Gy gamma-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.


CONCLUSIONS
Keratinocytes apoptosis is partly dependent on ROS production after exposure to gamma-rays. In addition, the differential radiosensitivity of keratinocytes is linked to different oxidative stress responses.
Isoir
Muriel
M
Institut de Radioprotection et de Sûreté Nucléaire IRSN, Service de Radiobiologie d'Epidémiologie, Direction de la Radioprotection de l'Homme, Laboratoire de RadioPathologie, IRSN, B.P. no. 17, F-92262 Fontenay-aux-Roses Cedex, France.
Buard
Valérie
V
Gasser
Philippe
P
Voisin
Philippe
P
Lati
Elian
E
Benderitter
Marc
M
D000328:Adult; D017209:Apoptosis / Q000528:radiation effects*; D002374:Catalase / Q000378:metabolism; D002461:Cell Line, Transformed; D000078404:Epidermal Cells; D005260:Female; D020869:Gene Expression Profiling; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology* / Q000528:radiation effects*; D010084:Oxidation-Reduction / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects*; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000378:metabolism
D017382:Reactive Oxygen Species; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase