TRANSCRIPTOME 2002: From Functional Genomics to Systems Biology
March 10-13, 2002
Seattle, Washington, USA


The Immediate Early Gene Response of Human Keratinocytes to Gamma-Rays Analyzed by DNA Micro-Arrays

Jérôme Lamartine, Gilles Waksman, Xavier Gidrol, Michèle Martin, CEA, Service de Génomique Fonctionnelle, Evry, FRANCE

Epidermis keratinocyte is the first target cell of external exposures to genotoxic stress. Thus radiotherapy can induce early inflammation and desquamation of the epidermis, as well as keratosis or carcinoma as late effects. However, the response of keratinocytes to ionizing radiation (IR) is poorly characterised. We studied the early gene response of differentiated human keratinocytes to gamma-rays using cDNA microarrays. After 10 days in culture, HaCaT cells were irradiated with doses of 0.5, 2 and 15 Gy and total RNA was isolated at 3 and 24 hours. We used glass slides where 7600 human cDNAs were spotted. We found that 3800 genes were expressed in keratinocytes (50%). The number of genes that were at least 2-fold differentially expressed in irradiated cells versus control cells was dose dependent, varying at 3 hours from 4% of the genes after 0.5 Gy to 10 % after 15 Gy. The genes modulated by a dose of 0.5 Gy were not significantly different from those modulated by higher doses. Most of the response was lost at 24 hours. The present results revealed many potential regulators of IR response, such as transcription factors, and uncovered a large number of new markers of exposure among differentiation and metabolism genes.

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