Abstract
Background: Exposure of human skin to ionizing radiation may result in various effects such as inflammation, keratosis, fibrosis and cancer. 1α,25-Dihydroxyvitamin D3 (1α,25(OH)2D3), the biologically active metabolite of vitamin D, has been shown to exert pleiotropic effects on the skin. The aim of the study was to evaluate the effect of 1α,25(OH)2D3 on the radiation response of human keratinocytes. Materials and Methods: Keratinocytes (HaCaT), either untreated or pretreated with 1α,25(OH)2D3, were irradiated with 0-7.5 Gy. Growth curves were generated to determine cell proliferation. Cell survival was examined using a clonogenic assay. The cell surface expression of adhesion molecules was investigated by flow cytometry. Results: The cell growth and clonogenic survival of irradiated keratinocytes were both significantly increased by 1α,25(OH)2D3. Ionizing radiation caused an up-regulation of the cell surface expression of intercellular adhesion molecule-1 (ICAM-1) and integrins beta1 (CD29), alpha2 (CD49b), alpha5 (CD49e) and alpha6 (CD49f) in keratinocytes, which was inhibited by 1α,25(OH)2D3. Conclusion: The data suggest that 1α,25(OH)2D3 may be a promising agent to modify the radiation reaction, thus offering new options in radiotherapy and oncology.
Footnotes
- Received March 10, 2006.
- Accepted March 27, 2006.
- Copyright© 2006 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved