Conflicts of interest None declared.
Vitamin D protects keratinocytes from deleterious effects of ionizing radiation
Article first published online: 20 AUG 2008
© 2008 The Authors. Journal Compilation © 2008 British Association of Dermatologists
British Journal of Dermatology
Volume 160, Issue 1, pages 151–161, January 2009
How to Cite
Langberg, M., Rotem, C., Fenig, E., Koren, R. and Ravid, A. (2009), Vitamin D protects keratinocytes from deleterious effects of ionizing radiation. British Journal of Dermatology, 160: 151–161. doi: 10.1111/j.1365-2133.2008.08797.x
M.L. and C.R. contributed equally to this work. R.K. contributed equally as senior author.
- Issue published online: 15 DEC 2008
- Article first published online: 20 AUG 2008
- Accepted for publication 20 March 2008
- c-Jun NH2-terminal kinase;
- ionizing radiation;
- vitamin D
Background Radiotherapy can induce severe skin responses that may limit the clinically acceptable radiation dose. The responses include erythema, dry and moist desquamation, erosions and dermal–epidermal blister formation. These effects reflect injury to, and reproductive failure of, epidermal cells and may also be due to dysregulation of the tissue remodelling process caused by excessive proteolytic activity. Calcitriol, the hormonally active vitamin D metabolite, protects keratinocytes from programmed cell death induced by various noxious stimuli.
Objective To examine whether calcitriol protects proliferating keratinocytes from the damage inflicted by ionizing radiation under conditions similar to those employed during radiotherapy.
Methods Autonomously proliferating HaCaT keratinocytes, used as a model for basal layer keratinocytes, were irradiated using a linear accelerator. Cell death was monitored by vital staining, executioner caspase activation, lactic dehydrogenase release and colony formation assay. Induction of matrix metalloproteinase-9 was assessed by gelatinase activity assay and mRNA determination. Levels of specific proteins were determined by immunoblotting.
Results Treatment with calcitriol inhibited both caspase-dependent and -independent programmed cell death occurring within 48 h of irradiation and increased the colony formation capacity of irradiated cells. These effects may be attributable to inhibition of the c-Jun NH2-terminal kinase cascade and to upregulation of the truncated antiapoptotic isoform of p63. Treatment with the hormone also attenuated radiation-induced increase in matrix metalloproteinase-9 protein and mRNA levels.
Conclusions The results of this study suggest that active vitamin D derivatives may attenuate cell death and excessive proteolytic activity in the epidermis due to exposure to ionizing radiation in the course of radiotherapy.