1alpha,25-Dihydroxyvitamin D3 modulates the response of human keratinocytes to ionizing radiation exposure.

Background: Exposure of human skin to ionizing radiation may result in various effects such as inflammation, keratosis, fibrosis and cancer. 1alpha,25-Dihydroxyvitamin D3 (1alpha,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 1alpha,25(OH)2D3 on the radiation response of human keratinocytes.

Modulation of X-ray-induced apoptosis in human keratinocytes (HaCaT) by 1,25-dihydroxyvitamin D3.

Possible effects of 1,25-dihydoxyvitamin D3 (vitamin D) on ionizing radiation-induced cell damage have been unknown until now. The task of the present study was to analyze, in a human keratinocyte cell line (HaCaT), the effects of a preincubation with vitamin D on the X-ray-induced mRNA expression of different genes related to apoptosis (gene array). The first results show that ionizing radiation leads to a down-regulation of various apoptosis-relevant genes in HaCaT cells pretreated with vitamin D.