Growth-inhibitory effects of 1,25-dihydroxyvitamin D3 on normal and psoriatic keratinocytes

Abstract

The effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the growth and DNA synthesis of cultured human keratinocytes obtained from involved and uninvolved psoriatic epidermis and normal epidermis were studied. Treatment with 10-8 M and 10-7 M of 1,25(OH)2D3 inhibited cell growth as follows: 58.5 ± 19.3% and 21.3 ± 13.6% in normal keratinocytes (n = 6); 43.8 ± 22.8% and 17.8 ± 12.3% in psoriatic uninvolved keratinocytes (n = 4); 51.7 ± 18.2% and 13.2 ± 6.4% in psoriatic involved keratinocytes (n = 6). Inhibition was virtually complete at 10-6 M. DNA synthesis as also inhibited by 10-8 M, 10-7 M and 10-6 M of 1,25(OH)2D3 as follows: 70.0 ± 8.3%, 59.0 ± 6.8% and 16.7 ± 4.0%, respectively, in normal keratinocytes (n = 3); 78.5 ± 13.5%, 51.5 ± 25.5% and 24.5 ± 21.5%, respectively, in psoriatic uninvolved keratinocytes (n = 2); and 69.3 ± 14.5%, 41.3 ± 19.1% and 14.8 ± 11.2%, respectively, in psoriatic involved keratinocytes (n = 4). These results indicate that 1,25(OH)2D3 functions as a growth inhibitor for cultured human keratinocytes derived from both normal and psoriatic skin.