Tacalcitol, an active vitamin D3, induces nerve growth factor production in human epidermal keratinocytes.

The human epidermal keratinocyte cell line K-TL-1, developed from a benign epidermal tumor, was cultured in the presence of the synthetic vitamin D3 analogue tacalcitol [1alpha,24(R)-dihydroxyvitamin D3] to assess the effects on the production of nerve growth factor (NGF). Confluent K-TL-1 cells were cultured with 10(-8) M of tacalcitol. Supernatants and cell homogenates were collected and NGF concentrations were determined by enzyme-linked immunosorbent assay. The concentration of NGF in the supernatants of cultures treated with tacalcitol peaked within 24 h after the start of tacalcitol treatment and remained stable for 96 h. This NGF induction caused by tacalcitol was dose-dependent, showing an ED50 between 10(-10) and 10(-9) M. Induction of NGF mRNA expression by tacalcitol was also observed by RT-PCR, indicating that tacalcitol induced NGF expression through transcriptional activation. These results suggest that active vitamin D3 could treat peripheral neuropathy by inducing NGF production in the skin. Copyright 2001 S. Karger AG, Basel