Effects of UVA and L-ascorbic acid on nuclear factor-kappa B in melanocytes and in HaCaT keratinocytes.

Nuclear factor-kappaB (NFkappaB) is a pleiotropic transcriptional activator, which is a sensitive transcriptional factor for free radicals and activates multiple target genes. UVA is very efficient in inducing free radicals in human skin cells. L-ascorbic acid is regarded as a scavenger of UVA-induced free radicals in human keratinocytes. In epidermis, melanocytes and keratinocytes play an important protective role against skin photodamage. In the present study, we aimed to investigate the role of NFkappaB on photodamage in melanocytes and keratinocytes. Normal human melanocytes (NHM) and HaCaT keratinocytes were treated with UVA (500 mJ/cm(2), 1,000 mJ/cm(2)) and/or L-ascorbic acid (100 microM, 250 microM). NFkappaB binding activity was analysed by electrophoretic mobility shift assay. NFkappaB binding activity was increased by UVA irradiation in HaCaT keratinocytes, but it was not affected in NHM. On the other hand, L-ascorbic acid decreased NFkappaB binding activity both in UVA-irradiated and in non-irradiated NHM. In contrast, NFkappaB binding activity in HaCaT keratinocytes was increased after treatment with L-ascorbic acid. In addition, L-ascorbic acid synergistically induced NFkappaB binding activity with UVA irradiation. The contrary response on NFkappaB binding activity in NHM and HaCaT keratinocytes indicated that the redox regulation might be different on photoprotective action in melanocytes and keratinocytes. Copyright 2002 S. Karger AG, Basel