P Larsson1, K Ollinger, I Rosdahl. 1. Department of Biomedicine and Surgery Division of Dermatology, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden. perla@ibk.liu.se
Abstract
BACKGROUND: Despite compelling evidence that ultraviolet (UV) irradiation causes melanoma the knowledge concerning reaction pathways and signalling transduction in melanocytes is still limited. OBJECTIVES: To evaluate the protective capacity of alpha-tocopherol and beta-carotene during UVA and UVB irradiation of human melanocytes in vitro. METHODS: Primary cultures of normal human melanocytes were irradiated by different wavelengths within the UV spectrum (UVA 6 J cm(-2), UVB 60 mJ cm(-2)). Redox alterations and apoptosis were studied and the protective potential of alpha-tocopherol and beta-carotene was evaluated. RESULTS: UVA and UVB irradiation decreased the intracellular concentration of reduced glutathione and activated the transcription factor nuclear factor (NF)-kappaB, detected as the increased level of the p65 subunit and translocation to the nucleus. This coincided with a rise in the level of gamma-glutamyl-cysteine-synthetase, the rate-limiting enzyme of the glutathione synthesis. UVA and UVB caused apoptotic cell death as detected by nuclear fragmentation and caspase activation 24 h postirradiation. Pretreatment with alpha-tocopherol prevented UVA- and UVB-induced glutathione loss, NF-kappaB translocation and diminished apoptosis, but beta-carotene did not show a similar protective capacity. Further, exposure to alpha-tocopherol by itself reduced cell proliferation rate. CONCLUSIONS: UVA and UVB irradiation affected the intracellular redox state and increased the frequency of apoptosis in human melanocytes in vitro. alpha-Tocopherol might be a useful substance in protecting melanocytes from UV-induced damage.
BACKGROUND: Despite compelling evidence that ultraviolet (UV) irradiation causes melanoma the knowledge concerning reaction pathways and signalling transduction in melanocytes is still limited. OBJECTIVES: To evaluate the protective capacity of alpha-tocopherol and beta-carotene during UVA and UVB irradiation of human melanocytes in vitro. METHODS: Primary cultures of normal human melanocytes were irradiated by different wavelengths within the UV spectrum (UVA 6 J cm(-2), UVB 60 mJ cm(-2)). Redox alterations and apoptosis were studied and the protective potential of alpha-tocopherol and beta-carotene was evaluated. RESULTS: UVA and UVB irradiation decreased the intracellular concentration of reduced glutathione and activated the transcription factor nuclear factor (NF)-kappaB, detected as the increased level of the p65 subunit and translocation to the nucleus. This coincided with a rise in the level of gamma-glutamyl-cysteine-synthetase, the rate-limiting enzyme of the glutathione synthesis. UVA and UVB caused apoptotic cell death as detected by nuclear fragmentation and caspase activation 24 h postirradiation. Pretreatment with alpha-tocopherol prevented UVA- and UVB-induced glutathione loss, NF-kappaB translocation and diminished apoptosis, but beta-carotene did not show a similar protective capacity. Further, exposure to alpha-tocopherol by itself reduced cell proliferation rate. CONCLUSIONS: UVA and UVB irradiation affected the intracellular redox state and increased the frequency of apoptosis in human melanocytes in vitro. alpha-Tocopherol might be a useful substance in protecting melanocytes from UV-induced damage.
Authors: Alexandra Charruyer; Sean M Bell; Miyuki Kawano; Sounthala Douangpanya; Ten-Yang Yen; Bruce A Macher; Keigo Kumagai; Kentaro Hanada; Walter M Holleran; Yoshikazu Uchida Journal: J Biol Chem Date: 2008-04-14 Impact factor: 5.157