Print Email Facebook Twitter (Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes Title (Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes Author Wenczl, E. van der Schans, G.P. Roza, L. Kolb, R.M. Timmerman, A.J. Smit, N.P.M. Pavel, S. Schothorst, A.A. Centraal Instituut voor Voedingsonderzoek TNO Publication year 1998 Abstract The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by culturing at two different concentrations, basic (0.01 mM) or high (0.2 mM), of L-tyrosine, the main precursor of melanin. In parallel, pheo- and total melanin contents of the cells were determined. Identical experiments were performed with two melanocyte cultures derived from a skin type I and a skin type VI individual. For the first time the correlation between UVA-induced genotoxicity and pheo-/total melanin content has been investigated. We observed that cultured in basic medium, the skin type VI melanocytes contained 10 times more total melanin and about seven times more pheomelanin than the skin type I melanocytes. Elevation of tyrosine level in the culture medium resulted in an increase of both pheo- and total melanin levels in both melanocyte cultures; however, the melanin composition of skin type I melanocytes became more pheomelanogenic, whereas that of skin type VI melanocytes remained the same. The skin type VI melanocytes cultured in basic medium demonstrated a very high sensitivity (1.18 ssb per 1010 Da per kJ per m2) toward UVA that is probably related to their high pheo- and total melanin content. Their UVA sensitivity, however, did not change after increasing their melanin content by culturing at high tyrosine concentration. In contrast, the skin type I melanocytes demonstrated a low sensitivity (0.04 ssb per 1010 Da per kJ per m2) toward UVA when cultured in basic medium, but increasing their melanin content resulted in a 3-fold increase in their UVA sensitivity (0.13 ssb per 1010 Da per kJ per m2). These results demonstrate that UVA-irradiated cultured human melanocytes are photosensitized by their own synthesized chromophores, most likely pheomelanin and/or melanin intermediates. Subject NutritionSingle-strand breaksMelaninTyrosineCell cultureCell levelDna damageDna determinationHumanHuman cellMelanocyteNucleotide sequencePhotosensitivityPriority journalRadiation exposureUltraviolet a radiationCells, CulturedDNA DamageDNA, Single-StrandedGamma RaysHumansMelaninsMelanocytesPhotosensitizing AgentsSunscreening AgentsUltraviolet Rays To reference this document use: http://resolver.tudelft.nl/uuid:2e558ff3-13c5-4add-9ff3-ea0a72a1629e DOI https://doi.org/10.1046/j.1523-1747.1998.00357.x TNO identifier 234641 ISSN 0022-202X Source Journal of Investigative Dermatology, 111 (4), 678-682 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.