title: Beta-carotene suppresses UVA-induced HO-1 gene expression in cultured FEK4.
abstract: The ultraviolet region of sunlight causes a significant oxidative stress to human skin cells and modulates expression of a series of genes in dermal fibroblasts and other cell types. The human heme oxygenase 1 (HO-1) gene is strongly activated within the first hours that follow UVA irradiation of normal human dermal fibroblasts (FEK4) and this response is being used as a marker of oxidative stress in cells. It has been shown that the induction of this gene occurs via singlet oxygen ((1)O(2)) produced upon interaction of UVA radiation with an as yet undefined cellular chromophore. Carotenoids, as the most potent singlet oxygen quenchers in nature, are expected to effectively suppress the UVA-induced HO-1 gene activation in human cells. In this study, we measured the suppression of UVA-induced levels of HO-1 mRNA after the addition of a series of six all-trans-beta-carotene concentrations (0.07, 0.2, 0.8, 2.3, 8.0, and 21 microM) to the culture medium of exponentially growing FEK4 cells. The corresponding levels of beta-carotene uptake and apo-carotenal formation were measured following HPLC separation. The results of this study show a concentration-dependent suppression of UVA- (250 kJ/m(2)) induced transcriptional activation of HO-1 in exponentially growing FEK4 cells by beta-carotene. Suppression occurred at concentrations that have been observed in human plasma after dietary supplementation with beta-carotene.
authors.affiliation: Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom.
authors.forename: Marika C
authors.initials: MC
authors.lastname: Trekli
authors.forename: George
authors.initials: G
authors.lastname: Riss
authors.forename: Regina
authors.initials: R
authors.lastname: Goralczyk
authors.forename: Rex M
authors.initials: RM
authors.lastname: Tyrrell
mesh_terms: D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D004355:Drug Stability; D005347:Fibroblasts / Q000201:enzymology*; D015870:Gene Expression / Q000187:drug effects* / Q000528:radiation effects; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics*; D051547:Heme Oxygenase-1; D006801:Humans; D008565:Membrane Proteins; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin; D014466:Ultraviolet Rays; D019207:beta Carotene / Q000378:metabolism / Q000494:pharmacology* / Q000528:radiation effects
chemical_list: D003470:Culture Media; D008565:Membrane Proteins; D012333:RNA, Messenger; D019207:beta Carotene; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1