title: Comparing the effects of mitochondrial targeted and localized antioxidants with cellular antioxidants in human skin cells exposed to UVA and hydrogen peroxide.
abstract: Skin cancer and aging are linked to increased cellular reactive oxygen species (ROS), particularly following exposure to ultraviolet A (UVA) in sunlight. As mitochondria are the main source of cellular ROS, this study compared the protective effects of mitochondria-targeted and -localized antioxidants (MitoQ and tiron, respectively) with cellular antioxidants against oxidative stress-induced [UVA and hydrogen peroxide (H2O2)] mitochondrial DNA (mtDNA) damage in human dermal fibroblasts. With the use of a long quantitative PCR assay, tiron (EC50 10 mM) was found to confer complete (100%) protection (P<0.001) against both UVA- and H2O2-induced mtDNA damage, whereas MitoQ (EC50 750 nM) provided less protection (17 and 32%, respectively; P<0.05). This particular protective effect of tiron was greater than a range of cellular antioxidants investigated. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway provides cellular protection against oxidative stress. An ELISA assay for the Nrf2 target gene heme oxygenase-1 (HO-1) and studies using Nrf2 small interfering RNA both indicated that tiron's mode of action was Nrf2 independent. The comet assay showed that tiron's protective effect against H2O2-induced nuclear DNA damage was greater than the cellular antioxidants and MitoQ (P<0.001). This study provides a platform to investigate molecules with similar structure to tiron as potent and clinically relevant antioxidants.
authors.affiliation: 1Dermatological Sciences, Institute of Cellular Medicine, Medical School, Framlington Pl., Newcastle University, Newcastle upon Tyne, NE2 4HH, UK. m.a.birch-machin@ncl.ac.uk.
authors.forename: Anne O
authors.initials: AO
authors.lastname: Oyewole
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Wilmot
authors.forename: Mark
authors.initials: M
authors.lastname: Fowler
authors.forename: Mark A
authors.initials: MA
authors.lastname: Birch-Machin
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D012867:Skin / Q000166:cytology* / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D009943:Organophosphorus Compounds; D014451:Ubiquinone; C429014:mitoquinone; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D006861:Hydrogen Peroxide
keywords: DNA damage; Nrf2; ROS; mitochondria; reactive oxygen species; ultraviolet radiation