Please use this identifier to cite or link to this item: doi:10.22028/D291-29313
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Title: UVA-induced carbon-centred radicals in lightly pigmented cells detected using ESR spectroscopy
Author(s): Kassouf, Nick
Kay, Christopher
Volkov, Arsen
Chiang, Shih-Chieh
Birch-Machin, Mark A.
El-Khamisy, Sherif F.
Haywood, Rachel M.
Language: English
Title: Free radical biology & medicine
Volume: 126
Startpage: 153
Endpage: 165
Publisher/Platform: Elsevier
Year of Publication: 2018
Publikation type: Journal Article
Abstract: Ultraviolet-A and melanin are implicated in melanoma, but whether melanin in vivo screens or acts as a UVA photosensitiser is debated. Here, we investigate the effect of UVA-irradiation on non-pigmented, lightly and darkly pigmented melanocytes and melanoma cells using electron spin resonance (ESR) spectroscopy. Using the spin trap 5,5 Dimethyl-1-pyrroline N-oxide (DMPO), carbon adducts were detected in all cells. However, higher levels of carbon adducts were detected in lightly pigmented cells than in non-pigmented or darkly pigmented cells. Nevertheless, when melanin levels were artificially increased in lightly pigmented cells by incubation with L-Tyrosine, the levels of carbon adducts decreased significantly. Carbon adducts were also detected in UVA-irradiated melanin-free cell nuclei, DNA-melanin systems, and the nucleoside 2'-deoxyguanosine combined with melanin, whereas they were only weakly detected in irradiated synthetic melanin and not at all in irradiated 2'-deoxyguanosine. The similarity of these carbon adducts suggests they may be derived from nucleic acid- guanine - radicals. These observations suggest that melanin is not consistently a UVA screen against free-radical formation in pigmented cells, but may also act as a photosensitizer for the formation of nucleic acid radicals in addition to superoxide. The findings are important for our understanding of the mechanism of damage caused by the UVA component of sunlight in non-melanoma and melanoma cells, and hence the causes of skin cancer.
DOI of the first publication: 10.1016/j.freeradbiomed.2018.07.019
Link to this record: hdl:20.500.11880/27854
ISSN: 1873-4596
Date of registration: 20-Sep-2019
Faculty: NT - Naturwissenschaftlich- Technische Fakultät
Department: NT - Chemie
Professorship: NT - Prof. Dr. Christopher Kay
Collections:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

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