Sunlight damage to cellular DNA : focus on oxidatively generated lesions.
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2017
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Resumo
The routine and often unavoidable exposure to solar ultraviolet (UV) radiation makes it one of the most
significant environmental DNA-damaging agents to which humans are exposed. Sunlight, specifically UVB and
UVA, triggers various types of DNA damage. Although sunlight, mainly UVB, is necessary for the production of
vitamin D, which is necessary for human health, DNA damage may have several deleterious consequences, such
as cell death, mutagenesis, photoaging and cancer. UVA and UVB photons can be directly absorbed not only by
DNA, which results in lesions, but also by the chromophores that are present in skin cells. This process leads to
the formation of reactive oxygen species, which may indirectly cause DNA damage. Despite many decades of
investigation, the discrimination among the consequences of these different types of lesions is not clear.
However, human cells have complex systems to avoid the deleterious effects of the reactive species produced by
sunlight. These systems include antioxidants, that protect DNA, and mechanisms of DNA damage repair and
tolerance. Genetic defects in these mechanisms that have clear harmful effects in the exposed skin are found in
several human syndromes. The best known of these is xeroderma pigmentosum (XP), whose patients are
defective in the nucleotide excision repair (NER) and translesion synthesis (TLS) pathways. These patients are
mainly affected due to UV-induced pyrimidine dimers, but there is growing evidence that XP cells are also
defective in the protection against other types of lesions, including oxidized DNA bases. This raises a question
regarding the relative roles of the various forms of sunlight-induced DNA damage on skin carcinogenesis and
photoaging. Therefore, knowledge of what occurs in XP patients may still bring important contributions to the
understanding of the biological impact of sunlight-induced deleterious effects on the skin cells.
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Ultraviolet radiation, DNA lesions, DNA repair, Photoaging, Skin cancer
Citação
SCHUCH, A. P. et al. Sunlight damage to cellular DNA: focus on oxidatively generated lesions. Free Radical Biology & Medicine, v. 107, p. 110-124, 2017. Disponível em: <http://www.sciencedirect.com/science/article/pii/S0891584917300382?via%3Dihub>. Acesso em: 15 set. 2017.