title: Oxidative Damage to RPA Limits the Nucleotide Excision Repair Capacity of Human Cells.
abstract: Nucleotide excision repair (NER) protects against sunlight-induced skin cancer. Defective NER is associated with photosensitivity and a high skin cancer incidence. Some clinical treatments that cause photosensitivity can also increase skin cancer risk. Among these, the immunosuppressant azathioprine and the fluoroquinolone antibiotics ciprofloxacin and ofloxacin interact with UVA radiation to generate reactive oxygen species that diminish NER capacity by causing protein damage. The replication protein A (RPA) DNA-binding protein has a pivotal role in DNA metabolism and is an essential component of NER. The relationship between protein oxidation and NER inhibition was investigated in cultured human cells expressing different levels of RPA. We show here that RPA is limiting for NER and that oxidative damage to RPA compromises NER capability. Our findings reveal that cellular RPA is surprisingly vulnerable to oxidation, and we identify oxidized forms of RPA that are associated with impaired NER. The vulnerability of NER to inhibition by oxidation provides a connection between cutaneous photosensitivity, protein damage, and increased skin cancer risk. Our findings emphasize that damage to DNA repair proteins, as well as to DNA itself, is likely to be an important contributor to skin cancer risk.
authors.affiliation: Francis Crick Institute, Clare Hall Laboratory, South Mimms, Herts, UK.
authors.forename: Melisa
authors.initials: M
authors.lastname: Guven
authors.affiliation: Francis Crick Institute, Clare Hall Laboratory, South Mimms, Herts, UK.
authors.forename: Reto
authors.initials: R
authors.lastname: Brem
authors.affiliation: Francis Crick Institute, Clare Hall Laboratory, South Mimms, Herts, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Macpherson
authors.affiliation: Francis Crick Institute, Clare Hall Laboratory, South Mimms, Herts, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Peacock
authors.affiliation: Francis Crick Institute, Clare Hall Laboratory, South Mimms, Herts, UK. Electronic address: peter.karran@crick.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Karran
mesh_terms: D002478:Cells, Cultured; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015151:Immunoblotting; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D018384:Oxidative Stress; D010787:Photosensitivity Disorders / Q000209:etiology / Q000503:physiopathology*; D017319:Photosensitizing Agents / Q000009:adverse effects / Q000494:pharmacology; D051716:Replication Protein A / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000209:etiology / Q000503:physiopathology*; D013866:Thioguanine / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D004268:DNA-Binding Proteins; D017319:Photosensitizing Agents; D051716:Replication Protein A; D013866:Thioguanine