title: An in vivo analysis of MMC-induced DNA damage and its repair.
abstract: Mitomycin C (MMC) induces various types of DNA damages that cause significant cytotoxicity to cells. Accordingly, repair of MMC-induced damages involves multiple repair pathways such as nucleotide excision repair, homologous recombination repair and translesion bypass repair pathways. Nonetheless, repair of the MMC-induced DNA damages in mammals have not been fully delineated. In this study, we investigated potential roles for Xeroderma pigmentosum (XP) proteins in the repair of MMC-induced DNA damages using an assay that detects the ssDNA patches generated following treatment with MMC or 8'-methoxy-psoralen (8-MOP) + UVA (ultraviolet light A). Human wild-type cells formed distinctive ssDNA foci following treatment with MMC or 8-MOP + UVA, but not with those inducing alkylation damage, oxidative damage or strand-break damage, suggesting that the foci represent ssDNA patches formed during the crosslink repair. In contrast to wild-type cells, mutant defective in XPE orXPG did not form the ssDNA foci following MMC treatment, while XPF mutant cells showed a significantly delayed response in forming the foci. A positive role for XPG in the repair of MMC-induced DNA damages was further supported by observations that cells treated with MMC induced a tight association of XPG with chromatin, and a targeted inhibition of XPG abolished MMC-induced ssDNA foci formation, rendering cells hypersensitive to MMC. Together, our results suggest that XPG along with XPE and XPF play unique role(s) in the repair of MMC-induced DNA damages.
authors.affiliation: Department of Biochemistry and Molecular Biology, Microbiology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Young-Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Su-Jung
authors.initials: SJ
authors.lastname: Park
authors.forename: Samantha L M
authors.initials: SL
authors.lastname: Ciccone
authors.forename: Chong-Rak
authors.initials: CR
authors.lastname: Kim
authors.forename: Suk-Hee
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D018929:Cell Culture Techniques; D002843:Chromatin / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology; D004720:Endonucleases / Q000502:physiology; D005347:Fibroblasts; D006801:Humans; D016685:Mitomycin / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000502:physiology; D018384:Oxidative Stress; D014157:Transcription Factors / Q000502:physiology; D000099250:DNA Excision Repair Protein ERCC-5
chemical_list: D000903:Antibiotics, Antineoplastic; D002843:Chromatin; D004268:DNA-Binding Proteins; D004720:Endonucleases; D016685:Mitomycin; D009687:Nuclear Proteins; D014157:Transcription Factors; D000099250:DNA Excision Repair Protein ERCC-5; C117669:DDB2 protein, human; C095888:xeroderma pigmentosum group F protein