Processing of anthracycline-DNA adducts via DNA replication and interstrand crosslink repair pathways.
Anthracycline chemotherapeutics are well characterised as poisons of topoisomerase II, however many anthracyclines, including doxorubicin, are also capable of forming drug-DNA adducts. Anthracycline-DNA adducts present an unusual obstacle for cells as they are covalently attached to one DNA strand and stabilised by hydrogen bonding to the other strand. We now show that in cycling cells processing of anthracycline adducts through DNA replication appears dominant compared to processing via transcription-coupled pathways, and that the processing of these adducts into DNA breaks is independent of topoisomerase II. It has previously been shown that cells deficient in homologous recombination (HR) are hypersensitive to adduct forming treatments. Given that anthracycline-DNA adducts, whilst not true crosslinks, are associated with both DNA strands, the role of ICL repair pathways was investigated. Mus81 is a structure specific nuclease implicated in Holliday junction resolution and the resolution of branched DNA formed by stalled replication forks. We now show that ICL repair deficient cells (Mus81(-/-)) are hypersensitive to anthracycline-DNA adducts and ET-743, a compound which causes a chemically similar type of DNA damage. Further analysis of this mechanism showed that Mus81 does not appear to cause DNA breaks resulting from either anthracycline- or ET743-DNA adducts. This suggests Mus81 processes these novel forms of DNA damage in a fundamentally different way compared to the processing of classical covalent crosslinks. Improved understanding of the role of DNA repair in response to such adducts may lead to more effective chemotherapy for patients with BRCA1/2 mutations and other HR deficiencies.
Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria 3086, Australia.
R A
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Bilardi
K-I
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Kimura
D R
DR
Phillips
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Cutts
D000818:Animals; D018943:Anthracyclines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004260:DNA Repair; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004149:Dioxoles / Q000494:pharmacology; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism*; D052236:Fanconi Anemia Complementation Group D2 Protein / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000235:genetics; D018922:HL-60 Cells; D059765:Homologous Recombination; D006801:Humans; D044005:Tetrahydroisoquinolines / Q000494:pharmacology; D000077606:Trabectedin
D018943:Anthracyclines; D018736:DNA Adducts; D004268:DNA-Binding Proteins; D004149:Dioxoles; C499905:FANCD2 protein, human; D052236:Fanconi Anemia Complementation Group D2 Protein; D044005:Tetrahydroisoquinolines; C055850:barminomycin II; D004720:Endonucleases; C498772:MUS81 protein, human; D004250:DNA Topoisomerases, Type II; D000077606:Trabectedin