title: Decarbamoyl mitomycin C (DMC) activates p53-independent ataxia telangiectasia and rad3 related protein (ATR) chromatin eviction.
abstract: Interstrand crosslinks induce DNA replication fork stalling that in turn activates the ATR-dependent checkpoint and DNA repair on nuclear chromatin. Mitomycin C (MC) and Decarbamoyl Mitomycin C (DMC) induce different types of DNA crosslinks with DMC being a more cytotoxic agent. We previously reported that the novel DMC induced β-interstrand DNA crosslinks induce a p53-independent form of cell death. The p53-independent DMC cytotoxicity associates with the activation, and subsequent depletion, of Chk1. In this study we further dissect the novel DMC signal transduction pathway and asked how it influences chromatin-associated proteins. We found that treatment with DMC, but not MC, stimulated the disassociation of ATR from chromatin and re-localization of ATR to the cytoplasm. The chromatin eviction of ATR was coupled with the formation of nuclear Rad51 foci and the phosphorylation of Chk1. Furthermore, DMC but not MC, activated expression of gadd45α mRNA. Importantly, knocking down p53 via shRNA did not inhibit the DMC-induced disassociation of ATR from chromatin or reduce the activation of transcription of gadd45α. Our results suggest that DMC induces a p53-independent disassociation of ATR from chromatin that facilitates Chk1 checkpoint activation and Rad51 chromatin recruitment. Our findings provide evidence that ATR chromatin eviction in breast cancer cells is an area of study that should be focused on for inducing p53-independent cell death.
authors.affiliation: a Department of Biological Sciences; Hunter College and The Graduate Center Biology Program ; City University of New York ; New York , NY USA.
authors.forename: Gu
authors.initials: G
authors.lastname: Xiao
authors.forename: Pao
authors.initials: P
authors.lastname: Kue
authors.forename: Rahul
authors.initials: R
authors.lastname: Bhosle
authors.forename: Jill
authors.initials: J
authors.lastname: Bargonetti
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D002843:Chromatin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D059765:Homologous Recombination / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D008937:Mitomycins / Q000494:pharmacology*; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D000071877:Checkpoint Kinase 1; D002843:Chromatin; D004247:DNA; D008937:Mitomycins; D009687:Nuclear Proteins; D010768:Phosphoserine; D011494:Protein Kinases; D051135:Rad51 Recombinase; D016159:Tumor Suppressor Protein p53; D048051:p38 Mitogen-Activated Protein Kinases; C439070:GADD45A protein, human; D000097642:GADD45 Proteins; C067795:10-decarbamoylmitomycin C; C576597:ATR protein, human; C000605867:CHEK1 protein, human
keywords: ATR; ATR, Ataxia Telangiectasia and Rad3 Related; Cdc25, cell division cycle 25.; ChIP, chromatin immunoprecipitation; Chk1, checkpoint serine/threonine protein kinase 1; DDR, DNA damage response; DMC, Decarbamoyl Mitomycin C; DOX, doxycycline; HR, homologous recombination; ICLs, interstrand cross-links; MC, Mitomycin C; NER, nuclear excision repair; PCNA, Proliferating Cell Nuclear Antigen; RPA, replication protein A; TNBCs, triple negative breast cancers; breast cancer; cell death; chromatin; interstrand crosslink; mitomycin C; p53