title: High levels of RAD51 perturb DNA replication elongation and cause unscheduled origin firing due to impaired CHK1 activation.
abstract: In response to replication stress ATR signaling through CHK1 controls the intra-S checkpoint and is required for the maintenance of genomic integrity. Homologous recombination (HR) comprises a series of interrelated pathways that function in the repair of DNA double strand breaks and interstrand crosslinks. In addition, HR, with its key player RAD51, provides critical support for the recovery of stalled forks during replication. High levels of RAD51 are regularly found in various cancers, yet little is known about the effect of the increased RAD51 expression on intra-S checkpoint signaling. Here, we describe a role for RAD51 in driving genomic instability caused by impaired replication and intra-S mediated CHK1 signaling by studying an inducible RAD51 overexpression model as well as 10 breast cancer cell lines. We demonstrate that an excess of RAD51 decreases I-Sce-I mediated HR despite formation of more RAD51 foci. Cells with high RAD51 levels display reduced elongation rates and excessive dormant origin firing during undisturbed growth and after damage, likely caused by impaired CHK1 activation. In consequence, the inability of cells with a surplus of RAD51 to properly repair complex DNA damage and to resolve replication stress leads to higher genomic instability and thus drives tumorigenesis.
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Ann Christin
authors: AC
authors: Parplys
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Jasna Irena
authors: JI
authors: Seelbach
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Saskia
authors: S
authors: Becker
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Matthias
authors: M
authors: Behr
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Agnieszka
authors: A
authors: Wrona
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Camilla
authors: C
authors: Jend
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.|b Tumor Biology Department; National Cancer Institute; Cairo University ; Cairo , Egypt.
authors: Wael Yassin
authors: WY
authors: Mansour
authors: d Department of Tumor Biology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Simon Andreas
authors: SA
authors: Joosse
authors: e Institute of Pathology; University Hospital Schleswig-Holstein-Campus ; Lübeck , Germany.
authors: Horst-Werner
authors: HW
authors: Stuerzbecher
authors: f Leibniz Institute for Age Research - Fritz Lipmann Institute ; Jena , Germany.|g Faculty of Biochemistry and Molecular Medicine; University of Oulu ; Oulu , Finland.
authors: Helmut
authors: H
authors: Pospiech
authors: c Department of Radiotherapy and Radiooncology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Cordula
authors: C
authors: Petersen
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Ekkehard
authors: E
authors: Dikomey
authors: a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.
authors: Kerstin
authors: K
authors: Borgmann
mesh_terms: D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage / Q000235:genetics / Q000502:physiology; D004260:DNA Repair / Q000235:genetics / Q000502:physiology; D004261:DNA Replication / Q000235:genetics / Q000502:physiology; D042822:Genomic Instability / Q000235:genetics / Q000502:physiology; D059765:Homologous Recombination / Q000235:genetics / Q000502:physiology; D006801:Humans; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
chemical_list: D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D051135:Rad51 Recombinase
keywords: CHK1 activation; RAD51 overexpression; genomic instability; homologous recombination; replication fork elongation