title: Human PIF1 helicase supports DNA replication and cell growth under oncogenic-stress.
abstract: Unwinding duplex DNA is a critical processing step during replication, repair and transcription. Pif1 are highly conserved non-processive 5'->3' DNA helicases with well-established roles in maintenance of yeast genome stability. However, the function of the sole member of Pif1 family in humans remains unclear. Human PIF1 is essential for tumour cell viability, particularly during replication stress, but is dispensable in non-cancerous cells and Pif1 deficient mice. Here we report that suppression of PIF1 function slows replication fork rates and increases arrested forks during normal cycling conditions. Importantly, PIF1-dependent replication impediments impair S-phase progression and reduce proliferation rates of RAS oncogene-transformed fibroblasts, where replication fork slowing is exacerbated, but not parental, non-cancerous cells. Disrupted fork movement upon PIF1-depletion does not enhance double-stranded break formation or DNA damage responses but affects resumption of DNA synthesis after prolonged replication inhibitor exposure, accompanied by diminished new origin firing and mainly S-phase entry. Taken together, we characterised a functional role for human PIF1 in DNA replication that becomes important for cell growth under oncogenic stress. Given that oncogenes induce high levels of replication stress during the early stages of tumorigenesis, this function of PIF1 could become critical during cancer development.
authors.affiliation: Academic Unit of Molecular Oncology, Department of Oncology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Gagou
authors.affiliation: Academic Unit of Molecular Oncology, Department of Oncology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Anil
authors.initials: A
authors.lastname: Ganesh
authors.affiliation: Academic Unit of Molecular Oncology, Department of Oncology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Phear
authors.affiliation: Light Microscopy Facility, Department of Biomedical Science, University of Sheffield, Firth Court, Sheffield, UK.
authors.forename: Darren
authors.initials: D
authors.lastname: Robinson
authors.affiliation: School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: Eva
authors.initials: E
authors.lastname: Petermann
authors.affiliation: Academic Unit of Molecular Oncology, Department of Oncology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Angela
authors.initials: A
authors.lastname: Cox
authors.affiliation: Academic Unit of Molecular Oncology, Department of Oncology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Meuth
mesh_terms: D048708:Cell Growth Processes / Q000502:physiology; D002461:Cell Line, Transformed; D004265:DNA Helicases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics / Q000502:physiology*; D005347:Fibroblasts; D042822:Genomic Instability; D045325:HCT116 Cells; D006801:Humans; D009857:Oncogenes; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D014162:Transfection; D018631:ras Proteins / Q000235:genetics
chemical_list: D034741:RNA, Small Interfering; D004265:DNA Helicases; D018631:ras Proteins; C508765:PIF1 protein, human