title: Polo-like kinase 1 depletion induces DNA damage in early S prior to caspase activation.
abstract: Polo-like kinase 1 (Plk1) plays several roles in mitosis, and it has been suggested to have a role in tumorigenesis. We have previously reported that Plk1 depletion results in cell death in cancer cells, whereas normal cells survive similar depletion. However, Plk1 depletion together with p53 depletion induces cell death in normal cells as well. This communication presents evidence on the sequence of events that leads to cell death in cancer cells. DNA damage is detected at the first S phase following Plk1 depletion and is more severe in Plk1-depleted p53-null cancer cells. As a consequence of Plk1 depletion using lentivirus-based small interfering RNA techniques, prereplicative complex (pre-RC) formation is disrupted at the G(1)/S transition, and DNA synthesis is reduced during S phase of the first cycle after depletion. The levels of geminin, an inhibitor of DNA pre-RC, and Emi1, an inhibitor of anaphase-promoting complex/cyclosome, are elevated in Plk1-depleted cells. The rate of cell cycling is slower in Plk1-depleted cells than in control cells when synchronized by serum starvation. Plk1 depletion results in disrupted DNA pre-RC formation, reduced DNA synthesis, and DNA damage before cells display severe mitotic catastrophe or apoptosis. Our data suggest that Plk1 is required for cell cycle progression not only in mitosis but also for DNA synthesis, maintenance of DNA integrity, and prevention of cell death.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138, USA. hyim@fas.harvard.edu
authors.forename: Hyungshin
authors.initials: H
authors.lastname: Yim
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Erikson
mesh_terms: D017209:Apoptosis / Q000502:physiology; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000502:physiology; D064248:Geminin; D006367:HeLa Cells; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000502:physiology*; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D000097869:Polo-Like Kinase 1
chemical_list: D020169:Caspases; D018797:Cell Cycle Proteins; D002843:Chromatin; D004247:DNA; D004268:DNA-Binding Proteins; D044783:F-Box Proteins; D064248:Geminin; D006657:Histones; D026161:MADS Domain Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000097869:Polo-Like Kinase 1; C498960:FBXO5 protein, human; C577995:GMNN protein, human; C468783:H2AX protein, human