title: Loss of p53 induces M-phase retardation following G2 DNA damage checkpoint abrogation.
abstract: Most cell lines that lack functional p53 protein are arrested in the G2 phase of the cell cycle due to DNA damage. When the G2 checkpoint is abrogated, these cells are forced into mitotic catastrophe. A549 lung adenocarcinoma cells, in which p53 was eliminated with the HPV16 E6 gene, exhibited efficient arrest in the G2 phase when treated with adriamycin. Administration of caffeine to G2-arrested cells induced a drastic change in cell phenotype, the nature of which depended on the status of p53. Flow cytometric and microscopic observations revealed that cells that either contained or lacked p53 resumed their cell cycles and entered mitosis upon caffeine treatment. However, transit to the M phase was slower in p53-negative cells than in p53-positive cells. Consistent with these observations, CDK1 activity was maintained at high levels, along with stable cyclin B1, in p53-negative cells. The addition of butyrolactone I, which is an inhibitor of CDK1 and CDK2, to the p53-negative cells reduced the floating round cell population and induced the disappearance of cyclin B1. These results suggest a relationship between the p53 pathway and the ubiquitin-mediated degradation of mitotic cyclins and possible cross-talk between the G2-DNA damage checkpoint and the mitotic checkpoint.
authors.affiliation: Department of Life Science, Graduate School of Natural Science and Technology, General Education Hall, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Ishikawa, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Minemoto
authors.forename: Sanae
authors.initials: S
authors.lastname: Uchida
authors.forename: Motoaki
authors.initials: M
authors.lastname: Ohtsubo
authors.forename: Mari
authors.initials: M
authors.lastname: Shimura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sasagawa
authors.forename: Masato
authors.initials: M
authors.lastname: Hirata
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakagama
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Ishizaka
authors.forename: Katsumi
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D016590:Aphidicolin / Q000494:pharmacology; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000378:metabolism; D042846:CDC2-CDC28 Kinases; D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D016195:G2 Phase; D006801:Humans; D008938:Mitosis; D009856:Oncogene Proteins, Viral / Q000378:metabolism; D010641:Phenotype; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012097:Repressor Proteins; D016196:S Phase; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; C068651:E6 protein, Human papillomavirus type 16; D004791:Enzyme Inhibitors; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; D016590:Aphidicolin; D002110:Caffeine; D004317:Doxorubicin; C082868:butyrolactone I; D011494:Protein Kinases; C102333:histone H1 kinase; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D015107:4-Butyrolactone