title: AFX-like Forkhead transcription factors mediate cell-cycle regulation by Ras and PKB through p27kip1.
abstract: The Forkhead transcription factors AFX, FKHR and FKHR-L1 are orthologues of DAF-16, a Forkhead factor that regulates longevity in Caenorhabditis elegans. Here we show that overexpression of these Forkhead transcription factors causes growth suppression in a variety of cell lines, including a Ras-transformed cell line and a cell line lacking the tumour suppressor PTEN. Expression of AFX blocks cell-cycle progression at phase G1, independent of functional retinoblastoma protein (pRb) but dependent on the cell-cycle inhibitor p27kip1. Indeed, AFX transcriptionally activates p27kip1, resulting in increased protein levels. We conclude that AFX-like proteins are involved in cell-cycle regulation and that inactivation of these proteins is an important step in oncogenic transformation.
authors.affiliation: Department of Hematology, University Medical Center, Utrecht, The Netherlands.
authors.forename: R H
authors.initials: RH
authors.lastname: Medema
authors.forename: G J
authors.initials: GJ
authors.lastname: Kops
authors.forename: J L
authors.initials: JL
authors.lastname: Bos
authors.forename: B M
authors.initials: BM
authors.lastname: Burgering
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000502:physiology*; D017173:Caenorhabditis elegans; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D016193:G1 Phase / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; C108803:FOXO4 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C467200:Foxo1 protein, mouse; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D018631:ras Proteins