title: Modeling mutations in the G1 arrest pathway in human gliomas: overexpression of CDK4 but not loss of INK4a-ARF induces hyperploidy in cultured mouse astrocytes.
abstract: Nearly all human gliomas exhibit alterations in one of three genetic loci governing G1 arrest: INK4a-ARF, CDK4, or RB. To discern the roles of CDK4 amplification and INK4a-ARF loss in gliomagenesis, we compared the behavior of astrocytes lacking a functional INK4a-ARF locus with astrocytes overexpressing CDK4. Either a deficiency of p16(INK4a) and p19(ARF) or an increase in Cdk4 allows cultured astrocytes to grow without senescence. Astrocytes overexpressing CDK4 grow more slowly than INK4a-ARF-deficient astrocytes and convert to a tetraploid state at high efficiency; in contrast, INK4a-ARF-deficient cells remain pseudodiploid, consistent with properties observed in human gliomas with corresponding lesions in these genes.
authors.affiliation: Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, 20892 USA. eholland@notes.mdacc.tmc.edu
authors.forename: E C
authors.initials: EC
authors.lastname: Holland
authors.forename: W P
authors.initials: WP
authors.lastname: Hively
authors.forename: V
authors.initials: V
authors.lastname: Gallo
authors.forename: H E
authors.initials: HE
authors.lastname: Varmus
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology*; D002478:Cells, Cultured; D051358:Cyclin-Dependent Kinase 4; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis*; D016193:G1 Phase; D005910:Glioma / Q000235:genetics*; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D011003:Ploidies; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D011506:Proteins; D011518:Proto-Oncogene Proteins; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C495900:CDK4 protein, human; C495902:Cdk4 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases