title: G1/S cell cycle arrest provides anoikis resistance through Erk-mediated Bim suppression.
abstract: Proper attachment to the extracellular matrix is essential for cell survival. Detachment from the extracellular matrix results in an apoptotic process termed anoikis. Anoikis induction in MCF-10A mammary epithelial cells is due not only to loss of survival signals following integrin disengagement, but also to consequent downregulation of epidermal growth factor (EGFR) and loss of EGFR-induced survival signals. Here we demonstrate that G(1)/S arrest by overexpression of the cyclin-dependent kinase inhibitors p16(INK4a), p21(Cip1), or p27(Kip1) or by treatment with mimosine or aphidicolin confers anoikis resistance in MCF-10A cells. G(1)/S arrest-mediated anoikis resistance involves suppression of the BH3-only protein Bim. Furthermore, in G(1)/S-arrested cells, Erk phosphorylation is maintained in suspension and is necessary for Bim suppression. Following G(1)/S arrest, known proteins upstream of Erk, including Raf and Mek, are not activated. However, retained Erk activation under conditions in which Raf and Mek activation is lost is observed, suggesting that G(1)/S arrest acts at the level of Erk dephosphorylation. Thus, anoikis resistance by G(1)/S arrest is mediated by a mechanism involving Bim suppression through maintenance of Erk activation. These results provide a novel link between cell cycle arrest and survival, and this mechanism could contribute to the survival of nonreplicating, dormant tumor cells that avert apoptosis during early stages of metastasis.
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Collins
authors.forename: Maurico J
authors.initials: MJ
authors.lastname: Reginato
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Paulus
authors.forename: Dennis C
authors.initials: DC
authors.lastname: Sgroi
authors.forename: Joshua
authors.initials: J
authors.lastname: Labaer
authors.forename: Joan S
authors.initials: JS
authors.lastname: Brugge
mesh_terms: D000818:Animals; D023102:Anoikis / Q000502:physiology*; D016590:Aphidicolin / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004791:Enzyme Inhibitors / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D016193:G1 Phase / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008898:Mimosine / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C493956:CDKN1A protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016590:Aphidicolin; D008898:Mimosine; D048049:Extracellular Signal-Regulated MAP Kinases