title: p27(Kip1) induces quiescence and growth factor insensitivity in tamoxifen-treated breast cancer cells.
abstract: Tamoxifen, a selective estrogen-receptor modulator, is effective in the treatment and prevention of breast cancer, but therapeutic resistance is common. Pure steroidal antiestrogens are efficacious in tamoxifen-resistant disease and, unlike tamoxifen, arrest cells in a state of quiescence from which they cannot reenter the cell cycle after growth factor stimulation. We now show that in hydroxytamoxifen-treated cells, transduction of the cell cycle inhibitor p27(Kip1) induces quiescence and insensitivity to growth stimulation by insulin/insulin-like growth factor I and epidermal growth factor/transforming growth factor alpha. Furthermore, reinitiation of cell cycle progression by insulin/insulin-like growth factor I in hydroxytamoxifen-arrested cells involves dissociation of the corepressors nuclear receptor corepressor (N-CoR) and silencing mediator for retinoid and thyroid hormone receptor (SMRT) from nuclear estrogen receptor alpha and redistribution to the cytoplasm, a process that is inhibited by mitogen-activated protein/extracellular signal-regulated kinase, but not phosphatidylinositol 3'-kinase, inhibitors. These data suggest that agents that up-regulate p27(Kip1) or inhibit growth factor signaling via the extracellular signal-regulated kinases should be tested as therapeutic strategies in tamoxifen-resistant breast cancer.
authors.affiliation: Cancer Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Australia.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Carroll
authors.forename: Danielle K
authors.initials: DK
authors.lastname: Lynch
authors.forename: Alexander
authors.initials: A
authors.lastname: Swarbrick
authors.forename: Jack-Michel
authors.initials: JM
authors.lastname: Renoir
authors.forename: Boris
authors.initials: B
authors.lastname: Sarcevic
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Daly
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Musgrove
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sutherland
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004268:DNA-Binding Proteins / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D000077267:Fulvestrant; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D011960:Receptors, Estrogen / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology*; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D006133:Growth Substances; C539127:NCOR1 protein, human; C539130:NCOR2 protein, human; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D011960:Receptors, Estrogen; D012097:Repressor Proteins; D020845:Selective Estrogen Receptor Modulators; D025521:Tumor Suppressor Proteins; D013629:Tamoxifen; D050760:Cyclin-Dependent Kinase Inhibitor p27; C016601:afimoxifene; D000077267:Fulvestrant; D004958:Estradiol