title: CSF-1 activates MAPK-dependent and p53-independent pathways to induce growth arrest of hormone-dependent human breast cancer cells.
abstract: The CSF-1 receptor (CSF-1R) is expressed in >50% of human breast cancers. To investigate the consequence of CSF-1R expression, hormone-dependent human breast cancer cell lines, MCF-7 and T-47D, were transfected with CSF-1R. Unexpectedly, CSF-1 substantially inhibited estradiol (E2) and insulin-dependent proliferation of MCF-7 transfectants (MCF-7fms) and prevented cyclin E/cdk2 and cyclin A/cdk2 activation, consistent with a G1 arrest. In contrast, CSF-1 increased DNA synthesis in T-47D transfectants (T-47Dfms) alone and with E2 or insulin. In response to CSF-1, there was a marked and sustained upregulation of the cyclin-dependent kinase inhibitor, p21Waf1/Cip1, in MCF-7fms but not T-47Dfms. CSF-1 also markedly upregulated cyclin D1 in MCF-7fms. The coordinate increase in cyclin D1 and p21 had the effect of decreasing the specific but not absolute activity of cyclin D1/cdk4. p53 was not involved since CSF-1 induction of p21 was unaffected by dominant-negative p53 expression. ERK activation by CSF-1 was robust and sustained in MCF-7fms and to a much lesser extent in T-47Dfms. Using pharmacological and transient transfection approaches, we showed that ERK activation was necessary and sufficient for p21 induction in MCF-7fms. Moreover, activated MEK inhibited E2-stimulated cdk2 activity. Our findings indicate that the consequence of CSF-1R-mediated signals in human breast cancer cells is dependent on the genetic background of the particular tumor.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University Medical School, St. Louis, Missouri, MO 63110, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Nambirajan
authors.forename: J G
authors.initials: JG
authors.lastname: Moffat
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D042846:CDC2-CDC28 Kinases; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D019938:Cyclin D1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D019927:Cyclin E / Q000187:drug effects / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000187:drug effects / Q000378:metabolism; D016213:Cyclins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism* / Q000494:pharmacology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016160:Retinoblastoma Protein / Q000187:drug effects / Q000378:metabolism; D016196:S Phase / Q000187:drug effects; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007328:Insulin; D011518:Proto-Oncogene Proteins; D011960:Receptors, Estrogen; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; D004958:Estradiol; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495900:CDK4 protein, human; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases; C482576:MAP3K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one