title: Insulin-like growth factor binding protein-related protein 1 inhibits proliferation of MCF-7 breast cancer cells via a senescence-like mechanism.
abstract: Elevated insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) mRNA in senescent human mammary epithelial cells suggested that the IGFBP-3 gene product may inhibit cell proliferation. To test this hypothesis, we used a retroviral vector to express IGFBP-rP1 cDNA in the IGFBP-rP1-deficient MCF-7 breast cancer cell line. Compared with control vector-transduced cells, cumulative cell numbers for IGFBP-rP1-transduced polyclonal or clonal cell cultures were reduced by 39 and 74%, respectively, after 1 week. Medium conditioned by IGFBP-rP1-producing cultures reduced cumulative cell numbers in parental MCF-7 cultures by 20% compared with medium from cultures of a control vector-transduced cell line. Nuclear fragmentation analysis and cell proliferation assays completed in the presence of the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone excluded apoptosis as the responsible mechanism. The percentage of cells containing senescence-associated beta-galactosidase activity was doubled compared with control cell cultures. Flow cytometry analysis indicated that twice as many noncycling cells were present in the IGFBP-rP1-transduced MCF-7 cell cultures compared with controls. These findings indicate that IGFBP-rP1 is an inhibitor of MCF-7 breast cancer cell proliferation and may act via a cellular senescence-like mechanism.
authors.affiliation: Department of Pathology, University of Washington School of Medicine, Seattle 98195, USA.
authors.forename: Heather-Marie P
authors.initials: HM
authors.lastname: Wilson
authors.forename: Roger S
authors.initials: RS
authors.lastname: Birnbaum
authors.forename: Martin
authors.initials: M
authors.lastname: Poot
authors.forename: LeBris S
authors.initials: LS
authors.lastname: Quinn
authors.forename: Karen
authors.initials: K
authors.lastname: Swisshelm
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D001943:Breast Neoplasms; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D061945:Caspase Inhibitors; D002455:Cell Division / Q000502:physiology; D016922:Cellular Senescence / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation / Q000502:physiology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D018969:Insulin-Like Growth Factor Binding Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C102529:insulin-like growth factor binding protein-related protein 1; D001616:beta-Galactosidase