title: Delineating an oncostatin M-activated STAT3 signaling pathway that coordinates the expression of genes involved in cell cycle regulation and extracellular matrix deposition of MCF-7 cells.
abstract: A number of studies have demonstrated that the STAT pathway is an important signaling cascade utilized by the IL-6 cytokine family to regulate a variety of cell functions. However, the downstream target genes of STAT activation that mediate the cytokine-induced cellular responses are largely uncharacterized. The aims of the current study are to determine whether the STAT signaling pathway is critically involved in the oncostatin M (OM)-induced growth inhibition and morphological changes of MCF-7 cells and to identify STAT3-target genes that are utilized by OM to regulate cell growth and morphology. We show that expression of a dominant negative (DN) mutant of STAT3 in MCF-7 cells completely eliminated the antiproliferative activity of OM, whereas expression of DN STAT1 had no effect. The growth inhibition of breast cancer cells was achieved through a concerted action of OM on cell cycle components. We have identified four cell cycle regulators including c-myc, cyclin D1, c/EBPdelta, and p53 as downstream effectors of the OM-activated STAT3 signaling cascade. The expression of these genes is differentially regulated by OM in MCF-7 cells, but is unaffected by OM in MCF-7-dnStat3 stable clones. We also demonstrate that the OM-induced morphological changes are correlated with increased cell motility in a STAT3-dependent manner. Expression analysis of extracellular matrix (ECM) proteins leads to the identification of fibronectin as a novel OM-regulated ECM component. Our studies further reveal that STAT3 plays a key role in the robust induction of fibronectin expression by OM in MCF-7 and T47D cells. These new findings provide a molecular basis for the mechanistic understanding of the effects of OM on cell growth and migration.
authors.affiliation: Department of Veterans Affairs Palo Alto Health Care System, CA 94304, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.forename: Cong
authors.initials: C
authors.lastname: Li
authors.forename: Hartmut
authors.initials: H
authors.lastname: Halfter
authors.forename: Jingwen
authors.initials: J
authors.lastname: Liu
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000096:biosynthesis / Q000235:genetics; D018816:Genes, cdc; D006801:Humans; D009154:Mutation; D053683:Oncostatin M; D010455:Peptides / Q000378:metabolism*; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D005353:Fibronectins; C508351:OSM protein, human; D010455:Peptides; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D053683:Oncostatin M; D019938:Cyclin D1; D051742:Transcription Factor CHOP