title: Convergence of p53 and transforming growth factor beta (TGFbeta) signaling on activating expression of the tumor suppressor gene maspin in mammary epithelial cells.
abstract: Using two-dimensional difference gel electrophoresis, we identified the tumor suppressor gene maspin as a transforming growth factor beta (TGFbeta) target gene in human mammary epithelial cells. TGFbeta up-regulatesMaspin expression both at the RNA and protein levels. This up-regulation required Smad2/3 function and intact p53-binding elements in the Maspin promoter. DNA affinity immunoblot and chromatin immunoprecipitation revealed the presence of both Smads and p53 at the Maspin promoter in TGFbeta-treated cells, suggesting that both transcription factors cooperate to induce Maspin transcription. TGFbeta did not activate Maspin-luciferase reporter in p53-mutant MDA-MB-231 breast cancer cells, which exhibit methylation of the endogenous Maspin promoter. Expression of ectopic p53, however, restored ligand-induced association of Smad2/3 with a transfected Maspin promoter. Stable transfection of Maspin inhibited basal and TGFbeta-stimulated MDA-MB-231 cell motility. Finally, knockdown of endogenous Maspin in p53 wild-type MCF10A/HER2 cells enhanced basal and TGFbeta-stimulated motility. Taken together, these data support cooperation between the p53 and TGFbeta tumor suppressor pathways in the induction of Maspin expression, thus leading to inhibition of cell migration.
authors.affiliation: Department of Cancer Biology, Mass Spectrometry Research Center, Breast Cancer Research Program, Vanderbilt-Ingram Comprehensive Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Shizhen Emily
authors.initials: SE
authors.lastname: Wang
authors.forename: Archana
authors.initials: A
authors.lastname: Narasanna
authors.forename: Corbin W
authors.initials: CW
authors.lastname: Whitell
authors.forename: Frederick Y
authors.initials: FY
authors.lastname: Wu
authors.forename: David B
authors.initials: DB
authors.lastname: Friedman
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Arteaga
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D016147:Genes, Tumor Suppressor; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D015843:Serpins / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects*; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
chemical_list: C085344:SERPIN-B5; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D015843:Serpins; D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D016159:Tumor Suppressor Protein p53