Convergence of p53 and transforming growth factor beta (TGFbeta) signaling on activating expression of the tumor suppressor gene maspin in mammary epithelial cells.

Wang SE, Narasanna A, Whitell CW, Wu FY, Friedman DB, Arteaga CL
J Biol Chem. 2007 282 (8): 5661-9

PMID: 17204482 · PMCID: PMC4015524 · DOI:10.1074/jbc.M608499200

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.

MeSH Terms (15)

Cell Line, Tumor Cell Movement Epithelial Cells Genes, Tumor Suppressor Humans Mammary Glands, Human Promoter Regions, Genetic Serpins Signal Transduction Smad2 Protein Smad3 Protein Transcriptional Activation Transforming Growth Factor beta Tumor Suppressor Protein p53 Up-Regulation

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