title: Specific interactions between Smad proteins and AP-1 components determine TGFβ-induced breast cancer cell invasion.
abstract: Deregulation of the transforming growth factor β (TGFβ) signal transduction cascade is functionally linked to cancer. In early phases, TGFβ acts as a tumor suppressor by inhibiting tumor cell proliferation, whereas in late phases, it can act as a tumor promoter by stimulating tumor cell invasion and metastasis. Smad transcriptional effectors mediate TGFβ responses, but relatively little is known about the Smad-containing complexes that are important for epithelial-mesenchymal transition and invasion. In this study, we have tested the hypothesis that specific members of the AP-1 transcription factor family determine TGFβ signaling specificity in breast cancer cell invasion. Using a 3D model of collagen-embedded spheroids of MCF10A-MII premalignant human breast cancer cells, we identified the AP-1 transcription factor components c-Jun, JunB, c-Fos and Fra1 as essential factors for TGFβ-induced invasion and found that various mesenchymal and invasion-associated TGFβ-induced genes are co-regulated by these proteins. In situ proximity ligation assays showed that TGFβ signaling not only induces complexes between Smad3 and Smad4 in the nucleus but also complexes between Smad2/3 and Fra1, whereas complexes between Smad3, c-Jun and JunB could already be detected before TGFβ stimulation. Finally, chromatin immunoprecipitations showed that c-Jun, JunB and Fra1, but not c-Fos, are required for TGFβ-induced binding of Smad2/3 to the mmp-10 and pai-1 promoters. Together these results suggest that in particular formation of Smad2/3-Fra1 complexes may reflect activation of the Smad/AP-1-dependent TGFβ-induced invasion program.
authors.affiliation: Ludwig Institute for Cancer Research, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Sundqvist
authors.forename: A
authors.initials: A
authors.lastname: Zieba
authors.forename: E
authors.initials: E
authors.lastname: Vasilaki
authors.forename: C
authors.initials: C
authors.lastname: Herrera Hidalgo
authors.forename: O
authors.initials: O
authors.lastname: Söderberg
authors.forename: D
authors.initials: D
authors.lastname: Koinuma
authors.forename: K
authors.initials: K
authors.lastname: Miyazono
authors.forename: C-H
authors.initials: CH
authors.lastname: Heldin
authors.forename: U
authors.initials: U
authors.lastname: Landegren
authors.forename: P
authors.initials: P
authors.lastname: Ten Dijke
authors.forename: H
authors.initials: H
authors.lastname: van Dam
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D020782:Matrix Metalloproteinases / Q000235:genetics; D008648:Mesoderm / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009361:Neoplasm Invasiveness; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*; D000099169:Fos-Related Antigen 1
chemical_list: D020782:Matrix Metalloproteinases; D017395:Plasminogen Activator Inhibitor 1; D017346:Protein Serine-Threonine Kinases; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000099169:Fos-Related Antigen 1; C581727:JunB protein, human