A SNAIL1-SMAD3/4 transcriptional repressor complex promotes TGF-beta mediated epithelial-mesenchymal transition.
Epithelial-mesenchymal transition (EMT) is essential for organogenesis and is triggered during carcinoma progression to an invasive state. Transforming growth factor-beta (TGF-beta) cooperates with signalling pathways, such as Ras and Wnt, to induce EMT, but the molecular mechanisms are not clear. Here, we report that SMAD3 and SMAD4 interact and form a complex with SNAIL1, a transcriptional repressor and promoter of EMT. The SNAIL1-SMAD3/4 complex was targeted to the gene promoters of CAR, a tight-junction protein, and E-cadherin during TGF-beta-driven EMT in breast epithelial cells. SNAIL1 and SMAD3/4 acted as co-repressors of CAR, occludin, claudin-3 and E-cadherin promoters in transfected cells. Conversely, co-silencing of SNAIL1 and SMAD4 by siRNA inhibited repression of CAR and occludin during EMT. Moreover, loss of CAR and E-cadherin correlated with nuclear co-expression of SNAIL1 and SMAD3/4 in a mouse model of breast carcinoma and at the invasive fronts of human breast cancer. We propose that activation of a SNAIL1-SMAD3/4 transcriptional complex represents a mechanism of gene repression during EMT.
Vincent
Theresa
T
Ludwig Institute for Cancer Research, Stockholm Branch, 17177 Stockholm, Sweden.
Neve
Etienne P A
EP
Johnson
Jill R
JR
Kukalev
Alexander
A
Rojo
Federico
F
Albanell
Joan
J
Pietras
Kristian
K
Virtanen
Ismo
I
Philipson
Lennart
L
Leopold
Philip L
PL
Crystal
Ronald G
RG
de Herreros
Antonio Garcia
AG
Moustakas
Aristidis
A
Pettersson
Ralf F
RF
Fuxe
Jonas
J
D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics; D002461:Cell Line, Transformed; D002467:Cell Nucleus / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008648:Mesoderm / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism*; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D015820:Cadherins; C497796:SMAD4 protein, human; C000604407:SNAI1 protein, human; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C000604429:Snai1 protein, mouse; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D016212:Transforming Growth Factor beta