NF-κB is essential for epithelial-mesenchymal transition and metastasis in a model of breast cancer progression
Margit A. Huber, … , Hartmut Beug, Thomas Wirth
Margit A. Huber, … , Hartmut Beug, Thomas Wirth
Published August 16, 2004
Citation Information: J Clin Invest. 2004;114(4):569-581. https://doi.org/10.1172/JCI21358.
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Article Oncology

NF-κB is essential for epithelial-mesenchymal transition and metastasis in a model of breast cancer progression

Abstract

The transcription factor NF-κB is activated in a range of human cancers and is thought to promote tumorigenesis, mainly due to its ability to protect transformed cells from apoptosis. To investigate the role of NF-κB in epithelial plasticity and metastasis, we utilized a well-characterized in vitro/in vivo model of mammary carcinogenesis that depends on the collaboration of the Ha-Ras oncoprotein and TGF-β. We show here that the IKK-2/IκBα/NF-κB pathway is required for the induction and maintenance of epithelial-mesenchymal transition (EMT). Inhibition of NF-κB signaling prevented EMT in Ras-transformed epithelial cells, while activation of this pathway promoted the transition to a mesenchymal phenotype even in the absence of TGF-β. Furthermore, inhibition of NF-κB activity in mesenchymal cells caused a reversal of EMT, suggesting that NF-κB is essential for both the induction and maintenance of EMT. In line with the importance of EMT for invasion, blocking of NF-κB activity abrogated the metastatic potential of mammary epithelial cells in a mouse model system. Collectively, these data provide evidence of an essential role for NF-κB during distinct steps of breast cancer progression and suggest that the cooperation of Ras- and TGF-β–dependent signaling pathways in late-stage tumorigenesis depends critically on NF-κB activity.

Authors

Margit A. Huber, Ninel Azoitei, Bernd Baumann, Stefan Grünert, Andreas Sommer, Hubert Pehamberger, Norbert Kraut, Hartmut Beug, Thomas Wirth

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EpRas cells expressing TD-IκBα fail to undergo EMT, while CA–IKK-2 expre...
EpRas cells expressing TD-IκBα fail to undergo EMT, while CA–IKK-2 expression drives EMT in the absence of TGF-β (analysis on porous support). EpRas cells expressing the empty vector control, TD-IκBα, or CA–IKK-2 were cultivated on porous supports for 7 days in the presence (+) or absence (–) of TGF-β (5 ng/ml; days 2–7). (A) Photographs of cultivated cells are shown; regions with strands of spindle-shaped mesenchymal cells are indicated by red dotted lines. Original magnification, ×100. (B) Quantification of the area on porous supports covered by mesenchymal strands as percentage relative to total area covered by adherent cells (cultures shown in A; day 6). (C) E-cadherin levels in EpRas cells expressing empty vector, TD-IκBα, or CA–IKK-2 and not treated with TGF-β were determined by Western blot analysis with an E-cadherin–specific antibody (E-Cad; upper panel). Subsequent stripping and reprobing of the blot with a p65/RelA–specific antibody (lower panel) was done to demonstrate equal loading. (D) Cells as indicated were cultivated on porous supports for 7 days in the presence or absence of TGF-β (5 ng/ml; days 2–7). Cells were immunostained for E-cadherin or vimentin (red) with DAPI counterstaining for DNA (blue), as described in Methods. Regions of mesenchymal, E-cadherin–negative and vimentin-positive cells are outlined by white dotted lines and correspond to the “mesenchymal” areas shown in A (red dotted lines). Original magnification, ×400.