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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Figure 5

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TD-IκBα expressed in EpRas cells prevents EMT, whereas CA–IKK-2 induces ...
TD-IκBα expressed in EpRas cells prevents EMT, whereas CA–IKK-2 induces EMT in the absence of TGF-β (analysis in collagen gels). EpRas cells expressing the empty vector control, TD-IκBα, or CA–IKK-2 were seeded into collagen gels, were allowed to form structures for 3–5 days, and were left untreated for no induction (–) or were induced to undergo EMT by the addition of TGF-β (+) for 5–6 days. (A) Left column, culture without TGF-β for 7 days; middle column, culture without TGF-β for 5 days, plus TGF-β treatment (5 ng/ml) for 1 day; right column, culture without TGF-β for 5 days, plus TGF-β treatment (5 ng/ml) for 5 days. Photographs of representative tubular structures with lumina (yellow arrows) or distended chords and strands of invasive cells with mesenchymal morphology (white arrows) are shown. Original magnification, ×100. (B) Quantification of mesenchymal structures (see white arrows in A for the CA–IKK-2, –TGF-β culture) as the percentage relative to that of 60 randomly chosen structures per gel after 3 days of culture in the absence of TGF-β. Below graph, n indicates the number of collagen gels analyzed. Bars represent the standard deviations obtained in analyzing individual collagen gels. (C) Collagen gel structures were stained for the epithelial marker E-cadherin (first and second columns) or the mesenchymal marker vimentin (third and fourth columns). Bottom row, second from left (CA–IKK-2–expressing cells, –TGF-β): GFP expression (green) of structures stained for E-cadherin. Inset, third panel from left, middle row (TD-IκBα–expressing cells, +TGF-β): disintegrating structure stained for E-cadherin. Inset, second panel from right, bottom row (CA–IKK-2–expressing cells, –TGF-β): GFP expression (green) of structures stained for vimentin. Original magnification, ×400.