Journal Article

EMT-associated up-regulation of L1CAM provides insights into L1CAM-mediated integrin signalling and NF-κB activation

Helena Kiefel, Sandra Bondong, Marco Pfeifer, Uwe Schirmer, Natalie Erbe-Hoffmann, Heiner Schäfer, Susanne Sebens and Peter Altevogt

in Carcinogenesis

Volume 33, issue 10, pages 1919-1929
Published in print October 2012 | ISSN: 0143-3334
Published online July 2012 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgs220
EMT-associated up-regulation of L1CAM provides insights into L1CAM-mediated integrin signalling and NF-κB activation

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Expression of L1 cell adhesion molecule (L1CAM) is associated with poor prognosis in a variety of human carcinomas including breast, ovarian and pancreatic ductal adenocarcinoma (PDAC). Recently we reported that L1CAM induces sustained nuclear factor kappa B (NF-κB) activation by augmenting the autocrine production of interleukin 1 beta (IL-1β), a process dependent on interaction of L1CAM with integrins. In the present study, we demonstrate that transforming growth factor β1 (TGF-β1) treatment of breast carcinoma (MDA-MB231) and PDAC (BxPc3) cell lines induces an EMT (epithelial to mesenchymal transition)-like phenotype and leads to the expression of L1CAM. In MDA-MB231 cells, up-regulation of L1CAM augmented expression of IL-1β and NF-κB activation, which was reversed by depletion of L1CAM, L1CAM-binding membrane cytoskeleton linker protein ezrin, β1-integrin or focal adhesion kinase (FAK). Over-expression of L1CAM not only induced NF-κB activation but also mediated the phosphorylation of FAK and Src. Phosphorylation was not induced in cells expressing a mutant form of L1CAM (L1-RGE) devoid of the integrin-binding site. FAK- and Src-phosphorylation were inhibited by knock-down of various components of the integrin signalling pathway such as β1- and α5-integrins, integrin-linked kinase (ILK), FAK and the phosphoinositide 3-kinase (PI3K) subunit p110β. In summary, these results reveal that during EMT, L1CAM promotes IL-1β expression through a process dependent on integrin signalling and supports a motile and invasive tumour cell phenotype. We also identify important novel downstream effector molecules of the L1CAM–integrin signalling crosstalk that help to understand the molecular mechanisms underlying L1CAM-promoted tumour progression.

Journal Article.  5911 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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