E-Cadherin Inhibits Cell Surface Localization of the Pro-Migratory 5T4 Oncofetal Antigen in Mouse Embryonic Stem Cells

Abstract

Epithelial-mesenchymal transition (EMT) events occur during embryonic development and are important for the metastatic spread of epithelial tumors. We show here that spontaneous differentiation of mouse embryonic stem (ES) cells is associated with an E-to N-cadherin switch, up-regulation of E-cadherin repressor molecules (Snail and Slug proteins), gelatinase activity (matrix metalloproteinase [MMP]-2 and -9), and increased cellular motility, all characteristic EMT events. The 5T4 oncofetal antigen, previously shown to be associated with very early ES cell differentiation and altered motility, is also a part of this coordinated process. E-and N-cadherin and 5T4 proteins are independently regulated during ES cell differentiation and are not required for induction of EMT-associated transcripts and proteins, as judged from the study of the respective knockout ES cells. Further, abrogation of E-cadherin-mediated cell-cell contact in undifferentiated ES cells using neutralizing antibody results in a reversible mesenchymal phenotype and actin cytoskeleton rearrangement that is concomitant with translocation of the 5T4 antigen from the cytoplasm to the cell surface in an energy-dependent manner. E-cadherin null ES cells are constitutively cell surface 5T4 positive, and although forced expression of E-cadherin cDNA in these cells is sufficient to restore cell-cell contact, cell surface expression of 5T4 antigen is unchanged. 5T4 and N-cadherin knockout ES cells exhibit significantly decreased motility during EMT, demonstrating a functional role for these proteins in this process. We conclude that E-cadherin protein stabilizes cortical actin cytoskeletal arrangement in ES cells, and this can prevent cell surface localization of the promigratory 5T4 antigen.

Inhibition of tumor growth and metastasis by a self-therapeutic nanoparticle

“…Our data showed that AuNP treatment ensued a change in the localization of E-Cad from a more perinuclear site to the cell membrane, which further supports reversal of EMT upon nanoparticle treatment (Fig. 2H) (42)(43)(44). Since EMT is recognized to confer drug resistance and metastatic potential to cancer cells (11)(12)(13), AuNPs may find wide applications to sensitize drug-resistant cancer cells to chemotherapeutics and to prevent metastasis.…”

Cell signalling pathways underlying induced pluripotent stem cell reprogramming

“…MET is a feature of both mouse [41] and human [42] somatic cell reprogramming and involves the loss of mesenchymal characteristics such as motility and the acquisition of epithelial characteristics such as cell polarity and expression of the cell adhesion molecule E-CADHERIN, perhaps explaining why E-cadherin can replace Oct4 in the reprogramming process [43] . MET and the opposite transition, epithelial-to-mesenchymal transition (EMT), are key features of embryogenesis [44] , tumour metastasis [45] and both mouse [46] and human [47] ES cell differentiation. Interestingly, the MET that marks the initiation of cellular reprogramming is reversible since removal of the reprogramming factors from mouse "preiPS" cells after induction of reprogramming has been shown to lead to reversion of the cells to a mesenchymal phenotype [36] , thus demonstrating that continued transgene expression is necessary to allow cells to progress to the maturation stage.…”

The Function of E-cadherin in ES Cell Pluripotency

“…Firstly, E-cadherin functions to maintain cell-cell contact and this is likely to effect localisation of plasma membrane proteins. Our demonstration that E-cadherin inhibits cell surface localisation of the pro-migratory factor 5T4 Spencer et al, 2007) suggests that Ecadherin expression exerts a physical effect on the localisation of plasma membrane proteins. Unpublished data in our lab has revealed that loss of E-cadherin in mES cells does not affect cell surface expression of gp130 or the LIFR (Hawkins, unpublished), suggesting that alterations in signalling pathways in E-cadherin-/-mES cells are not due to changes in the localisation of pluripotency-associated receptors.…”

“…For example, we have demonstrated that loss of E-cadherin in mouse and hES cells results in translocation of the promigratory molecule 5T4 from the cytoplasm to the plasma membrane and that this is associated with altered actin cytoskeleton arrangement and induction of cell polarisation Spencer et al, 2007). In addition, it has been reported that E-cadherin mediated cell-cell contact regulates expression of Eph receptors and Ephrins (Orsulic and Kemler, 2000).…”

“…As a result, E-cadherin expression can be used as a useful non-invasive tool to assess the pluripotent status of ES cells (Spencer et al, 2011). Since EMT/metastasis is difficult to study in vivo, ES cells may provide a useful model system for the study of this process Spencer et al, 2007). Our analysis of the EMT event during mES cell differentiation has enabled an understanding of the hierarchy of this process.…”