Epithelial-mesenchymal transition and nuclear β-catenin induced by conditional intestinal disruption of Cdh1 with Apc is E-cadherin EC1 domain dependent

// Julia Matheson 1, * , Claudia Buhnemann 1, * , Emma J. Carter 1 , David Barnes 1 , Hans-Jurgen Hoppe 1 , Jennifer Hughes 1 , Stephen Cobbold 1 , James Harper 1 , Hans Morreau 2 , Mirvat Surakhy 1 , A. Bassim Hassan 1 1 Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, United Kingdom 2 Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands Correspondence to: A. Bassim Hassan, email: bass.hassan@path.ox.ac.uk Keywords: E-cadherin, Apc, intestine, β-catenin, adhesion complex Received: October 07, 2015     Accepted: August 08, 2016     Published: August 23, 2016 ABSTRACT Two important protein-protein interactions establish E-cadherin ( Cdh1 ) in the adhesion complex; homophilic binding via the extra-cellular (EC1) domain and cytoplasmic tail binding to β-catenin. Here, we evaluate whether E-cadherin binding can inhibit β-catenin when there is loss of Adenomatous polyposis coli (APC) from the β-catenin destruction complex. Combined conditional loss of Cdh1 and Apc were generated in the intestine, intestinal adenoma and adenoma organoids. Combined intestinal disruption ( Cdh1 fl/fl Apc fl/fl Vil-CreERT2 ) resulted in lethality, breakdown of the intestinal barrier, increased Wnt target gene expression and increased nuclear β-catenin localization, suggesting that E-cadherin inhibits β-catenin. Combination with an intestinal stem cell Cre ( Lgr5CreERT2 ) resulted in Apc Δ/Δ recombination and adenoma, but intact Cdh1 fl/fl alleles. Cultured Apc Δ/Δ Cdh1 fl/fl adenoma cells infected with adenovirus-Cre induced Cdh1 fl/fl recombination ( Cdh1Δ/Δ ), disruption of organoid morphology, nuclear β-catenin localization, and cells with an epithelial-mesenchymal phenotype. Complementation with adenovirus expressing wild-type Cdh1 (Cdh1-WT) rescued adhesion and β-catenin membrane localization, yet an EC1 specific double mutant defective in homophilic adhesion (Cdh1-Mut W2A, S78W ) did not. These data suggest that E-cadherin inhibits β-catenin in the context of disruption of the APC-destruction complex, and that this function is also EC1 domain dependent. Both binding functions of E-cadherin may be required for its tumour suppressor activity.