Study of cell-cell adhesion formation and dynamics in cancer cells using a hybrid cell-lipid bilayer system.

Abstract

The formation and regulation of connections between cells play a crucial role in maintaining tissue homeostasis and tumour repression. In many tissues, particular importance comes to adherens junctions that are formed by the binding of E-cadherin proteins at the surface of adjacent cells, followed by their clustering and recruitment of catenins and other adaptor proteins on the intracellular site linking the protein complex to the actomyosin cytoskeleton. This process depends on multiple parameters such as the mobility, density, type of cadherins, and the mechanical forces acting on the cadherin-catenin complexes and can change dramatically during developmental stages or in diseases such as cancer. To study the initial steps of adherens junction formation in a controlled environment in cancer cells, we have established a reconstituted system of cells adhering to supported lipid bilayers decorated with extracellular domains of E-cadherin proteins. This reconstituted system allowed us to capture the initiation and dynamics of cadherin interactions, the real-time localisation and clustering of adaptor proteins and the maturation of adherens junction in cancer cells over time using live cell imaging with confocal and total internal reflection microscopy. To understand the importance of the different parameters and to mimic the cell/tissue abnormalities occurring in cancer scenarios, we then perturb the controlled system by varying cadherin density, membrane mobility and inducing mechanical stress by confining the cell system over time. We find, for example, that reduced E-cadherin mobility leads to the formation of stable regions showing actin enrichment and that confinement increases the steady state adhesion zone. This approach provides new insights about cell surface dynamics during cell-cell adhesion and can improve our understanding of the role of cell mechanics and E-cadherin organisation patterns in cancer progression.