title: Topographic confinement of epithelial clusters induces epithelial-to-mesenchymal transition in compliant matrices.
abstract: Epithelial cells disengage from their clusters and become motile by undergoing epithelial-to-mesenchymal transition (EMT), an essential process for both embryonic development and tumor metastasis. Growing evidence suggests that high extracellular matrix (ECM) stiffness induces EMT. In reality, epithelial clusters reside in a heterogeneous microenvironment whose mechanical properties vary not only in terms of stiffness, but also topography, dimensionality, and confinement. Yet, very little is known about how various geometrical parameters of the ECM might influence EMT. Here, we adapt a hydrogel-microchannels based matrix platform to culture mammary epithelial cell clusters in ECMs of tunable stiffness and confinement. We report a previously unidentified role of ECM confinement in EMT induction. Surprisingly, confinement induces EMT even in the cell clusters surrounded by a soft matrix, which otherwise protects against EMT in unconfined environments. Further, we demonstrate that stiffness-induced and confinement-induced EMT work through cell-matrix adhesions and cytoskeletal polarization, respectively. These findings highlight that both the structure and the stiffness of the ECM can independently regulate EMT, which brings a fresh perspective to the existing paradigm of matrix stiffness-dependent dissemination and invasion of tumor cells.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Washington University, Saint Louis, MO 63130, USA.
authors.forename: Samila
authors.initials: S
authors.lastname: Nasrollahi
authors.affiliation: Department of Mechanical Engineering and Materials Science, Washington University, Saint Louis, MO 63130, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Pathak
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D003599:Cytoskeleton / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D040542:Mechanotransduction, Cellular; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
chemical_list: D015820:Cadherins; D014746:Vimentin; D051416:Focal Adhesion Protein-Tyrosine Kinases