Integrin-linked kinase tunes cell-cell and cell-matrix adhesions to regulate the switch between apoptosis and EMT downstream of TGFβ1. Author Ayse Kilinc, Siyang Han, Lena Barrett, Niroshan Anandasivam, Celeste Nelson Publication Year 2021 Type Journal Article Abstract Epithelial-mesenchymal transition (EMT) is a morphogenetic process that endows epithelial cells with migratory and invasive potential. Mechanical and chemical signals from the tumor microenvironment can activate the EMT program, thereby permitting cancer cells to invade the surrounding stroma and disseminate to distant organs. Transforming growth factor β1 (TGFβ1) is a potent inducer of EMT that can also induce apoptosis depending on the microenvironmental context. In particular, stiff microenvironments promote EMT while softer ones promote apoptosis. Here, we investigated the molecular signaling downstream of matrix stiffness that regulates the phenotypic switch in response to TGFβ1 and uncovered a critical role for integrin-linked kinase (ILK). Specifically, depleting ILK from mammary epithelial cells precludes their ability to sense the stiffness of their microenvironment. In response to treatment with TGFβ1, ILK-depleted cells undergo apoptosis on both soft and stiff substrata. We found that knockdown of ILK decreases focal adhesions and increases cell-cell adhesions, thus shifting the balance from cell-matrix to cell-cell adhesion. High cell-matrix adhesion promotes EMT whereas high cell-cell adhesion promotes apoptosis downstream of TGFβ1. These results highlight an important role for ILK in controlling cell phenotype by regulating adhesive connections to the local microenvironment. Keywords Animals, Mice, Signal Transduction, Cell Line, Cell Adhesion, Cell Movement, Epithelial Cells, Epithelial-Mesenchymal Transition, Transforming Growth Factor beta1, Focal Adhesions, Apoptosis, Cell-Matrix Junctions, Protein Serine-Threonine Kinases Journal Mol Biol Cell Volume 32 Issue 5 Pages 402-412 Date Published 2021 Mar 01 ISSN Number 1939-4586 DOI 10.1091/mbc.E20-02-0092 Alternate Journal Mol Biol Cell PMCID PMC8098849 PMID 33405954 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML