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Zyxin is a Transforming Growth Factor-β (TGF-β)/Smad3 target gene that regulates lung cancer cell motility via integrin α5β1.
J. Biol. Chem. 287, 31393-31405 (2012)
Although TGF-beta acts as a tumor suppressor in normal tissues and in early carcinogenesis, these tumor suppressor effects are lost in advanced malignancies. Single cell migration and epithelial-mesenchymal transition (EMT), both of which are regulated by TGF-beta, are critical steps in mediating cancer progression. Here, we sought to identify novel direct targets of TGF-beta signaling in lung cancer cells and have indentified the zyxin gene as a target of Smad3-mediated TGF-beta 1 signaling. Zyxin concentrates at focal adhesions and along the actin cytoskeleton; as such, we hypothesized that cytoskeletal organization, motility, and EMT in response to TGF-beta 1 might be regulated by zyxin expression. We show that TGF-beta 1 treatment of lung cancer cells caused rapid phospho-Smad3-dependent expression of zyxin. Zyxin expression was critical for the formation and integrity of cell adherens junctions. Silencing of zyxin decreased expression of the focal adhesion protein vasodilator-activated phosphoprotein (VASP), although the formation and morphology of focal adhesions remained unchanged. Zyxin-depleted cells displayed significantly increased integrin alpha 5 beta 1 levels, accompanied by enhanced adhesion to fibronectin and acquisition of a mesenchymal phenotype in response to TGF-beta 1. Zyxin silencing led to elevated integrin alpha 5 beta 1-dependent single cell motility. Importantly, these features are mirrored in the K-ras-driven mouse model of lung cancer. Here, lung tumors revealed decreased levels of both zyxin and phospho-Smad3 when compared with normal tissues. Our data thus demonstrate that zyxin is a novel functional target and effector of TGF-beta signaling in lung cancer. By regulating cell-cell junctions, integrin alpha 5 beta 1 expression, and cell-extracellular matrix adhesion, zyxin may regulate cancer cell motility and EMT during lung cancer development and progression.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
EPITHELIAL-MESENCHYMAL TRANSITIONS; TGF-BETA; ACTIN-POLYMERIZATION; TUMOR-SUPPRESSOR; ALPHA-ACTININ; II RECEPTOR; PROTEIN; ADHESION; TRANSDIFFERENTIATION; SMAD3
ISSN (print) / ISBN
0021-9258
e-ISSN
1083-351X
Quellenangaben
Volume: 287,
Issue: 37,
Pages: 31393-31405
Publisher
American Society for Biochemistry and Molecular Biology
Reviewing status
Peer reviewed
Institute(s)
Institute of Lung Health and Immunity (LHI)