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Special Focus Content: Epithelial-mesenchymal transition in tumor metastasis: a method to the madness - Review

Mechanisms of the epithelial–mesenchymal transition by TGF-β

    Michael K Wendt*

    Department of Pharmacology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado 80045, USA

    *Both authors are equal contributors to this work.

    Search for more papers by this author

    ,
    Tressa M Allington*

    Department of Pharmacology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado 80045, USA

    *Both authors are equal contributors to this work.

    Search for more papers by this author

    &
    William P Schiemann

    † Author for correspondence

    Department of Pharmacology, MS-8303, University of Colorado Denver, Anschutz Medical Campus, RC1 South Tower, Room L18–6110, 12801 East 17th Avenue, PO Box 6511, Aurora, CO 80045, USA.

    Published Online:https://doi.org/10.2217/fon.09.90

    The formation of epithelial cell barriers results from the defined spatiotemporal differentiation of stem cells into a specialized and polarized epithelium, a process termed mesenchymal–epithelial transition. The reverse process, epithelial–mesenchymal transition (EMT), is a metastable process that enables polarized epithelial cells to acquire a motile fibroblastoid phenotype. Physiological EMT also plays an essential role in promoting tissue healing, remodeling or repair in response to a variety of pathological insults. On the other hand, pathophysiological EMT is a critical step in mediating the acquisition of metastatic phenotypes by localized carcinomas. Although metastasis clearly is the most lethal aspect of cancer, our knowledge of the molecular events that govern its development, including those underlying EMT, remain relatively undefined. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that oversees and directs all aspects of cell development, differentiation and homeostasis, as well as suppresses their uncontrolled proliferation and transformation. Quite dichotomously, tumorigenesis subverts the tumor suppressing function of TGF-β, and in doing so, converts TGF-β to a tumor promoter that stimulates pathophysiological EMT and metastasis. It therefore stands to reason that determining how TGF-β induces EMT in developing neoplasms will enable science and medicine to produce novel pharmacological agents capable of preventing its ability to do so, thereby improving the clinical course of cancer patients. Here we review the cellular, molecular and microenvironmental mechanisms used by TGF-β to mediate its stimulation of EMT in normal and malignant cells.

    Papers of special note have been highlighted as: ▪ of interest ▪▪ of considerable interest

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