title: Efficient TGFβ-induced epithelial-mesenchymal transition depends on hyaluronan synthase HAS2.
abstract: Epithelial-mesenchymal transition (EMT) is a developmental program, which can be adopted by cancer cells to increase their migration and ability to form metastases. Transforming growth factor β (TGFβ) is a well-studied inducer of EMT. We demonstrate that TGFβ potently stimulates hyaluronan synthesis via upregulation of hyaluronan synthase 2 (HAS2) in NMuMG mammary epithelial cells. This stimulatory effect requires the kinase active type I TGFβ receptor and is dependent on Smad signaling and activation of the p38 mitogen-activated protein kinase. Knockdown of HAS2 inhibited the TGFβ-induced EMT by about 50%, as determined by the phase contrast microscopy and immunostaining using the EMT marker ZO-1. Furthermore, real-time PCR analysis of the EMT markers fibronectin, Snail1 and Zeb1 revealed decreased expressions upon HAS2 suppression, using specific small interfering RNA (siRNA) for HAS2. Removal of the extracellular hyaluronan by Streptomyces hyaluronidase or inhibiting the binding to its cell surface receptor CD44 by blocking antibodies, did not inhibit TGFβ-induced EMT. Interestingly, HAS2 suppression completely abolished the TGFβ-induced cell migration, whereas CD44 knockdown did not. These observations suggest that TGFβ-dependent HAS2 expression, but not extracellular hyaluronan, has an important regulatory role in TGFβ-induced EMT.
authors.affiliation: Ludwig Institute for Cancer Research, Science for life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Porsch
authors.forename: B
authors.initials: B
authors.lastname: Bernert
authors.forename: M
authors.initials: M
authors.lastname: Mehić
authors.forename: A D
authors.initials: AD
authors.lastname: Theocharis
authors.forename: C-H
authors.initials: CH
authors.lastname: Heldin
authors.forename: P
authors.initials: P
authors.lastname: Heldin
mesh_terms: D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects* / Q000235:genetics*; D055785:Gene Knockdown Techniques; D014453:Glucuronosyltransferase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis; D042361:Mammary Glands, Human / Q000378:metabolism / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D018960:Hyaluronan Receptors; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C101754:HAS2 protein, human; D000076002:Hyaluronan Synthases; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I