title: Epithelial-mesenchymal transition stimulates human cancer cells to extend microtubule-based invasive protrusions and suppresses cell growth in collagen gel.
abstract: Epithelial-mesenchymal transition (EMT) is a crucial event in tumor invasion and metastasis. However, most of past EMT studies have been conducted in the conventional two-dimensional (2D) monolayer culture. Therefore, it remains unclear what invasive phenotypes are acquired by EMT-induced cancer cells. To address this point, we attempted to characterize EMT cells in more physiological, three-dimensional (3D) collagen gel culture. EMT was induced by treating three human carcinoma cell lines (A549, Panc-1 and MKN-1) with TGF-ß. The TGF-ß treatment stimulated these cells to overexpress the invasion markers laminin γ2 and MT1-MMP in 2D culture, in addition to the induction of well-known morphological change and EMT marker expression. EMT induction enhanced cell motility and adhesiveness to fibronectin and collagen in 2D culture. Although EMT cells showed comparable cell growth to control cells in 2D culture, their growth rates were extremely suppressed in soft agar and collagen gel cultures. Most characteristically, EMT-induced cancer cells commonly and markedly extended invasive protrusions in collagen gel. These protrusions were mainly supported by microtubules rather than actin cytoskeleton. Snail-introduced, stable EMT cells showed similar protrusions in 3D conditions without TGF-ß. Moreover, these protrusions were suppressed by colchicine or inhibitors of heat shock protein 90 (HSP-90) and protein phosphatase 2A. However, MMP inhibitors did not suppress the protrusion formation. These data suggest that EMT enhances tumor cell infiltration into interstitial stroma by extending microtubule-based protrusions and suppressing cell growth. The elevated cell adhesion to fibronectin and collagen and high cell motility also seem important for the tumor invasion.
authors.affiliation: Graduate School of Integrated Science, Yokohama City University, Yokohama, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Oyanagi
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.forename: Shouichi
authors.initials: S
authors.lastname: Higashi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D018929:Cell Culture Techniques; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D003094:Collagen / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007797:Laminin / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D007797:Laminin; D016212:Transforming Growth Factor beta; D003094:Collagen