title: TGFβ induces epithelial-mesenchymal transition of thyroid cancer cells by both the BRAF/MEK/ERK and Src/FAK pathways.
abstract: The epithelial-mesenchymal transition (EMT) is a crucial process in tumour progression, by which epithelial cells acquire a mesenchymal phenotype, increasing its motility and the ability to invade distant sites. Here, we describe the molecular mechanisms by whichV600EBRAF, TGFβ and the Src/FAK complex cooperatively regulate EMT induction and cell motility of anaplastic thyroid cancer cells. Analysis of EMT marker levels reveals a positive correlation between TGFβ and Snail expression, with a concomitant downregulation of E-cadherin, accompanied by an increase of cell migration and invasion. Furthermore, we show thatV600EBRAF depletion by siRNA or inhibition of its activity by treatment with its inhibitor PLX4720 reverses the TGFβ-mediated effects on Snail, E-cadherin, migration and invasion. Moreover,V600EBRAF induces TGFβ secretion through a MEK/ERK-dependent mechanism. In addition, TGFβ activates the Src/FAK complex, which in turn regulates the expression of Snail and E-cadherin as well as cell migration. The inhibition of Src with the inhibitor SU6656 or abrogation of FAK expression with a specific siRNA reverses the TGFβ-induced effects. Interestingly, we demonstrate that activation of the Src/FAK complex by TGFβ is independent ofV600EBRAF signalling, since inhibition of this oncogene does not affect its phosphorylation. Our data strongly suggest that TGFβ induces EMT and aggressiveness of thyroid cancer cells by parallel mechanisms involving both theV600EBRAF/MEK/ERK and Src/FAK pathways independently. Thus, we describe novel functions for Src/FAK in mediating the EMT program and aggressiveness regulated by TGFβ, establishing the inhibition of these proteins as a possible effective approach in preventing tumour progression ofV600EBRAF-expressing thyroid tumours. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Campus Universitario, Alcalá de Henares, Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Baquero
authors.affiliation: Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Campus Universitario, Alcalá de Henares, Madrid, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Jiménez-Mora
authors.affiliation: Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Campus Universitario, Alcalá de Henares, Madrid, Spain.
authors.forename: Adrián
authors.initials: A
authors.lastname: Santos
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Lasa
authors.affiliation: Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Campus Universitario, Alcalá de Henares, Madrid, Spain. antonio.chiloeches@uah.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Chiloeches
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement; D058750:Epithelial-Mesenchymal Transition; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D009154:Mutation; D009361:Neoplasm Invasiveness; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013964:Thyroid Neoplasms / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D007211:Indoles; C528407:PLX 4720; D013449:Sulfonamides; D016212:Transforming Growth Factor beta; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D019061:src-Family Kinases; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: EMT; Src/FAK; TGFβ; V600EBRAF; thyroid cancer