title: Integrin-dependent cell growth and survival are mediated by different signals in thyroid cells.
abstract: Cell adhesion to extracellular matrix regulates proliferation and survival of several cell types including epithelial thyroid cells. Activation of integrin receptors by binding to extracellular matrix generates a complex cell type-dependent signaling. Adhesion to extracellular matrix induces proliferation and survival in primary cultures of thyroid cells and induces survival in immortalized human thyrocytes. In this study we demonstrate that in immortalized human thyrocyte cells, adhesion to immobilized fibronectin (FN) stimulates DNA synthesis and proliferation through the p21Ras/MAPK pathway, whereas cell survival is mediated by phosphatidylinositol 3-kinase (PI3K) signal pathway. Integrin activation by immobilized FN induced phosphorylation of pp125 focal adhesion kinase and paxillin and induced the formation of focal adhesion kinase/Grb-2/Sos complex. Western blot and in vitro kinase assay demonstrated the activation of Ras and the p44/p42 MAPK/ERK1/2. Inhibition of p21Ras activity and inhibition of MAPK enzymatic activity completely arrested cell growth but did not induce cell death. Integrin activation by cell adhesion to FN also induced activation of PI3K. Inhibition of PI3K enzymatic activity induced apoptosis demonstrated by annexin V-binding assay and loss of cellular DNA content. These results demonstrate that in thyroid cells adhesion to FN regulates proliferation through the p21Ras/MAPK signal pathway, whereas integrin-mediated cell survival is mediated by PI3K.
authors.affiliation: Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, 80131 Naples, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Illario
authors.forename: Virginia
authors.initials: V
authors.lastname: Amideo
authors.forename: Adele
authors.initials: A
authors.lastname: Casamassima
authors.forename: Michele
authors.initials: M
authors.lastname: Andreucci
authors.forename: Tiziana
authors.initials: T
authors.lastname: di Matola
authors.forename: Claudia
authors.initials: C
authors.lastname: Miele
authors.forename: Guido
authors.initials: G
authors.lastname: Rossi
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Fenzi
authors.forename: Mario
authors.initials: M
authors.lastname: Vitale
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D005353:Fibronectins / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051380:GRB2 Adaptor Protein; D006801:Humans; D016023:Integrins / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D015689:Oncogene Protein p21(ras) / Q000378:metabolism; D051419:Paxillin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D020664:Son of Sevenless Proteins / Q000378:metabolism; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D005353:Fibronectins; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D016023:Integrins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; D020664:Son of Sevenless Proteins; D004247:DNA; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020928:Mitogen-Activated Protein Kinases; D015689:Oncogene Protein p21(ras)