| |||
Cell-matrix Adhesion (cell-matrix + adhesion)
Selected AbstractsEchistatin inhibits pp125FAK autophosphorylation, paxillin phosphorylation and pp125FAK,paxillin interaction in fibronectin-adherent melanoma cellsFEBS JOURNAL, Issue 16 2000Rossella Della Morte Echistatin, a snake-venom RGD-containing protein, was previously shown to disrupt cell-matrix adhesion by a mechanism that involves the reduction of pp125FAK tyrosine phosphorylation levels. The aim of this study was to establish the sequence of events downstream pp125FAK dephosphorylation that could be responsible for echistatin-induced disassembly of actin cytoskeleton and focal adhesions in fibronectin-adherent B16-BL6 melanoma cells. The results obtained show that echistatin induces a decrease of both autophosphorylation and kinase activity of pp125FAK. One hour of cell exposure to echistatin caused a 39% decrease of pp125FAK Tyr397 phosphorylation and a 31% reduction of pp125FAK autophosphorylation activity as measured by immune-complex kinase assay. Furthermore, 1 h of cell treatment by echistatin produced a 63% decrease of paxillin phosphorylation, as well as a reduction in the amount of paxillin bound to pp125FAK. Immunofluorescence analysis of echistatin treated cells showed the concomitant disappearance of both paxillin and pp125FAK from focal adhesions. The reduction of paxillin phosphorylation may represent a critical step in the pathway by which disintegrins exert their biological activity, including the inhibition of experimental metastasis in vivo. [source] Compact spheroid formation by ovarian cancer cells is associated with contractile behavior and an invasive phenotypeINTERNATIONAL JOURNAL OF CANCER, Issue 9 2009Katharine L. Sodek Abstract Ovarian cancer cells are present in malignant ascites both as individual cells and as multicellular spheroid aggregates. Although spheroid formation affords protection of cancer cells against some chemotherapeutic agents, it has not been established whether a relationship exists between invasive behavior and predisposition to spheroid formation. Aspects of spheroid formation, including cell-matrix adhesion, remodeling and contractility are characteristic myofibroblast-like behaviors associated with fibrosis that contribute to tumor growth and dissemination. We explored the possibility that cell behaviors that promote spheroid formation also facilitate invasion. Our analysis of 6 human ovarian cancer cell lines indicated that ovarian cancer cells possessing myofibroblast-like properties formed compact spheroids and invaded 3D matrices. These cells readily contracted collagen I gels, possessed a spindle-like morphology, and had elevated expression of genes associated with the TGF,-mediated fibrotic response and/or ,1 integrin function, including fibronectin (FN), connective tissue growth factor (CTGF/CCN2), lysyl oxidase (LOX1), tissue transglutaminase 2 (TGM2) and urinary plasminogen activator receptor (uPAR). Whereas cell aggregation was induced by TGF,, and by ,1-integrin overexpression and activation, these treatments did not stimulate the contractile activity required for spheroid compaction. The positive relationship found between compact spheroid formation and invasive behavior implies a preferential survival of an invasive subpopulation of ovarian cancer cells, as cells in spheroids are more resistant to several chemotherapeutics. Preventing the formation of ovarian cancer spheroids may represent a novel strategy to improve the efficacy of existing therapeutics. © 2008 Wiley-Liss, Inc. [source] PR-39 coordinates changes in vascular smooth muscle cell adhesive strength and locomotion by modulating cell surface heparan sulfate,matrix interactionsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2001John H. Chon PR-39 is proline-rich peptide produced at sites of tissue injury. While the functional properties of this peptide have not been fully defined, PR-39 may be an important regulator of processes related to cell-matrix adhesion since it reportedly upregulates syndecan-4, which is a critical determinant of focal adhesion formation. The ability of PR-39 to modulate the adhesion and chemokinetic migration behavior of arterial smooth muscle cells (SMCs) in a fashion coordinated with syndecan-4 expression was investigated. Treatment of SMCs with PR-39 did not alter syndecan-1 mRNA, but did induce a two-fold increase in syndecan-4 mRNA (P,<,0.0001) and significantly enhanced cell surface expression of both syndecan-4 (P,<,0.01) and heparan sulfate (HS) (P,<,0.05). These observations were consistent with an observed increase in cell-matrix adhesive strength (P,<,0.05) and a reduction in cell speed (P,<,0.01) on fibronectin-coated substrates. Incubation of PR-39 treated cells with a soluble fibronectin derived heparin-binding peptide, as a competitive inhibitor of heparan sulfate/matrix interactions, abolished these effects. These data suggest that PR-39 mediated alterations of cell adhesion and motility may be related, in part, to the increased expression of heparan sulfate glycosaminoglycans (GAGs) that accompany the upregulation of cell surface syndecan-4. Futhermore, this investigation supports the notion that factors which control syndecan-4 expression may play an important role in regulating adhesion related cell processes. © 2001 Wiley-Liss, Inc. [source] Transmembrane signal transduction of the ,IIb,3 integrinPROTEIN SCIENCE, Issue 7 2002Kay E. Gottschalk Abstract Integrins are composed of noncovalently bound dimers of an ,- and a ,-subunit. They play an important role in cell-matrix adhesion and signal transduction through the cell membrane. Signal transduction can be initiated by the binding of intracellular proteins to the integrin. Binding leads to a major conformational change. The change is passed on to the extracellular domain through the membrane. The affinity of the extracellular domain to certain ligands increases; thus at least two states exist, a low-affinity and a high-affinity state. The conformations and conformational changes of the transmembrane (TM) domain are the focus of our interest. We show by a global search of helix,helix interactions that the TM section of the family of integrins are capable of adopting a structure similar to the structure of the homodimeric TM protein Glycophorin A. For the ,IIb,3 integrin, this structural motif represents the high-affinity state. A second conformation of the TM domain of ,IIb,3 is identified as the low-affinity state by known mutational and nuclear magnetic resonance (NMR) studies. A transition between these two states was determined by molecular dynamics (MD) calculations. On the basis of these calculations, we propose a three-state mechanism. [source] LRIG1, a candidate tumour-suppressor gene in human bladder cancer cell line BIU87BJU INTERNATIONAL, Issue 4 2006Wei-Min Yang OBJECTIVES To determine the effects of LRIG1 on the growth, migration and invasion of bladder cancer cells and the mechanisms underlying such effects. MATERIALS AND METHODS The plasmid pLRIG1-green fluorescence protein (GFP) was transfected into BIU87 bladder cancer cells by Lipofectamine2000 (Invitrogen, Groningen, the Netherlands), and the cells that expressed LRIG1 stably were screened out by G418. The changes in LRIG1 and epidermal growth factor receptor (EGFR) protein levels were measured by Western blot; growth curves were estimated by the tetrazolium (MTT) assay; then cell-cell adhesion, cell-matrix adhesion and cell invasion assays were used to measure proliferation, adhesion and invasion in LGIR1-transfected and control cells. RESULTS The LRIG1 protein level in pLRIG1-GFP transfected cells was significantly higher than that in control cells, while the EGFR protein level was significantly lower. pLRIG1-GFP transfected cells had less proliferation than control cells. Contrasting with non-LRIG1-transfected cells, the invasion and cell-matrix adhesion ability of pLRIG1-GFP transfected cells decreased markedly, and conversely the homotypic cell-cell adhesion ability was significantly higher. CONCLUSIONS LRIG1 might act as a tumour-suppressor gene, participating in negative feedback control of EGFR expression, which inhibits bladder cancer cells from growth, migration and invasion. [source] RNAi knockdown of the focal adhesion protein TES reveals its role in actin stress fibre organisationCYTOSKELETON, Issue 3 2005Elen Griffith Abstract TES was originally identified as a candidate tumour suppressor gene and has subsequently been found to encode a novel focal adhesion protein. As well as localising to cell-matrix adhesions, TES localises to cell-cell contacts and to actin stress fibres. TES interacts with a variety of cytoskeletal proteins including zyxin, mena, VASP, talin and actin. There is evidence that TES may function in actin-dependent processes as overexpression of TES results in increased cell spreading and decreased cell motility. Together with TES's interacting partners, these data suggest that TES might be involved in regulation of the actin cytoskeleton. Here, for the first time, we have used RNAi to successfully knockdown TES in HeLa cells and we demonstrate that loss of TES from focal adhesions results in loss of actin stress fibres. Similarly, and as previously reported, RNAi-mediated knockdown of zyxin results in loss of actin stress fibres. TES siRNA treated cells show reduced RhoA activity, suggesting that the Rho GTPase pathway may be involved in the TES RNAi-induced loss of stress fibres. We have also used RNAi to examine the requirement of TES and zyxin for each other's localisation at focal adhesions, and we propose a hierarchy of recruitment, with zyxin being first, followed by VASP and then TES. Cell Motil. Cytoskeleton 60:140,152, 2005. © 2005 Wiley-Liss, Inc. [source] |