Integrins uncouple Src-induced morphological and oncogenic transformation

J Biol Chem. 2008 May 9;283(19):13243-51. doi: 10.1074/jbc.M800927200. Epub 2008 Mar 7.

Abstract

Expression of activated mutants of c-Src in epithelial cells can induce tumorigenicity. In addition to such oncogenic transformation, the cells undergo a dramatic morphological transformation: cell-cell contacts are disrupted, spreading on extracellular matrix proteins is suppressed, actin stress fibers and focal contacts are lost, and podosomes are formed. We have previously shown that integrin alphavbeta3 strongly supports Src-mediated oncogenic transformation through an interaction at the beta3 cytoplasmic tail. Our current findings demonstrate that this interaction does not affect Src-mediated morphological alterations, thus separating oncogenic from morphological transformation. Moreover, beta1 and beta3 integrins differently affect the various aspects of Src-induced morphological transformation. High levels of beta3, but not beta1, integrins can prevent Src-induced cell rounding although stress fiber disassembly and podosome formation still occur. Studies using chimeric integrin subunits demonstrate that this protection requires the beta3 extracellular domain. Finally, like tumor formation, podosome assembly occurs independent of beta3 phosphorylation. Instead, phosphorylation of beta1 is required to suppress Rho-mediated contractility in order to assemble podosomes. Thus, integrins regulate Src-mediated oncogenic transformation and various aspects of morphological transformation through dissociable pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Adhesion
  • Cell Line
  • Cell Shape*
  • Cell Transformation, Neoplastic*
  • Cytoplasm / metabolism
  • Cytoskeleton / metabolism
  • Enzyme Activation
  • Humans
  • Integrin beta Chains / classification
  • Integrin beta Chains / genetics
  • Integrin beta Chains / metabolism*
  • Phosphorylation
  • rhoA GTP-Binding Protein / metabolism
  • src-Family Kinases / metabolism*

Substances

  • Integrin beta Chains
  • src-Family Kinases
  • rhoA GTP-Binding Protein