Adhesion-mediated squamous cell carcinoma survival through ligand-independent activation of epidermal growth factor receptor

Am J Pathol. 2004 Oct;165(4):1315-29. doi: 10.1016/S0002-9440(10)63390-1.

Abstract

The survival and growth of squamous epithelial cells require signals generated by integrin-matrix interactions. After conversion to squamous cell carcinoma, the cells remain sensitive to detachment-induced anoikis, yet in tumor cell aggregates, which are matrix-deficient, these cells are capable of suprabasal survival and proliferation. Their survival is enhanced through a process we call synoikis, whereby junctional adhesions between neighboring cells generate specific downstream survival signals. Here we show that in squamous cell carcinoma cells, E-cadherin-mediated cell-cell contacts specifically induce activation of epidermal growth factor receptor (EGFR). EGFR activation in turn triggers the ERK/MAPK signaling module, leading to elevation of anti-apoptotic Bcl-2. After intercellular adhesion, formation of adherens junctions triggers the formation of E-cadherin-EGFR complexes, correlating with EGFR transactivation. Analysis of the process with a dominant-negative EGFR mutant indicated that activation of EGFR is ligand-independent. Our data implicate cell-cell adhesion-induced activation of EGFR as a cooperative mechanism that generates compensatory survival signaling, protecting malignant cells from detachment-induced death.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anoikis / physiology
  • Cadherins / metabolism*
  • Carcinoma, Squamous Cell / metabolism*
  • Cell Adhesion / physiology*
  • Cell Communication / physiology*
  • Cell Line, Tumor
  • Cell Survival
  • Enzyme Activation / physiology
  • ErbB Receptors / metabolism*
  • Fluorescent Antibody Technique
  • Humans
  • Immunoblotting
  • Ligands
  • Mitogen-Activated Protein Kinases / metabolism
  • Precipitin Tests
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Signal Transduction / physiology*
  • Transcriptional Activation
  • Transfection

Substances

  • Cadherins
  • Ligands
  • Proto-Oncogene Proteins c-bcl-2
  • ErbB Receptors
  • Mitogen-Activated Protein Kinases