Radiation-induced caveolin-1 associated EGFR internalization is linked with nuclear EGFR transport and activation of DNA-PK

Mol Cancer. 2008 Sep 12;7:69. doi: 10.1186/1476-4598-7-69.

Abstract

Background: To elucidate the role of src kinase in caveolin-1 driven internalization and nuclear transport of EGFR linked to regulation of DNA-repair in irradiated cells.

Results: Ionizing radiation resulted in src kinase stabilization, activation and subsequent src mediated caveolin-1 Y14- and EGFR Y845-phosphorylations. Both phosphorylations were radiation specific and could not be observed after treatment with EGF. Inhibition of EGFR by the antibody Erbitux resulted in a strong accumulation of caveolin/EGFR complexes within the cytoplasm, which could not be further increased by irradiation. Radiation-induced caveolin-1- and EGFR-phosphorylations were associated with nuclear EGFR transport and activation of DNA-PK, as detected by phosphorylation at T2609. Blockage of src activity by the specific inhibitor PP2, decreased nuclear transport of EGFR and inhibited caveolin-1- and DNA-PK-phosphorylation. Knockdown of src by specific siRNA blocked EGFR phosphorylation at Y845, phosphorylation of caveolin-1 at Y14 and abolished EGFR transport into the nucleus and phosphorylation of DNA-PK. Consequently, both knockdown of src by specific siRNA and also inhibition of src activity by PP2 resulted in an enhanced residual DNA-damage as quantified 24 h after irradiation and increased radiosensitivity.

Conclusion: Src kinase activation following irradiation triggered caveolin-1 dependent EGFR internalization into caveolae. Subsequently EGFR shuttled into the nucleus. As a consequence, inhibition of internalization and nuclear transport of EGFR blocked radiation-induced phosphorylation of DNA-PK and hampered repair of radiation-induced double strand breaks.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / radiation effects
  • Antibodies, Monoclonal / pharmacology
  • Antibodies, Monoclonal, Humanized
  • Caveolin 1 / metabolism*
  • Cell Line, Tumor
  • Cell Nucleus / metabolism*
  • Cetuximab
  • DNA Breaks, Double-Stranded
  • DNA Repair
  • DNA-Activated Protein Kinase / metabolism*
  • ErbB Receptors / metabolism*
  • Humans
  • Phosphorylation / radiation effects
  • RNA, Small Interfering / metabolism
  • Transfection
  • src-Family Kinases / metabolism

Substances

  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Caveolin 1
  • RNA, Small Interfering
  • ErbB Receptors
  • src-Family Kinases
  • DNA-Activated Protein Kinase
  • Cetuximab