title: Radiation-induced caveolin-1 associated EGFR internalization is linked with nuclear EGFR transport and activation of DNA-PK.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Radiobiology and Environmental Research, Department of Radiation Oncology University of Tübingen, Röntgenweg 11, 72076 Tübingen, Germany. klaus.dittmann@uni-tuebingen.de
authors.forename: Klaus
authors.initials: K
authors.lastname: Dittmann
authors.forename: Claus
authors.initials: C
authors.lastname: Mayer
authors.forename: Rainer
authors.initials: R
authors.lastname: Kehlbach
authors.forename: H Peter
authors.initials: HP
authors.lastname: Rodemann
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000528:radiation effects; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D051242:Caveolin 1 / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D000068818:Cetuximab; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D010766:Phosphorylation / Q000528:radiation effects; D034741:RNA, Small Interfering / Q000378:metabolism; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D051242:Caveolin 1; D034741:RNA, Small Interfering; D066246:ErbB Receptors; D019061:src-Family Kinases; D051747:DNA-Activated Protein Kinase; D000068818:Cetuximab
references.citation: Nat Rev Mol Cell Biol. 2007 Mar;8(3):185-94
references.pmid: 17318224
references.citation: Int J Radiat Biol. 2007 Nov-Dec;83(11-12):781-91
references.pmid: 18058366
references.citation: Radiat Res. 1998 Dec;150(6):648-55
references.pmid: 9840184
references.citation: Radiother Oncol. 2008 Mar;86(3):383-90
references.pmid: 18037521
references.citation: Exp Cell Res. 2007 Sep 10;313(15):3349-63
references.pmid: 17643422
references.citation: J Biol Chem. 2005 Sep 2;280(35):31182-9
references.pmid: 16000298
references.citation: Cancer Res. 2007 Sep 1;67(17):8240-7
references.pmid: 17804738
references.citation: FEBS Lett. 2006 Dec 11;580(28-29):6674-8
references.pmid: 17126326
references.citation: Int J Mol Med. 2007 Jul;20(1):3-10
references.pmid: 17549382
references.citation: Proc Natl Acad Sci U S A. 2007 Aug 7;104(32):13092-7
references.pmid: 17670948
references.citation: Mol Cancer Res. 2007 Aug;5(8):863-72
references.pmid: 17699110
references.citation: EMBO J. 1996 Oct 1;15(19):5314-25
references.pmid: 8895576
references.citation: EMBO Rep. 2005 Oct;6(10):942-8
references.pmid: 16113650
references.citation: Mol Cell Biol. 2005 Aug;25(15):6391-403
references.pmid: 16024778
references.citation: Nature. 1970 Aug 15;227(5259):680-5
references.pmid: 5432063
references.citation: J Biol Chem. 2006 Oct 27;281(43):32714-23
references.pmid: 16943190
references.citation: Cell Signal. 2006 Oct;18(10):1633-46
references.pmid: 16495036
references.citation: Clin Cancer Res. 2006 Jul 1;12(13):4119-26
references.pmid: 16818713
references.citation: Endocrinology. 2004 Sep;145(9):4232-43
references.pmid: 15192046
references.citation: J Biol Chem. 2005 Apr 15;280(15):14597-604
references.pmid: 15708852
references.citation: Cancer Res. 2007 Nov 1;67(21):10129-37
references.pmid: 17974954
references.citation: Radiother Oncol. 2005 Aug;76(2):157-61
references.pmid: 16024112
references.citation: Front Biosci. 2008 Jan 01;13:1857-65
references.pmid: 17981673
references.citation: Radiother Oncol. 2007 Sep;84(3):328-34
references.pmid: 17714814
references.citation: Semin Cell Dev Biol. 2007 Aug;18(4):459-70
references.pmid: 17692542
references.citation: Oncogene. 1997 Sep 4;15(10):1191-7
references.pmid: 9294612
references.citation: J Biol Chem. 2006 Sep 8;281(36):25903-14
references.pmid: 16847054
references.citation: J Biol Chem. 2007 Mar 2;282(9):6582-7
references.pmid: 17189255
references.citation: Radiother Oncol. 2005 Aug;76(2):143-50
references.pmid: 16024124
references.citation: Clin Cancer Res. 2007 Nov 15;13(22 Pt 1):6555-60
references.pmid: 18006754
references.citation: Biochim Biophys Acta. 2005 Dec 30;1746(3):349-63
references.pmid: 16440447
references.citation: Oncogene. 2007 Oct 18;26(48):6851-62
references.pmid: 17471232
references.citation: Oral Oncol. 2007 Feb;43(2):193-8
references.pmid: 16854613
references.citation: Int J Radiat Oncol Biol Phys. 2008 Jan 1;70(1):203-12
references.pmid: 17996386
references.citation: Biochem Biophys Res Commun. 1995 Oct 24;215(3):1078-87
references.pmid: 7488034
references.citation: Biochem Biophys Res Commun. 2008 Jan 18;365(3):555-61
references.pmid: 18023415
references.citation: J Biol Chem. 2006 May 19;281(20):14486-93
references.pmid: 16407214