Format

Send to

Choose Destination
Radiother Oncol. 2008 Mar;86(3):383-90. Epub 2007 Nov 26.

Activation of protein kinase Cepsilon stimulates DNA-repair via epidermal growth factor receptor nuclear accumulation.

Author information

1
Department of Radiation Oncology, University of T├╝bingen, Germany

Abstract

PURPOSE:

To elucidate the interaction between radioprotector O-phospho-l-tyrosine (P-Tyr) with epidermal growth factor receptor (EGFR).

METHODS:

Molecular effects of P-Tyr at the level of EGFR responses were investigated in vitro with TP53-wildtype bronchial carcinoma cell line A549, which is radio-protected by P-Tyr treatment. Nuclear EGFR accumulation was followed by confocal microscopy and Western blotting. PKCepsilon protein expression was impaired by specific siRNA. Residual DNA-damage was quantified with gammaH(2)AX foci analysis.

RESULTS:

P-Tyr mediated radio-protection was associated with nuclear EGFR accumulation. Radiation-induced nuclear EGFR presented increased phosphorylation at residue No. T654. We identified PKCepsilon as responsible for T654-phosphorylation. Knockdown of PKCepsilon by siRNA blocked both radiation- and P-Tyr-triggered nuclear EGFR accumulation. Furthermore, nuclear accumulation of EGFR was associated with increased phosphorylation of DNA-dependent protein kinase (DNA-PK) at residue No. T2609, essential for DNA-repair. Consequently P-Tyr mediated effects upon DNA-PK resulted in a significant reduction of radiation-induced residual gammaH(2)AX-foci. Knockdown of PKCepsilon increased radiation-induced residual damage and abolished the P-Tyr associated radioprotection. In addition, P-Tyr mediated radioprotection was completely absent in colony formation assay.

CONCLUSION:

The data presented herein suggest that P-Tyr-treatment mediates activation of PKCepsilon, which triggers nuclear EGFR accumulation. Nuclear EGFR is involved in phosphorylation of DNA-PK at Thr2609, which has a significant impact upon DNA-DSB repair.

PMID:
18037521
DOI:
10.1016/j.radonc.2007.10.041
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center