The PERK/ATF4/LAMP3-arm of the unfolded protein response affects radioresistance by interfering with the DNA damage response

Anika Nagelkerke, Johan Bussink, Albert J van der Kogel, Fred C G J Sweep, Paul N Span*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

75 Citations (Scopus)


BACKGROUND AND PURPOSE: Lysosome-associated membrane protein 3 (LAMP3) is induced by the PKR-like ER kinase (PERK)/activating transcription factor 4 (ATF4)-arm of the unfolded protein response (UPR) during hypoxia. LAMP3 has prognostic value in breast cancer patients treated with radiotherapy. Here, we specifically investigated the role of the PERK/ATF4/LAMP3-arm in the radiation response of breast cancer cells.

MATERIAL AND METHODS: Radiosensitivity of breast cancer cells was examined after siRNA-mediated knockdown of PERK, ATF4 and LAMP3. Activation of DNA damage repair proteins was evaluated by Western blotting and immunocytochemistry.

RESULTS: Knockdown of the PERK/ATF4/LAMP3-arm and chemical inhibition of PERK could radiosensitise MDA-MB-231 cells significantly. Western blot analysis of several DNA damage repair proteins showed that LAMP3 knockdowns had an attenuated DNA damage response after radiation compared to controls. γ-H2AX foci analysis revealed that LAMP3 knockdowns had a reduced number of positive cells after irradiation, indicating that their DNA damage repair signalling response is decreased. In addition, the effect of autophagy inhibition was examined and revealed a radiosensitising effect and the presence of residual γ-H2AX foci.

CONCLUSIONS: The PERK/ATF4/LAMP3-arm causes radioresistance of breast cancer cells by increasing DNA damage repair signalling. Inhibition of PERK and/or autophagy may sensitise tumours to radiotherapy.

Original languageEnglish
Pages (from-to)415-21
Number of pages7
JournalRadiotherapy and Oncology
Issue number3
Publication statusPublished - Sept-2013
Externally publishedYes


  • Activating Transcription Factor 4/antagonists & inhibitors
  • Autophagy
  • Breast Neoplasms/radiotherapy
  • Cell Line, Tumor
  • DNA Damage
  • Female
  • Histones/analysis
  • Humans
  • Lysosome-Associated Membrane Glycoproteins/antagonists & inhibitors
  • Neoplasm Proteins/antagonists & inhibitors
  • Protein Phosphatase 1/physiology
  • Radiation Tolerance
  • Unfolded Protein Response
  • eIF-2 Kinase/antagonists & inhibitors

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