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Updated: May 9, 2026

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay
Published on: June 9, 2017
The PERK/ATF4/LAMP3-arm of the unfolded protein response affects radioresistance by interfering with the DNA damage
Anika Nagelkerke1, Johan Bussink, Albert J van der Kogel
1Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, The Netherlands; Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, The Netherlands.
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.
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