Inhibition of EGFR nuclear translocation attenuate radioresistance through decreased p-DNA-PK expression in cervical cancer cells.

Abstract

e17011 Background: The commonly used treatment for cervical cancer is radiotherapy. However, the resistance to irradiation and metastasis at the advanced stage is a common reason for the poor prognosis and high mortality. This study was designed to elucidate the role of epidermal growth factor receptor (EGFR) nuclear translocation in radioresistance, and its correlation with DNA damage repair pathway in the cervical cancer cells. Methods: The dynamic expression of EGFR, DNA-dependent protein kinase (DNA-PK), PDK-1, PKN1 and their phosphorylation level in irradiated cervical cancer cell line CaSki at 0 10 20 40 minutes was determined by western blotting. Besides, nuclear localization signal (NLS) peptide inhibitor and control peptides was synthesized and treated cells before irradiation to elucidate the correlation between EGFR nuclear translocation and DNA damage repair after irradiation. Results: Expression of EGFR, protein kinase N1 (PKN1), and DNA-PK in nucleus was increased after irradiation in CaSki cells. Irradiation also enhanced the phosphorylation level of EGFR at Thr654, PKN1 at T774 and DNA-PK at T2609. Inhibition of EGFR nuclear translocation by NLS peptide decreased the expression level of EGFR and DNA-PK in the nucleus, and attenuated their phosphorylation process. Conclusions: EGFR nuclear translocation riggered by irradiation promoted DNA damage repair in irradiated cervical cancer cells. This work facilitated us to understand the possible molecular mechanism of the resistance to irradiation in the treatment of cervical cancer, providing a potentially potent clinical method to cancer therapy.