Determination of binding affinities between nuclear localization signal peptides of irradiated EGFR and KPNA using single-molecule pull-down assay and development of assay system for inhibitor screening

Abstract

Epidermal growth factor receptor (EGFR) is transported into the nucleus during irradiation therapy and can cause the radiation resistance. It has been shown that irradiation activates EGFR transport to the nuclear by karyopherin alpha (KPNA) in the classical pathway, whereas ligand-activated EGFR binds with karyopherin subunit beta 1 (KPNB1). Phosphorylation of T654 located within the nuclear localization signal (NLS) of EGFR is known to activate radiation-induced nuclear EGFR transport. Therefore, we investigated the binding affinities between the NLS peptides of EGFR ((RRRHIVRKRXLRR657)-R-645) and KPNA using a single-molecule pull-down assay in this study. We also showed the possible assay system for developing small molecules to modulate nuclear EGFR transport by high throughput screening, which potentially reduces the resistance during radiation therapy.