Nimotuzumab, an EGFR‑targeted antibody, promotes radiosensitivity of recurrent esophageal squamous cell carcinoma.

Local tumor recurrence is one of the main causes for the failure of esophageal cancer treatment following radiotherapy. Previous studies have demonstrated that epidermal growth factor receptor (EGFR)‑targeted therapy combined with radiotherapy is expected to become an effective means to control tumor recurrence. The aim of the present study was to investigate the effect and mechanism of nimotuzumab (an EGFR‑targeted antibody) in the treatment of recurrent esophageal carcinoma. The radiation responses of two esophageal squamous carcinoma cell lines, EC109 and TE‑1, with or without nimotuzumab, were first evaluated by CCK‑8 assay. Colony formation and apoptosis were used to measure anti‑proliferation effects. It was demonstrated that nimotuzumab arrested the cell cycle at the G2 phase in vitro. Western blotting and immunofluorescence analysis were used to determine signaling pathway changes. It was observed that nimotuzumab inhibited phosphorylation of EGFR in EC109 cells. Furthermore, recurrent tumor models were established and it was identified that the degree of tumor hypoxia was positively associated with EGFR overexpression. In EC109 cell xenografts, nimotuzumab combined with radiation led to a significant delay in recurrent tumor growth compared with that of radiation alone (P<0.001 for 0 Gy pre‑irradiation, P=0.005 for 20 Gy pre‑irradiation, P=0.005 for 10 Gy pre‑irradiation). These results suggest that nimotuzumab combined with radiation may be an effective means to control recurrent esophageal squamous cell carcinoma with EGFR overexpression.