Inhibition of NF-κB improves sensitivity to irradiation and EGFR-TKIs and decreases irradiation-induced lung toxicity.

Resistance to radiotherapy and to EGFR tyrosine kinase inhibitors (EGFR-TKIs), as well as therapy-related lung toxicity, are serious problems in the treatment of lung cancer. NF-κB has been reported to be associated with radioresistance. Therefore, we evaluated its effects on sensitivity to irradiation and to EGFR-TKIs; irradiation-induced lung toxicity; and the effects of irradiation on sensitivity to EGFR-TKIs. We used IKKβ inhibitor IMD 0354 or p65 depletion to explore their effects on sensitivity to irradiation and to EGFR-TKIs in vitro and in vivo. We evaluated the efficacy of IMD 0354 in a radiation-induced pulmonary-fibrosis mouse model. Irradiation enhanced activation and expression of MET and therefore suppressed the sensitivity of lung cancer cells to irradiation or EGFR-TKIs. Inhibition of NF-κB by IMD 0354 or by p65 depletion reversed irradiation-induced MET activation and increased the sensitivity of lung cancer cells to irradiation, to EGFR-TKIs and to the combination thereof in vitro and in vivo. In addition, IMD 0354 significantly reduced lung toxicity in a murine model of irradiation-induced pneumonia and lung fibrosis. These findings indicated that NF-κB inhibition can improve sensitivity to irradiation and to EGFR-TKIs and can decrease irradiation-induced lung toxicity in lung cancer.