Response and resistance to NF-κB inhibitors in mouse models of lung adenocarcinoma

Lung adenocarcinoma is a frequently diagnosed cancer type and a leading cause of cancer death worldwide. We recently demonstrated in an autochthonous mouse model of this disease that genetic inhibition of the NF-κB pathway affects both the initiation and maintenance of lung cancer, identifying this pathway as a promising therapeutic target. In this study, we tested the efficacy of small molecule NF-κB inhibitors in mouse models of lung cancer. In murine lung adenocarcinoma cell lines with high NF-κB activity, the proteasome inhibitor Bortezomib efficiently reduced nuclear p65, repressed NF-κB target genes and rapidly induced apoptosis. Bortezomib also induced lung tumor regression in vivo and prolonged the survival of tumor bearing Kras(LSL-G12D/wt);p53(flox/flox) mice. In contrast, Kras(G12D/wt) lung tumors, which have low levels of nuclear NF-κB, do not respond to Bortezomib, suggesting that nuclear NF-κB may be a biomarker to predict treatment response to drugs of this class. Following repeated treatment, initially sensitive lung tumors became resistant to Bortezomib. A second NF-κB inhibitor, Bay-117082, showed similar therapeutic efficacy and acquired-resistance in mice. Our results using preclinical mouse models support the NF-κB pathway as a potential therapeutic target for a defined subset of lung adenocarcinoma.