Emerging roles of Nrf2 signal in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) causes considerable mortality in the world. Owing to molecular biological progress, treatments in adenocarcinoma have evolved revolutionarily while those in squamous lung cancer remain unsatisfied. Recent studies revealed high-frequency alteration of Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-like factor 2 (Keap1/Nrf2) pathway within squamous lung cancer, attracting researchers to focus on this particular pathway. In NSCLC patients, deregulated Nrf2 signal is recognized as a common feature at both DNA and protein level. Emerging associations between Nrf2 and other pathways have been elucidated. MicroRNA was also implicated in the regulation of Nrf2. Agents activating or antagonizing Nrf2 showed an effect in preclinical researches, reflecting different effects of Nrf2 during tumor initiation and progression. Prognostic evaluation demonstrated a negative impact of Nrf2 signal on NSCLC patients' survival. Considering the importance of Nrf2 signal in NSCLC, further studies are required in the future.