Down-regulation of lipocalin 2 suppresses the growth of human lung adenocarcinoma through oxidative stress involving Nrf2/HO-1 signaling

Lipocalin 2 (LCN2), a multifunctional secretory protein known as neutrophil gelatinase-associated lipocalin (NGAL), is expressed in a variety of cancers. However, little is known about the biological functions of NGAL in the development of lung adenocarcinoma. In the present study, we primarily found that NGAL expression was up-regulated in human lung adenocarcinoma tissues. Additionally, depletion of NGAL expression decreased the ability of cell proliferation and induced cell apoptosis. Furthermore, with the addition of N-acetylcysteine, a scavenger of reactive oxygen species (ROS), it was found that NGAL depletion was sufficient to cause apoptosis of lung adenocarcinoma cells by generating ROS through the inhibition of the nuclear factor E2-related factor 2/heme oxygenase-1 anti-oxidant pathway. Finally, the effect of NGAL down-regulation on the growth of human lung adenocarcinoma was determined in BALB/c nude mice. These findings demonstrate that NGAL may be a potential therapy target for patients with lung adenocarcinoma.