Neutrophil Gelatinase-associated Lipocalin Acts as a Protective Factor against H₂O₂ Toxicity

Background: Lipocalin 2 (Lcn2, NGAL) is a member of the lipocalin superfamily for which a variety of functions have been reported. However, the precise biological roles of NGAL are not fully known. We have investigated the ability of NGAL to prevent H₂O₂ toxicity, which is considered to be the classical inducer of oxidative stress caused by ROS generation in an in vitro model. Methods: NGAL cDNA was isolated from HepG2 cell line and cloned to pcDNA3.1(+) vector. The construct was transfected to CHO cell line. Stable clones were generated, and the expression of NGAL was determined by RT-PCR, Western blot analysis and ELISA. NGAL gene in A549 cell line was downregulated with the siRNA. CHO and A549 cells were intoxicated with H₂O₂ and cell proliferation was performed by MTT assay. Apoptotic cells were detected by flow cytometry. Results: Cell proliferation was higher in CHO expressing NGAL in doses of 5 and 10 mM H₂O₂ after 2 h compared with the control. H₂O₂ was also more toxic in the presence of NGAL siRNA compared with the control in A549 cell. Our results also revealed that NGAL protect cells from apoptosis. Conclusions: Overall, our results revealed for the first time a new function for NGAL/Lcn2: acting as a protective factor against H₂O₂ toxicity. In the future, NGAL may have the potential application to ameliorate the toxicity induced by oxidative stress conditions.