Neutrophil Gelatinase-associated Lipocalin Acts As a Protective Factor Against H(2)O(2) 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 H(2)O(2) 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 H(2)O(2) 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 H(2)O(2) after 2h compared with the control. H(2)O(2) 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 H(2)O(2) toxicity. In the future, NGAL may have the potential application to ameliorate the toxicity induced by oxidative stress conditions.