Background and objective To detect the expression of neutrophil gelatinase-assoeiated lipocalin (NGAL) in the different differentiations of lung cancer tissues and to study the mechanism of invasion of A549 cells affected by NGAL.Methods The expression of NGAL was detected by immunochemistry in lung cancer tissue and the tissue around edge of the cancer. The effect of NGAL expression on A549 cells was observed by using qRT-PCR and Western blot. The abilities of invasion and metastasis were evaluated by transwell invasion and migration assay, and cell scratch assayin vitro. The protein expression of E-cadherin, Vimentin was measured by immunolfuoresence and Western blot.ResultsThe positive expression rate of NGAL was 76.32% (58/76) in the lung cancer, 13.3% (4/30) in adjacent tissue by immunochemistry. NGAL expres-sion levels in the lung cancer tissues were signiifcantly higher than that in adjacent tissues. The rate of migration and invasion in NGAL-siRNA group was 60.4%±6.4% compared to 50.5%±4.4% in the control group, there was a significant difference (P<0.05). Vimentin was suppressed, and E-cadherin was upregulated when NGAL was inhibited. MMP-2 and MMP-9 de-creased when NGAL was knocked down.ConclusionThe expression level of NGAL is highly expressed in lung cancer. NGAL may be one of important indicators involved in lung cancer inifltrated and transferred. NGAL might be one of potential targets for lung cancer treatment.