Aim To study the role of TNF-α/NF-κB signaling in matrix metalloproteinase ( MMP)-9 expres-sion induced by lipopolysaccharide ( LPS ) in airway epithelial cells, and to investigate the effects of lenti-virus mediated RNAi targeting a disintegrin and metal-loproteinase 17 ( ADAM17 ) gene on MMP-9 expression induced by LPS. Methods The ADAM17 siRNA ex-pression vector was constructed, and packaged to re-combinant lentivirus in 293T cells. The HBE4-E6/E7 cells were pretreated for 30 min by NF-κB inhibitor ( PDTC) and a recombinant human TNFR p75-Fc fu-sion protein ( Etanercept) , or infected by the recombi-nant lentivirus for 72 h, and then stimulated for 24 h by LPS or TNF-α. The release of TNF-α was detected by ELISA. The mRNA and protein levels of MMP-9 were analyzed respectively by RT-PCR and Western blot. NF-κB activity was detected by electrophoretic mobility shift assay. Results LPS and TNF-α signifi-cantly increased MMP-9 mRNA and protein expressions and the activation of NF-κB in HBE4-E6/E7 cells ( P<0. 05 ) . Etanercept and PDTC significantly inhibited MMP-9 expression and the activation of NF-κB induced by LPS ( P<0. 05 ) . Lentivirus mediated RNAi targe-ting ADAM17 significantly decreased TNF-α produc-tion, inhibited MMP-9 mRNA and protein expressions and the activation of NF-κB induced by LPS in HBE4-E6/E7 cells ( P <0. 05 ) . Lentivirus mediated RNAi targeting ADAM17 did not inhibit MMP-9 mRNA and protein expressions and the activation of NF-κB in-duced by TNF-α ( P>0. 05 ) . And PDTC significantly inhibited MMP-9 mRNA and protein expressions and the activation of NF-κB induced by TNF-α ( P <0. 05 ) . Conclusions TNF-α/NF-κB signaling partic-ipates in the regulation of MMP-9 expression induced by LPS in airway epithelial cells, and lentivirus-media-ted RNAi targeting ADAM17 plays an important role in that signaling pathway upstream by regulating TNF-αrelease.