Inhibitory effect of 17-AAG on L. pneumophila -induced IL-8 expression.(A) A549 cells were incubated with 1 μM 17-AAG for 16 h prior to infection with varying concentrations of AA100jm strain for 6 h. RT-PCR was performed to check the changes of IL-8 mRNA expression after 17-AAG treatment in L. pneumophila-infected A549 cells. (B) Attenuation of L. pneumophila-induced NF-κB DNA binding by 17-AAG treatment. A549 cells were treated with (+) or without (-) 17-AAG for 16 h prior to infection with varying concentrations of L. pneumophila for 3 h. The nuclear extracts were isolated from A549 cells infected with L. pneumophila and incubated with 32P-labeled oligonucleotides corresponding to NF-κB. (C) hsp90 protects IKKα and IKKβ from proteasomal degradation. A549 cells either were pretreated with LLnL (20 μM) for 1 h, followed or not followed by addition of 17-AAG (1 μM) and incubation for 16 h, or were treated with 17-AAG for 16 h or left untreated as indicated. Whole cell extracts were immunoblotted with specific antibodies against each protein. Representative results of three similar experiments in each panel are shown.