Figure 2.

15d-PGJ₂ inhibits the transcriptional activation of the IL-8 promoter by preventing the activation of NF-κB via an IκB-α–dependent pathway. (a) Caco-2 cells cotransfected with either an IL-8 promoter luciferase reporter gene or the PPAR-γ–regulated reporter plasmid, acyl-CoA X 3-TK-LUC, were treated with various concentrations of 15d-PGJ₂ for 24 hours, followed by stimulation with IL-1β (5 ng/mL). (b) EMSAs of nuclear extracts isolated from Caco-2 cells treated with either 15d-PGJ₂ or methyl acetate for 24 hours and followed by IL-1β stimulation (5 ng/mL) for the times indicated. A double-stranded oligonucleotide spanning the NF-κB element in the IL-8 promoter was used as a probe. (c) IκB-α Western blot of proteins isolated from Caco-2 cells treated with 15d-PGJ₂ or methyl acetate for 24 hours and followed by IL-1β stimulation (5 ng/mL) for the times indicated.