SFN reduces mPGES-1 activity in treated cells but does not inhibit activity in purified microsomes.

A, SFN treatment of intact cells inhibited mPGES-1 activity, A549 cells were pretreated with or without different concentrations of SFN for 30 minutes and then 1 ng/ml IL1b was added for another 24 hours. mPGES-1 activity was assayed as conversion of PGH2 to PGE2 by microsomal fractions in a mass-spectrometry assay with PGE2(D4) as internal standard. The chromatographic peak height under the m/z = 351.2 ion elution was normalized by internal standard (PGE2d4) peak height under the m/z = 355.2. *, P<0.05, **, P<0.01 vs. IL1b treated samples (mean ± SEM; n = 3). B, Addition of SFN to purified microsomes in vitro did not inhibit mPGES-1 activity. Microsomal fractions of A549 cells were collected and treated with or without different concentrations of SFN for 2 hours and then mPGES-1 activity was assayed as A.