15d-PGJ2 enhances sensitivity to TRAIL in a PPAR γ-independent manner. (A) Western blot analysis and PPARγ transcription factor assay. KOB cells were treated for 24 hours with indicated concentrations of sFCB or 15d-PGJ2. 20 μg of the cell extract was used for the Western blot analysis and 10 μg of the nuclear extract was used for the transcription factor assay. (B) 3.5 × 105 KOB cells/mL were incubated for 48 hours with 2.5 μg/mL of sFCB, 10 μM 15d-PGJ2, 500 ng/mL of TRAIL, or a combination thereof. The indicated concentrations of GW9662 were added in the sFCB + TRAIL or 15d-PGJ2 + TRAIL setting, and cell proliferation was assessed by MTS assay. (C) Effect of siRNA on PPARγ expression. At 24 hours after transfection, cells were incubated with or without 2.5 μg/mL of sFCB and 10 μM 15d-PGJ2 for 24 hours, and Western blot analysis was performed using 20 μg of the cell extract. (D) Effect of siRNA on cell proliferation. At 24 hours after transfection, cells were treated for 48 hours with 2.5 μM of sFCB, 10 μmol/L 15d-PGJ2, 500 ng/mL of TRAIL, or a combination thereof. Cell proliferation was assessed by MTS assay. Values are expressed as mean plus or minus SD.
