Fig. 4. COX-2 siRNA-transfection of cells inhibits the anti-apoptotic effects of PGE2. (A) Cells were stably transfected with 10 nM COX-2 siRNA and then exposed to PGE2 for 48 h. Total proteins were then isolated from the cells and analyzed by Western blotting with anti-caspase-3, -lamin B, and -actin antibodies. Actin expression remained consistent, and was used as a reference. (B) HL-60 cells were harvested at 24 h and stained with PI, after which DNA content was analyzed by flow cytometry. Sub-G1 fractions of COX-2 siRNA-transfected cells (%) were plotted against PGE2 and menadione treatments for 24 h. (C) Cells were transfected with COX-2 siRNA before exposure to PGE2 for 24 h and supernatant medium was collected to assay the extracellular PGE2 levels using an EIA kit. The values presented are the means ± SD from the measurements of three independent wells performed in a single experiment.
