Characteristics of SSRI-induced apoptosis in group I BL cells.

(A) L3055 cells treated with fluoxetine for 24 hours then double stained with syto 16 and PI for FACS analysis; percent cells viable (green), apoptotic (blue), and necrotic (red) are indicated. (B) L3055 transfected with either bcl-2, or empty vector treated for 24 hours with control medium, 20 μM fluoxetine, 20 μM paroxetine, or 100 μM citalopram, before analysis for forward versus side scatter. Percent viable cells remaining (black dots) are indicated; dead cells are in red. (C-E) L3055 cells were treated with SSRIs as for panel B. (C-D) Cells were treated for 6 hours and then stained for active caspases before analysis by (C) flow cytometry (percent cells active caspase positive indicated) or (D) confocal microscopy, counterstained with Hoechst nuclear dye (blue) and PI to detect dead and membrane-compromised cells (red) (activated caspases stain green). (E) Cells were treated for 24 hours, then stained with the cationic dye JC-1 for confocal microscopy. Mitochondrial depolarization is indicated by a shift from red to green fluorescence. (F) Cells were treated for 24 hours, then stained with the acridine orange for fluorescence microscopy. (G) Cells were treated as for panel F but using L3055 bcl-2-transfectants. (H) L3055 cells were cultured for 17 hours with either control medium, anti-μ chain antibody (anti-IgM, 10 μg/mL), or fluoxetine (20 μM); cell lysates prepared and equal amounts of protein (25 μg) resolved on 10% SDS-PAGE before blotting for PARP-1. The intact 112-kDa and cleaved 89-kDa protein are indicated by arrows. Each result is representative of at least 3 individual experiments.