Figure 4

C16 ceramide sensitizes metastatic human colon carcinoma cells to Fas-mediated apoptosis. A. SW620 cells were treated with LCL85 (5 μM) for 24 h. Cells were then lysed and measured for ceramide contents. Shown are representative results of one of two independent measurements. B. Exogenous C16 ceramide sensitizes tumor cell to Fas-mediated apoptosis. SW620 cells were treated with C16 ceramide for 1 h at the indicated concentrations, and then cultured in the absence or presence of FasL for approximately 24 h. Cells were stained with Annexin V and PI and analyzed by flow cytometry. The apoptotic cell death is indicated at the top right corner of each plot. Shown are results of one of three representative experiments. C. Quantification of apoptosis as shown in B. % FasL-induced cell death is calculated by the formula: % Annexin V⁺ and PI⁺ cells in the presence of FasL- % Annexin V⁺ and PI⁺ cells in the absence of FasL. Column: mean; Bar: SD.