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. 2018 Feb 12;9(18):14228–14250. doi: 10.18632/oncotarget.24479

Figure 3. IFNβ induces apoptosis via the extrinsic pathway in NPC cells.

Figure 3

Figure 3

Figure 3

(A) Effect of caspase inhibitors on NPC cells treated with IFNβ. Pretreatment of NPC cells with the pan-caspase inhibitor Z-VAD-fmk or the caspase-8 inhibitor Z-IETD-fmk but not the caspase-9 inhibitor Z-LEHD-fmk inhibits IFNβ-mediated apoptosis in IFNβ-sensitive NPC cell lines. Inhibitors were added at 10 μM 1 h prior to IFNβ. Apoptosis was determined by measurement of subG1-content. Data of all experiments are shown at 72 h after IFNβ treatment. Quantitative data are reported as means ± S.E.M. (triplicate samples). *: p < 0.05; **: p < 0.01; ***: p < 0.001 (B) Activation kinetics of caspases-8, and −3/7 in NPC-cells treated with IFNβ for 72 h. Activation of caspase-8 starts at 12 h of incubation with IFNβ, activation of caspases-3/7 is first noted after 24 h. Caspase activation was measured by the Caspase Glo® assay as described in the method section. Quantitative data are reported as means ± S.E.M. (n = 5). (C) Immunblot for caspases-8 and −3. Treatment with IFNβ leads to cleavage of caspases-8 and −3 in IFNβ-sensitive NPC cell lines but not in NPC cell line C666-1 and nasoepithelial cell line NP69. Cells were treated for 24 h with 1,000 U/ml IFNβ.