Figure 5
From: Doxorubicin and etoposide sensitize small cell lung carcinoma cells expressing caspase-8 to TRAIL
Time-dependent changes in the expression level of apical proteins involved in TRAIL signaling pathway and an esesential role of caspase-8 in apoptosis induced by combined treatment of doxorubicin and TRAIL in U1690 cells. (A) Cleavage of PARP, caspase-8, cFLIPL, and the level of cFLIPS, FADD, and DR5 in U1690 cells treated (4, 8, 12, 24 h) with TRAIL (100 ng/ml), doxorubicin (1 μM) or their combination. An equal loading was controlled using anti-G3PDH antibody. (B) The surface level of DR5 in U1690 cells untreated or treated (24 h) with doxorubicin (1 μM), detected by flow cytometry, using specific primary mouse anti-DR5 antibody, followed by anti-mouse secondary AlexaFluor-488-conjugated antibody. Cells incubated with secondary antibody alone (marked by asterisk) were used to check the background fluorescence. Results are representative of three independent experiments. (C) Cleavage of PARP or caspase-8, -3, -2 in U1690 cells transfected (48 h) with control or caspase-8 siRNA, and then treated (11 or 16 h) with TRAIL (100 ng/ml), doxorubicin (1 μM) or their combination. An equal loading was verified using anti-G3PDH antibody. An asterisk indicated unspecific antibody staining. (D) Cleavage of PARP and level of caspase-8 in U1690 cells transfected (48 h) with control or caspase-8 siRNA, then transfected with pcDNA-MACH alpha 1 (caspase-8) expressing vector (200 ng) and treated (16 h) with TRAIL (100 ng/ml), doxorubicin (1 μM) or their combination. An equal loading was verified using anti-G3PDH antibody.