Figure 3

Characteristic of apoptosis induced by combinatory treatment of doxorubicin/etoposide and TRAIL in U1285 and U1690 SCLC cells. (A) Cleavage of PARP, caspase-8, and caspase-3 in U1285 and U1690 cells after treatment (24 h) with TRAIL (1000 ng/ml) or PKC412 (1 μM). (B) Cleavage of PARP in U1285 cells treated (24 h) with TRAIL (100 ng/ml), doxorubicin (dox, 1, 2 μM) or their combinations, and in U1690 cells treated (24 h) with TRAIL (100 ng/ml), doxorubicin (0.25, 0.5, 1 μM) or their combinations. (C) Cleavage of PARP and caspase-8 in U1690 cells treated (24 h) with TRAIL (100 ng/ml), etoposide (etop, 2.5 and 5 μM) or their combinations. (D) Cleavage of PARP and caspase-8 in U1690 cells treated (24 h) with TRAIL (10, 50, 250 ng/ml), doxorubicin (1 μM) or their combinations. For (A-D), an equal loading was verified using G3PDH or anti-β-actin antibody. All results are representative of three independent experiments. (E) Caspase-3 and caspase-2 activities (fold increase to control) in U1690 cells treated (24 h) with TRAIL (10, 50, 100, 250 ng/ml), doxorubicin (1 μM) or their combinations (for details see Materials and methods). Results are means ± S.E.M. of three independent experiments. Statistical significance: P < 0.05, (*) versus control, (+) versus TRAIL, (x) versus doxorubicin.