fig1

Figure 1. Acquired BTZ-resistant A549 cells demonstrate reversed phenotypic TRAIL sensitivity. (A) The clonogenic outgrowth was significantly reduced in both the H460BTZR (not measurable) and A549BTZR cells after exposure to 100 ng/mL TRAIL for 6 h; (B) Western blot analysis of caspase and PARP cleavage shows the enhanced cleavage already after 6 h in the A549BTZR cells; (C) BID and XIAP were reduced in the A549BTZR cells after exposure to 100 ng/mL TRAIL for 6 and 24 h; (D) the ZVAD (100 µg/mL) completely reduced the TRAIL-enhanced apoptosis after 24 h exposure as determined with Flow Cytometry; (E) Incubation with 30 μM necrostatin for 24 h did not result in reduced TRAIL-induced apoptosis as determined with Flow Cytometry; (F) Expression of TRAIL in A549BTZR cells as determined with Flow cytometry. Similarly, the TRAIL expression was not different between parental and resistant variants of H460 and SW1573 cells. The values are the means ± SEM and the western blots depicted represent at least three independent experiments. Similarly, the effect of TRAIL was significantly higher in A549BTZR compared to A549 cells. ^**P < 0.001; ^*P < 0.01. BTZ: Bortezomib; TRAIL: TNF-related apoptosis-inducing ligand; TNF: tumor necrosis factor; BID: BH3 Interacting Domain Death Agonist; XIAP: X-linked inhibitor of apoptosis protein.