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. 2008 Dec 18;41(1):14–23. doi: 10.1165/rcmb.2008-0320OC

Figure 3.

Figure 3.

Apoptotic resistance of spheroids to bortezomib plus TRAIL is not likely due to the NF-κB pathway. (A) TRAIL fails to activate the NF-κB pathway in A549 cells. A549/NF-κB–luc monolayers were pretreated with nothing or with the NF-κB inhibitor, BAY 11-7082 (10 μM), for 1 hour, and then exposed to TRAIL (1 or 10 ng/ml) or TNF-α (50 ng/ml) for 5 hours. TNF-α induced a strong luciferase signal; the expected inhibition by BAY confirmed that the luciferase activity represented NF-κB signaling. TRAIL did not induce NF-κB signaling. (B) NF-κB is activated by TNF in monolayers (open bars) and spheroids (solid bars) equally, and is inhibited equally by bortezomib. A549/NF-κB–luc monolayers and spheroids were pretreated with nothing or with bortezomib (100 nM or 1,000 nM) for 1 hour, and then exposed to TRAIL (1 ng/ml) or TNF-α (50 ng/ml) for 5 hours. NF-κB was activated by TNF-α in both monolayers and spheroids, and was equally inhibited by bortezomib. NF-κB was not activated by TRAIL in either monolayers or spheroids (*different from baseline; †different from TNF-α stimulation; mean ± SD; n = 3; P < 0.01).