Figure 6

17-AAG interfered with the amount and activity of 26S proteasome in A549 cells. (A) 17-AAG treatment reduced the amount of 26S proteasome presented in A549 cells. A549 cells were treated with DMSO and various concentrations (100 nM, 250 nM and 500 nM) of 17-AAG for 24 hours. The expression of 26S proteasome was revealed by Western blot analysis. Actin was used as an internal control. Relative ratio of expression was shown. (B) Inhibition of Hsp90 with 17-AAG reduced proteasome activity in A549 cells. Cells were treated with various concentrations of 17-AAG and 4 μM of MG-132 (positive control) for 24 h. Cells were washed with PBS and lysed with TNESV buffer without protease inhibitor. Cell lysate were analyzed for proteasome activity using synthetic fluorogenic peptide succinyl-Leu-Leu-Val-Tyr-7-amino-4-methylcoumarin. Statistical significance (p < 0.05) between experimental samples and the DMSO control is denoted by "*". (C) Inhibition of 26S proteasome increased the amount of survivin in A549 cells. A549 cells were treated with DMSO and various concentrations (1000 nM, 2000 nM, 4000 nM and 8000 nM) of the 26S proteasome inhibitor, MG-132, for 24 hours. The expression of survivin was revealed by Western blot analysis. Actin was used as an internal control. Relative ratio of expression was shown.