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. 2010 Nov 25;32(2):216–223. doi: 10.1093/carcin/bgq242

Fig. 1.

Fig. 1.

ITCs significantly inhibit proteasome activity in a variety of cells. (A) Structures of BITC, PEITC, SFN and NMPEA, a structural analog of PEITC without ITC functionality. (B) U266 cells were treated with a series of concentrations of BITC, PEITC and SFN for 4 h. Chymotrypsin-like, caspase-like and trypsin-like proteasome activities were measured using Suc-LLVY-AMC, Z-LLE-AMC and Boc-LRR-AMC substrates, respectively. White bars: chymotrypsin-like activity; striped bars: trypsin-like activity; black bars: caspase-like activity. (C) Inhibiting proteasome activity by PEITC is time-dependent and long lasting. U266 cells were treated with 10 μM PEITC for up to 24 h. NMPEA was used as a negative control. (D) A variety of cancer cells, including HeLa, A549, HT-29, PC-3 and MCF-7, were treated with 10 μM BITC for 4 h. Chymotrypsin-like activity was measured in cell lysates before (white bars) and after (black bars) the treatment (upper panel). The ubiquitinated proteins in the same cell lysates were immunoblotted (lower panel). *P < 0.05; **P < 0.01.