FIGURE 4.

Neither TOK-001 nor abiraterone increase the rate of AR degradation. A and B, representative AR degradation time-course experiment in LNCaP cells is shown. AR protein was measured at 4-h intervals from LNCaP cells cultured in androgen-free media and co-treated with cycloheximide (CHX, 100 μm) and 20 μm TOK-001 (TOK-20) or 20 μm abiraterone alcohol (abiraterone). AR protein expression was also measured from vehicle control cells treated with CHX+DMSO (for TOK-001 (A)) or CHX+ethanol (for abiraterone alcohol (B)). AR levels are expressed relative to the time at t = 0. For both compounds, compared with vehicle, p = NS (Mann-Whitney). In a separate experiment, LNCaP cells were co-treated with cycloheximide (100 μm) and MG132 (5 μm). C, Western blot analysis of AR steady-state protein levels in LNCaP cells treated for 24 h with 17-HASs (TOK, 20 μm TOK-001; ABIR, 20 μm abiraterone alcohol) in the absence or presence of MG132 (5 μm). The levels of α-tubulin were determined as a loading control. D, Western blot analysis of AR steady-state protein levels in LAPC-4 cells treated for 24 h with TOK-001 (20 μm) in the absence or presence of MG132 (5 μm). The levels of α-tubulin were determined as a loading control.