LC/BRY-mediated apoptosis requires new protein synthesis.

(A) U937 cells were pretreated with varying concentrations of the protein synthesis inhibitor cycloheximide (1 hour) prior to the addition of LC plus BRY (24 hours). Apoptosis was determined by morphologic analysis of Wright-Giemsa–stained cytospins. (B,C) Cells were pretreated with varying concentrations of the RNA synthesis inhibitors α-amanitin or actinomycin D (1 hour) prior to LC/BRY exposure. Values represent the means for triplicate experiments (± SEM). Vehicle (open bar), BRY (left-hatched bar), LC (right-hatched bar), LC plus BRY (cross-hatched bar). (D) Cells were exposed to LC (BRY as above in the presence or absence of 5 mM L-NAC, after which the percentage of apoptotic cells was determined as previously described. Values represent the means for 3 separate experiments (± SEM).