Figure 4. Inhibition of FAO facilitates mitochondrial permeability transition after ABT-737 treatment independently of p53.

(A) OCI-AML3 cells expressing a shRNA targeting p53 or their vector control counterparts were treated with 100 μmol/l EX alone or in combination with 2 μmol/l ABT-737 for 24 hours. Apoptosis was quantitated as described in Methods. Inset shows a representative Western blot of p53 and β-actin from lysates of p53 shRNA and vector shRNA cells treated with 5 μmol/l Nutlin 3a for 6 hours. (B) U937 cells were treated with 100 μmol/l EX alone or in combination with increasing doses of ABT-737 for 24 hours. Apoptosis was analyzed as above. (A and B) *P < 0.005 versus ABT-737 alone. (C) OCI-AML3 cells were cultured alone or on MSC feeder layers followed by 6 hours of treatment with 100 μmol/l EX alone or in combination with 1 or 3 μmol/l ABT-737. The levels of cytochrome c in the cytosolic fraction were determined by immunoblotting. (D and E) OCI-AML3 cells were cultured as in C and exposed to 100 μmol/l EX for 6 hours. Mitochondrial suspensions were exposed to the indicated concentrations of ABT-737, and the release of AIF (D) and cytochrome c (E) were determined by immunoblot. (F) MOLM-13 cells were cultured alone or on MSC feeder layers and exposed to 50 and 100 μmol/l EX for 6 hours. Mitochondrial suspensions were exposed to 2 μmol/l ABT-737, and the release of cytochrome c and AIF were determined by immunoblot.