FIGURE 1.

Knockdown of FAS, but not ACC-α or ACL, induces tumor cell apoptosis. A, cell death was monitored by measuring the level of DNA fragments present within immunocaptured nucleosomes (left panel). Tumor cells were exposed to 25 nm siRNA targeting FAS, ACC-α, or ACL or non-silencing control siRNA for 72 h (MDA-MB-435 and PC-3 cells) or 96 h (MCF-7 and LNCaP cells). Cells were lysed, and DNA fragmentation was measured by enzyme-linked immunosorbent assay. Values are normalized to Lipofectamine 2000 (mock)-transfected controls and are the means ± S.E. of at least three replicates per treatment. Knockdown of FAS, ACC-α, and ACL was verified by Western blotting (MDA-MB-435 cells (right panels) and MCF-7, PC-3, and LNCaP cells (supplemental Fig. 1)). B, the de novo synthesis of palmitate and the enrichment of acetyl-CoA were measured by gas chromatography/mass spectrometry in MDA-MB-435 cells transfected with 25 nm siRNA targeting either FAS or ACC-α or a non-silencing control and labeled with [U-¹³C]glucose. Values are the means ± S.E. of two independent experiments.