Figure 2. Fatty acid synthesis and proteasome pathways exhibit crosstalk.

A, PC-3 cells were treated with vehicle, orlistat (25 µmol/L), bortezomib, (5 nmol/L), C75 (9 µg/ml), or the combination of bortezomib and orlistat or C75 for 16 hours and subjected to immunoblot analysis with antibodies specific for ubiquitin and β-actin. B, Three separate experiments of PC-3 cells treated as in A were quantified by measuring intensity of the exposure from ubiquitin antibody in each treatment as compared to vehicle treated lanes using UN-SCAN-IT (Orem, UT). Asterisks indicate statistical significance measured by student’s t test (P ≤ 0.05). C, PC-3 cells, DU145 cells and FS4 fibroblasts were incubated with the indicated concentrations of bortezomib for two hours followed by the addition of ¹⁴C-acetate (1 µCi) for two hours. Cells were collected, washed and lipids were extracted and quantified relative to vehicle-treated control as described in Experimental Methods. Asterisks indicate statistical significance by student’s t test (P ≤ 0.05). D, PC-3 cells were treated with vehicle or bortezomib (20 nmol/L) for 4 or 6 hours in duplicate. Cells were collected for immonoblot analysis using antibodies specific to fatty acid synthase, ubiquitin, or β-actin. Images represent cropped immunoblots. Full length scans available in supplementary data figure 2.