FIG. 5.
Fatty acid synthase is overexpressed and correlated to radioresistance in rSCC-61. Panel A: Western blot analysis of FASN and quantification (P < 0.001) showing increased expression in rSCC-61 cells. GAPDH staining was performed to show equal protein loading. Panel B: Fatty acid synthase activity assay. FASN-dependent oxidation of NADPH with or without orlistat treatment was measured as described in the Materials and Methods section. rSCC-61 have significantly higher (P < 0.01) FASN activity that is reduced upon the addition of the FASN inhibitor orlistat. Panel C: 14C-Palmitate uptake. SCC-61 and rSCC-61 were cultured and incubating with 14C-palmitate for 15, 30 and 60 min. Exogenous palmitate uptake in rSCC-61 cells was twofold lower than in SCC-61. Panel D: Fatty acid oxidation assay. SCC-61 cells demonstrate a significant reliance on utilization of exogenous palmitate to respond to energy demand compared to rSCC-61. Purple box: basal respiration; blue box: uncoupling of mitochondria; green box: maximal respiration.