Figure 1.

Expression of FASN in relation to resistance to BRAF inhibitors. (A) LM16 R cells were transfected with a mixture of two FASN-directed siRNAs (5 nM each, 10 nM final). The levels of FASN were evaluated by Western blotting 72 h after transfection, when drug treatment started, and at the end of drug treatment (144 h after transfection). Equal loading of SDS-PAGE is shown by tubulin. (B) Seventy-two hours after transfection, cells were analyzed for sensitivity to PLX4032 (3 µM) by CCK8 and LDH assays, and by caspase 3/7 and caspase 8 activation assays. *** p < 0.0001 by one-way ANOVA followed by Bonferroni correction. (C) Negative correlation between FASN mRNA (left) and protein (right) expression and IC₅₀ values of PLX-4720 in BRAF-V600 E mutant melanoma cell lines from CCLE. (D) Negative correlation between FASN protein expression and IC₅₀ values of PLX4032 in six sensitive (parental) and resistant cell lines. Spearman’s correlation coefficients and p values are indicated for each plot. (E) Sensitivity of melanoma cells to PLX4032 and to the FASN inhibitor orlistat. IC₅₀ values of orlistat for LM16 R and LM16 parental cells were 12.40 µM ± 3.2 and 27.43 µM ± 5.3, p = 0.0138 by unpaired Student’s t test. IC₅₀ values for PLX4032 were 11.62 ± 4.6 and 0.08 ± 0.04 µM.