fig2
Figure 2. Lipid composition of WM164 and HT144 cells while acquiring resistance to dabrafenib. (A) Lipids were quantified using a shotgun-based triple quadrupole mass spectrometry approach. Pie charts show the mole percentage (mol%) of the four major GPL classes in mammalian cell membranes (i.e., PC, PE, PI and PS), and SM in WM164 and HT144 cells during treatment with dabrafenib (0, 30 and 105 days). Mean ratio displayed n = 3 biological replicates. See also Supplementary Figures 2 and 3; (B) Mole percentage (mol%) of GPLs (GPL = PC + PE + PS + PI), SM and Chol during incubation with dabrafenib at 0 days (drug-naïve), 7-30 days (DTP), 60 days (DTPP) and 105 days (PDRC). See also Supplementary Table 1; (C) Mole percentage (mol%) of Chol and CE relative to total lipid (GPL + SM + Chol + CE) in drug-naïve, DTP and PDRC states. Error bars represent SD. Symbols above the bars indicate values that are statistically different from the drug-naïve state (0 d): **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001. “#” indicates values that are statistically different from all other states with P ≤ 0.0001. Symbols connected by brackets indicate statistically significant differences between the corresponding groups; (D) Histograms represent the normalised abundance of the major GPL (i.e., PC, PE, PI, PS) and SM species based on the sum composition (i.e., total number of carbons and degree of unsaturation of the two acyl chains that make up each lipid). This methodology does not distinguish lipid isomers [e.g., fatty acyl, stereospecific numbering position or double bond location(s)]. See also Supplementary File 1 for absolute values and statistical analysis using 2-way ANOVA with Dunnett’s multiple comparisons test. GPL: Glycerophospholipid; PC: phosphatidylcholine; PE: phosphatidylethanolamine; PI: phosphatidylinositol; PS: phosphatidylserine; SM: sphingomyelin; Chol: cholesterol; DTP: drug-tolerant persister; DTPP: drug-tolerant proliferative persister; PDRC: permanent drug-resistant cell; CE: cholesteryl ester; SD: standard deviation; ANOVA: analysis of variance.
