Figure 2. Lapatinib-Resistant BT474 Cells Exhibit Increased Exogenous Fatty Acid Uptake but No Difference in FA Synthesis.

(A–I) rBT474 cells were cultured in lapatinib-free medium 1 week prior to analysis.

(A and B) Representative image of BT474 and rBT474 cells stained with oil red O (scale bars indicates 20 μm) from 3 experiments (A), with quantification of 200–300 cells shown in (B).

(C and D) Representative confocal microscopy image of BT474 and rBT474 stained with BODIPY 493/503 (the scale bar indicates 20 μm) from 3 experiments (C), with quantification of 200–300 cells shown in (D).

(E) Western blot of BT474 and rBT474 cell lysates for key mediators of FA synthesis, uptake, and β-oxidation.

(F) Surface CD36 protein expression in BT474 and rBT474 cells was assessed by flow cytometry. Results shown are representative of 3 experiments, with quantification shown for mean CD36-positive population ± SEM.

(G) BT474 and rBT474 cells were cultured in the presence of 2 μM BODIPY FL C16 for the indicated periods of time. Median fluorescence intensity (MFI) was measured by flow cytometry. Depicted is the MFI of three replicate samples per time point ± SD from one representative experiment of 3.

(H) BT474 and rBT474 cells were cultured in the presence of (−)-C75 or lapatinib for 2 h before an additional 4 h of exposure to 0.667 μCi/mL ¹⁴C-acetate. Incorporation was determined as described previously (Olsen et al., 2010). Results depict the mean levels of ¹⁴C incorporation ± SD from 4 experiments.

(I) BT474 and rBT47 cells were treated with 10 μg (−)-C75/mL or DMSO for 48 h. Cell proliferation was measured by MTS assay as described previously described (Canfield et al., 2015).

Data are shown as the means ± SEM from 5 experiments. Significance was assessed by non-paired Student’s t test, with significance set at *p < 0.05, ***p < 0.0005.