Figure 4
Sorafenib toxicity is increased by the glycolytic inhibitor 2-deoxy-glucose.
(a). Cytotoxic effect of SFB (5 μM) and 2DG (20 mM), applied as single agents or in combination, in LCSC-2 cells. Percentage of dead (Propidium Iodide-permeant) cells was determined by flow cytometry after 24 hours exposure to the drugs. The dashed line indicates the expected value for simple additivity, cleared of background cell death (Dmso), calculated by the Bliss Independence Model (see Supplementary Methods). A white circle in the SFB + 2DG bar indicates the amount of cell death entirely attributable to the drug combination, cleared of the background. ** indicates p < 0.01 compared to vehicle; interaction denotes a significant “cell (row × column) effect” in the two-way ANOVA test. Histogram representative of several independent experiments (b). MTT Assay under the same conditions as in a. Bars are mean ± SD of three independent experiments, each in duplicate. Line and statistics are as in panel a. (c). Evaluation of SFB toxicity and SFB + 2DG interaction in B16 mouse melanoma cells. Cells were analysed for PI exclusion as in a, after 24 hours exposure to the drugs. Rotenone (Rot, 5 μM), mimics the effect of SFB (2.5 μM) and synergizes with 2DG. Bars are mean ± SD of duplicate samples. * = p < 0.05 and ** = p < 0.01 compared to Dmso. Statistics as in panel a. Panel representative of two independent experiments. (d) MTT assay showing lack of response to SFB (5 μM) of HEK293 –POLG1 (D890N) cells grown in doxycycline 50 ng/ml for 10 days to deplete mtDNA (Dox+); Dox- are non-induced cells that retain mtDNA. Picture representative of two independent experiments. Statistics as in panel a.
