Identifying off-target effects of etomoxir reveals that carnitine palmitoyltransferase I is essential for cancer cell proliferation independent of β-oxidation
Fig 2
Mitochondrial respiration and nutrient utilization do not show a dose response to etomoxir because 200 μM etomoxir (EX) has an off-target effect on respiratory complex I.
(A) Nutrient utilization after BT549 cells were treated with vehicle control, 10 μM etomoxir, or 200 μM etomoxir for 48 hours (n = 3). (B) Mitochondrial stress test of whole cells (BT549) after treatment with vehicle control, 10 μM etomoxir, or 200 μM etomoxir for 1 hour (n = 4). (C) Measured and calculated parameters of mitochondrial respiration (generated from data in Fig 2B). (D) 200 μM etomoxir leads to changes in state I respiration but does not affect state II respiration, indicating that 200 μM directly inhibits complex I of the electron transport chain (n = 3). (E) Isotopologue distribution pattern of citrate after BT549 cells were labeled with U-13C glucose for 12 hours (n = 3). (F) Isotopologue distribution pattern of citrate after BT549 cells were labeled with U-13C glutamine for 6 hours (n = 3). All data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001. The oxygen consumption rate (OCR) was corrected for nonmitochondrial respiration. AA, antimycin A; FCCP, carbonyl cyanide p-trifluoromethoxyphenylhdrazone; oligo, oligomycin; rot, rotenone; suc, succinate.