Targeting the Lactate Transporter MCT1 in Endothelial Cells Inhibits Lactate-Induced HIF-1 Activation and Tumor Angiogenesis
Figure 4
Lactate triggers HIF-1 induction in normoxic endothelial cells.
Lactate was used at 10 mM for 24-h. (A) HIF-1α mRNA was detected using qRT-PCR in HUVECs incubated with lactate. ns, non-significant; n = 4. (B and C). HIF-1α protein expression was detected by western blot in BAECs incubated with lactate and/or (B) 5 µg/ml Actinomycin D (**p<0.01, ***p<0.005, ns, non-significant compared to control, n = 3–4); (C) increasing concentrations of 2-oxoglutarate. *p<0.05, **p<0.01; n = 5–6. (D) ODD-driven luciferase activity was assessed in HUVECs incubated with 150 µM CoCl2 or lactate. **p<0.01; n = 5. (E) Intracellular pyruvate was detected using an enzymatic assay in HUVECs incubated with lactate. **p<0.01; n = 4. (F–H) HIF-1α protein expression was detected by western blot. (F) BAECs were incubated with lactate, oxamate (10 mM), and/or acetate (10 mM). **p<0.01, ***p<0.005, ns, non-significant compared to control cells without lactate; n = 4–16. (G) HUVECs transfected with the indicated siRNA were incubated with lactate. *p = 0.0170, **p = 0.0019 compared to control; ##p = 0.0056 compared to lactate alone; n = 3–9. (H) BAECs were incubated with pyruvate (10 mM), lactate, or not. **p<0.01 compared to control; n = 3–19. (A–H) Error bars reflect mean ± SEM.