Figure 1.

Expression of NAC1 promotes glycolysis in hypoxic tumor cells. (a) HeLa cells were transfected with a non-targeting RNA (siNT) or NAC1-targeted siRNA, and exposed to hypoxia (1% O₂) for 24 h. Metabolic intermediates were measured using liquid chromatography-mass spectrometry (LC-MS), and normalized to cell numbers. (b) HeLa or SKOV3 cells were transfected with a siNT or NAC1 siRNA, and then incubated under normoxia (20% O₂) or hypoxia (1% O₂) for 24 h. Lactate and glucose in the culture medium, and cellular ATP, were measured and normalized to cell numbers. (c) ES-2 cells were transfected with an empty vector or V5-NAC1 expression vector. Twelve hours later, cells were cultured under hypoxia for 24 h. Lactate and glucose in the culture medium, and cellular ATP, were measured and normalized to cell numbers. (d) HeLa cells were transfected with a siNT or NAC1 siRNA, followed by incubation under normoxia or hypoxia for 24 h. mRNAs of lactate dehydrogenase-A (LDHA) and GLUT1 were determined by quantitative reverse transcriptase (RT)–PCR and plotted after normalization. LDHA and GLUT1 protein were examined by western blot, with β-actin as a loading control. Bars are mean ±s.d. (n=3). (e) Glucose uptake and tumor growth in mice inoculated with Hela cells expressing a control shRNA or NAC1-targeted shRNA. ¹⁸F-FDG uptake was analyzed by Micro PET. White squares point to tumors. Data shown are mean±s.d. (n=5).