FIGURE 1.

GM-CSF augments 2-deoxyglucose uptake and glycolytic flux in human macrophages via PFKFB3. (A and B) Human monocytes were differentiated to macrophages. Cells were exposed to human GM-CSF (10 ng/mL) for the specified time duration, and phosphorylation of STAT5 in Y694 (A) and levels of glycolytic enzymes (B) were determined. Addition of GM-CSF induced significant expression of hexokinase-1, hexokinase-2, and mainly PFKFB3. (C) Cells exposed to native GM-CSF demonstrated increased PFKFB3 expression compared with incubation with heat-inactivated GM-CSF (10 min at 80°C). (D) GM-CSF–mediated increase in PFKFB3 expression (right) was decreased with addition of silencer to PFKFB3 but not by selective PFKFB3 inhibiter 3PO, demonstrating specificity of silencer. Cells were treated with mixture of siPFKFB3 for silencing PFKFB3 18 h before challenge with GM-CSF. Results show mean ± SD. *P < 0.05 vs. same condition in control (absence of GM-CSF or 0 h). **P < 0.01 vs. same condition in control (absence of GM-CSF or 0 h). ^##P < 0.01 for scRNA vs. siPFKFB3 with or without 3PO. a.u. = arbitrary units; GAPDH = glyceraldehyde 3-phosphate dehydrogenase; HK = hexokinase; scRNA = scrambled RNA.