Nicotinamide Inhibits Glycolysis of HL-60 Cells by Modulating Sirtuin 1 (SIRT1)/Peroxisome Proliferator-Activated Receptor γ Coactivator 1α (PGC-1α)/Hypoxia-Inducible Factor-2α (HIF2α) Signaling Pathway

BACKGROUND Nicotinamide can affect differentiation and proliferation of leukemia cells. This research aimed to explore the regulatory effect of nicotinamide on glycolysis metabolism of leukemia cells and to clarify the associated mechanisms. MATERIAL AND METHODS HL-60 cells were treated with nicotinamide and divided into 0.1, 1, and 10 μmol/l groups. HL-60 cells without any administration were assigned as negative control (CT group). Glucolytic activity was evaluated by detecting lactic acid production, and glucose level was measured using glucose consumption assay. Apoptosis of HL-60 was examined using flow cytometry assay, when cells were cultured for 24 h. Expressions of sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator 1alpha (PGC-1alpha), and hypoxia-inducible factor-2alpha (HIF2alpha) were evaluated using a reverse transcription PCR assay and Western blotting assay, respectively. RESULTS Nicotinamide remarkably decreased lactic acid production and glucose levels in leukemia cells compared with that of the CT group (p<0.05). Nicotinamide significantly induced the apoptosis of HL-60 cells compared to that of the negative control group (p<0.05). Nicotinamide significantly inhibited the SIRT1/PGC-1alpha/HIF2alpha signaling pathway mRNAs compared to that of the CT group (p<0.05). Nicotinamide remarkably reduced mitochondrial regulatory factors SIRT1/PGC-1alpha expression compared to that in the CT group (p<0.05). Nicotinamide obviously downregulated HIF2alpha compared with that of the CT group (p<0.05). Moreover, all of the above nicotinamide-induced effects, including glycolytic activity, apoptosis, and expression of SIRT1/PGC-1alpha/HIF2alpha, were changed in a dose-dependent manner. CONCLUSIONS Nicotinamide can inhibit glycolysis of HL-60 cells by inhibiting the mitochondrial regulatory factor SIRT1/PGC-1alpha and suppressing transcription factor HIF2alpha.