NAD+/SIRT1 pathway regulates glycolysis to promote oxaliplatin resistance in colorectal cancer

Figure 2 DNA damage induces NAD+ depletion and inhibits SIRT1 expression. A: Western blot analysis of γ-H2AX and PARP expression in HCT116-WT and HCT116 Oxa-R cells. Each bar represents means ± SD of three separate experiments. ^aP < 0.05. β-Actin was used as the internal reference; B: Western blot analysis shows SIRT1 expression in HCT116 Oxa-R cells treated with different concentrations of oxaliplatin (40, 80 μM) for 12 or 24 hours. GAPDH was used as the internal reference; C: Flow cytometry results indicate that NAD+ levels are lower in HCT116 Oxa-R cells than in HCT116-WT cells. Treatment with oxaliplatin (40 μM) for 12 hours induced NAD+ depletion in HCT116 Oxa-R cells, whereas treatment with rucaparib (5 μM) for 12 hours inactivated PARP and reversed oxaliplatin-induced NAD+ depletion. The data are presented as the means ± SD. ^aP < 0.05; ^bP < 0.01; ^cP < 0.001; D: Treatment with rucaparib (5 μM) for 12 hours reversed the oxaliplatin-induced reduction in SIRT1 expression. Each bar represents means ± SD of three separate experiments. ^aP < 0.05.