Figure 3.

IDH1^R132H and not 2-HG alone leads to a drop in NADPH and NAD⁺ concentrations and sirtuin activity in glioblastoma cells but not in astrocytes: Concentrations of NADPH/t and NAD⁺/t were measured in cell lysates of stably transduced cell lines from three different transductions and in triplicates using the NAD⁺/NADH and NADP⁺/NADPH Quantification Kit (MBL). The activity of NAD⁺ dependent sirtuins was measured using the HDAC Fluorimetric Cellular Activity Assay Kit (Enzo Life Science). The values were normalized to the mean value of the empty vector cells and the means of normalized values were compared (* p < 0.05; ** p < 0.01; one-way analysis of variance (ANOVA) followed by Dunnett’s post-hoc t-test). (a) Normalized values of NADPH levels (top) and NADPt levels (middle) as well as NADPH/NADPt ratios (bottom) are given. (b) IDH1^R132H led to a significant drop in NADt (top) and NAD⁺ (middle) levels in glioblastoma cells, but not in astrocytes. Sirtuins showed less enzymatic activity in IDH1^R132H glioblastoma cells compared to the empty vector cells (bottom).