Figure 1

Cisplatin decreases PRPP availability and purine and DNA synthesis, and reduces intracellular ATP and NAD: augmentation by amino acid deprivation. Dih10 cells (A, B, D–G) or IGROV-1 cells (C) were incubated for 6 h (A–D), 3 h (E), or 14 h (F,G) in complete medium or lysine-, arginine-, or leucine-deficient medium in the absence or presence of the indicated concentrations of cisplatin (A), 100 µM cisplatin (B,D–G), or 35 µM cisplatin (C). (A–C) [8-¹⁴C]-hypoxanthine incorporation into purine nucleotides was measured during the last 20 min of the incubation to assess PRPP availability. (D) [¹⁴C]-formate incorporation into purines was measured during the last 90 min of the incubation as a measure of de novo purine synthesis. (E) [³H]-thymidine incorporation into DNA was measured during the last 60 min of the incubation. (F,G) The intracellular content of ATP and NAD were measured by a luciferase-based and a cycling colorimetric assay, respectively. In all panels, each symbol in the bar graphs is the mean of duplicate samples from an independent experiment, with the bar height representing the mean value of all experiments and the error bars indicating the standard deviation. *, **, ***, and **** indicate p < 0.05, < 0.01, < 0.001, and < 0.0001, respectively, for the indicated comparisons. # in Panel A indicates p < 0.001 for comparison between complete and lysine-deficient medium for each of the four cisplatin concentrations. CDDP, cisplatin; PRPP, phosphoribosyl-pyrophoshate.