Fig. 6: Formate release by mitochondrial 1C flux is required for TH9619-mediated trapping of 10-CHO-THF.
From: Formate overflow drives toxic folate trapping in MTHFD1 inhibited cancer cells
a, TH9619 blocks purine synthesis in MTHFD2−/− cells. b, Exogenous supply of sodium formate and hypoxanthine can induce the TH9619 folate trapping mechanism and block thymidylate synthesis in MTHFD2−/− cells. c–g, Cell viability dose–response curves of SW620 MTHFD2−/− cells treated for 96 h with TH9619 (c), TH9975 (d), MTX (e), DS18561882 (f) or SHIN1 (g) and 50 μM hypoxanthine, 1 mM sodium formate, 50 μM thymidine or vehicle (cultured in RPMI-dFBS), two representative experiments displayed as means ± s.d. (n = 4 independent cell cultures). h, Hypoxanthine and TH9619 cause folate trapping in WT cells. Treatment with AICAr bypasses the block in de novo purine synthesis and releases the folate trap by AICAR Tfase consumption of 10-CHO-THF. i–k, Cell viability dose–response curves of SW620 WT cells treated for 96 h with TH9619 (i), TH9975 (j) or MTX (k) and vehicle or increasing AICAr concentrations (cultured in RPMI-dFBS), two representative experiments are shown as means ± s.d. (n = 4 independent cell cultures for TH9619 and TH9965, n = 2 for MTX). l, [U-13C]serine-derived formate release rate of SW620 WT cells treated for 24 h with 1 μM TH9619 or TH9975, 50 μM hypoxanthine and 50 μM thymidine (cultured in RPMI-dFBS), means ± s.d. (n = 3); one-way ANOVA with Dunnett’s multiple comparisons test. P values indicate comparisons to the DMSO control.
