Fig. 4. ATF4-dependent fructolysis rescues glucose-deprivation impaired proliferation and colony formation of GBM cells and is required to maintain GBM growth.

a, b Indicated GBM cells without or with ATF4 KO (a) or ATF4 binding deficiency in the promoters of SLC2A5 or ALDOB (b) were cultured under glucose-deprived condition supplemented without or with fructose for 3 days. The cells were then collected and counted. c, d Indicated GBM cells without or with ATF4 KO (c) or ATF4 binding deficiency in the promoters of SLC2A5 or ALDOB (d) were cultured under glucose-deprived condition supplemented without or with fructose for 14 days. The cells were then fixed by 4% paraformaldehyde and stained with crystal violet. Colony formation areas in each dish were analyzed by ImageJ software. e, f Luciferase-expressing U87 cells without or with ATF4 KO (e) or ATF4 binding deficiency in the promoters of SLC2A5 or ALDOB (f) were intracranially injected into athymic nude mice (n = 5). Luminescence intensity derived from tumors was measured on day 3 and day 21 post tumor-cell injection. Relative luminescence intensity was shown. a.u., arbitrary unit. g, h Luciferase-expressing U87 cells without or with ATF4 KO (g) or ATF4 binding deficiency in the promoters of SLC2A5 or ALDOB (h) were intracranially injected into athymic nude mice (n = 5). The survival times of the mice were recorded. Frc (−) and Frc (+) represent without and with 10 mM fructose supplementation, respectively (a–d). WT, wild type; dSLC2A5-C1/2 and dALDOB-C1/2, cell clone 1/2 with disruption of the CARE motifs located within the promoters of SLC2A5 and ALDOB, respectively (b, d, f, h). Data represent the mean ± SD of six (a, b) or four (c, d) independent experiments and the mean ± SEM of 5 mice (e, f). P values were determined by the two-tailed Student’s t-test (a–d), one-way ANOVA (e, f), or two-tailed log-rank test (g, h). Source data are provided as a Source Data file.