Fig 2: Correlation between FDG uptake, Hexose-6-phosphate dehydrogenase (H6PD) enzymatic activity, and the hyperglycemia-related redox damage at a regional level. The correlation plots between the slope of Patlak regression, H6PD enzymatic activity, and malondialdehyde (MDA) content are displayed in the anterior (Panels A and C) and posterior brain (Panels B and D) of control (blue) and STZ (brown) mice. Due to the design of the study protocol, only 12 mice (n = 6 controls and n = 6 STZ) underwent both FDG PET and biochemical analyses. R2 and P values of the Pearson correlations are reported in each panel.

Fig 3: Metabolomic profiling of partial glutamine deprivation regulated pathways. (A–C) Metabolomic analysis in MDA and MCF7 cells: heat maps representation of substrate levels response to low glutamine condition (LG) by free amino acids, glycolysis intermediates and TCA metabolites, respectively (n = 6). (D) NADH/NAD ratio (n = 7) and (E) ATP/AMP ratio of MDA (red) and MCF7 (blue) cultures under CTR (dark) and LG (pale) condition (n = 8). Heat maps representation of glutamine shortage effect on substrate levels of glucosamine pathway (F) and PPP (G) in MDA and MCF7 cells. (H,I) Relative optical density (ROD), normalized versus the housekeeping signal, of G6PD (H) and H6PD (I) in MDA (red) and MCF7 (blue) cells grown under CTR (dark) or LG (pale) condition, n = 3. (J) Representative WB signals of G6PD, H6PD and ß-Actin, used as the housekeeping protein: HE and LE represent high and low exposure picture, respectively. (K) NADPH/NADP ratio and (L) quantification of malondialdehyde (MDA) content in cells grown under CTR or LG condition n = 3. Data are expressed as mean ± SD. Data are represented as mean ± SD. * = p < 0.05; ** = p < 0.01; *** = p < 0.001; **** = p < 0.0001.

Fig 4: CircDYRK1A inhibits the malignant phenotypes and glutamine metabolism in GC cells by upregulating the expression of FBXO4 through miR-889-3p. AGS cells were transduced with sh-FBXO4-1 or sh-FBXO4-2. A Expression of FBXO4 in AGS cells determined by RT-qPCR. AGS cells were transduced with sh-FBXO4 and/or circDYRK1A, and HGC-27 cells were transduced with oe-FBXO4 and/or sh-circDYRK1A. B Expression of FBXO4, circDYRK1A and miR-889-3p in AGS cells and HGC-27 cells determined by RT-qPCR. C Proliferation of AGS cells and HGC-27 cells detected by EdU assay. D Migration of AGS and HGC-27 cells detected by Transwell assay. E Invasion of AGS and HGC-27 cells detected by Transwell assay. F Expression of glutamine in AGS and HGC-27 cells measured using the kit. G Expression of glutamic acid in AGS and HGC-27 cells measured using the kit. H Expression of a-KG in AGS and HGC-27 cells measured using the kit. I Protein levels of GLS and GDH in AGS and HGC-27 cells measured by Western blot analysis. The cell experiment was repeated three times. * p < 0.05

Fig 5: miR-889-3p reverses the inhibitory effect of circDYRK1A on malignant phenotypes of GC cells. AGS cells were transduced with miR-889-3p mimic and/or circDYRK1A, and HGC-27 cells were transduced with miR-889-3p inhibitor and/or sh-circDYRK1A. A Expression of circDYRK1A and miR-889-3p in AGS and HGC-27 cells determined by RT-qPCR. B Proliferation of AGS and HGC-27 cells detected by EdU assay. C Migration of AGS and HGC-27 cells detected by Transwell assay. D Invasion of AGS and HGC-27 cells detected by Transwell assay. E Expression of glutamine in AGS and HGC-27 cells measured using the kit. F Expression of glutamic acid in AGS and HGC-27 cells measured using the kit. G Expression of a-KG in AGS and HGC-27 cells measured using the kit. H Protein levels of GLS and GDH in AGS and HGC-27 cells measured by Western blot analysis. The cell experiment was repeated three times. * p < 0.05