Fig. 7

The expression levels of SSP enzymes are positively correlated with levels of AMPK T172 phosphorylation and HIF-1α expression in human GBM specimens and poor GBM patient prognosis. A IHC staining of human GBM specimens was performed with the indicated antibodies (n = 50). Representative images from the staining of four different specimens are shown. Scale bar, 100 μm. B The IHC stains were scored, and correlation analyses were performed. The Pearson correlation test was used. Note that the scores of some samples overlapped. C Kaplan–Meier analyses for GBM patients with high or low level of SSP. D Network with DEGs, biological functions, glycolytic metabolism, and SSP using IPA in S/G-deprived U87MG cells, compared to control. The analysis involved a fold change cut-off value of ± 1.3. Red and green colors indicate genes that were upregulated and downregulated, respectively, compared to the control. Reactive oxygen species (ROS), AMPK, and HIF-1α are added for analysis of the relationships among the genes for the biological functions, glycolytic metabolism, and SSP. Figure S1A of the SI provides the details of shape, which originate from Ingenuity Systems (http://www.ingenuity.com). E Schematic of the regulation of Brain Tumor Serine metabolism (BTS); AMPK-HIF-1α signaling-enhanced glucose-derived de novo serine biosynthesis to promote the proliferation and survival of GBM and brain tumor growth under the brain microenvironment of limited serine/glycine