Individualized diversity in the extracellular metabolome of live human gliomas

BackgroundThe extracellular microenvironment modulates cancer behavior. Although radiographic contrast enhancement is an ominous finding in gliomas, it remains unclear if the associated blood-brain barrier disruption merely reflects or functionally supports tumor aggressiveness. MethodsWe utilized intra-operative microdialysis to sample the extracellular metabolome of radiographically diverse regions during fifteen neurosurgical resections. The global extracellular metabolome of recovered microdialysate was evaluated via ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and assessed using enrichment and correlation analyses. ResultsAmong 162 named metabolites identified via ultra-performance liquid chromatography tandem mass spectrometry, guanidinoacetate (GAA), was 126.32x higher in enhancing tumor than in adjacent brain. 48 additional metabolites were 2.05-10.18x more abundant in enhancing tumor than brain. With exception of GAA, and 2-HG in IDH-mutant gliomas, differences between non-enhancing tumor and brain microdialysate were comparatively modest and less consistent. The enhancing but not the non-enhancing glioma metabolome was significantly enriched for plasma-associated metabolites largely comprising amino acids and carnitines. ConclusionsOur findings suggest that metabolite diffusion through a disrupted blood-brain barrier may largely define the enhancing extracellular glioma metabolome. Future studies are needed to determine how the altered extracellular metabolome impacts glioma behavior.