Abstract 2279: Evaluating the metabolic status of gioma microenvironment at single-cell resolution
Authors: Carcanholo Felipe Pimenta , Fonseca Livia Maria , Simões Renan Lima , Uyemura Sergio Akira , Malta Tathiane Maistro 
Published: March 2024

Abstract
Gliomas are brain tumors with low therapeutic response, markedly heterogeneous, and very proliferative. Mutations in the isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes are present in most lower-grade gliomas and less frequent in high-grade gliomas. The reprogramming of energy metabolism marks cancer to support rapid tumor growth and tumor survival. The remodeling of the epigenome in gliomas with and without IDH1/2 mutations is associated with changes in the energy metabolism, which has implications for the evolution of the tumor and for patient outcomes. Comprehending the metabolic reprogramming of different subtypes of gliomas is crucial to understanding tumor development and for the identification of better treatment targets. In this research, we explored the cell-to-cell metabolic variability using public single-cell RNA-seq (scRNA-seq) data of IDH wild-type (IDHwt) and IDH-mutant (IDHmut) gliomas. We analyzed 13,000+ single cells from four datasets [IDHwt (n=7,930), IDHmut codel (n=3,304), IDHmut non-codel (n=6,333), and IDHwt/K27M mutant (n=4,084)]. Data was processed using Seurat. CopyKat was used to distinguish malignant from non-malignant cells. Known marker genes were used to identify normal cell populations (macrophages, T cells, oligodendrocytes). Finally, ssGSEA was used to create a score of activity of 70 important metabolic pathways extracted from KEGG, for each individual cell. Our exploratory analysis revealed a metabolic heterogeneity among malignant cells even within the same patient. Steroid biosynthesis and valine/leucine/isoleucine biosynthesis are the top contributors to metabolic heterogeneity. Oxidative phosphorylation (OXPHOS), fatty acid metabolism (FA), and tricarboxylic acid cycle (TCA) are among the highest metabolic activities. Comparing the distinct glioma subtypes, IDHmut codel showed the lowest OXPHOS, TCA, and glycolysis/gluconeogenesis (GLYCO) activities, suggesting a potential link between low metabolic activity and better prognosis. Comparing astrocytomas IDHmut and IDHwt we observed lower TCA, GLYCO, and FA activities in mutant tumors. Overall, malignant cells showed higher metabolic activity than non-malignant cells of the same tumor. The metabolic microenvironment of IDHmut differed the most compared to the other subtypes. Immune and normal cells could also be distinguished by their metabolic features. We observed subpopulations of T cells and macrophages presenting distinct metabolic activity which may reflect distinct immune activation stages. Collectively, we covered the heterogeneity in energy metabolism of gliomas with potential prognostic value. Understanding the metabolic status of cells in the tumor microenvironment could shed light on intratumoral heterogeneity and aid in identifying therapeutic vulnerabilities.
Citation Format: Felipe Pimenta Carcanholo, Livia Maria Fonseca, Renan Lima Simões, Sergio Akira Uyemura, Tathiane Maistro Malta. Evaluating the metabolic status of gioma microenvironment at single-cell resolution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2279.