A driver role for GABA metabolism in controlling stem and proliferative cell state through GHB production in glioma

Elias A El-Habr,Hervé Chneiweiss,Stéphanie Puget,Bryan M Wittmann,Joanna Lipecka,Charlotte Schmitt,Emna Mahfoudhi,Chris Ottolenghi,Johan Pallud,Penelope Korkolopoulou,Ghislaine Morvan-Dubois,Ariane Sharif,Ashwin Narayanan,Thierry Virolle,Vivaldo Moura‐Neto ,Fanny Burel‐Vandenbos ,Lisa Oliver,Tomohiro Yamaki,Maïté Verreault ,Isabelle Plo,François‐Xavier Lejeune ,Maxime Janin,Bertrand Devaux,Alexandra Bogeas,Paulo Lucas Cerqueira Coehlo,Luiz Gustavo Dubois ,Mohamed Fareh,Laurent Turchi,Pascale Varlet,Marie‐Pierre Junier

doi:10.1007/s00401-016-1659-5

Abstract

Cell populations with differing proliferative, stem-like and tumorigenic states co-exist in most tumors and especially malignant gliomas. Whether metabolic variations can drive this heterogeneity by controlling dynamic changes in cell states is unknown. Metabolite profiling of human adult glioblastoma stem-like cells upon loss of their tumorigenicity revealed a switch in the catabolism of the GABA neurotransmitter toward enhanced production and secretion of its by-product GHB (4-hydroxybutyrate). This switch was driven by succinic semialdehyde dehydrogenase (SSADH) downregulation. Enhancing GHB levels via SSADH downregulation or GHB supplementation triggered cell conversion into a less aggressive phenotypic state. GHB affected adult glioblastoma cells with varying molecular profiles, along with cells from pediatric pontine gliomas. In all cell types, GHB acted by inhibiting α-ketoglutarate-dependent Ten–eleven Translocations (TET) activity, resulting in decreased levels of the 5-hydroxymethylcytosine epigenetic mark. In patients, low SSADH expression was correlated with high GHB/α-ketoglutarate ratios, and distinguished weakly proliferative/differentiated glioblastoma territories from proliferative/non-differentiated territories. Our findings support an active participation of metabolic variations in the genesis of tumor heterogeneity.

Highlights

Tumor development is a complex process mixing clonal selection and dynamic changes in cell states including phenotypic differentiation of cancer stem cells, which leads to tumors composed of heterogeneous cancer cell populations [20, 21]
We focused on GBM stem-like cells, which share with embryonic stem cells (ESC) transcription factors such as Nanog that govern their behavior [9]
Gas chromatography/ mass spectrometry (GC/MS) and liquid chromatography/ MS/MS analysis of whole cell extracts and secreted culture media showed that all identified metabolic intermediates and endpoint products of energy metabolic pathways, i.e., glycolysis, tricarboxylic acid (TCA) cycle, and anaplerotic glutaminolysis were significantly reduced in TG1-miR, as exemplified by α-KG a key metabolite of the TCA cycle that can be replenished through anaplerotic reactions (Table S2)

Summary

Introduction

Tumor development is a complex process mixing clonal selection and dynamic changes in cell states including phenotypic differentiation of cancer stem cells, which leads to tumors composed of heterogeneous cancer cell populations [20, 21]. De novo glioblastoma (GBM), the most common and malignant primary brain tumor in adults, is a paradigmatic example of heterogeneous tumors. This malignant glioma remains incurable, with all patients relapsing despite aggressive multimodal therapies [43]. The role of metabolism in the genesis of tumor cells and/or territories with differing states of aggressiveness remains unexplored. Following the recent discovery that the differentiation of embryonic stem cells (ESC) depends on fluctuations in the levels of the metabolite α-ketoglutarate (α-KG) [8], we envisaged that changes in metabolism could drive cancer cell phenotypic differentiation rather than be a passive adaptation to differentiation

Methods

Results

Conclusion