Oncometabolitic control of tumor growth and epileptogenesis in IDH mutated gliomas: D2HG signaling mechanism.

Project Information

GliomaSignals

Grant agreement ID: 865592

DOI

10.3030/865592

EC signature date 16 April 2020

Start date 1 June 2020

End date 31 May 2027

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 875 135,00

EU contribution

€ 1 875 135,00

Coordinated by

INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE
France

Periodic Reporting for period 3 - GliomaSignals (Oncometabolitic control of tumor growth and epileptogenesis in IDH mutated gliomas: D2HG signaling mechanism.)

Reporting period: 2023-06-01 to 2024-11-30

Summary of the context and overall objectives of the project

Dysregulated growth processes of gliomas interact with pro-epileptic plasticity of brain circuits in such a way that the excitatory transmitter glutamate promotes autocrine tumor invasion as well as epileptic synchrony in surrounding cortical regions. Most low-grade gliomas are associated with mutations of Isocitrate DesHydrogenase (IDH) genes which lead to an excess of the oncometabolite D-2Hydroxyglutarate (D2HG). With a structure mimicking glutamate, D2HG is thought to participate in both epileptogenic and oncologic processes. Importantly, while epileptic activity is accentuated, tumor prognosis is improved in affected people. My preliminary data now suggest a dual function for D2HG, acting as a glutamatergic agonist at high levels, but as an antagonist in the presence of glutamate. Solving this paradox will be a step forward in glioma science.
The GliomaSignals project will examine the role of D2HG in the neurobiology of gliomas bringing electrophysiology concepts and tools to neuro-oncology, seeking to transform our understanding. It seeks to better understand how D2HG modulates glutamatergic signaling, affects neuronal excitability and tumor growth, and to detect the extent to which tumor infiltration colocalizes with epileptic remodeling. In vivo and in vitro work mostly on human tissue will aim at:
1- Map biomarkers of epileptic activity / tumor infiltration by cortical recordings during surgery using unique next generation Neurogrid electrodes
2- Correlate D2HG levels, glutamate concentrations and tumor infiltration with recordings in peritumoral cortex at an unprecedented resolution
3- Identify D2HG effects on glutamate signaling in human tissue slices producing epileptic activities and in a rodent model
4- Explore D2HG long-term effects on epileptic activity and tumor growth / infiltration in co-cultures of tumors with surrounding peritumoral cortex by exploiting our unique capabilities for long-term human cortex organotypic cultures.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During these first 30 months of the project, we have developed / improved the techniques and performed the first experiments in order to unravel the role of the IDH mutated gliomas oncometabolite D2HG on glutamatergic signaling and glioma growth & epileptogenicity.
Cortical activities during human glioma surgery have been recorded in awake conditions in order to characterize the tumor vs infiltrated peritumoral vs remote healthy areas, by correlating electrophysiological activity patterns to tumor cell infiltration and MRI data (paper in preparation). The spatio-temporal pattern of epileptic activities in human postoperative peritumoral cortical tissues have been characterized and we developed software tools to better identify specific activity types (including high frequency oscillations), map them and explore their dynamics (paper in preparation). Currently, we are preparing the first trial of conductive polymer PEDOT:PSS coated microelectrodes (electrode development, electronics, reglementary preparation) during neurosurgeries.
The effects of oncometabolite D2HG on various types of AMPA, NMDA and GABAA receptors have been investigated in order to better understand its role in neuronal activities remodeling and glioma growth in vivo. In vitro studies using xenopus oocytes have been completed and we started to characterize D2HG effects on human neurons synaptic signaling ex vivo. The protocol for organotypic human postoperative cortex culture preparation has been improved. We achieved a significant percentage of cultures maintaining activity for over one week which allows us to perform co-cultures of both glioma and cortical tissues. Moreover, we have created a new in vivo rodent model of glioblastoma in which human cell lines, characterized by variable invasivity features, are grafted in the brain of an immunodeficient mouse. IDH mutation was introduced in the cell lines to study its effects. In order to explore the specific effects of D2HG (one of the multiple consequences of IDH mutation) a cannula is inserted into the brain to deliver relevant concentrations of D2HG via an implanted miniature osmotic pump. Finally, we have collaborated on the work exploring the effects of antiseizure medications on glioblastoma prognosis (in line with our fundamental research) (Pallud et al. Neurology 2022).

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The GliomaSignals project uses an electrophysiological approach to improve our knowledge on common oncological and epileptological mechanisms occurring in brain gliomas and in the sur-rounding peritumoral tissue. Shared mechanisms based either on glutamatergic metabolism or on chloride regulation and GABAergic signaling between glioma cells growth invasion and the genesis of abnormal epileptic activities is a new exciting issue in oncology and epilepsy fields and pave the way for therapies for both processes.
The study is performed almost exclusively on human material, which is a best option in translational research at the era of the 3R: Replacement-Reduction-Refinement. The tools developed in the GliomaSignals project will benefit both the research and patients’ care. In particular, electrophysiological epileptogenicity and tumor infiltration biomarkers will help to optimize neurosurgery. At the same time, the human cortical and tumoral cultures model will be indispensable for discovery and validation of cellular and molecular mechanisms involved in various neurological conditions, for identification of new pathways to treat gliomas and associated epilepsy, as well as new therapy development and preclinical drug testing.

Workpackages and work in progress of GliomaSignals project