Elucidating the tumor microenvironment of IDH mutated gliomas

• Applicant: Sevin Turcan, Ph.D.
• Subject Area: Molecular and Cellular Neurology and Neuropathology ; Hematology, Oncology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 424180224

In the first funding period, we a) performed whole-brain labeling and identified differences in microglial morphologies in different anatomical regions of control and IDH mutant tumor-implanted brains. We started building pipelines to register the light-sheet fluorescence microscopy (LSFM)-acquired mouse brains and automatically detect/segment microglia in entire brain regions, b) assessed the impact of physiological amounts of 2-HG on in vitro primary cells, and c) correlated in vitro microglia signature with in vivo data through scRNA-sequencing on IDH1 mutant tumor-implanted mouse brains. Our goal now is to extend these findings using LSFM, single cell and spatial genomics to study the effect of 2-HG on tumor growth. The integration of microscopy and genomics data will allow for a comprehensive understanding of tumor-associated microglia (TAM) diversity in brain tumors. The improved LSFM analysis pipeline will enable researchers to analyze whole-brain LSFM images accurately, providing valuable insights into the brain and its functions. In addition, we envision that the analytical pipelines developed in this study will be applicable to other cell types and tumors, paving the way for new insights into complex biological systems. For the prolongation period, we propose two aims: Aim 1. Develop and optimize an LSFM analysis pipeline for phenotypic and spatial characterization of microglia in IDH1 mutant gliomas. The goal of this aim is to investigate the response of microglia in preclinical IDH mutant glioma models. The study aims to further understand of the distribution of microglia in the brain and to develop an improved LSFM analysis pipeline to automatically detect, segment and localize microglia with respect to anatomical brain regions. As a part of this aim, we will also evaluate the impact of inhibiting the enzymatic function of mutant IDH1 using the small molecule inhibitor vorasidenib, on the spatial distribution of microglia. The overall goal of Aim 1 is to elucidate the complex interactions between microglia and mutant IDH1 tumors, with the potential to uncover new therapeutic targets and treatment options for these tumors. Aim 2. Investigate microglia activation phenotypes using spatial transcriptomics. In this aim, we propose to perform spatial transcriptomics to investigate compartmentalized changes in TAM gene expression profiles in the tumor microenvironment (TME) in preclinical IDH mutant glioma models. We will characterize gene expression profiles of TAMs, which play critical roles in shaping the TME and modulating the immune response to gliomas. Through these analyses, we aim to uncover the dynamic changes in TAM gene expression that occur within different regions of the glioma TME, providing new insights into the mechanisms of immune evasion and identifying potential targets for immunotherapy.

• DFG Programme: Research Grants