CNSC-07. MECHANISMS OF GLIOBLASTOMA-INDUCED CORTICAL REMODELING IDENTIFY THERAPEUTIC VULNERABILITIES

Abstract

Abstract Prior work demonstrated synaptic integration of malignant gliomas into neural circuits induces local hyperexcitability and tumor proliferation. However, prognostication and therapeutic vulnerabilities are lacking from preclinical models. Here, we integrate in vivo and in vitro neurophysiology spatially matched with gene expression programs and protein signaling mechanisms across 66 IDH WT glioblastoma patients to identify thrombospondin-1 (TSP-1) as a molecular driver of glioma-induced network remodeling. Bulk and single cell RNA-sequencing of 11 intratumoral regions maintaining functional connectivity (13,730 cells analyzed) revealed a distinct neurogenic signature enriched for the synaptogenic factor TSP-1. Mechanistic and functional studies validating therapeutic vulnerabilities to TSP-1 silencing by shRNA knockdown and FDA-approved inhibitors (Gabapentin and LSKL) of excitatory synapse formation through the gabapentin a2d-1 receptor was performed in vitro and in vivo. Glioma-neuron co-culture of TSP-1 overexpressing cells demonstrated increased Ki67 proliferation and tumor microtube (TMT) formation when cultured in the presence of neurons. Pharmacological inhibition of TSP-1 using gabapentin or TSP-1 shRNA inhibited the proliferation and TMT-mediated expansion. Hippocampal xenografted mice with TSP-1 over expressing primary patient cultures demonstrated shorter survival and gabapentin treatment of xenografted mice significantly reduced the proliferation of TSP-1 overexpressing cells in vivo. Electrophysiological properties of glioma-neuron co-cultures analyzed using multi-electrode array (MEA) demonstrated increased neuronal spiking activity and network burst synchrony in the presence of TSP-1 over expressing cells. Strikingly, these increases were eliminated in the presence of gabapentin. We modeled survival risk in patients incorporating the effects of glioma intrinsic neuronal activity, molecular, therapeutic, and clinical factors on overall survival by recursive partitioning. Three risk groups were identified based on tumor intrinsic neuronal activity, pre- and post-operative tumor volume with shortest overall survival in patients with glioma intrinsic neuronal activity. These data identify glioma-induced secretion of TSP-1 as a key contributor of tumor proliferation shedding light on new therapies.