Novel GABAAR antagonists target networked gene hubs at the leading edge in high-grade gliomas

Ion channel activity underlying biological processes that drive high-grade gliomas (HGG) is largely unknown. We aimed to determine the networking of ion channel genes and validate their expression within HGG patient tumors, to identify ion channel-targeting drugs that would inhibit tumor-promoting processes.

We used weighted gene co-expression network analysis (WGCNA) of RNAseq data to identify ion channel gene hubs in diffuse midline glioma (DMG) and glioblastoma. Using scRNA-seq, spatial transcriptomics, and immunohistochemistry, we characterized the expression of identified hubs within patient tumors, validating their role by testing the efficacy of ion channel inhibitors alone or in combination with radiation and temozolomide on the growth and invasion of patient-derived glioblastoma explant organoids (GBOs).

Network analysis revealed a preserved HGG "neuronal regulation" module, containing the greatest number of ion channels, with its corresponding genes concentrated at the tumor's leading edge. Hubs within this module included γ-Aminobutyric-acid type A receptor (GABAAR) genes GABRA1 (α1) and GABRG2 (γ2), which immunohistochemically colocalized with GABAergic synaptic markers at the leading edge. GBOs failed to retain this synaptic architecture but expressed a glioblastoma hub GABRA5 (α5), a component of extrasynaptic GABAARs. S44819, an α5-GABAAR antagonist strongly inhibited GBO invasion, with GABA(A)-compound 1b, a partial antagonist of GABAARs, robustly inhibiting GBO proliferation and invasion. Moreover, combined with standard-of-care (SOC) regimens, the anti-invasive properties of both compounds were enhanced in GBOs.

Our co-expression network analysis identified key ion channels at the leading edge in HGGs, which can be targeted by GABAAR-acting drugs to disrupt tumor progression.