Fig. 4: GABAergic signalling drives DMG proliferation.

a, Electrophysiological recording of DMG cells xenografted into hippocampal CA1 in response to optogenetic stimulation of interneurons (top), and PTX-sensitive glioma current in response to optogenetic stimulation of GABAergic interneurons (bottom). The diagram was created using BioRender (https://biorender.com). b, In vivo optogenetic stimulation of DLX–ChRmine interneurons near xenografted DMG cells in the CA1 region of the hippocampus. The illustrations were created using BioRender (https://biorender.com). c, Proliferation index (EdU⁺/HNA⁺ cells) after optogenetic stimulation or mock stimulation (n = 6 mice; stimulation, n = 8 mice, P = 0.0075; two-tailed Student’s t-test; left), and representative images of DLX–ChRmine interneurons (red) near xenografted DMG cells expressing EdU (green) and HNA (white; right). Scale bar, 25 µm. d, Representative trace of GABAergic PSC in DMG elicited by electrical stimulation in the presence of NBQX before and after perfusion of 10 μM lorazepam (LZP; top), and quantification of current amplitude (n = 3 cells from 3 mice; P = 0.0386, two-tailed paired Student’s t-test; right). e–g, H3K27M⁺ diffuse midline glioma: dose-dependent (2 mg kg⁻¹ (low) and 8 mg kg⁻¹ (high)) effect of LZP treatment in mice with patient-derived DMG xenografts, SU-DIPG-XIII-FL (n = 7 mice (vehicle), n = 8 mice (low) and n = 7 mice (high); P = 0.0374 (e)), SU-DIPG-50 (n = 7 mice (vehicle), n = 9 mice (low) and n = 8 mice (high); P = 0.0573 (f)) and SU-DIPG-VI (n = 8 mice (vehicle), n = 8 mice (low) and n = 6 mice (high); P = 0.0075 (g); one-way ANOVA). The straight brackets denote Dunnett’s multiple comparisons test between two groups (vehicle versus high: P = 0.0228 (e), P = 0.033 (f) and P = 0.0041 (g)). The curved brackets denote a post-test for linear contrast among all groups (P = 0.0124 (e), P = 0.0181 (f) and P = 0.002 (g)). Representative images of xenografted SU-DIPG-VI cells in the pons expressing Ki67 (red) and HNA (white) are also shown (g, right). Scale bar, 25 µm. h, Kaplan–Meier survival curves of mice xenografted with patient-derived DMG cells (SU-DIPG-XIII-pons) and treated with LZP or vehicle (n = 5 mice per group), demonstrating a significant reduction in survival in mice treated with a high dose of LZP (red asterisk; P = 0.0495, Mantel–Cox test), and a dose-dependent reduction in survival (black asterisk; P = 0.0320, log-rank test for trend). i, Hemispheric high-grade glioma: LZP treatment in mice with patient-derived pcGBM (SU-pcGBM2) xenografts (n = 4 mice (vehicle), n = 3 mice (low) and n = 4 mice (high); left), and representative images of xenografted SU-pcGBM2 cells expressing Ki67 (red) and HNA (white; right). Scale bar, 25 µm. One-way ANOVA. All data are mean ± s.e.m. *P < 0.05 and **P < 0.01.

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