Abstract 3355: Unraveling the molecular mechanisms of glioma migration: Exploring the role of cell intrinsic and stromal ephrin receptor-ligand signaling

Abstract Diffuse invasion, a hallmark of malignant gliomas, makes these tumors surgically incurable and is the ultimate cause of death. While glioma cells can migrate along blood vessels and in neuron-rich regions, their preferred route of migration is along white matter (WM) tracts, which allows tumor cells to spread to the contralateral hemisphere with devastating neurocognitive consequences. The underlying mechanisms of in vivo glioma cell migration are poorly understood. There is emerging evidence that glioblastoma multiforme (GBM) cells may hijack migration mechanisms used during brain development. Accordingly, we used a neonatal plasmid electroporation GBM model (CRISPR-Cas9, -Cre, gRNAs targeting NF1, p53, PTEN, and piggyBac-glast) to generate a highly penetrant diffusely invasive glioma models with preference for migration along myelinated fiber tracts including the corpus callosum (CC). To test the in vivo role of integrin-mediated migration, tumors were generated using conditional integrin β1f/f (ITGB1) or focal adhesion kinase (FAKf/f) mice. Both ITGB1 and FAK null GBM cells (confirmed by western blot analysis) showed diffuse infiltration similar to WT mice, suggesting that integrin signaling is not essential for in vivo GBM cell migration. Next, we tested the role ephrin-signaling using a series of transgenic neonatal mice, including EPH-B1-/-, -B2-/-, -B1/2-/-, -kinase-dead (KD) and a gain-of-function mutant). EPH1/2-/- GBM, but not the other genetic models, consistently formed tumors which showed no diffuse single-cell infiltration, but rather grew as a solid expanding mass. An extensive panel of in vitro studies comparing WT and EPHB1/2-/- GBM patterns of growth and migration, including time-lapse random walk, neurosphere radial migration, migration along patterned surfaces, and laminin-coated confined 3D channels, showed similar patterns of migration, despite the marked differences in vivo. These contrasting in vivo and in vitro results raise the possibility that EPH-B1/2 receptors may require their cognate ephrin ligands to facilitate migration through the WM tracts. To test this hypothesis, we are using Ephrin-B1f/f, B2f/f mice for in vivo cell-type specific deletion in WM tract stroma cells and primary astrocytes derived from these mice for ex vivo co-culture studies. Our preliminary data suggest that EPH/EPHRIN interactions may regulate GBM cell migration. Citation Format: Jesung Moon, Xiaofei Gao, Peiguo Ding, Fnu Bilal, Smita Rindhe, Ning Gao, Digant P. Dave, Mark Henkemeyer, Elizabeth A. Maher, Robert M. Bachoo. Unraveling the molecular mechanisms of glioma migration: Exploring the role of cell intrinsic and stromal ephrin receptor-ligand signaling abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3355.