Abstract 5230: Co-culture with glioblastoma stem-like cells induces neuron death

Abstract The vast majority of GBMs recur by 2 years after standard of care treatment, which includes radiotherapy. As a model for investigating the biology of recurrent GBMs, we used brain tumor xenografts initiated from human glioblastoma stem-like cells (GSCs). In this system brain tumors were irradiated (10Gy) on Day 35 after implantation into right striatum of nude mice and allowed to regrow for an additional 21 days. In untreated mice tumor cells are shown to invade throughout the right hemisphere with a high degree of cell-cell contact with mouse neurons as determined by immunohistochemical staining for NeuN, a marker for neuronal soma. In mice irradiated with 10Gy, tumors that regrow are less invasive with a loss of neurons. These data suggest that GBM cells may have a detrimental effect on neuronal survival. Of note, while recent literature suggests neurons contribute to GBM growth, seizures are a frequent occurrence in GBM patients, which may reflect neuronal toxicity. As an in vitro model for investigating the mechanisms mediating the loss of neurons in the recurrent GBM xenografts, neurons differentiated from iPSC derived Neural Progenitor cells (NPC) were directly cocultured with GFP-positive GSCs in stem cell growth medium. After the initiation of coculture the number of neurons and GSCs were determined from 24-96h. As compared to GSCs cultured alone, there was no difference in the number of GSCs in cocultures out to 96h. However, as compared to neurons cultured alone, there was a significant reduction in the number of neurons in cocultures beginning at 48h with further decreases out to 96h. These data suggest that GSCs induce neuron toxicity. As an initial step towards defining the mechanism through which GSCs induce neuronal death, cell culture supernatants from neurons, GSCs and cocultures were subjected to cytokine profiling after 48h. As compared to cell-free media, neuron culture media predominantly contained Osteopontin, TIMP-1 and TIMP-2, which have been implicated in neuron differentiation and functional development, while GSC culture media contained FGF-4, FGF-7 and TGFβ-3, which have been associated with GBM growth. However, in media isolated from cocultures MCPs, Angiogenin and IL-8 were uniquely detected suggesting an interaction between GSCs and neurons resulted in the production of these cytokines. IL-8, the most abundant cytokine detected in the coculture media, has previously been associated with neuron toxicity. These data suggest that interactions between GSCs and neurons alter cytokine levels, which then leads to neuron death. This effect may account for the loss of neurons observed in the GBM xenografts that regrow after irradiation. Citation Format: Komal Nalinkant Rawal, Charlotte Degorre, Philip J. Tofilon. Co-culture with glioblastoma stem-like cells induces neuron death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5230.