A Human Neuronal Co-Culture System Reveals Early Tumor-Neuron Communication and Targetable Pathways in Glioblastoma

BackgroundGlioblastoma (GB, IDH wild type) is the most aggressive primary brain tumor in adults, with recurrence driven by residual tumor cells that re-establish interaction with surrounding neurons. While neuronal activity is recognized as a driver of GB progression, the earliest neuronal responses to tumor contact remain poorly understood. Existing models rarely capture these acute events or the heterogeneity of responses generated by tumors of different origins, limiting insight into the earliest neuron-tumor interactions. MethodsWe developed a dual-interface human iPSC-derived neuronal culture system to investigate acute neuronal responses to glioblastoma exposure. Neurons were challenged with either established GB cell lines or patient-derived glioblastoma cells (PDGCs). Using quantitative proteomics, high-resolution imaging, and immunological assays, we characterized compartment-specific neuronal changes and mapped activated signaling pathways. We also screened selective inhibitors for their effects on both tumor proliferation and neuronal integrity. FindingsWithin 24 hours of exposure, neurons displayed synaptic remodeling and activation of GB-related signaling cascades. Proteomic analysis of GB exposed neurons revealed enrichment of pathways associated with GB and abnormalities in neuronal circuits. Notably, the U-87MG cell line, but not PDGCs, induced pronounced synaptic disruption, neurite retraction, and MAPK pathway activation, with distinct molecular signatures across neuronal compartments. ERK1/2 and p38 MAPK signaling were differentially activated depending on the GB cells source, correlating with specific structural and functional synaptic alterations. Targeted inhibition of MAPK components significantly suppressed U-87MG proliferation and preserved neuronal architecture. InterpretationWe present a human neuronal culture model that detects and discriminates the earliest neuron-derived responses to glioblastoma from diverse tumor sources. By linking neuronal remodeling to tumor-specific signaling pathways, the platform uncovers both the heterogeneity of neuron-tumor interactions and early, targetable vulnerabilities. This system offers a translational tool to advance understanding of GB recurrence and to guide development of therapies with dual neuroprotective and anti-tumor efficacy. In BriefEarly interactions between glioblastoma and human neurons drive rapid, source-specific synaptic remodeling mediated by compartmental MAPK pathway activation. This neuronal co-culture model identifies distinct profiles of tumor-neuron communication, highlights synaptic vulnerability as a therapeutic axis, and demonstrates that MAPK pathway inhibition yields both neuroprotective and anti-tumor effects. SummaryGlioblastoma (GB) co-opts neuronal circuits to drive tumor progression, yet the earliest neuronal responses that may shape recurrence remain poorly defined. We developed a human iPSC-derived neuronal co-culture model that captures acute communication between neurons and glioblastoma from diverse sources, including serum-adapted cell lines and patient-derived cells. Within 24 hours, glioma-exposed neurons exhibited synaptic remodeling and activation of tumor-associated signaling pathways. High-resolution imaging and proteomics revealed compartment-specific synaptic alterations, with ERK1/2 and p38 MAPK signaling differentially engaged depending on the tumor source, corresponding to distinct structural and functional outcomes. Pharmacologic inhibition of MAPK components both suppressed tumor cells growth and preserved neuronal integrity. By modeling source-dependent and early neuron-tumor interactions, this platform not only identifies MAPK signaling as a critical mediator of synaptic vulnerability but also provides a clinically relevant tool for investigating the mechanisms of glioblastoma recurrence. It offers a framework for developing therapies that target the dual vulnerabilities of tumor progression and circuit remodeling. Highlights O_LIA dual-interface human iPSC-derived neuronal co-culture system models early neuron-glioblastoma (GB) interaction. C_LIO_LISerum-adapted U-87MG, but not serum-free patient-derived GB cells, induces pronounced synaptic disruption and neurite retraction. C_LIO_LIGlobal proteome of neurons reveals GB-associated signatures and neuronal circuit alterations in response to both U-87MG and patient-derived GB cells. C_LIO_LIERK1/2 and p38 MAPK signaling are differentially activated in neuronal compartments, depending on GB source. C_LIO_LIMAPK pathway inhibition suppresses U-87MG proliferation and preserves neuronal integrity, revealing actionable neuroprotective and anti-tumor targets. C_LI