Cancer-neuronal crosstalk in glioblastoma: neuronal-dependent mechanisms in tumor progression

Glioblastoma (GBM) remains the most aggressive primary brain tumor of the adults, with dismal prognosis despite multimodal therapy. Traditional tumor-centric approaches have failed to fully explain the mechanisms underlying GBM progression and recurrence, highlighting the relevance of the tumor microenvironment and, more recently, of neurons as active players in cancer biology. We established an in vitro neuro-tumor unit (NTU) by co-culturing patient-derived Glioblastoma Stem-like cells (GSCs) with murine neurons and astrocytes. GSC proliferation was boosted by neurons and neuronal activity, but not by astrocytes alone. Across 11 GSC lines encompassing diverse GBM genomic and transcriptional profiles, most exhibited increased proliferation in response to neuronal signals (‘sensitive’ GSC, senGSC), whereas a minority remained refractory (‘refractory’ GSC, refGSC). Importantly, in our NTU model, we did not detect neuron-tumor bona fide synapses; rather, senGSC proliferation appeared to result from a combination of soluble factors and close physical interactions converging on the MAPK/ERK signaling pathway. In senGSC, the proliferation boost was coupled with metabolic adaptation characterized by glycolysis upregulation and de novo OXPHOS activation to support the increased energy demand. Differently, refGSC cocultured with neurons relied almost exclusively on glycolysis. Bulk RNA sequencing further revealed different transcriptional response in sen- and refGSC. While refGSC upregulated cell death-related pathways in response to neuronal cues, senGSC predominantly activated proliferation-associated biological processes. In addition, a core set of neuronal-induced genes was consistently associated in senGSC with proliferation, prominently converging on the regulatory nodes of FOXM1 and Cyclin B1. Notably, those nodes are implicated not only in cell-cycle progression, but also in modulating cell-metabolism. Collectively, our findings reveal that neurons and their activity promote GSC proliferation as well as metabolic and transcriptional reprogramming, establishing neurons as critical modulators of GBM growth. By dissecting heterogeneous responses among GSCs, our results underscore the role of neurons as supporters of GBM. This work strengthens the emerging field of cancer neuroscience and opens therapeutic opportunities aimed at disrupting neuron-GBM crosstalk and preventing tumor progression while preserving brain function.