Cholinergic neuron-to-glioblastoma synapses in a human iPSC-derived co-culture model.

Glioblastoma (GBM) integrates extensively into brain-wide neuronal circuits; however, neuron-tumor interactions have largely been studied with glutamatergic neurons in animal models. The role of neuromodulatory circuits for GBM biology in all-human cell systems remains unclear. Here, we report a co-culture system employing patient-derived GBM organoids and human induced pluripotent stem cell (hiPSC)-derived cholinergic neurons. We provided evidence of structural human cholinergic synaptic inputs onto GBM cells via trans-monosynaptic tracing and electron microscopy and functional synaptic interactions through the metabotropic CHRM3 receptor via calcium imaging. Deep single-cell RNA sequencing of co-cultures compared to GBM monocultures further revealed shifts in tumor transcriptional profiles toward a more proliferative state, with contributions from both diffusible factors and direct contacts, the latter of which are dependent on cholesterol biosynthesis. Together, our findings support the role of cholinergic inputs in promoting GBM progression and highlight hiPSC-derived co-culture models as a useful platform for cancer neuroscience.