Cancer-neuron interaction initiates neural mimicry and brain colonization in EGFR-mutant NSCLC

Brain metastasis is a major clinical challenge for patients with non-small cell lung cancer (NSCLC), and NSCLC patients with tumors harboring EGFR mutations have an increased risk of central nervous system (CNS) involvement, with up to 50-60% of patients developing CNS metastasis. The process of metastasizing to the brain is a complex multistep process in which tumor cells must cross the blood-brain barrier and adapt to the unique CNS environment. Recent studies in small cell lung cancer (SCLC) suggested that lung cancer cells residing in the brain acquired neural-like transcriptomic programs as compared to primary tumors in the lung. Given that EGFR mutant NSCLC tumor cells can exhibit lineage plasticity through processes including epithelial to mesenchymal transition (EMT) and SCLC or neuroendocrine transformation as part of acquired therapeutic resistance to EGFR inhibitors, we hypothesized that EGFR mutant NSCLC cells may interact with neuronal cells to facilitate CNS metastasis and lineage change. Here, we used in vitro and in vivo models to evaluate the impact of neuronal interaction on EGFR mutant NSCLC cells. We isolated primary murine neurons and co-cultured them with HCC827, HCC4006, and H1975 EGFR mutant NSCLC cells. After two days, immunofluorescent staining for neuronal markers, NeuN and MAP2, showed that EGFR mutant tumor cells co-cultured with neurons upregulated expression of these neuronal markers whereas tumor cells grown alone did not. Our in vivo models of EGFR mutant NSCLC brain tumors supported the enrichment of neuronal, synaptic, and axonal genes in cancer cells exposed to neuronal interaction. Moreover, we performed spatial transcriptomic analysis of human EGFR mutant NSCLC brain tumors paired with primary lung tumors to evaluate alteration of tumor microenvironment (TME) compartments associated with brain metastasis. Together, we propose neural mimicry as a potential mechanism exploited by EGFR-mutant NSCLC cells growing in the brain microenvironment. Our study further sheds light on novel targets for disrupting cancer-neuron interaction to inhibit the growth of brain metastasis in EGFR mutant NSCLC.