Sema3A regulates tumor associated neural remodeling and promotes tertiary lymphoid structures activation to restrain PDAC progression

Pancreatic ductal adenocarcinoma (PDAC) is driven by a dense desmoplastic stroma, immunosuppressive tumor microenvironment, and aberrant nerve density. Semaphorin 3A (Sema3A) have shown promise in normalizing tumor vasculature and restraining PDAC growth. Therefore, we engineered a mutant isoform (Mut-Sema3A) with high affinity for its receptor PlexinA4, achieving enhanced tumor growth inhibition and suppression of liver metastases. scRNA-seq analysis revealed that Mut-Sema3A treatment increased CD8⁺ T cells and confocal analyses showed a reprogramming in tertiary lymphoid structures (TLSs) toward a functionally mature, anti-tumor state by enriching activated CD8⁺ T, CD4⁺ T, and plasma cells. Given semaphorins’ role as axon-repellent cues, we investigated Mut- Sema3A’s effects on innervation using human iPSC-derived neurons. Revealing that Mut-Sema3A induced dose- dependent neuronal cytotoxicity and apoptosis while reducing neurite outgrowth. Importantly, PDAC cells promoted significant neurite growth in co-culture, which Mut-Sema3A markedly suppressed, counteracting cancer-driven neuronal remodeling. In addition, neuron-conditioned media enhanced PDAC cell survival and proliferation, highlighting tumor-supportive neuron activity. In vivo orthotopic studies confirmed that Mut-Sema3A reduced tumor hyperinnervation and impaired tumor-associated nerve density, normalizing innervation patterns toward healthy tissue. Overall, Mut-Sema3A hinders PDAC progression through dual mechanisms: reducing tumor hyperinnervation and promoting an immunologically active microenvironment with mature TLSs, potentially acting synergistically to limit tumor growth.