Pancreatic tumor expressed growth factors activate a neural-like program in human fibroblasts which is associated with poor prognosis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers, with a 5-year survival of less than 14%. The tumor microenvironment (TME) plays a central role in PDAC progression and is composed primarily of cancer-associated fibroblasts (CAFs), together with smaller populations of tumor, nerve, and immune cells. Recently, a population of stromal cells exhibiting a neural-like program has been identified within the PDAC TME, and its presence correlates with poor outcomes and chemoresistance. However, the origin of these neural-like cells and their role in tumor progression remain unclear. In a related project using Xenium spatial transcriptomics, we found that some CAFs express this neural-like program and often cluster near tumor cells. Based on this, we hypothesized that this program can be activated in CAFs through exposure to growth factors secreted by PDAC cells.To validate our Xenium findings, we performed cyclic immunofluorescence on 32 macrodissected PDAC samples across disease stages, staining for tumor, fibroblast, and neural markers. These analyses showed that a subset of CAFs expresses a neural-like program. Unbiased clustering further demonstrated that higher densities of neural-program-activated CAFs, as well as their closer proximity to tumor cells, are associated with disease progression. Next, we investigated in vitro the relationship between tumor cells and the neural-like program in human cell line fibroblasts. When co-cultured with PDAC cells, fibroblasts promoted tumor growth and activated neural markers even without added growth factors, indicating that tumor cells can drive this reprogramming. After gemcitabine treatment, neural-program-activated fibroblasts survived better than normal fibroblasts, while tumor cells remained sensitive. This suggests that the neural-like program enhances fibroblast survival rather than directly promoting tumor chemoresistance, potentially supporting the proliferation of residual tumor cells, although this requires further validation.Finally, we aimed to identify the mechanisms underlying neural-like program activation. Xenium data highlighted several neural-associated growth factors as candidates. Exposing human fibroblast cell lines to combinations of these factors showed that two of them were sufficient to induce neural markers. Re-analysis of mass cytometry data identified the downstream signaling pathways involved, and the use of inhibitors confirmed these findings.Overall, our work shows that PDAC cells can activate a neural-like program in fibroblasts through growth factor-mediated signaling and implicates this plasticity as a contributor to tumor progression and treatment resistance. Further dissecting this process could reveal new intervention points to limit CAF support for the tumor and enhance chemotherapy effectiveness in PDAC.