Longitudinal Analysis of Matched Patient Biospecimens Reveals Neural Reprogramming of Cancer-Associated Fibroblasts...

Pancreatic ductal adenocarcinoma (PDAC), the most common subtype of pancreatic cancer, is a deadly disease with a complex tumor microenvironment (TME). Cytotoxic combination chemotherapy treatments are the mainstay of PDAC therapy, but patients rapidly develop chemoresistance, highlighting the need to elucidate how chemotherapy alters the TME and whether these changes drive chemoresistance. Here, we examined matched pre- and post-treatment tissue specimens using single-cell RNA-sequencing and found near-universal enrichment after treatment of axonal guidance genes in cancer-associated fibroblasts (CAFs). These neural CAFs were enriched near sites of perineural invasion, coinciding with regions of increased tumor cell proliferation, and were enriched in tumor areas distant from nerves after chemotherapy. Metastatic recurrent lesions had the highest prevalence of neural CAFs versus primary tumors and untreated metastases. Neural CAFs showed elevated non-canonical WNT mediators and axonal guidance genes, which complemented matching cognate binding partners in tumor epithelial cells, suggesting a role in tumor-stroma crosstalk. Additionally, in vitro studies revealed enrichment of axonal guidance genes in patient-derived CAF lines upon exposure to chemotherapy or tumor cells. Altogether, these findings implicate fibroblast-derived axonal-guidance genes in promoting PDAC invasion and point to a promising therapeutic target for this disease.