Vitamin d receptor-mediated stromal reprogramming suppresses pancreatitis and enhances pancreatic cancer therapy

The poor clinical outcome in pancreatic ductal adenocarcinoma (PDA) has been attributed to intrinsic resistance to chemotherapy and a growth-permissive tumor microenvironment. Quiescent pancreatic stellate cells (PSCs) are neuroendocrine, nestin-positive, lipid-accumulating cells whose homologues in the liver are the principal repository of Vitamin A esters. Upon activation, lipid droplets are lost and via transdifferentiation they become the key cell type responsible for driving the severe desmoplasia that characterizes PDA. Despite their critical role in PDA progression and chemoresistance, therapeutic strategies targeting PSCs are lacking. Here we identified the vitamin D receptor (VDR) as a master genomic regulator of PSC activation and function. In vitro we demonstrate that VDR activation reduces expression in PSCs of genes implicated in activation, inflammation, and extracellular matrix production, as well as restoring lipid droplet integrity. In vivo, the VDR ligand calcipotriol enhances the anti-tumor effects of gemcitabine by increasing intratumoral concentration 5-fold, reducing tumor volume to near baseline and lowering metastases by more than 65%. These findings implicate VDR as a master regulator of PSC activation and identify a novel therapeutic approach for the treatment of pancreatic cancer.