Downregulation of the CCK-B Receptor in Pancreatic Stellate Cells Blocks Molecular Proliferative Pathways and...

Pancreatic cancer is characterized by an extensive fibrotic stroma largely driven by activated pancreatic stellate cells (PSCs)/fibroblasts, which also function to support tumor growth and metastasis. Cholecystokinin-B receptors (CCK-BRs) are expressed on pancreatic stellate cells (PSCs) and have emerged as a key regulator of PSC activation and tumor-stromal interactions. We hypothesized that disrupting CCK-BR function shifts PSCs to a more quiescent phenotype and reduces their pro-fibrotic and tumor-supportive activity to decrease growth of pancreatic cancer. Murine PSCs were genetically engineered with CRISPR-Cas9 to knockout the CCK-BR. In a series of experiments, the role of the CCK-BR expression was evaluated on cell migration, proliferation, differentially expressed genes, molecular signaling pathways, and in co-culture with murine pancreatic cancer epithelial cells. Next, primary human pancreatic stellate cells were treated with proglumide, a CCK-BR antagonist, to study the effects of pharmacologic blockade of the CCK-BR on cellular signaling and proliferative pathways by RNA sequencing. Knockout of the CCK-BR led to significant decreases in PSC activation and the ability to stimulate growth of pancreatic cancer cells in co-culture. Both genetic knockdown and pharmacologic blockade of the CCK-BR downregulated genes implicated in fibrosis, proliferation, fibroblast activation, and tumorigenesis, while genes implicated in apoptosis and tumor suppression were upregulated. Flow cytometry showed increased apoptosis markers in CCK-BR-knockout cells compared to controls. These experiments combine transcriptomic profiling with functional validation to provide a comprehensive analysis of how targeting CCK-BR interrupts the cross-communication between cancer cells and fibroblasts. Blockade or downregulation of the CCK-BR on pancreatic fibroblasts may provide a strategy to disrupt oncogenic signaling pathways and reprogram the tumor microenvironment.