Mast cell corticotropin-releasing factor receptor 1 contributes to pancreatic cancer pain via mitogen-activated protein kinase/sphingosine kinases type 1 signaling

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer often accompanied by persistent abdominal pain and stress, significantly compromising patients' quality of life. Previous studies have identified mast cells as crucial contributors to pancreatic cancer-related pain. This study aimed to investigate the role of the mast cell receptor corticotropin-releasing factor receptor 1 (CRFR1) and delineate its underlying mechanisms in mediating pancreatic pain. In the current study, we demonstrated that painful patients with PDAC exhibited markedly increased mast cell infiltration in peritumoral tissues, but not in tumor tissues, along with elevated levels of CRF and mast cell-specific CRFR1 expression, compared to asymptomatic patients. Consistently, in orthotopic PDAC mice models, flow cytometry and immunofluorescence staining confirmed increased CRFR1 expression in mast cells. Both pharmacological inhibition of CRFR1 and mast cell-specific CRFR1 knockout suppressed mast cell degranulation and alleviated cancer pain in male and female mice. Mechanistically, RNA sequencing, western blotting, and enzyme-linked immunosorbent assay indicated that CRFR1 activated mitogen-activated protein kinase (MAPK) pathway signaling, upregulated sphingosine kinases type 1 (SPHK1) expression, and increased sphingosine-1-phosphate (S1P) levels. A rescue experiment revealed that MAPK inhibition blocked CRFR1-induced SPHK1 upregulation in vitro. Importantly, the SPHK1 inhibitor PF543 reduced abdominal hyperalgesia in mice, whereas this effect was abolished in mast cell deficient mice. Moreover, SPHK1 knockdown by siRNA abolished CRFR1-induced mast cell degranulation. These findings highlight the critical role of mast cell CRFR1 in mediating abdominal hyperalgesia and identify the MAPK/SPHK1/S1P axis as an essential pathway, suggesting that targeting mast cell CRFR1 may be a promising therapeutic strategy for managing pancreatic cancer pain.