Abstract B112: Mast cell cross-talk with primary and metastatic pancreatic tumor cells

Abstract

Pancreatic ductal adenocarcinoma (PDAC), notorious for its fatality, claims a five-year survival rate of around 13%. PDAC is projected to become the second leading cause of cancer-related deaths by 2030. PDAC is often diagnosed at the advanced stage, where the tumor has spread to distant organs such as the liver and lung. The mechanism underlying tumor cell-mediated immunosuppression at metastatic sites, which enables their successful relocation and growth, is beginning to unfold. In our project, we focused on the mast cells, which have been shown to promote pancreatic tumor growth by aiding in angiogenesis and immunosuppression (via IL-10 secretion). However, the role of these cells in lung metastasis in pancreatic cancer remains unknown. Thus, we first assessed how the crosstalk between mast cells and primary and metastatic pancreatic tumor cells varies by performing in vitro co-culture experiments (1:1 ratio with cell culture inserts). We examined the impact of primary and metastatic pancreatic tumor cells on mast cells by performing bulk RNA sequencing and LC-MS/MS metabolomic analyses. In parallel, we also harvested tumor cells from these co-culture cohorts and performed bulk RNA sequencing to assess the effect of mast cells on tumor cells. For our mast cell model, we used MC/9 cells, an IL-3-dependent cloned mast cell line derived from mouse fetal liver. For co-culture studies, we used KPC1245 and KPC242 (primary pancreatic tumor cell lines) and a KPC242-derived lung metastatic cell line. Our data showed that both primary and metastatic cells significantly increased the expression of inflammatory mediators such as IL-13, IL-6, and tryptase in mast cells upon co-culture. Also, LC-MS/MS analyses showed significant alterations in the arginine and phenylalanine metabolic pathways in mast cells upon culture with primary or metastatic pancreatic tumor cell lines compared to the cultured-alone cohort. Notably, we also observed a concurrent increase in IL-13 receptor (IL-13ra1) expression on co-cultured pancreatic tumor cells, suggesting a possible crosstalk between these cells via the IL-13-IL-13 receptor signaling axis. Importantly, we observed a marked increase in several hypoxia-associated genes, including Adrenomedullin (Adm), Colony Stimulating Factor 2 Receptor Subunit Beta (CSF2Rb), DNA-damage-induced transcript 4 (Ddit4), and basic-helix-loop-helix family member e40 (Bhlhe40), in co-cultured pancreatic tumor cells compared to cultured-alone cohorts. Notably, the expression of this hypoxia-associated gene signature was similar between co-cultured primary and metastatic pancreatic tumor cells. Overall, our data showed that there is less distinction between primary and metastatic pancreatic tumor cell-mediated transcriptomics and metabolic alteration in mast cells. In parallel, mast cells also modulate the hypoxic signatures in pancreatic tumor cells.