Abstract 6169: Identification of molecules mediating natural killer cell-pancreatic stellate cell interactions

Abstract Pancreatic stellate cells (PSCs) are the main sources of cancer-associated fibroblasts in pancreatic ductal adenocarcinoma (PDAC), which account for at least 50% of PDAC’s total tumor volume and its dense desmoplastic stroma. In recent years, immune-stromal cell interactions have been the subject of research in a variety of diseases. Interestingly, natural killer (NK) cells are relatively understudied in PDAC and may be exploited to identify new treatment opportunities. We have explored how NK cell-PSC interactions are mediated by known NK cell ligands. Human PSC (hPSC, CRC-811) or PDAC (MIA-PaCa-2, PANC-1) cell lines were co-cultured with DiO stained NK cells (NK-92, donor NK cells) for 4 hours, then target cells were assessed for apoptosis by flow cytometry using AnnexinV and Sytox stains. We found that although NK cells lyse both PSCs and PDAC cells, there was more NK cell-mediated lysis against PSCs. Using flow cytometry, we found that PSCs express the well-known MICA/B ligand, which binds the activating NKG2D receptor on NK cells to initiate its cytotoxic activity. In co-culture, neutralizing MICA/B in vitro did not completely inhibit NK cell-mediated lysis of PSCs, suggesting other interactions need to be explored. To identify other molecular determinants, NK cell ligand and receptor expression was evaluated by quantitative PCR in human PSC, PDAC, NK, and other leukocytic (K562) cell lines. Cell surface validation of highly expressed NK cell ligands and receptors were confirmed by flow cytometry and/or Western blot. NK cell ligands that were both highly expressed and localized to the cell surface were: NKG2D ligands—MICA and ULBP2 (both activating), KIR2DS4 (CD158I) ligand—HLA-A (activating), and NKp44 ligands—NKp44L and PCNA (activating and inhibitory, respectively). Their corresponding receptors were also expressed and localized to the cell surface by NK cells. These results highlight novel NK cell-PSC interactions that may mediate immune suppression in PDAC. These findings warrant further investigation. Citation Format: Zoe X. Malchiodi, Allison Fitzgerald, Elena Galvano, Louis M. Weiner. Identification of molecules mediating natural killer cell-pancreatic stellate cell interactions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6169.