Abstract 2117: IFN-γ signaling in myeloid cells regulates pancreatic cancer growth and progression

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by low survival, early metastasis, and rapidly emerging resistance to therapy. Interferon gamma (IFN-γ) signaling pathway is one of the key regulators of the tumor microenvironment in numerous cancer settings and its possible key role in myeloid cells is suggested. Here we investigated the IFN-y signaling in myeloid cells during PDAC development, progression, and metastasis using mice with conditional ablation of IFNgR2 in myeloid cells (IFNgR2-Delta-Mye). We performed an orthotopical injection of cells derived from conditional murine pancreatic model (Pdx1Cre-Kras-P53, or “KPC” cells) into IFNgR2-LysMCre (IFNgR2-Delta-Mye) mice. Ablation of IFN-γ signaling in myeloid cells led to a higher tumor burden compared to controls. Subsequent RNA sequence analysis demonstrated that IFN-γR2 deficiency in myeloid cells resulted in increased TGFβ1 gene expression as well as changes in metabolic and growth factor pathways in macrophages isolated from tumor tissue. Immunofluorescent analysis demonstrated that IFN-γR2 deletion in myeloid cells led to changes in cancer cell differentiation, resulting in a loss of characteristic epithelial histological pattern and shifting it towards more aggressive phenotype, possible via TGFβ1 dependent mechanism. Using murine model of liver metastasis, we found that loss of IFN-γR2 in myeloid cells leads to increased metastatic outgrowth of PDAC KPC cells. This effect was partially dependent on the gut microbiota, as shown by “separated and co-housed mice” experiments. Deficiency of IFN-γR2 in myeloid cells resulted in increased recruitment and infiltration of monocytes in normal and tumor/metastatic liver tissues. Our data identifies myeloid cell type specific IFN-γ signaling pathway as an important regulator of pancreatic cancer progression and metastasis, that can be potentially exploited as a novel immunooncology target. Citation Format: Elena Ivleva, Natalia Andreeva, Sergei Grivennikov. IFN-γ signaling in myeloid cells regulates pancreatic cancer growth and progression [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 2117.