Abstract PO-125: The role of KDM6A in pancreatic cancer immune microenvironment

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in the United States, with a 10% 5-year survival rate. Immunosuppressive myeloid cells, including tumor-associated neutrophils (TANs), contribute to tumor development and treatment resistance. Lysine (K)-specific demethylase 6A (KDM6A) is one of the most frequently mutated epigenetic genes and a tumor suppressor in PDAC. However, the molecular mechanisms by which KDM6A contributes to PDAC development and whether KDM6A impacts the tumor immune microenvironment are unknown. This study established a genetically engineered pancreas-specific Kdm6a-knockout Ptf1aCre;LSL-KrasG12D/+;LSL-p53R172H/+ (KPC) PDAC mouse model to investigate the influence of KDM6A loss on PDAC development and tumor immune microenvironment. We found that KDM6A loss accelerated PDAC progression and increased metastases. Pancreata of mice with Kdm6a deficiency developed aggressive undifferentiated PDACs. Additionally, KDM6A loss led to increased infiltration of TANs and neutrophil extracellular traps (NETs) formation. Mechanistically, we used Bru-seq technology to investigate the impact of KDM6A on nascent RNA transcription. We demonstrated that many chemotactic cytokines related to neutrophil recruitment, specifically CXCL1, were upregulated in KDM6A-knockout PDAC cells. We further confirmed increased CXCL1 mRNA and protein levels in KDM6A-deficient human and mouse PDAC cells. In addition, immunohistochemical staining also confirmed the upregulated CXCL1 expression in both human and murine PDAC cells with KDM6A loss. TANs were found to express CXCR2, the receptor of CXCL1, by immunofluorescent analysis. To further confirm that cancer cells with KDM6A loss can attract neutrophils in vitro, we performed chemotaxis assays using both human neutrophils derived from PLB-985 cells and mouse primary neutrophils isolated from bone marrow and conditioned media from KDM6A- knockout or knockdown PDAC cells. We found that PDAC cells with KDM6A loss promoted neutrophil recruitment in vitro compared to KDM6A-retained PDAC cells. Furthermore, the CXCL1 neutralizing antibody reversed the chemotactic property of KDM6A-deficient PDAC cells, confirming that CXCL1 is the primary chemokine mediating the neutrophil recruitment. In summary, these findings shed light on the mechanism by which KDM6A loss promotes PDAC development, regulates tumor immune microenvironment, and suggests that the CXCL1-CXCR2 axis may be a candidate target for the treatment of PDAC, especially those with KDM6A mutations. Citation Format: Lin Jin, Jing Yang, Zhujun Yi, Hong S. Kim, Feng Tian, Jiaqi Shi. The role of KDM6A in pancreatic cancer immune microenvironment [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-125.