Abstract A095: Oncogenic KRAS signaling mediates NF-kB induced chemokine production by pancreas tumor cell

Abstract Pancreatic ductal adenocarcinoma (PDA) tumors develop an immunosuppressive tumor microenvironment (TME) in part through chemokine-directed recruitment of immune cells. The precise molecular mechanisms regulating this process remains poorly understood. Mining of single cell RNA data found eight differentially expressed chemokines by primary or metastatic PDA tumors compared to healthy pancreas. Among the chemokines was CCL20, the only ligand for CCR6. The increase in CCL20 was confirmed by immunofluorescence staining of human healthy pancreas and PDA tissues. Analysis of The Cancer Genome Atlas (TCGA) and the Genome Tissue Expression database (GTEx) show CCL20 expression is upregulated by all gastrointestinal cancers, but not other solid or hematological malignancies. CCL20 was found to be produced by epithelial tumor cells in both PDA and colorectal cancer (CRC), particularly the basal subtype and the iCMS2 subtype, respectively. Increased expression of CCL20 was found to be driven by NF-kB signaling, coinciding with increased expression of other NF-kB regulated chemokines such as CXCL2 and CXCL5. Increased CCL20 was observed in pancreatitis datasets, but was primary expressed by Th17 and myeloid cells and not the ductal cells suggesting that the malignant transformation of ductal cells is necessary for CCL20 production. Analysis of TCGA somatic mutation annotation files did not find any mutation or copy number signatures associated with increased CCL20 expression in both PDAC and CRC. Methylation of the CCL20 gene was decreased among CCL20 high TCGA samples. Analysis of chemokine production in vitro through ELISA and qPCR found that EGFR and receptor tyrosine kinase inhibition did not change the amount of CCL20 or CXCL2 ligand or transcript. While knockouts of DNA methyltransferase 1 or 3b slightly increased CCL20 and CXCL2 production, the observed increase was modest. However, significant decreases in both chemokines were observed with cell line resistance or treatment with KRAS G12D (MRTX1133) and RAS-MULTI(ON) (RMC-7977) inhibitors. Lastly, inhibition of CCL20-CCR6 signaling in vivo with a novel CCR6 inhibitor, CCL20-locked dimer (CCL20LD) resulted in increased dendritic cells recruited to orthotopic KPC tumors in mice. Together, these data suggest that mutated RAS alone is responsible for production of chemokines that modify the PDA TME and that RAS inhibitor resistant tumors may have a less immunosuppressive TME. Citation Format: Donovan Drouillard, Marissa Davies, Donna McCallister, Michael B. Dwinell. Oncogenic KRAS signaling mediates NF-kB induced chemokine production by pancreas tumor cell [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research—Emerging Science Driving Transformative Solutions; Boston, MA; 2025 Sep 28-Oct 1; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_3):Abstract nr A095.