Abstract A021: Examining the unconventional role of Ang–Tie2 signaling in pancreatic CAF/ECM unit function

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a five-year survival rate of ∼13%. Its aggressiveness is largely mediated by the expansive tumor microenvironment that includes functional units consisting of cancer-associated fibroblasts (CAFs) and CAF-generated extracellular matrix (ECM). Recent work from our lab identified that the synaptic neuronal protein, Netrin G1 (NetG1), is pathologically upregulated in pancreatic functional units, drives the unit’s pro-tumor functions, and correlated with poorer overall survival in PDAC patients with high fibroblastic NetG1 expression. The goal of this project is to determine whether comparisons of NetG1 high and low expressing CAFs could elucidate other novel pro-PDAC unit regulators. Using publicly available transcriptomic data of PDAC patient-matched normal-like fibroblasts and CAFs, CAFs were stratified into NetG1low or NetG1high expressing cohorts to identify differentially expressed genes (DEG). Computational analyses revealed a key network of 67 genes represented in 16 clusters from the initial 530 DEG input list. “Tie2 Signaling” was the largest enriched cluster, which is canonically known for being associated with endothelial cell function (e.g., angiogenesis) but has never been studied in association with pro-PDAC CAF/ECM units. Western blot analysis demonstrated that patient-derived pancreatic CAF/ECM units amply express Tie2 whose activity (denoted by phosphorylation) increases upon stimulation with the angiopoietin (Ang) ligands. Small molecule inhibition of CAF Tie2 can decrease both IL-6 and TGFβ secretion, to varying levels depending on patient background, suggesting that 1) loss of Tie2 signaling may affect CAF pro-tumorigenic functions and 2) there may be patient specific differences that contribute to CAF function. Indeed, we observed higher tumor burden in mice orthotopically co-injected with the most active patient-derived CAF line compared to the least active CAF. Transcriptomic data revealed, however, that our patient derived lines do not distinctly correlate with previously published CAF gene signatures. Studies determining whether repression of CAF Tie2 expression via CRISPRi can reduce this growth advantage in an orthotopic mouse model are underway. Collectively, these data suggest that Ang/Tie2-mediated signaling can influence CAF/ECM pro-tumorigenic functions and may provide a novel target to normalize the tumor-enabling microenvironment in PDAC patients. Citation Format: Jaye C. Gardiner, Sergio Santos, Khoa A. Tran, Mariia Dmitrieva, Aleksandr Dolskii, Janusz Franco-Barraza, Caneta Brown, Tiffany Luong, Edna Cukierman. Examining the unconventional role of Ang–Tie2 signaling in pancreatic CAF/ECM unit function [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): nr A021.