Abstract B023: Hypoxia supports CAF-mediated epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma

Abstract

Abstract The pancreatic ductal adenocarcinoma (PDAC) microenvironment is populated by distinct subtypes of cancer-associated fibroblasts (CAFs), including myofibroblastic CAFs (myCAFs) that synthesize and remodel the stromal matrix and inflammatory CAFs (iCAFs) that secrete cytokines and growth factors. Subpopulations of CAFs reside in regions of tumor hypoxia, which may play a role in determining CAF behaviors. We tested the hypothesis that iCAFs preferentially drive ductal cell epithelial-mesenchymal transition (EMT), which promotes PDAC chemoresistance, and that hypoxia promotes the iCAF phenotype. Cell-cell communication analysis using publicly available single-cell RNA sequencing (scRNA-seq) data of human tumors indicated that iCAFs secrete growth factors predicted to promote ductal cell EMT. This inference was confirmed in experiments showing that PDAC cells exhibit stronger EMT in response to conditioned medium from iCAFs than from myCAFs. Publicly available scRNA-seq data further indicated a correlation between hypoxia and the iCAF phenotype. qRT-PCR and immunofluorescence microscopy confirmed that hypoxia promotes the iCAF phenotype, and conditioned medium experiments demonstrated the preferential ability of hypoxic CAFs to utilize an NFκB-dependent pathway to secrete cytokines that promote EMT. A screen of 430 kinase inhibitors nominated specific growth factors that we validated to be EMT-inducing and generated by hypoxic CAFs. Finally, iterative indirect immunofluorescence imaging (4i) of tumor sections from KrasLSL-G12D/+; Trp53LSL-R172H/+, Pdx1-Cre; Rosa26YFP/YFP (KPCY) mice and quantitative image analysis demonstrated a spatial correlation in PDAC tumors between mesenchymal neoplastic cells and hypoxic CAFs. Our results raise the intriguing possibility that hypoxia cooperates with CAFs to promote EMT in PDAC and identify drug targets whose antagonism may interfere with a PDAC-stromal signaling process that promotes chemoresistance. Citation Format: Karl Kowalewski, Matthew Lazzara. Hypoxia supports CAF-mediated epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B023.