Abstract 5851: Cancer associated fibroblast crosstalk through VEGF increases tumor cell proliferation in human pancreatic ductal adenocarcinoma
Authors: Guinn Samantha , Tandurella Joseph , Patel Jignasha , Burkhart Richard , Zimmerman Jacquelyn , Jaffee Elizabeth 
Published: April 2023

Abstract
Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a classically heterogeneous tumor for which tumor cells comprise less than 40% of the total tumor mass. To better understand mechanisms of intercellular interactions driving tumor response or resistance to chemotherapy, it is crucial to account for the complex tumor microenvironment (TME). Cancer associated fibroblasts (CAFs) have been implicated as key drivers supporting mechanisms that both promote and restrain tumor growth. Using our model system that investigates interactions between CAFs and cancer cells, we show a novel intercellular interaction through VEGF signaling that drives proliferation.
Methods: We interrogate intracellular crosstalk in the PDAC TME using a novel 3-dimensional (3D), patient-matched coculture system of patient-derived organoids (PDO) and CAFs, obtained from patients undergoing surgical resection. Molecular characterization is performed by profiling with a 1200 analyte multiplex ELISA screen, multiparameter flow cytometry, bulk RNA sequencing of CAF and PDO cocultures, imaging mass cytometry (IMC) on patient samples, and qPCR.
Results: Secretome profiling of 7 patient-derived CAF lines demonstrated patient-specific heterogeneity in proteins such as: FGF-12, FGF3, and CD79a. Common CAF-derived signaling proteins with the potential to regulate intercellular crosstalk that were seen across all samples include CRP, IL-6R, R-Spondin and others. To better understand how factors change with intercellular interactions, we set up direct CAF-PDO cocultures over 4 days to identify global transcriptional changes using bulk RNAseq. Phenotypically, coculture drives gene expression changes in both PDO subtype (basal vs classical) and CAF subtype (prevalence of iCAFs vs myCAFs). We used these transcriptome data to identify pathways modulated by CAF-PDO crosstalk. Profiling coculture supernatant, we identified upregulation in VEGF secretion. In tandem, when we investigate cellular surface marker changes, we see upregulation of VEGFR2 on the surface of CAFs by flow cytometry. This interaction is accompanied by an increase in PDO proliferation seen in the coculture conditions. Ongoing experiments aim to investigate the impact of this relationship spatially using matched patient tissue.
Conclusions: Interactions between cancer cells and CAFs compound the complexity of the biology of the TME and contribute to poor patient outcomes; therefore, we have put forth a model that better represents these interactions through patient matched PDO - CAF cocultures. Using this model, we demonstrate a novel interaction through VEGF that enhances tumor cell proliferation. We introduce a targeted approach to investigating the complex biology of the TME to inform the mechanisms driving cancer biology in individual patients that can also be used to develop novel therapeutic targets.
Citation Format: Samantha Guinn, Joseph Tandurella, Jignasha Patel, Richard Burkhart, Jacquelyn Zimmerman, Elizabeth Jaffee. Cancer associated fibroblast crosstalk through VEGF increases tumor cell proliferation in human pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5851.