Abstract LB070: Trefoil factor I (TFF1) as a modulator of intrinsic and stroma induced chemoresistance in pancreatic ductal adenocarcinoma

Abstract Background: The classical and basal transcriptional subtypes of pancreatic ductal adenocarcinoma (PDAC) distinguish response to chemotherapy and patient prognosis. Trefoil Factor 1 (TFF1) expression is a common marker of the more therapeutically-responsive classical subtype. TFF1 is lost in the mesenchymal-like and chemoresistant transcriptional basal-like subtype of the disease. Using spatial transcriptomics, our group observed TFF1 expression is present in premalignancy, increasing from low to high-grade premalignant pancreatic intraepithelial neoplasia (PanIN). We also observed that fibroblasts surrounding these TFF1 expressing PanINs display a tumor-supportive cancer-associated fibroblast (CAF) like phenotype. Taken together, these observations led us to hypothesize that TFF1 may play a dual role in maintaining a chemo-responsive phenotype through the suppression of the epithelial-mesenchymal transition (EMT) process; and by promoting the activation and modulation of CAFs during early tumorigenesis that contribute to chemotherapy resistance in advanced PDAC. Thus, we sought to clarify the mechanism behind TFF1’s role in maintaining chemosensitivity through suppression of EMT and examine TFF1-CAF interactions as a potential driver of CAF contributions to the tumor-supportive PDAC tumor microenvironment. Methods: To test the dual role of TFF1 in PDAC, we overexpressed and knocked down TFF1 in PDAC cell lines (PANC02 and KPC) to assess changes in proliferation, invasion, and response to standard-of-care chemotherapies (FOLFIRINOX and Gemcitabine + Nab-Paclitaxel). Differential expression and gene set enrichment analyses of a compilation of human PDAC single-cell RNA-sequencing datasets were used to identify transcriptional changes linked to TFF1 expression. Subsequently, TFF1-mediated PDAC-CAF signaling was examined using ligand-receptor network inference analysis in the human single-cell data. To investigate TFF1-driven activation of the CAF phenotype, patient derived fibroblasts were treated with recombinant TFF1, and bulk RNA-seq analysis was performed to identify the activated signaling pathways. Results: PDAC cell lines over-expressing TFF1 displayed increased proliferation and decreased invasion, indicating a role for TFF1 in inhibiting tumor aggressiveness. Overexpression of TFF1 also enhanced the response to chemotherapeutics in vitro, while scRNAseq-based gene set enrichment analysis revealed significant downregulation of EMT pathways in TFF1-high cells. Recombinant TFF1 treatment of fibroblasts promoted a tumor-supportive CAF-like phenotype by upregulating CAF activation markers and enriching pathways associated with proliferation, such as the G2/M checkpoint, and ECM deposition, via the PI3K/AKT/mTOR pathway. Our results reveal TFF1 as a potential modulator of intrinsic tumor cell behavior and tumor-CAF interactions. Citation Format: Wisam Nazal Awadallah, Jacob Mitchell, Emma Kartalia, Jacquelyn W. Zimmerman, Daniel Zabransky, Elizabeth Jaffee, Laura Wood, Elana Fertig, Luciane T. Kagohara. Trefoil factor I (TFF1) as a modulator of intrinsic and stroma induced chemoresistance in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB070.