Abstract C032: The involvement of the splanchnic program at the cellular and molecular levels in pancreatic cancer associated fibroblasts

Abstract

Abstract Pancreatic Ductal Adenocarcinoma (PDAC) is characterized by a dense stroma primarily composed of cancer associated fibroblasts (CAFs). Our group recently performed a lineage tracing study using genetically engineered mouse models. This study demonstrated that CAFs and pancreatic tissue resident fibroblasts (TRFs) are both derived from the fetal splanchnic mesenchyme, an area of mesoderm next to the foregut endoderm. To determine whether two major subtypes of CAFs are derived from the splanchnic mesenchyme, I analyzed co-expression of the lineage tracing marker Tomato and CAF subtype marker a smooth muscle actin (aSMA). This suggests that both myofibroblasts (aSMA high) and inflammatory fibroblasts (aSMA low) are derived from the splanchnic mesenchyme. Furthermore, we found that transcription factor Gata6 is expressed in the splanchnic mesenchyme and in some CAFs. We constructed mouse genetic models where Gata6 is specifically deleted in fibroblasts. These Gata6 conditional knock out mice had increased tumor burden, suggesting that stromally-expressed Gata6 has a tumor restraining role. We derived CAF and TRF cell lines from these genetic mouse models and their littermate normal mice. My preliminary data suggest that several important fibroblast factors, including type I collagen, aSMA, and Interleukin 6, are upregulated in the Gata6 KO CAFs and TRFs relative to normal CAFs and TRFs. In summary, our study showed that two major subtypes of pancreatic CAFs are derived from the splanchnic mesenchyme, and splanchnic factors may play a role in adult pancreatic fibroblasts to regulate the expression of critical fibroblast genes. Citation Format: Tom Walter, Lu Han, Michael Ostrowski. The involvement of the splanchnic program at the cellular and molecular levels in pancreatic cancer associated fibroblasts [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 C032.