Abstract PO-121: Investigating the role of human cancer-associated fibroblasts in pancreatic cancer invasion using patient-derived PDAC organoids

Organoid cultures have emerged as a promising research model as they more accurately recapitulate in vivo tumor features and provide a system to study cancer invasion, among others. We have previously reported the development of a human pancreatic cancer organoid model using surgically resected PDAC tumors. This model has allowed us to characterize molecular alterations critical for invasion. Culturing PDAC organoids in collagen I gels identified the ability of organoids to invade using two distinct, morphologically defined invasive phenotypes. Interestingly, invasion of PDAC organoids in collagen I decreased after culturing and passaging them in Matrigel, suggesting the microenvironment plays a crucial role in promoting invasion. To identify factors that increase PDAC organoid invasion, we sought to investigate the relationship between human PDAC organoids and patient-derived cancer-associated fibroblasts (CAFs). CAFs are a key component of the PDAC microenvironment, characterized by their ability to perform a variety of functions, including deposition and remodeling of ECM as well as promoting tumor growth, among others. CAFs may induce tumor-suppressive or tumor-promoting effects, and the role of CAFs subtypes in PDAC invasion has not been studied extensively. CAFs are also a heterogeneous group of cells: two mutually exclusive and reversible subtypes of CAFs have been discovered (inflammatory and myofibroblastic, also known as iCAFs and myCAFs respectively) driven on paracrine and juxtacrine signaling mechanisms. We have investigated the impact of patient-derived CAFs on PDAC organoid invasion by using conditioned media of CAFs in monolayers, which expand as myCAFs. After 2-3 days of culture, media was collected and human PDAC organoids (100-150 total) from 5 patients were allowed to grow and invade in collagen I gels with or without the addition of CAF conditioned media. Our results show conditioned media of CAFs increases the invasiveness of PDAC organoids but does not increase the percentage of organoids invading. In order to identify potential heterogeneity between primary CAF cultures from different patients, we performed time-lapse analyses of organoids in collagen I gels with conditioned media from 3-4 patient-derived CAFs. Interestingly, we did not find any significant differences between primary CAF cultures in inducing PDAC organoid invasion, suggesting that the ability of CAFs to induce tumor cell invasion does not vary widely between different patients. However, we did observe some patient-derived organoids did not increase invasiveness upon addition of conditioned media from any of the CAF cultures, showing heterogeneity in tumor cells from different patients in response to invasion-inducing factors secreted by CAFs. Future studies will examine the ability of iCAFs to induce invasion in our organoid model and the differences between the secretomes of myCAFs and iCAFs. Citation Format: Bernat Navarro-Serer, Kenna Sherman, Laura D. Wood. Investigating the role of human cancer-associated fibroblasts in pancreatic cancer invasion using patient-derived PDAC organoids [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-121.