Abstract PR016: Aging modulates the tumor microenvironment of pancreatic cancer
Authors: Henríquez Joaquín Araos , Manansala Judhell , Teles Sara Pinto , Jihad Muntadher , Lloyd Eloise G. , Jassim Amir , Gilbertson Richard J. , Biffi Giulia 
Published: November 2022

Abstract
Pancreatic ductal adenocarcinoma (PDAC) has a very poor clinical outcome due to late diagnosis and resistance to therapies. Its epithelial compartment is surrounded by a cancer-associated fibroblast (CAF)-rich stroma that has been shown to be highly heterogeneous and promote therapy resistance and tumor growth. Importantly, the strongest risk factor for PDAC is age and half of patients are diagnosed when they are 75 years old or older. However, most pre-clinical studies of PDAC are performed on mouse models that are ~2-6 months old, which corresponds approximately to 20-30 human years. Thus, these models may not mimic the physiological state and molecular interactions between the tumor microenvironment (TME) and cancer cells of most PDAC cases. We hypothesize that the analysis of ageing models of PDAC will reveal new biology and targets for future therapeutic intervention. Our aim is to understand whether aging affects CAFs and immune cells and how this in turn impacts PDAC progression. To investigate this, we established new orthotopically-grafted organoid (OGO) aged mouse models of PDAC by injecting pancreatic cancer organoids derived from KPC (KrasLSL-G12D/+; Trp53LSL-R172H/+; Pdx1-Cre) mice into the pancreas of old (~18-month-old) C57BL/6J mice and compared these models to young (~3-month-old) OGO mice. We obtained tumor tissues for immunohistochemistry, flow cytometry and single-cell RNA-sequencing, plasma for cytokine arrays, and their tumor-free weight at endpoint. As a complementary strategy, we derived pancreatic stellate cells (PSCs), a precursor of CAFs, from old and young C57BL/6J mice and performed proliferation assays and transcriptomic analyses of PSCs cultured with PDAC organoid-conditioned media and of co-cultured KPC organoids and PSCs. We observed a significant weight loss and increasing concentrations of cytokines related to cancer cachexia in the plasma of aged PDAC mouse models in comparison to young mice. Moreover, we found that aging modulates the proliferative capacity, transcriptional signatures and gene interaction networks of CAFs in the PDAC TME. In particular, aging alters the composition of myofibroblastic CAF populations, while upregulating the expression of CAF inflammatory cytokines. Aging also reduced the abundance of macrophages and upregulated the expression of exhaustion-related genes in T cells. Moreover, we observed that old PSCs better support the proliferation of co-cultured PDAC organoids in growth factor-limiting conditions. This study suggests that aged mouse models of PDAC better recapitulate cachexia-related physiological changes observed in PDAC patients. Moreover, aging modulates aspects of the PDAC TME that are relevant for tumor progression, such as CAF composition and transcriptional signatures. We propose that these novel aged models could help identify new targets to improve the treatment of PDAC patients.
Citation Format: Joaquín Araos Henríquez, Judhell Manansala, Sara Pinto Teles, Muntadher Jihad, Eloise G. Lloyd, Amir Jassim, Richard J. Gilbertson, Giulia Biffi. Aging modulates the tumor microenvironment of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr PR016.