Abstract 4549: Macrophage-epithelial metabolic crosstalk impairs chemotherapy in pancreatic cancer

Abstract

Pancreatic ductal adenocarcinoma (PDA) remains a leading cause of cancer related death, contrasting a relatively low incidence rate. A principle barrier in PDA treatment is the physiology of the tumors, characterized by a densely fibrotic stroma, rich with immune cell infiltration including macrophages. Macrophages are polarized by environmental cues which dictate their function. In PDA, macrophages within the tumor (tumor associated macrophages, or TAMs) are strongly immunosuppressive, inhibiting both infiltration and activation of cytotoxic T-cells. Additionally, TAMs have been shown to drive resistance to chemotherapy, though the mechanism for which remains unclear. Several pathways have been described by which PDA cells recruit and polarize macrophages into TAMs, and the effects that TAMs have on the tumor microenvironment. These pathways have largely focused on signaling proteins, however, metabolic byproducts also influence the behavior of immune cells within the tumor microenvironment. To explore potential metabolic crosstalk, we have profiled the metabolic factors exchanged between PDA cells and TAMs. Among these, we have found that TAMs release metabolites which can regulate the response of PDA cells to chemotherapy. Importantly, this response is consistent across several murine and patient-derived pancreatic cancer cell lines, and this metabolite release appears to be a general property of anti-inflammatory macrophage metabolism. We further validated these findings in vivo, using a combination of pharmacological and genetic models to modulate myeloid cells within the tumor microenvironment. Taken together, these data suggest that further development of interventions which target either PDA-mediated polarization of TAMs or TAM-mediated inhibition of chemotherapy represent opportunities to improve the efficacy of currently available treatment options. Citation Format: Christopher J. Halbrook, Corbin Pontious, Ilya Kovalenko, Laura Lapienyte, Stephan Dreyer, Yaqing Zhang, Barbara Nelson, Hanna Hong, Daivid Chang, Jennifer P. Morton, Marina Pasca di Magliano, Costas A. Lyssiotis. Macrophage-epithelial metabolic crosstalk impairs chemotherapy in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4549.

Autofluorescence Imaging of 3D Tumor–Macrophage Microscale Cultures Resolves Spatial and Temporal Dynamics of Macrophage Metabolism

“…Next, RAW264.7 macrophages co-cultured in 3D with PyVMT breast cancer displayed changes in redox ratio consistent with metabolic changes from tumor stimulation in previous studies ( Fig 4A&C) (47). Differences in redox ratio and fluorescence lifetime measurements were observed between RAW264.7 macrophages in cytokine-stimulated 2D cultures ( Fig 2B) and tumorstimulated 3D cultures (Fig 4C-E), consistent with reported differences in intracellular metabolite concentration and metabolic flux based on stimulation condition (e.g., cytokines, tumor conditioned media) and culture in 2D vs. 3D (48,49). Additionally, 3D co-cultured RAW264s exhibited heterogeneous cell-level autofluorescence and pooled gene expression ( Fig 4B, F-H).…”

“…Z-scores for each metabolic autofluorescence variable were calculated for passively-and actively-migrating mouse macrophages in co-culture by subtracting the variable mean of the monoculture condition from the variable mean per condition, then dividing by the monoculture standard deviation at each time point (Fig 5F). Multi-class random forest models were generated from all 11 autofluorescence variables to classify passive and active migration in 3D mouse co-cultures across all timepoints (24,48, and 72 hours). High classification accuracy was observed for test data predictions for passive vs. active migration, with an accuracy of at least 85% for all test data predictions ( Fig 5G, Supplementary Fig 3Q).…”

Identification of Prognosis-Related Genes and Construction of Multi-regulatory Networks in Pancreatic Cancer Microenvironment by Bioinformatics Analysis

“…More and more studies have revealed that stroma not only served as a physical barrier to drug delivery and facilitated chemotherapy resistance, but also supported tumor growth and metastasis (39). Although gemcitabine is presently the standard option in the treatment of pancreatic cancer, stromal components including tumor-associated macrophages have been proven essential in delivering gemcitabine resistance in pancreatic cancer cells (40). Thus, investigating the mechanism of tumor microenvironment and identifying stromal components could impel a deeper understanding and contribute to a better prognosis of pancreatic cancer patients in clinical practice.…”

Cancer Models to Defeat Therapy Resistance in Pancreatic Ductal Adenocarcinoma

“…KPC mice treated with GEM combination treatments had prolonged survival compared to control mice, indicating that inhibiting macrophage recruitment has the potential to improve current PDAC therapies, as seen with FOLFIRINOX. 104 Özdemir et al used transgenic (Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox) mice with deleted αSMA+ myofibroblasts in pancreatic cancer. Myofibroblast depleted tumors did not respond to GEM and resulted in multiple adverse outcomes.…”