Pancreatic cancer cells render tumor-associated macrophages metabolically reprogrammed by a GARP and DNA methylation-mediated mechanism

Mengwen Zhang,Anqi Li,Qian Xiao,Xu Che,Xingyi Pan,Kenji Fujiwara,Noelle Jurcak,Stephen Muth,Jiaojiao Zhou,Lei Zheng,Zihai Li

doi:10.1038/s41392-021-00769-z

Abstract

How tumor-associated macrophages transit from a predominant antitumor M1-like phenotype to a protumoral M2-like phenotype during the development of pancreatic ductal adenocarcinoma (PDA) remains to be elucidated. We thus conducted a study by employing a PDA-macrophage co-culture system, an “orthotopic” PDA syngeneic mouse model, and human PDA specimens, together with macrophages derived from GARP knockout mice and multiple analytic tools including whole-genome RNA sequencing, DNA methylation arrays, multiplex immunohistochemistry, metabolism measurement, and invasion/metastasis assessment. Our study showed that PDA tumor cells, through direct cell–cell contact, induce DNA methylation and downregulation of a panel of glucose metabolism and OXPHOS genes selectively in M1-like macrophages, leading to a suppressed glucose metabolic status in M1-like but not in M2-like macrophages. Following the interaction with PDA tumor cells, M1-like macrophages are reprogrammed phenotypically to M2-like macrophages. The interaction between M1-like macrophages and PDA cells is mediated by GARP and integrin αV/β8, respectively. Blocking either GARP or integrin would suppress tumor-induced DNA methylation in Nqo-1 gene and the reprogramming of M1-like macrophages. Glucose-response genes such as Il-10 are subsequently activated in tumor-educated M1-like macrophages. Partly through Il-10 and its receptor Il-10R on tumor cells, M1-like macrophages functionally acquire a pro-cancerous capability. Both exogenous M1-like and M2-like macrophages promote metastasis in a mouse model of PDA while such a role of M1-like macrophages is dependent on DNA methylation. Our results suggest that PDA cells are able to reprogram M1-like macrophages metabolically and functionally through a GARP-dependent and DNA methylation-mediated mechanism to adopt a pro-cancerous fate.

Highlights

Pancreatic ductal adenocarcinoma (PDA) is one of the most stroma-rich cancers
PDA tumor cells induce DNA methylation of the NQO-1 and ALDH1a3 genes in macrophages When we were studying the interaction between the neoplastic cells and stromal fibroblasts in the PDAs, we found that neoplastic cells can induce DNA methylation at a whole-genome level in cancer-associated fibroblasts (CAFs).[5]
Quantitative RT-PCR confirmed that all the key genes in the glucose metabolism and oxidative phosphorylation (OXPHOS) pathways were downregulated in mouse Bone marrow-derived macrophages (BMDMs) after co-culturing with mouse PDA cells (Fig. 1d)

Summary

Introduction

Pancreatic ductal adenocarcinoma (PDA) is one of the most stroma-rich cancers. Accumulated evidence suggests that the stroma in the tumor microenvironment (TME) plays a critical role in PDA progression and distant metastasis.[1,2] The stroma is composed of fibroblast cells, immune cells, extracellular matrix, and many others. The naive stroma elements of the pancreas appear to be tumor suppressive as genetically depleting stroma elements promote the development and metastasis of PDA in the mouse model.[3,4] cancer-associated fibroblasts (CAFs) in the tumor-reprogrammed stroma of PDA acquire pro-cancerous capabilities.[5] Macrophages form another major stromal component of PDA. Bone marrow-derived macrophages (BMDMs), which give rise to the recruited macrophages in the tissue compartments including neoplasms, are polarized to distinct phenotypic and functional subsets including M1 macrophages and several types of M2 macrophages in response to various activation stimuli.[6]

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Results

Conclusion