RAW 264.7 Macrophage Polarization by Pancreatic Cancer Cells – A Model for Studying Tumour-promoting Macrophages

Abstract

Background/Aim: Tumour-associated macrophages (TAMs) are highjacked M2-polarized macrophages that especially promote pancreatic cancer growth. The aim of this study was to identify an easy-to-use cell culture model suitable for studying this interaction and macrophage polarization. Materials and Methods: Co-cultures of two cell lines, PDA6606 cells with RAW macrophages cells were used in vitro and in ovo. Macrophages were analyzed by microscopy, magnetic resonance imaging (MRI), and flow cytometry. Results: By comparing chemically-induced M1 and M2 macrophages, a clear induction of the M2 phenotype of RAW macrophages by PDA6606 pancreatic cancer cells was observed in vitro. In ovo, PDA6606 cells and conditioned media polarized macrophages to the M2 phenotype, which in turn promoted tumour growth and angiogenesis via their surface marker profiles and VEGF production. Conclusion: PDA6606 pancreatic cancer cells expectantly and potently induced M2 polarization of RAW264.7 macrophages. This model may be used to study pancreatic cancer-macrophage plasticity in e.g. drug research in vitro and in ovo.

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).…”

“…One limitation in our studies is the use of macrophage cell lines rather than primary macrophages. These macrophage cell lines (RAW264.7 and THP-1) were previously characterized under conditions similar to those tested in this study (11,43,47), so these cell lines were chosen to provide a validated model for autofluorescence imaging in 3D Stacks. However, RAW264.7 and THP-1 lines originated from monocytic leukemias, which introduce phenotypic and functional differences related to the origin site and malignant background compared to primary macrophages derived from peripheral blood or bone marrow (63,64).…”

Modifying the Tumour Microenvironment: Challenges and Future Perspectives for Anticancer Plasma Treatments

“…Macrophages are specialized cells able to present antigens to activate T cells and secrete cytokines to activate other cells. Tumour progression and TME modifications favour the differentiation of tumour-associated macrophages (TAM) toward a pro-tumourigenic phenotype (M2-like polarization) which secrete anti-inflammatory cytokines, in contrast to the proinflammatory (M1-like polarization) phenotype that contribute to the elimination of cancer cells [129,130]. TAMs are recruited to the tumour site by CCL2, CCL5, VEGF, and CSF1 and participate in a variety of pro-tumourigenic processes, such as angiogenesis (VEGF), cell proliferation (EGF) and epithelial-mesenchymal transition, tumour metastasis, immunosuppression (IL-10 and TGF-β), ECM remodelling (MMPs), and reduction of anticancer therapies efficacy [122].…”

Graphene-Modified CePO4 Nanorods Effectively Treat Breast Cancer-Induced Bone Metastases and Regulate Macrophage Polarization to Improve Osteo-Inductive Ability

“…In vitro, M2 macrophages directly regulate osteogenic differentiation of bone marrow mesenchymal stem cells (30,31). The mechanism may be due to proregenerative cytokines produced by M2 macrophages, such as TGF-β, VEGF, Ang-1 and IFG-1 (32).…”