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Updated: Jun 25, 2025
Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes
Published on: May 31, 2018
PGE2 induced miR365/IL-6/STAT3 signaling mediates dendritic cell dysfunction in cancer
Vipul K Pandey1, Kavitha Premkumar1, Priya Kundu1
1Immunology Section, Radiation Biology & Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Mumbai 400 085, India.
Aim:
To understand the mechanism of prostaglandin E2 (PGE2)-mediated immunosuppression in dendritic cells (DCs).
Main Methods:
In vivo experiments were conducted on 4T1 tumor bearing mice (TBM). In vitro experiments were performed in bone marrow-derived DCs (BMDCs), or spleen cells. Cytokines were monitored by ELISA/ELIspot. Gene expression was monitored by RT-PCR/flow cytometry.
Key Findings:
In silico, in vitro, and in vivo experiments in 4T1 TBM revealed that PGE2 induced IL-6/pSTAT3 signaling through EP4 receptors in DCs, resulting in their dysfunction. These effects were reversed by EP4 antibody neutralization, EP4 antagonist, and STAT3 inhibitory peptides. PGE2 induced IL-6 was regulated by miR-365, as its mimic inhibited PGE2 induced IL-6 and the inhibitor increased lL-6 levels in DC. Bio-informatic analysis in human mammary cancers also revealed a strong compared co-relation between PGE2 and IL-6 (Correlation AnalyzeR) (R = 0.94). Mice bearing PTGS-2 KD 4T1 tumors had decreased tumor burden, PGE2, EP4, IL-6, and pSTAT3 signaling, along with improved DCs and T cell functions. Treatment of mice with a cyclooxygenase-2 (COX-2) inhibitor or EP4 antagonist decreased tumor burden, and this effect of EP4 antagonist was abrogated upon in vivo depletion of CD11c cells, indicating the crucial role of PGE2 signaling in DCs in tumor progression.
Significance:
In summary, our data highlights the importance of dendritic cells in mediating PGE2-mediated immunosuppression and the use of EP4 or STAT3 inhibitors or miR365 mimics can restore immunogenicity in cancer.
Insights
Prostaglandin E2 (PGE2) causes immune suppression in dendritic cells (DCs) via IL-6/pSTAT3 signaling. Inhibiting EP4 receptors or STAT3 can restore anti-cancer immunity.
Area of Science:
- Immunology
- Cancer Biology
- Molecular Biology
Background:
- Prostaglandin E2 (PGE2) is a key mediator of immunosuppression in the tumor microenvironment.
- Dendritic cells (DCs) play a critical role in initiating anti-tumor immune responses.
- Understanding the mechanisms of PGE2-mediated DC dysfunction is crucial for developing effective cancer immunotherapies.
Purpose of the Study:
- To elucidate the molecular mechanisms by which PGE2 suppresses dendritic cell (DC) function.
- To investigate the role of EP4 receptors and downstream signaling pathways in PGE2-induced immunosuppression.
- To explore therapeutic strategies targeting the PGE2 pathway to restore anti-tumor immunity.
Main Methods:
- In vivo studies using 4T1 tumor-bearing mice and in vitro experiments with bone marrow-derived DCs (BMDCs).
- Analysis of cytokine production (ELISA/ELIspot) and gene expression (RT-PCR/flow cytometry).
- Bio-informatic analysis of human mammary cancer datasets and manipulation of microRNA (miR-365) expression.
Main Results:
- PGE2 induces IL-6 production and pSTAT3 signaling in DCs via EP4 receptors, leading to immune suppression.
- EP4 receptor blockade, STAT3 inhibition, or miR-365 mimics reversed PGE2-induced immunosuppression.
- Targeting cyclooxygenase-2 (COX-2) or EP4 receptors reduced tumor burden, with EP4 antagonist effects dependent on DCs.
- A strong correlation between PGE2 and IL-6 was observed in human mammary cancers.
Conclusions:
- Dendritic cells are central mediators of PGE2-induced immunosuppression in cancer.
- Inhibitors of EP4 or STAT3, or miR-365 mimics, represent promising therapeutic strategies to enhance anti-tumor immunity.
- Targeting the PGE2 pathway in DCs can effectively reduce tumor progression and restore immune function.
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