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Updated: Sep 11, 2025
Characterization of Immune Cell-derived Extracellular Vesicles and Studying Functional Impact on Cell Environment
Published on: June 2, 2020
eIF4E Enriched Extracellular Vesicles Induce Immunosuppressive Macrophages through HMGCR-Mediated Metabolic Rewiring
Sonam Mittal1, Minal Nenwani2,3, Ishaque Pulikkal Kadamberi1
1Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
Abstract:
Tumor driven immune suppression poses a significant impediment to the success of immunotherapy in ovarian cancer. Among the various mechanisms contributing to immune suppression, intracellular communication facilitated by tumor-derived extracellular vesicles (EVs) within the tumor microenvironment emerges as a pivotal factor influencing tumor growth. Here, it is demonstrated that extracellular vesicle-packaged eIF4E from tumor cells alters protein translation in macrophages, contributing to antitumor immune response. Mechanistically, tumor derived EV-packaged eIF4E significantly enhances the expression of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR), driving the synthesis and secretion of cholesterol. This, in turn, activates macrophages and causes immunosuppression through the X-box binding protein 1 and Programmed death-ligand 1 (XBP1/PD-L1) axis. Strikingly, both genetic and pharmacological depletion of HMGCR in macrophages effectively restores their antitumor activity. Clinically, elevated HMGCR expression in tumor-associated macrophages is associated with poor survival outcomes in ovarian cancer patients. The pivotal role of eIF4E is underscored here as a key signaling mediator, facilitating the communication between tumor and immune cells via EVs to promote immune suppression and suggesting HMGCR as a potential therapeutic target for tumor immunotherapy.
Insights
Tumor extracellular vesicles deliver eIF4E to macrophages, boosting cholesterol via HMGCR. This activates macrophages, suppressing antitumor immunity, but HMGCR inhibition restores immune response in ovarian cancer.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Tumor-induced immune suppression hinders ovarian cancer immunotherapy.
- Tumor-derived extracellular vesicles (EVs) mediate intercellular communication within the tumor microenvironment.
- EVs play a crucial role in regulating immune cell function and tumor progression.
Purpose of the Study:
- To investigate the role of tumor-derived extracellular vesicle (EV)-packaged eIF4E in modulating macrophage function.
- To elucidate the molecular mechanisms by which EVs induce immune suppression in ovarian cancer.
- To identify potential therapeutic targets for enhancing immunotherapy efficacy.
Main Methods:
- Analysis of EV composition and cargo.
- In vitro studies using macrophages and tumor cells.
- Genetic and pharmacological manipulation of HMGCR expression.
- Assessment of protein translation and immune cell activation.
- Clinical correlation studies using patient samples.
Main Results:
- Tumor-derived EVs package and transfer eIF4E to macrophages.
- EV-packaged eIF4E upregulates HMGCR expression in macrophages, increasing cholesterol synthesis.
- Elevated cholesterol promotes macrophage activation and immunosuppression via the XBP1/PD-L1 axis.
- Genetic or pharmacological inhibition of HMGCR restores antitumor macrophage activity.
- High HMGCR expression in tumor-associated macrophages correlates with poor patient survival.
Conclusions:
- Tumor-derived EVs utilize eIF4E to reprogram macrophages, promoting immune suppression through HMGCR-mediated cholesterol synthesis.
- Targeting HMGCR represents a promising therapeutic strategy to overcome immune evasion in ovarian cancer.
- eIF4E acts as a key mediator in tumor-immune cell communication via EVs, driving immunosuppression.
