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Arginase-1+ Exosomes from Reprogrammed Macrophages Promote Glioblastoma Progression
Juliana H Azambuja1,2,3, Nils Ludwig1,2, Saigopalakrishna S Yerneni4
1Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
Abstract:
Interactions between tumor cells and tumor-associated macrophages (TAMs) are critical for glioblastoma progression. The TAMs represent up to 30% of the glioblastoma mass. The role of TAMs in tumor progression and in the mechanisms underlying tumor growth remain unclear. Using an in vitro model resembling the crosstalk between macrophages and glioblastoma cells, we show that glioblastoma-derived exosomes (GBex) reprogram M1 (mediate pro-inflammatory function) and M2 (mediate anti-inflammatory function) macrophages, converting M1 into TAMs and augmenting pro-tumor functions of M2 macrophages. In turn, these GBex-reprogrammed TAMs, produce exosomes decorated by immunosuppressive and tumor-growth promoting proteins. TAM-derived exosomes disseminate these proteins in the tumor microenvironment (TME) promoting tumor cell migration and proliferation. Mechanisms underlying the promotion of glioblastoma growth involved Arginase-1+ exosomes produced by the reprogrammed TAMs. A selective Arginase-1 inhibitor, nor-NOHA reversed growth-promoting effects of Arginase-1 carried by TAM-derived exosomes. The data suggest that GBex-reprogrammed Arginase-1+ TAMs emerge as a major source of exosomes promoting tumor growth and as a potential therapeutic target in glioblastoma.
Insights
Glioblastoma exosomes reprogram macrophages into tumor-promoting cells. These reprogrammed cells release exosomes that enhance glioblastoma growth, suggesting a new therapeutic target involving Arginase-1.
Area of Science:
- Oncology
- Immunology
- Cell Biology
Background:
- Tumor-associated macrophages (TAMs) are key players in glioblastoma (GBM) progression, constituting a significant portion of the tumor mass.
- The precise roles of TAMs in GBM growth and progression are not fully understood.
- Glioblastoma-derived exosomes (GBex) are increasingly recognized for their role in intercellular communication within the tumor microenvironment.
Purpose of the Study:
- To investigate how glioblastoma-derived exosomes (GBex) influence macrophage polarization and function.
- To elucidate the mechanisms by which TAMs contribute to glioblastoma growth and proliferation.
- To identify potential therapeutic targets for glioblastoma based on exosome-macrophage interactions.
Main Methods:
- Utilized an in vitro co-culture model to mimic the interaction between glioblastoma cells and macrophages.
- Analyzed the reprogramming of M1 and M2 macrophages by GBex.
- Characterized the protein content of exosomes derived from reprogrammed TAMs.
- Assessed the impact of TAM-derived exosomes on glioblastoma cell migration and proliferation.
- Investigated the role of Arginase-1 in mediating the pro-tumor effects of TAM-derived exosomes using a specific inhibitor (nor-NOHA).
Main Results:
- Glioblastoma-derived exosomes (GBex) reprogram both M1 and M2 macrophages, generating pro-tumorigenic TAMs.
- Reprogrammed TAMs release exosomes containing immunosuppressive and growth-promoting proteins.
- TAM-derived exosomes enhance glioblastoma cell migration and proliferation.
- Arginase-1+ exosomes produced by reprogrammed TAMs are critical for promoting glioblastoma growth.
- Inhibition of Arginase-1 with nor-NOHA reversed the growth-promoting effects of TAM-derived exosomes.
Conclusions:
- Glioblastoma-derived exosomes reprogram macrophages, creating a pro-tumorigenic environment.
- Arginase-1+ TAM-derived exosomes are a significant factor in glioblastoma progression.
- Targeting Arginase-1+ TAM-derived exosomes represents a promising therapeutic strategy for glioblastoma.
