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Antagonizing Integrin β3 Increases Immunosuppression in Cancer.
Xinming Su1, Alison K Esser1, Sarah R Amend1
1Department of Medicine, Division of Oncology, Washington University School of Medicine, St. Louis, Missouri.
Cancer Research
|May 25, 2016
Summary
Integrin β3 antagonists may worsen cancer by promoting M2 macrophages and reducing CD8(+) T cells. Targeting integrin β3 in immune cells could improve cancer therapy outcomes.
Area of Science:
- Immunology
- Oncology
- Cell Biology
Background:
- Integrin β3 is a target for cancer therapy due to its role in tumor invasion, angiogenesis, and inflammation.
- Previous studies on integrin β3 antagonists have yielded disappointing or negative clinical results.
Purpose of the Study:
- To investigate the role of integrin β3 in tumor immunity.
- To determine the impact of integrin β3 deletion in macrophages on cancer progression.
- To evaluate the effects of integrin β3 antagonism on the tumor immune microenvironment.
Main Methods:
- Generated mice with integrin β3 deleted in macrophage lineage cells (β3KOM).
- Assessed tumor growth, immune cell infiltration (M2 macrophages, CD8(+) T cells), and signaling pathways (STAT1, STAT6) in mouse models.
- Administered integrin β3 antagonist cilengitide to evaluate its effects on tumor growth and immunity.
Main Results:
- β3KOM mice exhibited increased melanoma and breast cancer growth, characterized by more M2 macrophages and fewer CD8(+) T cells.
- Cilengitide treatment also enhanced tumor growth and M2 macrophage function.
- Integrin β3 signaling was found to promote M1 polarization (via STAT1) and suppress M2 polarization (via STAT6) in M2 myeloid cells.
- Disrupting CD8(+) T cells, macrophages, or macrophage integrin β3 signaling counteracted the tumor-promoting effects of integrin β3 antagonism.
Conclusions:
- Integrin β3 plays a crucial role in regulating the tumor immune microenvironment.
- Integrin β3 antagonism can promote tumor growth by altering macrophage polarization and T cell responses.
- Considering the impact of integrin β3 therapies on immune cells is essential for improving cancer treatment outcomes.
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