miR-182 targeting reprograms tumor-associated macrophages and limits breast cancer progression

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Alternatively activated (M2) tumor-associated macrophages (TAMs) promote tumor growth, making macrophage reprogramming a key therapeutic objective.
• Mechanisms driving TAM polarization are not fully understood, and effective macrophage-targeting strategies are needed.

Purpose of the Study:

• To investigate the role of miR-182 in TAM polarization and its potential as a therapeutic target for cancer treatment.
• To elucidate the molecular mechanisms by which cancer cells induce M2 polarization in macrophages.

Main Methods:

• Generated miR-182 knockout mice (constitutive and conditional in macrophages) to assess its role in breast tumor development.
• Utilized macrophage depletion and reconstitution experiments to confirm the role of macrophages in miR-182's effect.
• Investigated the TGFβ signaling pathway and miR-182's direct targets, including TLR4 and NFκb, using molecular assays.
• Developed and tested antagomiR-182 delivered via extracellular vesicles for therapeutic targeting of macrophages in mouse breast cancer models.

Main Results:

• miR-182 knockout in macrophages significantly impaired M2-like TAMs and reduced breast tumor development.
• Cancer cell-derived TGFβ signaling induces miR-182 in macrophages, which suppresses TLR4, inactivates NFκb, and promotes M2 polarization.
• Therapeutic delivery of antagomiR-182 encapsulated in modified extracellular vesicles effectively inhibited miR-182 in TAMs, leading to reprogramming and tumor suppression in vivo.

Conclusions:

• The TGFβ/miR-182/TLR4 axis is a critical pathway regulating TAM polarization towards an M2 phenotype.
• Targeting miR-182 in macrophages represents a promising RNA-based therapeutic strategy for breast cancer treatment.
• Extracellular vesicle-mediated delivery of antagomiR-182 offers an effective approach for TAM-targeted cancer therapy.