Small extracellular vesicles promote stiffness-mediated metastasis

Area of Science:

• Biomedical Engineering
• Cancer Biology
• Extracellular Vesicles

Background:

• Tissue stiffness is a critical prognostic factor in breast cancer, linked to metastatic progression.
• Tumor microenvironment mechanics significantly influence cancer cell behavior and disease outcome.

Approach:

• Investigated the impact of physiological matrix stiffness on extracellular vesicle (EV) production and function in breast cancer models.
• Compared EVs from cancer cells cultured on soft (0.5 kPa) versus stiff (25 kPa) matrices, mimicking normal and tumor tissues.
• Utilized in vivo models (mice and zebrafish) and in vitro co-culture systems to assess EV-mediated metastasis and fibroblast activation.

Key Points:

• Stiff tumor tissue yields significantly more EVs than adjacent soft tissue.
• EVs from stiff matrices (stiff EVs) exhibit increased adhesion molecules (e.g., ITGα2β1, CD44) facilitating collagen IV binding.
• Stiff EVs show a 3-fold increase in organ homing ability in mice and promote cancer cell dissemination via chemotaxis in zebrafish.
• Exposure to stiff EVs induces a cancer-associated fibroblast (CAF) phenotype in normal lung fibroblasts.

Conclusions:

• Physiological matrix stiffness dictates EV quantity, protein cargo, and functional properties.
• EVs act as key mediators in stiffness-driven breast cancer metastasis.
• The mechanical microenvironment profoundly influences EV-mediated intercellular communication and cancer progression.