Crosstalk between tumor and stroma modifies CLIC4 cargo in extracellular vesicles

Area of Science:

• Oncology
• Cell Biology
• Cancer Metastasis

Background:

• Breast cancer metastasis to the lungs is a significant clinical challenge.
• The formation of a premetastatic niche in the lung is essential for successful metastatic seeding.
• The role of specific host factors in facilitating metastasis is not fully understood.

Purpose of the Study:

• To investigate the role of the oxidoreductase CLIC4 in breast cancer lung metastasis.
• To determine the source and regulation of CLIC4 in circulating extracellular vesicles (EVs).
• To explore the influence of host stroma on EV cargo incorporation.

Main Methods:

• Utilized mouse models of breast cancer with varying CLIC4 expression in hosts and tumor cells.
• Analyzed plasma-derived EVs for CLIC4 content.
• Assessed the development of lung premetastatic niches and metastatic seeding.
• Compared EV cargo in wildtype and CLIC4 knockout host environments.

Main Results:

• Host CLIC4 expression is required for lung metastasis; tumors grow but the premetastatic niche is defective without it.
• Primary breast cancer cells release EVs containing CLIC4, which are found in the plasma of tumor-bearing hosts.
• CLIC4-deficient tumor cells release EVs lacking CLIC4.
• Circulating EVs are devoid of CLIC4 when CLIC4-expressing tumors are grown in CLIC4 knockout hosts, indicating stromal influence.

Conclusions:

• Host CLIC4 is essential for establishing the lung premetastatic niche for breast cancer metastasis.
• Tumor-derived EVs carry CLIC4, but its incorporation is regulated by host stromal signals.
• CLIC4 in circulating EVs may serve as a potential biomarker for breast cancer progression.