Exosomes Derived from Radioresistant Breast Cancer Cells Promote Therapeutic Resistance in Naïve Recipient Cells

Area of Science:

• Oncology
• Cell Biology
• Cancer Research

Background:

• Radiation resistance is a major obstacle in breast cancer treatment, leading to recurrence and metastasis.
• Exosomes, vesicles carrying active cargo, can transfer biological information between cells.
• The role of exosomes in mediating radiation resistance in breast cancer is not fully understood.

Purpose of the Study:

• To investigate if exosomes secreted by radioresistant (RR) breast cancer cells can transfer the RR phenotype to non-RR cells.
• To explore the potential of exosomes as therapeutic targets for overcoming radiation resistance in breast cancer.

Main Methods:

• Isolation of exosomes from human (MDA-MB-231) and canine (REM134) breast cancer cell lines and their radioresistant counterparts.
• Treatment of non-RR recipient cells with exosomes derived from RR cells.
• Assessment of changes in cell viability, colony formation, chemotherapy/radiotherapy resistance, and tumoursphere formation in recipient cells.

Main Results:

• Exosomes from RR cells increased cell viability and colony formation in naïve recipient cells.
• Treatment with RR exosomes enhanced chemotherapy and radiotherapy resistance in both cancer stem cell and non-cancer stem cell populations.
• RR exosomes significantly increased the tumoursphere-forming ability of recipient cells, indicating enhanced cancer stem cell characteristics.

Conclusions:

• Exosomes secreted by radioresistant breast cancer cells can mediate and disseminate radiation resistance.
• These findings highlight exosomes as potential therapeutic targets for overcoming treatment resistance in breast cancer.
• Canine mammary cancer cell lines serve as valuable translational models for human breast cancer research.