Senescent CAFs Mediate Immunosuppression and Drive Breast Cancer Progression

Area of Science:

• Oncology
• Immunology
• Cell Biology

Background:

• The tumor microenvironment (TME) is critical in tumorigenesis, with its gene expression predicting breast cancer outcomes.
• Cancer-associated fibroblast (CAF) subtypes within the TME have unclear roles in tumor development.
• Identifying specific CAF roles is crucial for understanding and targeting breast cancer progression.

Purpose of the Study:

• To identify and characterize a specific subtype of cancer-associated fibroblasts (CAFs) involved in breast tumor progression.
• To elucidate the mechanism by which these fibroblasts promote tumor growth.
• To evaluate the therapeutic potential of targeting these cells in breast cancer.

Main Methods:

• Utilized the MMTV-PyMT;INK-ATTAC (INK) mouse model for breast cancer studies.
• Identified senescent CAFs (senCAFs) in mouse and human breast tumors.
• Assessed the impact of senCAFs on natural killer (NK) cell cytotoxicity and tumor growth.
• Investigated senCAF presence and predictive value in various human breast cancer subtypes (HER2+, ER+, triple-negative breast cancer, DCIS).

Main Results:

• Identified a subset of myofibroblast CAFs (myCAFs) as senescent (senCAFs) in breast tumors.
• Demonstrated that senCAFs secrete extracellular matrix that inhibits NK cell cytotoxicity, promoting tumor growth.
• Showed that eliminating senCAFs restores NK cell activity and restricts tumor growth.
• Confirmed senCAF presence in diverse human breast cancers and ductal carcinoma in situ (DCIS), where they correlate with tumor recurrence.

Conclusions:

• Senescent cancer-associated fibroblasts (senCAFs) actively promote breast cancer progression by impairing NK cell-mediated anti-tumor immunity.
• Targeting senCAFs, potentially through senolytic therapies, represents a promising strategy to restrain breast cancer development and recurrence.