Breast cancer cell-derived microRNA-155 suppresses tumor progression via enhancing immune cell recruitment and...

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• MicroRNA-155 (miR-155) expression in immune cells is linked to enhanced antitumor responses.
• The role of miR-155 in cancer is debated, with associations to both tumorigenesis and tumor suppression.
• The specific impact of tumor-derived miR-155 on breast cancer immunity requires further investigation.

Purpose of the Study:

• To investigate the role of tumor miR-155 expression, particularly from cancer cells, in antitumor immunity within breast cancer.
• To determine if miR-155 levels correlate with patient prognosis and immune profiles in breast cancer.
• To explore the potential of miR-155 as a therapeutic target for enhancing immunotherapy.

Main Methods:

• Bioinformatic analysis of human breast cancer databases.
• Murine models of breast cancer with manipulated miR-155 expression.
• Examination of human breast cancer specimens.
• Analysis of serum miR-155 levels in patients.

Main Results:

• Higher tumor miR-155 levels correlated with a favorable antitumor immune profile and improved patient outcomes.
• Overexpression of miR-155 in murine breast cancer cells increased T cell infiltration, slowed tumor growth, and enhanced sensitivity to immune checkpoint blockade (ICB) therapy.
• miR-155 upregulation in cancer cells increased CXCL9/10/11 production via SOCS1 inhibition and altered STAT1/STAT3 phosphorylation.
• Serum miR-155 levels positively correlated with tumor miR-155 levels and immune status in patients.

Conclusions:

• Elevated miR-155 in breast tumors and serum may serve as a favorable prognostic biomarker.
• Therapeutic strategies aimed at increasing miR-155 in breast tumors could potentially enhance the efficacy of ICB therapy by modulating the tumor immune microenvironment.