The Ribosomal Protein S19 Suppresses Antitumor Immune Responses via the Complement C5a Receptor 1

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Factors initiating tumor immunosuppression at the tumor-host interface are poorly understood.
• Tumor cells release molecules that modulate the immune microenvironment.
• Myeloid-derived suppressor cells (MDSCs) are key players in tumor-induced immunosuppression.

Purpose of the Study:

• To investigate the novel immunosuppressive properties of ribosomal protein S19 (RPS19) in cancer.
• To elucidate the mechanism by which RPS19 influences tumor-infiltrating immune cells.
• To evaluate the therapeutic potential of targeting RPS19 in preclinical cancer models.

Main Methods:

• Analysis of RPS19 expression in human breast and ovarian cancer cells.
• Investigation of RPS19 interaction with complement C5a receptor 1 (C5aR1) on MDSCs.
• Assessment of RPS19 effects on cytokine production, T cell phenotypes, and immune cell infiltration.
• Evaluation of therapeutic strategies involving RPS19 reduction or C5aR1 blockade in a breast cancer model.

Main Results:

• RPS19 is upregulated in cancer cells and released from apoptotic cells.
• RPS19 binds to C5aR1 on MDSCs, promoting their recruitment to tumors.
• RPS19 induces immunosuppressive cytokines (e.g., TGF-β) and promotes regulatory T cells while reducing CD8+ T cell infiltration.
• Targeting RPS19 or C5aR1 inhibits tumor growth and delays tumor development.

Conclusions:

• RPS19 is a novel mediator of tumor-induced immunosuppression.
• RPS19 promotes tumor growth by modulating the tumor immune microenvironment.
• Targeting RPS19 represents a promising preclinical strategy for enhancing anti-tumor T cell responses and cancer therapy.