A RIPK3-PGE₂ Circuit Mediates Myeloid-Derived Suppressor Cell-Potentiated Colorectal Carcinogenesis

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Receptor-interacting protein kinase 3 (RIPK3) is crucial for mucosal repair in inflammatory bowel diseases and colorectal cancer.
• The specific role of RIPK3 in tumor immunity within colorectal cancer remains largely unexplored.

Purpose of the Study:

• To investigate the function of RIPK3 in colorectal cancer immunity.
• To elucidate the molecular mechanisms by which RIPK3 influences tumor progression and immune cell activity.

Main Methods:

• Analysis of RIPK3 expression in colorectal cancer tissues and correlation with myeloid-derived suppressor cells (MDSCs).
• Investigation of RIPK3 deficiency effects on tumorigenesis and MDSC function in preclinical models.
• Molecular analyses of NFκB, COX-2, and prostaglandin E2 (PGE2) signaling pathways.
• Assessment of therapeutic interventions targeting COX-2 and PGE2 receptors.

Main Results:

• Decreased RIPK3 in colorectal cancer correlates with increased MDSC accumulation and enhanced immunosuppressive activity.
• RIPK3 deficiency promotes tumorigenesis via an NFκB-driven COX-2/PGE2 axis, which further suppresses anti-tumor immunity.
• PGE2 was found to suppress RIPK3 expression while upregulating NFκB and COX-2.
• Inhibition of COX-2 or PGE2 signaling reversed MDSC immunosuppression and reduced tumor growth.
• Correlations between RIPK3, COX-2 expression, and patient survival were observed in colorectal cancer databases.

Conclusions:

• A novel signaling pathway involving RIPK3, NFκB, COX-2, and PGE2 regulates tumor immunity in colorectal cancer.
• This pathway drives MDSC accumulation and immunosuppression, accelerating tumor growth.
• Targeting the RIPK3-PGE2 axis presents a promising therapeutic strategy for colorectal cancer immunotherapy.