The MicroRNA miR-223 Constrains Colitis-associated Tumorigenesis by Limiting Myeloid Cell Infiltration and Chemokine...

Area of Science:

• Immunology
• Gastroenterology
• Molecular Biology

Background:

• Aberrant intestinal inflammation is key in colitis-associated colorectal cancer (CAC) development.
• Mechanisms of myeloid immune cell involvement in CAC and the role of microRNAs are not fully understood.

Purpose of the Study:

• To investigate the role of microRNA-223 (miR-223) in myeloid-driven inflammation and CAC development.
• To elucidate how myeloid-specific microRNAs influence the inflammatory process from ulcerative colitis to tumorigenesis.

Main Methods:

• Utilized the azoxymethane (AOM)-dextran sodium sulfate (DSS) mouse model for CAC.
• Performed immunoprofiling, bone marrow chimera studies, and RNA sequencing.
• Investigated the effect of neutrophil depletion using anti-GR1 antibody.

Main Results:

• miR-223 knockout mice exhibited significantly larger tumors with increased proliferation and myeloid immune cell infiltration (neutrophils, monocytes, macrophages).
• Myeloid-expressed miR-223 was responsible for enhanced tumor proliferation and inflammation.
• Identified IL-6/IL-17a and STAT3 signaling pathways as contributors to CAC in miR-223 knockout mice.
• Neutrophil depletion reduced tumor burden in miR-223 knockout mice.

Conclusions:

• miR-223 is a critical regulator of mucosal inflammation, limiting myeloid-associated inflammation.
• miR-223 constrains the progression from ulcerative colitis to CAC.
• Targeting myeloid-specific microRNAs like miR-223 may offer therapeutic strategies for CAC.