CCL17 Promotes Colitis-Associated Tumorigenesis Dependent on the Microbiota

Area of Science:

• Immunology
• Oncology
• Microbiome research

Background:

• Colorectal cancer (CRC) is a significant cause of cancer mortality.
• Immune responses critically influence colitis-associated colon cancer (CAC).
• CCL17 (chemokine C-C motif ligand 17) is involved in inflammatory and immune responses.

Purpose of the Study:

• To investigate the role of CCL17 in the development of colitis-associated colon tumors.
• To analyze CCL17 expression patterns in the context of CAC.
• To understand the functional relevance of CCL17 in CAC progression.

Main Methods:

• Utilized CCL17-enhanced GFP-knockin mice for expression analysis.
• Induced colon tumors using azoxymethane and dextran sodium sulfate.
• Compared tumor development in CCL17-deficient and competent mice.
• Analyzed microbiota composition and susceptibility to apoptosis.

Main Results:

• CCL17 was upregulated in immune cells within colon tumors.
• CCL17-deficient mice exhibited fewer tumors compared to controls, despite similar inflammation.
• The protective effect in CCL17-deficient mice was microbiota-dependent.
• CCL17 deficiency altered microbiota and increased susceptibility to early apoptosis, impacting tumor initiation.

Conclusions:

• CCL17 promotes colitis-associated tumorigenesis.
• CCL17 influences intestinal microbiome composition.
• CCL17 reduces early apoptosis, thereby affecting tumor initiation in the colon.