MicroRNA-146a limits tumorigenic inflammation in colorectal cancer

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Chronic inflammation is a key driver of tumor development.
• Interleukin-17 (IL-17) signaling pathways are implicated in colorectal cancer (CRC) pathogenesis.
• MicroRNAs (miRNAs) are critical regulators of cellular processes, including inflammation and cancer.

Purpose of the Study:

• To investigate the role of microRNA-146a (miR-146a) in regulating colonic inflammation and associated tumorigenesis.
• To identify the molecular targets and mechanisms through which miR-146a exerts its effects on IL-17 signaling in colorectal cancer.
• To evaluate the therapeutic potential of modulating miR-146a or its targets in preclinical models of CRC.

Main Methods:

• Utilized miR-146a-deficient mouse models to study colitis-associated and sporadic colorectal cancer.
• Investigated the effects of myeloid-specific and intestinal epithelial cell (IEC)-specific miR-146a deletion on CRC development.
• Analyzed the targeting of RIPK2, TRAF6, and PTGES2 by miR-146a in myeloid cells and IECs.
• Assessed the therapeutic efficacy of miR-146a mimics and small molecule inhibitors of miR-146a targets in preclinical settings.

Main Results:

• MiR-146a-deficient mice exhibited increased susceptibility to colorectal cancer due to enhanced IL-17 signaling.
• MiR-146a deficiency in myeloid cells promoted CRC by increasing IL-17-inducing cytokines.
• MiR-146a deficiency in IECs promoted CRC by enhancing IL-17 responsiveness and targeting PTGES2.
• Preclinical administration of miR-146a mimics or inhibitors of its targets (TRAF6, RIPK2) ameliorated colonic inflammation and CRC.

Conclusions:

• MiR-146a acts as a crucial negative regulator of colonic inflammation and colorectal cancer by modulating IL-17 responses.
• Targeting miR-146a or its downstream effectors (RIPK2, TRAF6, PTGES2) represents a promising therapeutic strategy for CRC.