CCL24 recruits CCR3 + TAMs to promote immunosuppression via YAP1 activation and serves as a therapeutic target for Gracillin in colorectal cancer

Background: CC chemokines orchestrate intercellular communication and modulate tumor microenvironment.This study investigates the role of C-C motif chemokine ligand 24 (CCL24) in immune regulation in colorectal cancer (CRC).Methods: CCL24 expression and its clinical relevance in CRC were analyzed via bioinformatics and tissue microarrays.Genetic knockout of CCL24, or antibody-mediated inhibition of CCL24 was performed in AOM/DSS-induced mouse CRC models.CCL24 knockout (CCL24 ko ) CRC cells were co-cultured with macrophages or CD8 + T cells.Mouse MC38 CRC cells with CCL24 ko were implanted into C57BL/6 mice to generate subcutaneous or metastasis models.Molecular docking was conducted to identify potential pharmacological inhibitors of CCL24.Results: CCL24 is abundantly expressed in CRC tissues and linked to T cell dysfunction and unfavorable patient survival.Inhibition or knockout of CCL24 suppressed AOM/DSS-induced colorectal tumorigenesis in mice, reduced the population of tumor-associated macrophages (TAMs), and increased CD8 + T cell numbers.While the morphology of CCL24 ko cells showed minimal changes in vitro, their tumorigenic ability was reduced in immunocompetent but not in immunodeficient mice.CCL24 did not directly alter CD8 + T cell populations; instead, CCL24 + tumor cells recruited CCR3 + TAMs, which promote immunosuppression by promoting nuclear translocation of YAP1, a key transcription factor of the Hippo pathway.Gracillin, a natural compound, was identified as a CCL24 inhibitor and synergized with 5-fluorouracil and programmed cell death 1 monoclonal antibody therapies in allograft-bearing mice.Conclusion: CCL24 facilitates recruitment of CCR3 + TAMs, enhancing the immunosuppressive TME in CRC.Targeting CCL24 with agents like gracillin represents a promising therapeutic strategy.