Unlocking ESCC Progression: CCL15-CCR1 Axis Activates AKT/ERK1/2/c-Jun/CDK2 Pathway

Globally recognized as a major oncological concern, esophageal squamous cell carcinoma (ESCC) exhibits a high incidence rate among malignancies originating from the digestive system's epithelial lining. Tumor cells can secrete chemokine (C-C motif) ligand 15 (CCL15) to recruit C-C motif chemokine receptor 1 (CCR1)-positive macrophages, thereby facilitating immune evasion and promoting tumor progression. However, it remains unclear whether CCL15 secreted by tumor cells can also act directly on CCR1 expressed on the same tumor cells to exert tumor-regulatory effects. Here, we discovered that both CCL15 and CCR1 are significantly overexpressed in tumor tissues of patients diagnosed with ESCC. Moreover, baseline expression levels of CCR1 and CCL15 in ESCC cell lines EC109, TE-1, and KYSE150 were markedly higher than those in the normal esophageal epithelial line HET-1A. <i>In vitro</i> experiments demonstrated that recombinant human CCL15 (rhCCL15) significantly enhanced proliferation, migration, and invasion of EC109 and TE-1. While knockdown of CCL15 or CCR1 using lentiviral approaches markedly inhibited the proliferation and migration. Notably, CCR1 knockdown reversed the tumor-promoting effects of rhCCL15 on ESCC cells. Subsequent immunofluorescence co-localization and co-immunoprecipitation confirmed a direct interaction between CCR1 and CCL15. Mechanistically, PCR array analysis identified cyclin dependent kinase 2 (CDK2) as a downstream effecter of CCL15-CCR1 axis. Furthermore, through transcription factor prediction, protein-protein interaction (PPI) database analysis, and ChIP-qPCR assays, we demonstrated that CDK2 transcription is activated <i>via</i> CCL15-CCR1-mediated phosphorylation of c-Jun through the AKT/ERK1/2 pathway. In addition, we conducted a drug screening targeting CCR1 and identified Jervine as a potential CCR1 degrader. In summary, this study uncovers the relationship between CCL15-CCR1 axis and ESCC progression and provides insights into potential therapeutic strategies targeting this pathway.