Stromal CCL2/CXCL10/SPARC axes drive pro-tumor CHI3L1 expression for microenvironmental modulation in pancreatic cancer progression and therapeutic innovation

BACKGROUND: Chitinase-3-like-protein 1 (CHI3L1), a low-abundance protein in normal tissues, is markedly upregulated in the pancreatic tumor microenvironment (TME), where it promotes fibrosis and immune evasion. Spatial transcriptomics revealed enrichment of CHI3L1 at tumor-stroma interfaces, suggesting that cell-cell interactions regulate CHI3L1 expression. METHODS: We employed 2D and 3D multicellular culture models, incorporating pancreatic cancer cells, macrophages, and pancreatic stellate cells (PSCs), to recapitulate TME-mediated CHI3L1 induction. Mechanistic insights were gained through secretome profiling, chromatin immunoprecipitation (ChIP), and methylation-specific PCR. The therapeutic potential of targeting identified axes was evaluated in an orthotopic pancreatic adenocarcinoma (PDAC) mouse model. RESULTS: We identified CCL2, CXCL10, and SPARC as key secreted mediators during tumor-stroma crosstalk that cooperatively induced CHI3L1 expression in cancer cells via activation of NF-κB and STAT3. Specifically, inflammatory cytokines within the TME recruited macrophages to induce CCL2, which, in concert with PSCs, enhances CXCL10 and SPARC secretion. Mechanistically, NF-κB directly bound the CHI3L1 promoter, while STAT3 reduced DNA methyltransferase 1 levels, leading to promoter hypomethylation and epigenetic activation of CHI3L1. Clinically, high CHI3L1 expression correlated with the upregulated stromal CCL2, CXCL10, and SPARC levels, and the combined four-marker signature was an independent prognostic factor for both overall and disease-free survival in multivariable analysis. In vivo, blockade of the upstream stromal pathways (CCR2/CXCR3/TGFβR1) coupled with CHI3L1 neutralization reduced tumor growth and remodeled the immunosuppressive microenvironment in immunocompetent PDAC models. CONCLUSIONS: Our findings uncover a cooperative multicellular signaling network that orchestrates CHI3L1 expression in cancer via transcriptional and epigenetic reprogramming. Disrupting these upstream stromal pathways concurrently with CHI3L1 neutralization was associated with reduced T-cell exhaustion, offering a promising combinatorial approach for PDAC immunotherapy.