Vascular SMC-like CAF-derived THBS1 drives tumor-associated neutrophil recruitment to orchestrate an immunosuppressive microenvironment in gastric cancer.

The immunosuppressive tumor microenvironment (TME) remains a primary barrier to effective immunotherapy. Tumor-associated neutrophils (TANs) are key contributors to this immunosuppressive landscape; however, the mechanisms governing their recruitment and infiltration into tumor tissues remain poorly understood. In this study, we unravel a pro-tumorigenic role of thrombospondin-1 (THBS1) in gastric cancer (GC) mediated by TAN recruitment. By integrating single-cell RNA sequencing with immunohistochemical analyses, we demonstrated that THBS1 is predominantly expressed in vascular smooth muscle cell (VSMC)-like cancer-associated fibroblast (CAF), with lower expression observed in malignant epithelial cells. Notably, THBS1-expressing CAFs are significantly expanded in GC tissues. Accordingly, THBS1 is upregulated in GC, and its overexpression is clinically associated with malignant progression and poor prognosis. Genetic depletion of THBS1 in CAFs markedly suppressed GC progression both in vitro and in vivo. Furthermore, deconvolution analysis, patient-derived xenograft (PDX) models, and multiplex immunofluorescence (mIHC) revealed a pronounced spatial co-localization between THBS1-positive CAFs and TANs within GC tissues. TAN infiltration was significantly elevated in GC and positively correlated with THBS1 expression levels and adverse survival outcomes. Critically, neutralizing THBS1 with monoclonal antibodies or specifically knocking down THBS1 in CAFs dramatically reduced TAN infiltration in both PDX and nude mouse xenograft models. Mechanistically, THBS1 knockdown in CAFs impaired the autocrine production and secretion of key neutrophil-attracting chemokines, including CXCL1, CXCL5, and CXCL6. In summary, our findings underscore the significance of SMC-like CAF-derived THBS1 as a critical molecular mediator in the dynamic interplay between CAFs and TANs, ultimately driving GC progression.