MFAP2⁺ CAF reprogramming promotes bladder cancer invasion and an immunosuppressive microenvironment

Abstract Chemotherapy can reshape the bladder cancer stroma, but how tumor cells establish cancer-associated fibroblasts (CAF) states that support metastasis and immune suppression remains unclear. We investigated MFAP2-positive CAF using TCGA-BLCA and GEO cohorts, patient specimens, cell and mouse models, and single-cell and spatial transcriptomic analyses. MFAP2 was enriched in CAF and associated with poor survival in tumors with high CAF infiltration. Functional and biochemical experiments showed that CAF-derived MFAP2 promotes tumor cell migration, invasion, and metastasis through its association with ITGA3 and activation of FAK, JNK, and JUN. We further found that tumor-secreted TIMP1 activates STAT3 through CD63 and ITGB1 in fibroblasts, inducing an MFAP2-positive CAF state. This response was enhanced in some gemcitabine/cisplatin-resistant bladder cancer models, linking chemoresistance to stromal reprogramming. Single-cell communication and spatial analyses linked these CAF to M2-like macrophages and an immunosuppressive microenvironment, with CAF-derived CXCL12 and macrophage CXCR4 contributing to this interaction. Together, these findings support a reciprocal signaling circuit between tumor cells and CAF that promotes metastasis and immune suppression. TIMP1 and integrin/FAK signaling may offer therapeutic targets in TIMP1-high chemoresistant bladder cancer.