High expression of formin-2 can promote ovarian cancer chemoresistance via immunosuppressive macrophages.

Ovarian cancer (OC) remains a major threat to women's health, with chemoresistance driven by the immunosuppressive tumor microenvironment. Formin-2 (FMN2), a cytoskeletal regulator, was investigated for its role in OC chemoresistance and macrophage polarization. Bioinformatics analysis identified high FMN2 expression in chemotherapy-resistant OC cell lines, validated experimentally. Stable FMN2 knockdown cell lines were generated via lentiviral transfection. Functional assays revealed that FMN2 overexpression conferred chemoresistance in vitro and in vivo and promoted M2 macrophage polarization via the CCL2/JAK2/STAT3 pathway. Co-culture with M2 macrophages enhanced cisplatin (DDP) resistance in OC cells, mediated by CXCL1 secretion, which activated the epithelial-mesenchymal transition (EMT) pathway. Clinically, FMN2 levels correlated with CCL2 and CD206 (M2 marker) in platinum-resistant patients, and high FMN2, CCL2, or CD206 expression predicted poorer overall and disease-free survival. This study identifies FMN2 as a key mediator of chemoresistance and immune evasion in OC, proposing FMN2-CCL2-CD206 signaling and macrophage-derived CXCL1 as therapeutic targets and prognostic markers for chemotherapy response.