Foxp3 + Tregs Promote M2 Macrophage Polarization via Sirt1-ERK1/2- STAT3 Pathway in Ovarian Cancer Progression

Introduction: Epithelial Ovarian Cancer (EOC) is a highly aggressive gynecological malignancy with a high mortality rate primarily due to late-stage diagnosis and metastatic dissemination. Regulatory T cells (Tregs) have emerged as critical mediators of immune evasion, yet the role of Foxp3⁺ Tregs in modulating Tumor-Associated Macrophage (TAM) polarization and the underlying molecular mechanisms in EOC remains unclear. Methods: An orthotopic EOC mouse model and in vitro co-culture systems were employed to investigate the effects of Foxp3⁺ Tregs on TAM polarization. Quantitative Real-Time PCR (qRTPCR), flow cytometry, Western blotting, wound healing, and transwell assays were performed to assess gene expression, immune cell infiltration, and tumor cell migration/invasion. Foxp3 knockdown was achieved using Adeno-Associated Virus (AAV)-mediated delivery to evaluate its effects in vivo. Results: Foxp3⁺ Tregs induced macrophage polarization toward the M2 phenotype, characterized by downregulation of M1 markers (IL-1β, iNOS) and upregulation of M2 markers (IL-10, Arg-1). Mechanistically, Foxp3⁺ Tregs activated the Sirt1-ERK1/2-STAT3 signaling pathway while suppressing NF-κB activity. In vitro, Foxp3⁺ Tregs enhanced the migratory and invasive capacities of ovarian cancer cells, whereas in vivo Foxp3 knockdown significantly reduced tumor growth and M2 macrophage infiltration. Discussion: These findings suggest that Foxp3⁺ Tregs play a pivotal role in shaping the immunosuppressive tumor microenvironment in EOC by promoting M2 macrophage polarization through Sirt1-ERK1/2-STAT3 signaling and NF-κB suppression, ultimately facilitating tumor progression. Conclusion: Foxp3⁺ Tregs drive immunosuppressive macrophage polarization and ovarian cancer progression, highlighting Foxp3 as a potential therapeutic target for EOC treatment.