IFIT1+ Tumor-Associated Macrophages Suppress Cancer Stemness and Enhance Chemosensitivity via the TNFSF10-TNFRSF10B Axis in Epithelial Ovarian Cancer.
BACKGROUND Epithelial ovarian cancer (EOC) is typically diagnosed at an advanced stage and is associated with high mortality due to metastasis and chemoresistance. Cancer stem cells (CSCs) are central to EOC progression, recurrence, and treatment resistance, with their functional behavior shaped by the tumor immune microenvironment. While M1 and M2 macrophages have been well-characterized, the role of interferon-stimulated gene-enriched subpopulations, particularly interferon-induced protein with tetratricopeptide repeats 1 tumor-associated macrophages (IFIT1+ TAMs), in regulating CSC properties in EOC remains largely unexplored. METHODS Single-cell RNA sequencing (scRNA-seq) was utilized to map the myeloid landscape and trace transcriptomic evolution in EOC. An in vitro indirect culture model utilizing unpolarized macrophage (M0)-conditioned medium (CM) was established to assess baseline phenotypic alterations. Furthermore, targeted siRNA silencing (si-TNFRSF10B) combined with recombinant human tumor necrosis factor ligand superfamily member 10 (TNFSF10) (rhTRAIL) treatments were employed to evaluate the specific impact of the TNF-related apoptosis-inducing ligand (TRAIL)-Death receptor 5 (DR5) signaling axis on multidrug resistance and CD44 expression. RESULTS High-resolution scRNA-seq analysis revealed a stage-dependent decline in IFIT1+ TAMs, an interferon-primed subset that robustly expresses the TNFSF10 ligand during early-stage disease. In vitro assays showed that conditioned medium from M0 macrophages suppresses CSC features and enhances expression of the tumor necrosis factor receptor superfamily member 10B (Death receptor 5) (TNFRSF10B/DR5) in EOC cells. Mechanistic studies confirmed that exogenous rhTRAIL treatment markedly diminished CD44+ cell populations and enhanced sensitivity to chemotherapeutic agents. Notably, these antitumor effects were largely abrogated following siRNA-mediated silencing of the DR5 receptor in EOC cell lines. CONCLUSIONS Our findings reveal that IFIT1+ tumor-associated macrophages intrinsically harbor anti-cancer stem cell potential through the TNFSF10 ligand. Activation of the TNFSF10-TNFRSF10B pathway suppresses cancer stemness and may enhance chemosensitivity. These insights shed light on the functional diversity of macrophages, highlighting that driving tumor-associated macrophages toward a sustained, interferon-primed IFIT1+ phenotype represents a promising therapeutic approach to target cancer stem cell populations in epithelial ovarian cancer.