RNA‐seq and ATAC‐seq analysis of CD163 (+) macrophage‐induced progestin‐insensitive endometrial cancer cells

BACKGROUND: Progestins are used as fertility‐sparing regimens for young patients with stage 1A endometrioid endometrial cancer (EEC) and atypical endometrial hyperplasia (AEH). CD163(+) macrophages promote estrogen‐dependent EEC development, but whether they induce progestin insensitivity remains unclear. This study aimed to investigate the possible effects of CD163(+) macrophages on progestin response in AEH/EEC patients. METHODS: The number of infiltrating CD163(+) macrophages in progestin‐insensitive and ‐sensitive endometrial lesions was compared. The effects of CD163(+) macrophages on progestin responses and progesterone receptor (PR) expression in EC cells were evaluated in vitro. ATAC‐seq and RNA‐seq were combined to identify molecular/biological changes induced by CD163(+) macrophages in progestin‐insensitive EC cells. RESULTS: Increased CD163(+) macrophage infiltration was significantly associated with progestin insensitivity and longer treatment durations in AEH/EEC patients. Additionally, the number of CD163(+) macrophages was negatively correlated with PR expression in AEH/EEC tissues. Furthermore, the CD163(+) macrophage‐mediated microenvironment and secreted cytokines downregulated PR expression and impaired the response of EC cells to medroxyprogesterone acetate (MPA). RNA‐seq analysis demonstrated that CD163(+) macrophages antagonized PR signaling by blocking or even reversing MPA‐regulated differential gene expression. Based on RNA‐seq and ATAC‐seq analyses, extracellular matrix (ECM) signaling and ECM‐related transcription factors, FOXF2, POU1F1, and RUNX1were identified to potentially be involved in CD163(+) macrophage‐induced progestin insensitivity in endometrial cancer patients. CONCLUSIONS: We identified CD163(+) macrophages as an important mediator of progestin desensitization and an unfavorable factor for the efficacy of fertility‐preserving treatment in AEH/EEC patients.