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.