Single-Cell Transcriptomic Analysis Highlights the Impact of NFKB2-Mediated MIF-CD44 Signaling Axis in Endometrioid Endometrial Cancer

Background: The tumor microenvironment (TME) is a complex network driving endometrioid endometrial cancer (EC) progression. Previous analyses of the EC TME were often limited by a lack of detailed cellular annotations. Integrating single-cell RNA sequencing (scRNA-seq) data offers a comprehensive approach to reconstruct the TME, aiming to uncover novel mechanisms and therapeutic targets. Methods: We integrated public scRNA-seq data from 15 EC and 5 normal endometrium samples. Through detailed cell annotation, we performed comprehensive bioinformatic analyses, including pseudotime trajectories, copy number variation, and cell communication, to investigate mechanisms of EC development. Results: We identified nine cell types and characterized subpopulations of epithelial, macrophage, lymphocyte, and stromal fibroblast cells. The SOX9+LGR5- epithelial subtype showed elevated malignancy and NFKB pathway enrichment. The M2_like2 macrophage subtype played a critical role, engaging in robust MIF-(CD74+CD44) mediated communication with SOX9+LGR5- cells. Experimental validation confirmed MIF co-expression with E-cadherin in EC tissues. Furthermore, the transcription factor NFKB2 was found to mediate MIF's effect on the CD44 receptor in malignant epithelial cells. A pericyte-to-fibroblast transition in stromal cells may also support tumor growth, while an increase in CD8 exhausted/Treg cells and a decrease in cytotoxic CD8 cells suggest potential immune evasion. Conclusion: Our single-cell analysis details the EC TME landscape, revealing robust communication between M2_like2 macrophages and SOX9+LGR5- epithelial cells. We highlight a key mechanism where NFKB2 mediates MIF's pro-tumorigenic effects via the CD44 receptor, offering new insights into EC progression and potential therapeutic targets.