A Multicellular Coordinated Network Driving Lymphovascular Space Invasion in Endometrioid Endometrial Carcinoma

ABSTRACT

Lymphovascular space invasion (LVSI) is a critical factor linked to metastasis and poor outcomes in endometrioid endometrial carcinoma (EEC), yet its multicellular mechanisms remain unclear. Using single‐cell RNA sequencing of 3 LVSI‐present (LVSI+) EECs, 2 LVSI‐absent (LVSI−) EECs, and 2 normal endometrial samples, we delineated the cellular ecosystems underlying LVSI. LVSI+ EECs exhibited marked epithelial reprogramming, transitioning from differentiated ciliated epithelium to hyperproliferative and metabolically remodelled phenotypes, and contained TC4, a metastatic epithelial subset characterized by hypoxia, partial epithelial–mesenchymal transition, immunosuppression, and progesterone resistance. We also identified nine key genes in malignant epithelial cells associated with LVSI prognosis. The tumour microenvironment in LVSI+ EECs shifted from an inflammatory state dominated by epithelial cells to a collaborative network involving stromal and immune cells. This network was enriched in immunosuppressive ZNF683 + SOX4 + CD8+ T cells, Cycling_T cells, SPP1 + MMP9 + Mac, WNT5A_mCAF, Tip endothelial cells, and lymphatic endothelial cells. WNT5A_mCAF and SPP1 + MMP9 + Mac synergistically remodelled the extracellular matrix, promoted lymphangiogenesis and angiogenesis, and, together with endothelial cells, suppressed T‐cell activity via LGALS9–HAVCR2/CD44 inhibitory signalling, thereby establishing a niche conducive to vascular invasion. Using spatial multiplex immunofluorescence, we confirmed hypoxic tumour epithelial cells at the invasive front coexisting with an immunosuppressive microenvironment, and revealed spatial colocalization of PD‐L1+ tumour cells, PD‐L1+ macrophages, and PD‐1+ T cells within LVSI thrombi. Our comprehensive study provides deeper insights into LVSI as an actively coordinated multicellular process, potentially improving LVSI risk prediction, supporting treatment decision‐making, and informing new therapies targeting the tumour microenvironment.