Single-cell analysis reveals CD34(+)CD90(+) endothelial cells promote tumor metastasis in gallbladder cancer.

Gallbladder cancer (GBC) is the most common malignancy of the biliary tract, with high metastasis incidence and extremely low survival rate. The tumor endothelial cells (TECs) are fundamental components in the tumor microenvironment and significantly contribute to various tumor progression; however, the roles of TECs in GBC are poorly understood. Here, using single-cell RNA sequencing, we identify a GBC-enriched endothelial population-CD34(+)CD90(+) ECs (SAEndo2). The CD34(+)CD90(+) endothelial subset correlates with patients' poor prognosis and liver metastasis. In vitro and in vivo experiments suggest that CD34(+)CD90(+) ECs promote the GBC cell migration and metastasis, showing EndoMT properties. Moreover, CD34(+)CD90(+) ECs display enhanced activation of TGF-β signaling, and TGF-β inhibition abolishes the CD34(+)CD90(+) ECs' promotion effect on GBC cell migration. Collectively, our study provides a detailed profiling of endothelial cells in GBC and identifies an essential endothelial population that regulates GBC metastasis, laying new theoretical insight and offering a potential therapeutic target for GBC metastasis.