Single-cell RNA-Seq Reveals Transcriptional Landscape and Intra-tumor Heterogenicity in Gallbladder Cancer Liver Metastasis Microenvironment

Abstract Background: Gallbladder cancer (GBC) is a highly aggressive biliary epithelial malignancy. Tumor invasion and metastasis contributed to the high mortality of GBC patients. However, molecular mechanisms involved in GBC metastases are still little known. Methods: We performed single-cell RNA sequencing on GBC liver metastasis tissue and analyzed the data based on different cell types.Results: In this study, 8 cell types, including T cells, B cells, malignant cells, fibroblasts, endothelial cells, macrophages, dendritic cells, and mast cells were identified. Malignant cells displayed a high degree of intra-tumor heterogenicity and neutrophils could promote GBC progression in vitro. Besides, cytotoxic CD8+ T cells became exhausted and CD4+ Tregs presented immunosuppressive characteristics. Macrophages played an important role in the tumor microenvironment. We identified three distinct macrophage subsets and emerged M2 polarization. We also found that cancer-associated fibroblasts exhibited heterogeneity and promoted GBC metastasis. Conclusions: In conclusion, our work provided a landscape view at the single-cell level and may clear the way for the therapy of GBC metastases.