Deciphering the Cellular and Metabolic Landscape of Lymph Node Metastasis in Breast Cancer Using Single-Cell and Spatial Multi-Omics.

Metastasis is a major threat in breast cancer, often involving lymph node (LN) dissemination. However, the cellular composition and signaling networks within the metastatic microenvironment remain incompletely characterized, resulting in limited understanding of the molecular mechanisms driving LN metastasis. In this study, a comprehensive single-cell atlas of metastatic niches was constructed using single-cell RNA-sequencing data from 78 primary breast tumors and their paired LN metastatic samples. Among the epithelial cell subpopulations, distinct clusters representing early-disseminated cancer cells were identified. Notably, profound metabolic reprogramming and immune modulation was observed during the malignant transformation of epithelial cells, which may contribute to the invasive and metastatic phenotype of early-disseminated cancer cells. Furthermore, the communication network within the metastatic microenvironment has also been delineated systematically, where crosstalk among lymphocyte, macrophage, and epithelial cells drove immunosuppressive features of LN metastasis. To explore potential therapeutic interventions, computational drug repositioning was conducted and four tyrosine kinase receptor inhibitors were identified that may target key interactions within this crosstalk. These results were validated using spatial transcriptomics data of four metastatic LN tissue sections from an integrated single-cell RNA-sequencing cohort. Collectively, this study discussed the cellular architecture and regulatory interplay underlying LN metastasis in breast cancer, offering novel insights that may inform targeted therapeutic strategies for patients with metastatic disease.