A recent integrative analysis of single-cell sequencing and single-cell spatial mapping of lymph node metastasis in breast cancer reveals novel mechanisms of the metabolic-immune interaction that drive the spread of breast cancer. The findings from the study in The American Journal of Pathology, published by Elsevier, offer novel insights into the characteristics of the metastatic tumor microenvironment, providing a foundation for targeted therapeutic strategies.

Breast cancer remains the second most frequently diagnosed cancer globally and accounts for approximately 23.8% of cancer cases among women. It is a leading threat to women’s health, with lymph node metastasis a critical factor contributing to poor patient prognosis. Yet our understanding of the molecular mechanisms driving lymph node metastasis has been limited.

A collaborative team of researchers has now constructed the comprehensive “cell-metabolism-immunity” landscape of the breast cancer lymph node metastatic microenvironment by integrating single-cell RNA sequencing and spatial transcriptomics. This advanced tool precisely maps the activity of thousands of genes in their original locations. Researchers analyzed single-cell data from 78 paired primary breast cancer and lymph node metastasis samples, encompassing over 360,000 cells. Ten major cell types were identified, including epithelial cells, immune cells, and stromal cells.

“By combining advanced genetic sequencing and spatial mapping, we have gained unprecedented insights into the dynamic changes and cellular communication patterns within the metastatic microenvironment,” explains lead investigator Li Guo, PhD, State Key Laboratory of Flexible Electronics (LoFE) & Institute of Advanced Materials (IAM), School of Chemistry and Life Sciences, Nanjing University of Posts and Telecommunications, Nanjing, China.

Key drivers of metastasis: Early disseminated cancer cells (EDCs)

High-resolution clustering revealed a unique subpopulation of early disseminated cancer cells (EDCs) within epithelial cells. These EDCs exhibit enhanced invasive and metastatic capabilities through metabolic reprogramming (e.g., hypoxia response and glycolysis activation) and immune modulation, thereby establishing a microenvironment that facilitates tumor cell survival and suppresses immune function to accelerate metastasis.

Cellular communication network analysis uncovered a sophisticated three-way interaction between lymphocytes, macrophages, and epithelial cells in the metastatic microenvironment. Specifically, M2-type macrophages secrete cytokines like CCL22 and CXCL12, inducing an immunosuppressive microenvironment while driving malignant transformation of EDCs. Spatial transcriptomics validated that these interactions form distinct spatial regions in lymph node tissues, overlapping with the tumor invasion front.

“This systemic interaction between cancer cells, metabolism, and immunity is the core mechanism of lymph node metastasis and a potential therapeutic target,“ says co-lead investigator Tingming Liang, PhD, School of Life Science, Nanjing Normal University, Nanjing, China.

Novel strategies for precision therapy

The researchers identified four tyrosine kinase inhibitors targeting M2 macrophages, including pexidartinib hydrochloride and sunitinib malate. These drugs block immunosuppressive macrophage function by inhibiting key targets like CSF1R, thereby suppressing lymph node metastasis.

“These drugs have demonstrated safety in treating other cancers, and our findings provide a theoretical basis for their application in breast cancer metastasis,” notes Dr. Guo. “Future work will need to explore the metabolic vulnerabilities of EDCs and integrate clinical data to advance the development of innovative therapeutic strategies for patients.”

Source – Elsevier