April 02, 2026
A new study published in Nature uncovers a previously unrecognized three-dimensional morphogenetic program that drives metastatic outgrowth in breast cancer. By integrating single-cell RNA sequencing, spatial transcriptomics, and AI-assisted 3D imaging in human tumors, alongside functional validation in mouse models, researchers identified a structural growth pattern essential for the expansion of macrometastases.
The findings show that metastatic tumors activate a gene-expression program termed metastatic trabecular morphogenesis (MTM), which repurposes developmental branching mechanisms to form complex, lattice-like structures composed of epithelial cell cords. Notably, cells exhibiting high MTM activity were already present in primary tumors predisposed to metastasize, whereas tumors lacking this signature remained non-metastatic and displayed more compact growth patterns.
Further molecular analysis identified the transcription factors ETV1, ETV4, and ETV5 as key regulators of this process. These factors were found to be critical for metastatic expansion but not required for initial tumor formation or early dissemination. Additionally, the study highlights fibroblast growth factor (FGF) signaling through its receptor FGFR as a central and potentially targetable pathway sustaining this morphogenetic program.
By linking metastatic progression to a specific 3D developmental process, the study provides new insight into how cancer spreads and grows at distant sites, revealing distinct biological vulnerabilities that could be exploited to design targeted therapies aimed at preventing or limiting lethal metastatic disease.