Extraction of a Stromal Metastatic Gene Signature in Breast Cancer via Spatial Profiling

The identification of molecular characteristics that define metastatic disease is a primary research focus across numerous types of malignancies. Understanding the mechanisms that drive metastatic foci, which diverge significantly from the biology of primary tumors, and identifying new biomarkers specifically associated with metastatic disease, is of critical importance in oncology. Consequently, the characterization of the stroma associated with metastatic foci has been largely unexplored and remains an area requiring significant investigation. We identified a detailed transcriptional profile of the stromal compartment within primary tumors and corresponding metastatic foci using spatially resolved approaches. The identified stromal Met signature may serve as a prognostic biomarker and provide insights into the molecular mechanisms underlying the metastatic potential of the tumor microenvironment. 1x105 4T1 cells were resuspended in PBS and injected in the mammary fat pad of 8-week- old BALB/c mice. After 28 days from the inoculum, mice were sacrificed, and tumors and lungs were collected for histopathologicand spatial transcriptomical analyses. Four micrometer-thick FFPE sections were sliced and mounted on a Visium glass slide before undergoing HE staining.