Comparative omics reveals conserved extracellular matrix signatures during mammary tumor progression.

The extracellular matrix (ECM) plays a critical role in tumor progression by modulating cell adhesion, migration, and signaling; however, its contribution to metastatic progression in spontaneous mammary tumors remains poorly understood. Mammary tumors are among the most common neoplasms in female dogs and share histopathological and molecular similarities with human breast cancer, supporting their use as a comparative oncology model. To investigate ECM remodeling during tumor progression, we analyzed normal, non-metastatic, and metastatic canine mammary tissues using histological approaches and label-free quantitative proteomics. Publicly available human breast cancer transcriptomic datasets were interrogated for in silico validation of conserved molecular signatures. Proteomic profiling identified 12 differentially expressed ECM-related proteins: eight were upregulated (COL12A1, COL4A1, COL4A2, SERPINH1, SERPINF1, HTRA1, TNC, PCOLCE) and four were downregulated (MMRN1, ABI3BP, DPT, OGN). The downregulated proteins were further validated in human breast cancer transcriptomes. Collectively, these findings indicate active ECM remodeling during tumor progression, characterized by increased expression of proteins associated with matrix stiffness and invasiveness. This study highlights evolutionarily conserved mechanisms of ECM dysregulation in breast cancer and identifies potential matrix targets for translational research and biomarker development.