Cross-species ALP-associated gene signature from canine osteosarcoma stratifies metastatic status in human osteosarcoma: A comparative oncology approach.

Osteosarcoma (OSA) is an aggressive primary bone tumor of humans and dogs, with metastatic progression remaining the major determinant of poor outcome. Although serum alkaline phosphatase (ALP) has been investigated as a prognostic marker in OSA, its clinical value remains inconsistent across studies. We examined whether ALP-associated transcriptional programs in canine OSA could capture conserved tumor biology relevant to metastatic behavior in human OSA. Differential expression analysis of a canine OSA RNA-seq cohort, followed by repeated LASSO and Boruta feature selection, identified an 11-gene ALP-associated signature. This signature was mapped to human orthologs and evaluated in two independent human OSA transcriptomic cohorts for metastatic-status classification. Candidate genes were further assessed through structured literature review and dog-human orthology analysis. Across human validation datasets, the canine-derived signature showed moderate but reproducible discrimination of metastatic status, with AUC values of approximately 0.70-0.78 depending on cohort and classifier. Several candidate genes, including KEAP1, CCN3, NACC1, and TNFRSF6B, were linked to metastatic processes such as oxidative-stress response, extracellular matrix remodeling, stemness, immune evasion, and survival under stress. Additional survival analysis in the canine GSE238110 cohort showed that ALP status alone was not a statistically significant prognostic marker, although elevated ALP showed a weak trend toward poorer overall survival. These findings suggest that the signature represents an ALP-associated molecular phenotype rather than a direct serum-ALP prognostic surrogate. This study supports comparative oncology as a discovery framework for prioritizing conserved metastasis-related biomarkers requiring further validation.