Osteosarcoma (OSA) is a naturally occurring malignant bone tumor in both humans and canines that is characterized by aggressive local behavior and a high propensity for metastasis. Despite advances in diagnostic methods and therapies, long-term survival rates have remained stagnant, underscoring the great need for the development of biomarkers serving in the prognosis and diagnosis of OSA across species. Biomarkers, molecular indicators of disease presence or progression, are pivotal tools in oncology, offering the potential to determine risk stratification, guide targeted therapies, and monitor treatment response. This review provides an in-depth analysis of the current landscape of OSA biomarkers, highlighting diagnostic and prognostic markers identified across species. We highlighted the role of biomarkers, including protein, cellular, metabolic, imaging, genetic, and epigenetic markers, in osteosarcoma diagnosis and prognosis and categorized them across multiple domains. Furthermore, this review explores the utility of the canine model in osteosarcoma research, emphasizing its relevance to human OSA due to comparable diagnostic approaches, prognostic indicators, and clinical manifestations. With this review, we aim to demonstrate that integrating biomarker research across species can deepen the understanding of osteosarcoma pathogenesis and advance knowledge of its underlying biology, ultimately paving the way for precision medicine strategies that benefit both human and veterinary oncology.

Osteosarcoma is an aggressive primary bone malignancy affecting both humans and dogs, and canine osteosarcoma represents a valuable comparative model for investigating novel therapeutic strategies. Targeting tumour metabolism may enhance the efficacy of existing anticancer treatments. This study investigated whether the mitochondrial uncoupler BAM15 modifies the response of canine D17 osteosarcoma cells to regorafenib. Cells were treated with BAM15 (20 µM) or regorafenib (REG; IC₂₅, 8 µM; IC₅₀, 16 µM) alone or pretreated with BAM15 before regorafenib exposure. Treatment effects were assessed using viability assays, Annexin V/propidium iodide staining, cell-cycle analysis, Seahorse XF bioenergetic profiling, quantitative PCR, and Western blotting. BAM15 alone did not significantly affect cell metabolic activity. Combined treatment with BAM15 and regorafenib produced a significantly greater reduction in cell metabolic activity than regorafenib alone at IC₅₀, whereas no significant difference between treatments was observed at IC₂₅. Combined treatment at IC₅₀ increased late apoptotic and necrotic populations and disrupted cell-cycle distribution. BAM15 reduced oxidative phosphorylation-derived ATP production without detectable glycolytic compensation but did not further suppress mitochondrial ATP production beyond regorafenib effect alone. Combined treatment also induced transcriptional changes in stress-adaptation-related genes, while protein analysis revealed reduced BAX and BAX/BCL-2 ratio. These exploratory findings provide preliminary evidence that mitochondrial uncoupling by BAM15 may modify the response to regorafenib and support further mechanistic investigation and validation in additional tumour and non-malignant canine models.

Osteosarcoma is an aggressive primary bone malignancy affecting both humans and dogs, and canine osteosarcoma represents a valuable comparative model for investigating novel therapeutic strategies. Targeting tumour metabolism may enhance the efficacy of existing anticancer treatments. This study investigated whether the mitochondrial uncoupler BAM15 sensitises canine D17 osteosarcoma cells to regorafenib. Cells were treated with BAM15 (20 µM) or regorafenib (REG; IC25, 8 µM; IC50, 16 µM) alone or pretreated with BAM15 before regorafenib exposure. Treatment effects were assessed using viability assays, Annexin V/propidium iodide staining, cell-cycle analysis, Seahorse XF bioenergetic profiling, quantitative PCR, and Western blotting. BAM15 alone was not cytotoxic but significantly enhanced the regorafenib-induced reduction in cell viability at IC50, whereas no significant sensitising effect occurred at IC25. Combined treatment at IC50 increased late apoptotic and necrotic populations and disrupted cell-cycle distribution. BAM15 reduced oxidative phosphorylation-derived ATP production without detectable glycolytic compensation but did not further suppress mitochondrial ATP production beyond regorafenib alone. Combined treatment also induced transcriptional changes in stress-adaptation-related genes, while protein analysis revealed reduced BAX and BAX/BCL-2 ratio. These findings provide preliminary evidence that mitochondrial uncoupling may modify osteosarcoma responses to regorafenib and warrant further mechanistic validation.

Osteosarcoma (OSA) is a naturally occurring, malignant bone tumor in both humans and canines, characterized by aggressive local behavior and a high propensity for metastasis. Despite advances in diagnostic methods and therapies, long-term survival rates have remained stagnant, underscoring the great need for the development of biomarkers serving in the prognosis and diagnosis of OSA across species. Biomarkers, molecular indicators of disease presence or progression, are pivotal tools in oncology, offering the potential to determine risk stratification, guide targeted therapies, and monitor treatment response. This review provides an in-depth analysis of the current landscape of OSA biomarkers, highlighting diagnostic and prognostic markers identified across species. We highlighted the role of biomarkers in osteosarcoma diagnosis and prognosis, and categorized them across multiple domains, including protein, cellular, metabolic, imaging, genetic, and epigenetic markers. Furthermore, we explore the utility of the canine model in osteosarcoma research, emphasizing its relevance to human OSA due to comparable diagnostic approaches, prognostic indicators, and clinical manifestations. With this review, we aim to demonstrate that integrating biomarker research across species can deepen our understanding of osteosarcoma pathogenesis and advance knowledge of its underlying biology, ultimately paving the way for precision medicine strategies that benefit both human and veterinary oncology.