Creatine Kinase Blockade Disrupts Energy Metabolism and Redox Homeostasis to Suppress Osteosarcoma Progression.

Osteosarcoma is the most common primary malignant bone tumor in adolescents and young adults; yet survival outcomes have remained stagnated for decades, underscoring the urgent need for new therapeutic strategies. Creatine kinase (CK)-comprising cytosolic CKB and mitochondrial CK-maintains malignant behaviors by supporting high-energy phosphate transfer through the phosphocreatine (pCr) shuttle. Here, we pharmacologically inhibited CK activity in osteosarcoma models and evaluated proliferation, cell death modalities, mitochondrial function, stemness, motility, and tumor behavior. CK blockade consistently suppressed growth and clonogenicity and induced apoptosis as the predominant mode of death. It impaired ATP buffering capacity and disturbed mitochondrial homeostasis, accompanied by reduced expression of stemness-associated markers and diminished migration and invasion. In mouse models, CK inhibition significantly restrained tumor progression and dissemination. These results indicate that disabling the CK-pCr energy-buffering system reprograms cellular energetics toward apoptosis and less aggressive phenotypes. Our findings support targeting the CK pathway as a tractable metabolic vulnerability and a rational partner for cytotoxic regimens, with pathway-specific signaling alterations representing downstream consequences of central energetic collapse.