LncDARS‐AS1 Regulates ATP1A1 Stability and Enhances Na ⁺ /K ⁺ ATPase Activity to Promote Osteosarcoma Metastasis

Abstract Osteosarcoma, the most prevalent malignant bone tumour in children and adolescents, exhibits aggressive pulmonary metastasis and poor prognosis. This study identifies LncDARS‐AS1 as a key regulator of metastasis via modulation of ATP1A1, the catalytic subunit of Na⁺/K⁺ ATPase (NKA). Transcriptomic analyses, validated by qPCR in 217 osteosarcoma RNA samples, reveal that LncDARS‐AS1 is significantly upregulated in metastatic lesions and associated with adverse clinical outcomes. Functional assays confirm that silencing LncDARS‐AS1 suppresses osteosarcoma proliferation and metastasis in vitro and in vivo. Mechanistically, LncDARS‐AS1 directly binds ATP1A1, preventing its interaction with the UBQLN4 and subsequent proteasomal degradation, thereby enhancing NKA activity. Protein‐RNA interactions were validated using ChIRP, mass spectrometry, molecular docking, and molecular dynamics simulations. Functional NKA activity was assessed using ion‐sensitive fluorescent indicators and enzymatic assays. Additionally, digoxin, a cardiac glycoside targeting NKA, effectively inhibited tumour growth and metastasis at clinically safe concentrations. These findings uncover a novel LncDARS‐AS1/ATP1A1 axis that promotes osteosarcoma metastasis through inhibition of ubiquitin‐mediated degradation and provide a rationale for repurposing digoxin in osteosarcoma therapy. ATP1A1 emerges as a promising target for anti‐metastatic intervention.