AbstractBackgroundThe correlation between epithelial‐mesenchymal transition (EMT) and osteosarcoma (OS) has been widely reported. Integration of the EMT‐related genes to predict the prognosis is significant for investigating the mechanism of EMT in OS. Here, we aimed to construct a prognostic EMT‐related gene signature for OS.MethodsTranscriptomic and survival data of OS patients were downloaded from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO). We performed univariate Cox regression, least absolute shrinkage and selection operator (LASSO) regression, and stepwise multivariate Cox regression analysis to construct EMT‐related gene signatures. Kaplan–Meier analysis and time‐dependent receiver operating characteristic (ROC) were applied to evaluate its predictive performance. GSVA, ssGSEA, ESTIMATE, and scRNA‐seq were performed to investigate the tumor microenvironment, and the correlation between IC50 of drugs and ERG score was investigated. Furthermore, Edu and transwell experiments were conducted to assess the malignancy of OS cells.ResultsWe constructed a novel EMT‐related gene signature (including CDK3, MYC, UHRF2, STC2, COL5A2, MMD, and EHMT2) for outcome prediction of OS. According to the signature, patients stratified into high‐ and low‐ERG‐score groups exhibited significantly different prognoses. ROC curves and Kaplan–Meier analysis revealed a promising performance of the signature with external validation. GSVA, ssGSEA, ESTIMATE algorithm, and scRNA‐seq excavated EMT‐related pathways and suggested the correlation between ERG score and immune activation. Notably, the pivotal gene CDK3 was upregulated in OS tissue and positively related to OS cell proliferation and migration.ConclusionOur EMT‐related gene signature might reference OS risk stratification and guide clinical strategies as an independent prognostic factor in OS.