A chemoresistance- and lactylation-related lncRNA prognostic signature uncovers LINC01976/LDHA/lactylation regulatory axis in osteosarcoma chemoresistance

Osteosarcoma represents the most frequent primary malignant bone neoplasm in adolescents, with chemoresistance remaining a pivotal barrier to clinical cure and prognosis. Long non-coding RNAs (lncRNAs) are crucial epigenetic modulators governing malignant tumor progression, whereas lactylation constitutes a newly identified metabolic-epigenetic modification driving cancer chemoresistance. Nevertheless, the clinical significance and biological functions of chemoresistance- and lactylation-related lncRNAs (CRLR-lncRNAs) in osteosarcoma chemoresistance remain elusive. Osteosarcoma transcriptomic, clinical data, and scRNA-seq profiles were obtained from the TARGET database and the GSE152048 cohort, respectively. CRLR-lncRNAs were screened via Pearson correlation between lncRNAs and chemoresistance- and lactylation-related DEGs. A CRLR-lncRNA prognostic signature was constructed using LASSO and multivariate Cox regression, and validated by stratified survival analysis and nomogram. Functional enrichment, immune infiltration, drug sensitivity, tumor mutational burden (TMB), and Single-cell RNA-sequencing (scRNA-seq) analyses were further conducted. In vitro and in vivo assays were conducted to clarify the role and mechanism of the core lncRNA LINC01976 in osteosarcoma chemoresistance. Using the TARGET dataset, a novel prognostic signature consisting of 6 CRLR-lncRNAs was constructed and validated, exhibiting high accuracy in predicting 1-, 3-, and 5-year overall survival of osteosarcoma patients. It served as an independent prognostic factor superior to conventional clinicopathological indicators, with robust prognostic value across clinical subgroups and the capacity for individualized survival prediction. Functional enrichment analysis revealed enrichment in extracellular matrix remodeling, oncogenic signaling pathways, and immune-related processes. The signature effectively stratified patients into immune-active low-risk and immunosuppressive high-risk subgroups with distinct tumor immune microenvironments, TMB levels, and drug sensitivity. ScRNA-seq analysis confirmed the heterogeneous distribution and differential expression of signature lncRNAs between chemo-sensitive and chemo-resistant lesions. Notably, lactylation-related LINC01976 was upregulated in chemoresistant osteosarcoma and correlated with poor prognosis. Mechanistically, LINC01976 promotes cisplatin resistance in osteosarcoma both in vitro and in vivo by enhancing LDHA-dependent lactylation; specifically, LINC01976 upregulates LDHA expression, increasing intracellular lactate production and lysine lactylation levels alongside histone H3K18la, thus forming a LINC01976/LDHA/lactylation regulatory axis to further reinforce cisplatin resistance. The novel CRLR-lncRNA signature effectively predicts the prognosis, immune landscape, and chemosensitivity of osteosarcoma patients. LINC01976, a core signature lncRNA, promotes cisplatin resistance through LDHA-dependent lactylation and the formation of a regulatory axis, serving as a potential prognostic biomarker and therapeutic target for chemo-resistant osteosarcoma.