Single-cell RNA sequencing reveals HMGA2 involvement in neoplastic aggressiveness and endothelial cell senescence in chondrosarcoma

Chondrosarcoma (CHS) is a malignant bone tumor resistant to adjuvant treatment, with high-grade patients suffering an unfavorable prognosis. Therefore, a deeper insight into the tumor microenvironment is essential for developing effective treatments for advanced CHS. To decipher the cellular heterogeneity between CHS with differential malignancy and benign cartilage tumors, we performed single-cell RNA sequencing (scRNA-seq) on clinical specimens of high- and low-grade CHS, endochondroma and paratumoral tissues. The findings of transcriptional characteristics were validated by the bioinformatics analyses of public bulk datasets. The role of markers of interest was further explored by histological staining, in vitro and in vivo experiments. The results demonstrated that neoplastic cells and stromal cells predominated in the CHS tumor microenvironment. High-grade CHS presented aggravated proliferation and angiogenesis characteristics in neoplastic cells. The in silico analysis and functional experiments identified HMGA2 as a regulator of these malignant phenotypes and an independent predictor of poor outcome. Tumor-associated endothelial cells (TA-ECs) in CHS demonstrated senescent yet aggressive phenotypes underpinned by HBEGF. Moreover, HCHS exhibited more prevalent cellular communications between neoplastic cells and TA-ECs mediated by SPP1 and EGF pathways, with SPP1 and HBEGF both predicting unfavorable prognosis. Mechanistically, HMGA2 induced neoplastic secretion of SPP1, which provoked endothelial senescence and HBEGF release. Our findings implicate malignant characteristics in neoplastic cells and endothelial senescence associated with the histological grade of CHS and underscore the potential value of HMGA2 and SPP1 as actionable therapeutic targetes for advanced patients.