Single-cell RNA sequencing reveals osteosarcoma microenvironment differences between chemotherapy and without chemotherapy

Abstract

Background: Osteosarcoma(OS) is considered to be the most common primary bone tumor in adolescents. Currently, the main treatment for osteosarcoma is a combined neoadjuvant chemotherapy-surgery-adjuvant chemotherapy model. Unfortunately, this effective treatment regimen appears to have entered a bottleneck over the past 10 years, and the key mechanisms and mysteries triggered by osteosarcoma before and after chemotherapy have not been elucidated. This study aims to investigate the effects of osteosarcoma microenvironment between chemotherapy and without chemotherapy. Methods: We obtained data on 8 osteosarcoma cases that had undergone single-cell sequencing from a public database, including 4 cases each with and without chemotherapy. The single-cell expression profile of the degenerated nucleus pulposus was constructed by software analysis for cell filtering, data normalization, cell subcluster analysis, and cell type identification procedures, and marker genes for cell subclusters were obtained. The effects of different cell subclusters on the immune microenvironment of osteosarcoma with and without chemotherapy were further investigated by gene function analysis and pseudo time analysis. Results: The 8 osteosarcoma cases contained a total of about 100,000 single cells, and after quality control screening, a total of 80,552 cells were obtained and 8 major cell types were identified for subsequent analysis. The osteoblastic OS cells had the highest proportion of the eight major cell types, followed by the myeloid cells, osteoclasts, the proliferative OS cells, T and NK cells, endothelial cells, macrophages, and osteoblasts. Moreover, compared with the non-chemotherapy group, the heterogeneity exhibited by the chemotherapy group was also mainly reflected in several cell clusters with a high proportion. Conclusion: Revealed that oxidative phosphorylation, epithelial-mesenchymal transition, and angiogenesis are closely associated with anti-osteosarcoma deterioration, metastasis, and chemoresistance. In addition, hypoxia related genes (RGS5, CYGB, C1qtnf3) upregulated in chemotherapy have been found to be closely related to proliferation, migration, invasion and angiogenesis of osteosarcoma cells. MMP9 and MMP13 can indirectly promote tumor angiogenesis, and down-regulation of MMP9 and MMP13 may be one of the markers of prognosis in osteosarcoma patients. Downregulation of MHCI may lead to immune escape of tumor cells. Heat shock proteins (HSP) are involved in the activation and inhibition of osteosarcoma-associated pathways. These results present a deeper single-cell atlas of the tumor microenvironment for osteosarcoma and provide potential therapeutic targets for future treatment of osteosarcoma.