Project description:Purpose: The overall survival rate for metastatic osteosarcoma hovers around 20%. Responses to second-line chemotherapy, targeted therapies, and immunotherapies have demonstrated limited efficacy in metastatic osteosarcoma. Our objective is to validate differentially expressed genes and signaling pathways between non-metastatic and metastatic osteosarcoma, employing single-cell RNA sequencing (scRNA-Seq) and additional functional investigations. We aim to enhance comprehension of metastatic mechanisms and potentially unveil a therapeutic target. Methods: scRNA-Seq was performed on two primary osteosarcoma lesions (1 non-metastatic and 1 metastatic). Uniform manifold approximation and projection (UMAP) facilitated dimensionality reduction and cluster identification. Copy number variation (CNV) was predicted using InferCNV. CellChat characterized ligand-receptor-based intercellular communication networks. Differentially expressed genes underwent GO function enrichment analysis and GSEA. Validation was achieved through the GSE 52048 dataset, which identified PDGFD-PDGFRB as a common ligand-receptor pair with significant contribution. Immunohistochemistry assessed PDGFD and PDGFRB expression, while multicolor immunofluorescence and flow cytometry provided insight into spatial relationships and the tumor immune microenvironment. Kaplan-Meier survival analysis compared metastasis-free survival and overall survival between high and low levels of PDGFD and PDGFRB. Manipulation of PDGFD expression in primary osteosarcoma cells examined invasion abilities and related markers. Results: Ten clusters encompassing osteoblasts, osteoclasts, osteocytes, fibroblasts, pericytes, endothelial cells, myeloid cells, T cells, B cells, and proliferating cells were identified. Osteoblasts, osteoclasts, and osteocytes exhibited heightened CNV levels. Ligand-receptor-based communication networks exposed significant fibroblast crosstalk with other cell types, and the PDGF signaling pathway was activated in non-metastatic osteosarcoma primary lesions. These results were corroborated by the GSE 52048 dataset, confirming the prominence of PDGFD-PDGFRB as a common ligand-receptor pair. Immunohistochemistry demonstrated considerably greater PDGFD expression in non-metastatic osteosarcoma tissue and organoids, correlating with extended metastasis-free and overall survival. PDGFRB expression showed no significant variation between non-metastatic and metastatic osteosarcoma, nor strong correlations with survival times. Multicolor immunofluorescence suggested co-localization of PDGFD with PDGFRB. Flow cytometry unveiled a highly immunosuppressive microenvironment in metastatic osteosarcoma. Manipulating PDGFD expression demonstrated altered invasive abilities and marker expressions in primary osteosarcoma cells from both non-metastatic and metastatic lesions. Conclusions: scRNA-Seq illuminated the activation of the PDGF signaling pathway in primary lesions of non-metastatic osteosarcoma. PDGFD displayed an inhibitory effect on osteosarcoma metastasis, likely through the suppression of the EMT signaling pathway.

Project description:SaOS2 osteosarcoma cells were cultured with or without atorvastatin (10 µM) for 6, 15 or 24h (2 biological replcates). RNA were isolated and hybridized to RNG microarrays. Background Osteosarcoma is the most common primary tumor of bone. The rapid development of metastatic lesions and resistance to chemotherapy remain major mechanisms responsible for the failure of treatments and poor survival rate for patients. Methods We previously showed that the HMGCoA reductase inhibitors statins exhibit anti-tumoral effects on osteosarcoma cells. Here, using microarray analysis, we identify cyr61/CCN1 as a new target of statins. Modulations of expression of cyr61 were performed in human and murine osteosarcoma cell lines to investigate in vitro cell viability, migratory potential and invasiveness. Cyr61 expression was evaluated in 231 tissue cores from osteosarcoma patients using tissue microarray. Tumor behavior and metastases occurence were analysed by IM injection of modified osteosarcoma cells to BALB/c mice. Results Transcriptome comparisons revealed that statins down-regulate cyr61 expression in SaOS2 cells. Cyr61 silencing in human and murine osteosarcoma cell lines enhanced cell death, but reduced cell migration and cell invasion compared to parental cells whereas cyr61 overexpression had opposite effects. Tissue microarray analysis demonstrated that cyr61 protein expression is higher in human osteosarcoma compared to normal bone tissue and is further increased in metastatic tissues. In vivo, cyr61 overexpression in osteosarcoma cells enhanced lung metastases development whereas cyr61 silencing strongly reduced metastases in mice. Conclusion The results reveal that cyr61 expression increases with tumor grade in human osteosarcoma and demonstrate that cyr61 silencing inhibits in vitro osteosarcoma cell invasion and migration as well as in vivo lung metastases in mice. These data provide a novel molecular target for therapeutic intervention in metastatic osteosarcoma. Dye balance-experiment comparing atorvastatin versus untreated cells at 6, 15 and 24 hours using 2 biological replicates.

Project description:SaOS2 osteosarcoma cells were cultured with or without atorvastatin (10 µM) for 6, 15 or 24h (2 biological replcates). RNA were isolated and hybridized to RNG microarrays. Background Osteosarcoma is the most common primary tumor of bone. The rapid development of metastatic lesions and resistance to chemotherapy remain major mechanisms responsible for the failure of treatments and poor survival rate for patients. Methods We previously showed that the HMGCoA reductase inhibitors statins exhibit anti-tumoral effects on osteosarcoma cells. Here, using microarray analysis, we identify cyr61/CCN1 as a new target of statins. Modulations of expression of cyr61 were performed in human and murine osteosarcoma cell lines to investigate in vitro cell viability, migratory potential and invasiveness. Cyr61 expression was evaluated in 231 tissue cores from osteosarcoma patients using tissue microarray. Tumor behavior and metastases occurence were analysed by IM injection of modified osteosarcoma cells to BALB/c mice. Results Transcriptome comparisons revealed that statins down-regulate cyr61 expression in SaOS2 cells. Cyr61 silencing in human and murine osteosarcoma cell lines enhanced cell death, but reduced cell migration and cell invasion compared to parental cells whereas cyr61 overexpression had opposite effects. Tissue microarray analysis demonstrated that cyr61 protein expression is higher in human osteosarcoma compared to normal bone tissue and is further increased in metastatic tissues. In vivo, cyr61 overexpression in osteosarcoma cells enhanced lung metastases development whereas cyr61 silencing strongly reduced metastases in mice. Conclusion The results reveal that cyr61 expression increases with tumor grade in human osteosarcoma and demonstrate that cyr61 silencing inhibits in vitro osteosarcoma cell invasion and migration as well as in vivo lung metastases in mice. These data provide a novel molecular target for therapeutic intervention in metastatic osteosarcoma.

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MAGEA antigens as immunotherapeutic targets for advanced osteosarcoma

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