Preliminary study on the mechanism of OPN up-regulating PD-L1 to induce CD8 + T cell exhaustion in synovial sarcoma
Huifang Zhuo1,2, Xinyi Li1,3, Zhongxu Xue1,3
1Department of Pathology, Department of Pathology, the First Affiliated Hospital, Shihezi University School of Medicine, Shihezi University, Xinjiang, 832002, China.
Background:
Synovial sarcoma (SS) is a rare and highly malignant soft tissue sarcoma. The efficacy of existing therapies is limited, and new strategies are urgently needed. Osteopontin (OPN) promotes disease progression by regulating tumor-immune cell interaction and immunosuppressive microenvironment, which is a potential therapeutic target. The aim of this study was to investigate the role of OPN in SS immune regulation and tumor progression.
Methods:
A stable cell line with OPN knockdown was constructed using lentiviral transduction. RNA-seq and bioinformatics analysis were used to predict the correlation between OPN and immunity. Flow cytometry and ELISA were used to detect the changes in the number and function of CD8 + T cells. EDU, CCK-8 and Transwell chamber experiments were used to detect the proliferation, invasion and migration ability of SS. The protein interaction between OPN and PD-L1 was detected by molecular docking and Co-IP. The expression of PD-L1 was detected by Western blot and flow cytometry. The expression levels of OPN, PD-L1 and CD8 were detected by immunohistochemistry. To predict the correlation of OPN, PD-L1 and CD8 in sarcoma tissues and their clinical prognostic significance.
Results:
RNA-seq analysis revealed that OPN-associated differentially expressed genes were significantly enriched in immune response-related biological processes. Bioinformatics analysis demonstrated that OPN expression in sarcoma was associated with immune responses and T-cell activation, and was negatively correlated with immune cell infiltration. OPN induced CD8⁺ T-cell exhaustion, thereby promoting immune evasion and facilitating the proliferation, invasion, and migration of synovial sarcoma (SS) cells. Molecular docking and co-immunoprecipitation assays confirmed a direct protein-protein interaction between OPN and PD-L1, and knockdown of OPN resulted in a significant reduction in PD-L1 expression. In SS tissues, OPN was highly expressed, whereas PD-L1 and CD8 were expressed at low levels and exhibited a positive correlation. Furthermore, bioinformatics analysis showed that PD-L1 expression was positively correlated with CD8 expression in sarcoma, and low CD8 expression was associated with poor prognosis.
Conclusions:
We preliminarily propose that OPN promotes immune evasion in synovial sarcoma (SS) by regulating PD-L1 expression and subsequently inducing CD8⁺ T-cell exhaustion. This mechanism suggests that OPN may serve as a novel immunotherapeutic target and provides new insights into the development of immunotherapy strategies for SS.
Insights
Osteopontin (OPN) drives synovial sarcoma progression by promoting immune evasion and CD8+ T-cell exhaustion via PD-L1 regulation. Targeting OPN offers a novel immunotherapy strategy for this rare cancer.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Synovial sarcoma (SS) is a rare, highly malignant soft tissue sarcoma with limited therapeutic options.
- Osteopontin (OPN) is implicated in tumor progression by modulating tumor-immune cell interactions and the immunosuppressive microenvironment.
- Investigating OPN's role in SS immune regulation and tumor progression is crucial for developing new therapeutic strategies.
Purpose of the Study:
- To elucidate the role of Osteopontin (OPN) in regulating the immune microenvironment of synovial sarcoma (SS).
- To investigate the mechanism by which OPN influences tumor progression and immune evasion in SS.
- To explore OPN as a potential therapeutic target for SS immunotherapy.
Main Methods:
- Constructed OPN knockdown SS cell lines using lentiviral transduction.
- Utilized RNA-seq, bioinformatics, flow cytometry, ELISA, EDU, CCK-8, Transwell assays, molecular docking, and Co-IP to analyze OPN's effects.
- Assessed OPN, PD-L1, and CD8 expression via Western blot and immunohistochemistry in SS tissues.
Main Results:
- OPN knockdown significantly reduced SS cell proliferation, invasion, and migration.
- OPN was found to directly interact with PD-L1, and OPN knockdown decreased PD-L1 expression.
- OPN induced CD8+ T-cell exhaustion, promoting immune evasion and correlating with poor prognosis in SS patients.
Conclusions:
- Osteopontin (OPN) promotes immune evasion in synovial sarcoma (SS) by upregulating PD-L1 and inducing CD8+ T-cell exhaustion.
- The OPN-PD-L1 axis represents a potential therapeutic target for enhancing SS immunotherapy.
- This study provides novel insights into SS pathogenesis and suggests new avenues for immunotherapeutic strategies.
