1. Release of Exosomal PD-L1 in Bone and Soft Tissue Sarcomas and Its Relationship to Radiotherapy.
- Author
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Yoshida, Keisuke, Asanuma, Kunihiro, Matsuyama, Yumi, Okamoto, Takayuki, Hagi, Tomohito, Nakamura, Tomoki, and Sudo, Akihiro
- Subjects
OSTEOSARCOMA ,SARCOMA ,T cells ,PROGRAMMED death-ligand 1 ,IMMUNOTHERAPY ,ANTINEOPLASTIC agents ,BONE tumors ,DESCRIPTIVE statistics ,MICE ,GENE expression ,CELL lines ,ANIMAL experimentation ,SOFT tissue tumors ,EXOSOMES - Abstract
Simple Summary: Programmed death-ligand 1 (PD-L1) on the tumor cell surface binds to its receptor, programmed death-1 (PD-1), on T cells and inhibits their activity. Immunotherapy involving PD-L1 and PD-1 inhibition has provided a remarkable innovation in cancer therapy. Recently, the soluble form of PD-L1 (sPD-L1) has attracted attention for systemic immune suppression. In this study, we successfully showed that sarcoma cells can release functional exosomal PD-L1, one of the forms of sPD-L1. Furthermore, the release of exosomal PD-L1 derived from normal and sarcoma cells was shown to be induced by irradiation. These findings demonstrate that radiated cells, including normal cells and sarcoma cells, induce the systemic release of exosomal PD-L1, and combination therapy with anti-PD-1/PD-L1 antibody may block the immune activity of exosomal PD-L1. (1) Background: Exosomal PD-L1 has garnered attention owing to its role in instigating systemic immune suppression. The objective of this study is to elucidate whether bone and soft tissue sarcoma cells possess the capacity to secrete functionally active exosomal PD-L1 and whether radiotherapy (RT) induces the exosomal PD-L1 release. (2) Methods: Human osteosarcoma cell line 143B and human fibrosarcoma cell line HT1080 were utilized. Exosomes were isolated from the culture medium and blood via ultracentrifugation. The expression of PD-L1 on both tumor cells and exosomes was evaluated. The inhibitory effect on PBMC was employed to assess the activity of exosomal PD-L1. Post radiotherapy, changes in PD-L1 expression were compared. (3) Results: Exosomal PD-L1 was detected in the culture medium of tumor cells but was absent in the culture medium of PD-L1 knockout cells. Exosomal PD-L1 exhibited an inhibitory effect on PBMC activation. In tumor-bearing mice, human-derived exosomal PD-L1 was detected in the bloodstream. Following radiotherapy, tumor cells upregulated PD-L1, and human-derived exosomal PD-L1 were detected in the bloodstream. (4) Conclusions: Exosomal PD-L1 emanates from bone and soft tissue sarcoma cells and is disseminated into the circulatory system. The levels of PD-L1 in tumor cells and the release of exosomal PD-L1 were augmented after irradiation with RT. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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