Objective · To determine the expression of miRNA-7 in TWEAK-stimulated macrophages and their secreted exosomes;to investigate the role of exosomal miRNA-7 from TWEAK-stimulated macrophages in modulating the metastasis of epithelial ovarian cancer (EOC) cells.Methods · Real-time PCR analysis was used to determine the miRNA-7 expression in TWEAK-stimulated macrophages,their exosomes and recipient HO8910-PM cells.The activity of EGFR signaling pathway in HO8910-PM cells was detected by Western blotting analysis.AntagomiR-7 was used to downregulate the miRNA-7expressions in macrophage exosomes and then their effect on metastasis of HO8910-PM cells was examined by transwell assay.Results ·TWEAK increased the levels of miRNA-7 in macrophages and their secreted exosomes and also resulted in an elevated level of miRNA-7 in recipient HO8910-PM cells,which eventually reduced the activity of EGFR/AKT/ERK1/2 pathway.Pre-transfection of antagomiR-7 remarkably decreased the levels of miRNA-7 in macrophages,their secreted exosomes and the recipient EOC cells,with the enhancement of HO8910-PM metastasis.Conclusion · Exosomal miRNA-7 from TWEAK-stimulated macrophages plays a critical role in suppressing the metastasis of EOC cells by attenuation of EGFR signaling pathway.

BACKGROUND: The blocking of the programmed cell death protein (PD-1)/programmed death-ligand 1 (PD-L1) axis has been found to have an anticancer activity against various types of cancer by enhancing T cell immunity, while there are no studies linking the PD-1/PD-L1 axis to chemotherapy drugs in osteosarcoma (OS). The present study aimed to investigate the effects of blocking PD-1/PD-L1 axis on the cisplatin chemotherapy in OS in vitro and in vivo. METHODS: Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect PD-L1 mRNA in OS tissues. Cell proliferation and apoptosis were measured by Cell Counting Kit-8 (CCK-8) and flow cytometry assays, respectively. In vivo, the syngeneic mice were treated with cisplatin and anti-PD-1 antibody alone or jointly. RESULTS: In this study, it revealed that PD-L1 mRNA was highly expressed in OS tissues. Further inhibitory evaluation showed that the K7M2-LV cells (PD-L1 overexpression) co-cultured with PD-1 lymphocytes could promote K7M2 cell proliferation. Meanwhile, the combination of anti-PD-1 antibody and cisplatin significantly decreased the proliferation and increased the apoptosis of K7M2 cells in a co-culture system. In vivo, the combination of anti-PD-1 antibody and cisplatin significantly inhibited tumor growth, while the mechanisms did not involve regulatory T cells. CONCLUSION The present data suggested that the blocking of PD-1/PD-L1 axis had a positive prognostic value, which can enhance the chemotherapeutic effect of cisplatin in OS. These findings provide a rationale for utilizing PD1/PD-L1 blocking antibodies as a single agent to cure refractory OS in patients receiving cisplatin treatment.