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Metastasis is the main cause of death in osteosarcoma. Targeting the process of metastasis is a main strategy for osteosarcoma therapy. As a traditional Chinese medicine, Zanthoxylum nitidum (Roxb) has been applied to treat various diseases, including cancer. However, no evidence has been shown on the anti-metastasis effect of nitidine chloride (NC) that was extracted from Zanthoxylum nitidum (Roxb) on osteosarcoma cells, or its underling mechanisms. In the present study, we aimed to demonstrate the role of NC on the migration and invasion of osteosarcoma cells. Viability and proliferation of osteosarcoma cells were examined by MTT assay. Then, by appling scratch wound healing assay and Transwell assays, we evaluated migratory and invasive ability of the cells, respectively. Moreover, the expression of epithelial-to-mesenchymal transition (EMT) markers were determined after treatment with NC. Furthermore, the expression of Akt, GSK-3β and Snail were detected by western blot analysis. In addition, the GSK-3β activity was examined by GSK-3β kinase assay. Finally, an inhibitor of GSK-3β, lithium chloride (LiCl) was applied to testify the effect of NC on the expression of EMT markers and Snail. We found that the proliferative, migratory and invasive ability of the U2OS osteosarcoma cells were all suppressed when treated with NC. NC increased the expression of E-cadherin and decreased the expression of N-cadherin, vimentin and fibronectin in a dose-dependent manner. NC also exerted its ability to suppress the phosphorylation of Akt and GSK-3β so as to activate GSK-3β. Then, by using an GSK-3β inhibitor, LiCl, we revealed the effect of GSK-3β in the expression of EMT markers. The expression of Snail was inhibited when treated with NC and LiCl also reversed the NC-inhibited Snail expression. Taken together, these results revealed that NC suppressed EMT and decreased the invasive ability of osteosarcoma cells via the Akt/GSK-3β/snail signaling pathway.

Visfatin is considered to be a biomarker in various types of cancers. However, no evidence has been reported for the direct effect of visfatin on osteosarcoma cell metastasis. The aims of the present study were to investigate the influence of visfatin on the migration and invasion of osteosarcoma cells and clarify the underlying mechanism. The expression levels of epithelial-mesenchymal transition (EMT) markers, as well as the transcriptional factor Snail-1, were first detected at both the protein and mRNA levels in U2OS osteosarcoma cells after stimulation of visfatin. Then the expression of NF-κB (p65) was detected by western blot analysis, and siRNA of Snail-1 and inhibitor of NF-κB were used to investigate the effect of visfatin. Finally, migration and invasion of the cells were detected respectively by scratch wound healing and transwell assays. Visfatin downregulated E-cadherin and upregulated N-cadherin in concentration- and time-dependent manners at the protein and mRNA levels. The expression of Snail-1 was also upregulated. Moreover, visfatin also promoted the nuclear translocation of the NF-κB pathway. Administration of siRNA of Snail-1 and the inhibitor BAY11-7082 validated the roles of Snail-1 and NF-κB in the visfatin-induced regulation of EMT markers. Migration and invasion of U2OS osteosarcoma cells were promoted following the application of visfatin. These results demonstrated that visfatin enhances the migration and invasion of osteosarcoma cells via the NF-κB/Snail-1/EMT pathway.