Vitexin inhibited the invasion, metastasis, and progression of human melanoma cells by targeting STAT3 signaling pathway

In human melanoma cells, resistance to conventional chemotherapy and radiotherapy and rapid metastasis give melanoma a remarkable feature of the most aggressive and lethal. The low response rate of melanoma to existing treatment modalities is a substantial threat to patients and researchers. It is crucial to identify new therapeutic agents for the fatal malignancy melanoma. Vitexin is a flavonoid compound in many traditional Chinese medicines that exhibits antioxidant, anti-inflammatory and anti-tumour activities in many cancer cells. In our study, we elucidated the inhibitory effects of vitexin on invasion and metastasis in human melanoma A375 and C8161 cells in vitro. After vitexin treatment for 24 h or 48 h, the invasive ability and migration of melanoma cells were decreased in a dose- and time-dependent manners. In western blot analysis, we verified that vitexin inhibited the expression levels of MMP-2, MMP-9, vimentin, Slug and Twist which are known as the regulators of protein degradation and promote various cell behaviours such as migration and invasion. To further investigate the target signal that may be influenced by vitexin, immunofluorescence assay was performed to observe STAT3 localization and western blot results showed that vitexin decreased the expression of the phosphorylation of kinases that inducing STAT3 activation. Accordingly, we provide inspiring insight into the basic inhibition mechanism of vitexin, which will soon be an issue due to its scientific potential for further development as a novel anti-tumour agent for the clinical therapy of human melanoma.