Effect of Huaier on Melanoma Invasion, Metastasis, and Angiogenesis

Malignant melanoma (MM) is a highly metastatic and malignant cancer. Developing potential drugs with good efficacy and low toxicity for MM treatment is needed. Huaier, extracted from the mushroomTrametes robiniophilaMurr, has been widely used in clinical anticancer treatments in China. A previous work done by our group confirmed that Huaier could inhibit cell proliferation and induce apoptosis in human melanoma cells. The current study is aimed at investigating the effects of Huaier on melanoma metastasis and angiogenesisin vitroandin vivoand to explore its possible mechanism of action. Our results showed that Huaier not only significantly inhibited the metastasis of A375 cells at the concentration ranging from 4 to 16 mg/ml (P<0.05), which were determined by the wound healing assay and transwell assayin vitro, but also suppressed the MM tumor growth and metastatic cells to the liver in A375-bearing mice after oral administration at the dose of 5 mg/kg (P<0.05). In addition, Huaier treatment downregulated the expression of hypoxia-inducible factor-1 alpha(HIF-1 alpha), vascular endothelial growth factor (VEGF), astrocyte-elevated gene-1 (AEG-1), and N-cadherin, while it upregulated E-cadherin expression in both the A375 cells and tumor tissues, which was detected using western blotting and RT-PCR (P<0.05). Taken together, our data suggests that the antitumor and antimetastatic activities of Huaier are caused by the downregulation of the HIF-1 alpha/VEGF and AEG-1 signaling pathways and by the inhibition of epithelial-mesenchymal transition (EMT). This study provides a new insight into the mechanism of Huaier on antimetastatic therapy and a new scientific basis for comprehensive treatment strategies for MM.