Anthocyanins from Hibiscus sabdariffa calyx attenuate in vitro and in vivo melanoma cancer metastasis

Melanoma cell metastasis is the main cause of patient death. To develop more effective strategies for the prevention or treatment of melanoma, we investigated the inhibitory effects of HAs (the anthocyanin-rich extract from Hibiscus sabdariffa calyx) and explored underlying molecular mechanisms. In this study, we found that HAs significantly inhibited B16-F1 cell migration and suppressed HUVECs tube formation. Furthermore, the daily oral administration of HAs efficiently blocked blood vessel development, body weight, lung metastasis, tumors size, haemoglobin (Hb) content as well as CD31 expression of tumors. All these effects of HAs could be mediated via the PI3K/Akt and Ras/MAPK cascade pathways and its downstream effectors VEGF and MMP-2/-9, these proteins were remarkably reduced. These findings suggested for the first time that HAs could inhibit tumor growth, lung metastasis and tumor-angiogenesis. Based on the results, HAs is a potentially good candidate for alternative therapeutic strategies against melanoma development.