The Hop-Derived Prenylflavonoid Isoxanthohumol Inhibits the Formation of Lung Metastasis in B16-F10 Murine Melanoma Model

Isoxanthohumol (IXN), a prenylflavonoid from hops and beer, gained increasing attention as a potential chemopreventive agent. In the present study, IXN antimetastatic potential in vitro against the highly invasive melanoma cell line B16-F10 and in vivo in a murine metastatic model was investigated. Melanoma cell viability was diminished in a dose-dependent manner following the treatment with IXN. This decrease was a consequence of autophagy and caspase-dependent apoptosis. Additionally, the dividing potential of highly proliferative melanoma cells was dramatically affected by this isoflavanone, which was in correlation with an abrogated cell colony forming potential, indicating changes in their metastatic features. Concordantly, IXN promoted strong suppression of the processes that define metastasis- cell adhesion, invasion, and migration. Further investigation at the molecular level revealed that the abolished metastatic potential of a melanoma subclone was due to disrupted integrin signaling. Importantly, these results were reaffirmed in vivo where IXN inhibited the development of lung metastatic foci in tumor-challenged animals. The results of the present study may highlight the beneficial effects of IXN on melanoma as the most aggressive type of skin cancer and will hopefully shed a light on the possible use of this prenylflavonoid in the treatment of metastatic malignancies.