Irisin and Metastatic Melanoma: Selective Anti-Invasiveness Activity in BRAF Wild-Type Cells

Irisin is a newly discovered 12 kDa messenger protein involved in energy metabolism. Irisin affects signaling pathways in several types of cancer; however, the role of irisin in metastatic melanoma (MM) has not been described yet. We explored the biological effects of irisin in in vitro models of MM cells (HBLwt/wt, LND1wt/wt, Hmel1V600K/wt and M3V600E/V600E) capable of the oncogenic activation of BRAF. We treated MM cells with different concentrations of r-irisin (10 nM, 25 nM, 50 nM, 100 nM) for 24 h–48 h. An MTT assay highlighted that r-irisin did not affect the proliferation of MM cells. We subsequently treated MM cells with 10 nM r-irisin, corresponding to the dose exhibiting biological activity in vitro. Irisin reduced the invasive ability of only LND1wt/wt (p < 0.05), which highly expressed αv gene levels, but did not affect the invasion of BRAFmut cells. Gelatin zymography analysis showed a reduction in the enzymatic activity of MMP-2 and MMP-9 in BRAFwt/wt cells treated with 10 nM r-irisin. Moreover, gene expression analysis (qPCR) of MMP-2 and MMP-9 and of the fibrinolytic system (uPAR, uPA and PAI-1) highlighted a crucial role of 10 nM r-irisin treatment in the inhibition of pro-invasive systems in BRAFwt/wt. In conclusion, our results may suggest a possible differential role of irisin in melanoma cells.