Fig. 8

Possible role of melanoma-derived Exos in regulating the in vitro osteotropism of melanoma cells. a Soluble factors released by the bone fragment up-regulate membrane-CXCR7 levels in osteotropic melanoma cells (LCP), thus stimulating their migration towards the SDF-1 through the CXCR4/CXCR7 signaling activation. By contrast, not-osteotropic cells (SK-Mel28 and WM-266) are refractory to the stimulation from bone-derived soluble factors and SDF-1-mediated chemoattraction cannot be activated. b Exosomes released by osteotropic melanoma cells stimulate not-osteotropic cells to increase membrane levels of CXCR7 resulting in a reprogramming effect on their original chemoattraction toward SDF-1