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Fig. 6 | Journal of Translational Medicine

Fig. 6

From: Tumor-derived exosomes promote the in vitro osteotropism of melanoma cells by activating the SDF-1/CXCR4/CXCR7 axis

Fig. 6

Expression of CXCR7 is enhanced by BCM in ‘osteotropic’ cells and is induced by h-Exos in ‘not-osteotropic’ cells. a Levels of CXCR4 and CXCR7 were measured by flow-cytometry in osteotropic LCP and not-osteotropic SK-Mel28 cells following the stimulation with BCM (green) or h-Exos (yellow). Unstimulated (1% FBS) cells were the controls (blue). Histograms are the percentage of positive cells and mean fluorescence intensity (MFI) ratio relative to membrane (M) and intracellular (I) expression of CXCR4 (left) and CXCR7 (right). Neither BCM, nor h-Exos influenced the expression of CXCR4 in LCP cells. However, the stimulation with BCM significantly improved the MFI ratio of membrane levels of CXCR7 in LCP, while no variation was induced by h-Exos. By contrast, the stimulation of SK-Mel28 with BCM failed to modify CXCR4 and CXCR7 levels, while both percentage of positive cells and MFI ratio relative to CXCR7 membrane expression were significantly up-regulated by LCP-derived h-Exos. b, c Western blots confirmed a significant up-regulation (≈ 1.5-fold increase; p < 0.05) of membrane CXCR7 induced by LCP-derived h-Exos, while intracellular expression was similar to baseline. d Image is representative of flow cytometry of LCP-derived Exos revealing the absence of CXCR4 and CXCR7 on Exo membranes. The same Exos stained for CD81 served as positive control. Results are expressed as fold change from basal mRNA concentration (copy/µl) and represent mean ± SEM. Bars represent mean ± SEM. *p < 0.05

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