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Fig. 7 | Journal of Translational Medicine

Fig. 7

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

Fig. 7

Small interfering RNAs of CXCR4 and CXCR7 disables the osteotropism of melanoma cells. The contribution of each chemokine receptor in the osteotropism of LCP and SK-Mel28 cells was investigated by trans-well assays after silencing of either CXCR4 or CXCR7 with dedicated siRNAs. a The transfection efficiency of anti-CXCR4 and anti-CXCR7 siRNAs was evaluated by dd-PCR (left) and WB (right). Treatment with siRNAs restrained more than 50% of mRNA levels of CXCR4 and CXCR7 in both cell lines with respect to untreated cells, while were unchanged in scramble-treated cells. A similar decrease in terms of protein expression was demonstrated in the same cell lines. Results are expressed as fold change from basal mRNA concentration (copy/µl). b LCP silenced for CXCR4 or CXCR7 were studied in terms of migratory (left) and invasive (right) capacity using SDF-1 as chemoattractant, either in presence or absence of h-Exos, and compared to both scramble and untreated cells. Melanoma cells not stimulated by SDF-1 were the negative controls. Both the migratory and invasive capacity of LCP were increased by SDF-1 stimulation in scramble and untreated cells as compared to unstimulated populations, although they were impaired by silencing of either CXCR4 or CXCR7. Similar results were obtained using the h-Exos from SK-Mel28 cells. c Migration (left) and invasion (right) of untreated, scramble and silenced SK-Mel28 cells were not influenced by SDF-1 with respect to unstimulated cells. By contrast, the stimulation with h-Exos from LCP increased the migration and invasion of untreated and scramble cells that, conversely, were dampened by treatment with anti-CXCR4 and anti-CXCR7 siRNAs. Bars are mean ± SEM. *p < 0.05; **p < 0.01

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