Fig. 6

Exosomal miR-155 regulates the proangiogenic switch of CAFs in vitro. a, b Western blot and densitometry analysis showed that treatment with exosomes from miR-155-mimic-transfected B16 cells downregulated the expression of SOCS1, elevated the phosphorylation levels of JAK2 and STAT3, and upregulated the expressions of MMP9, VEGFa, and FGF2. Whereas treatment with exosomes from anti-miR-155-transfected B16F10 cells resulted in the opposite effects. The ratios of the expressions of SOCS1, MMP9, VEGFa, and FGF2, and the phosphorylation levels of JAK2 and STAT3 are indicated below the panels. c, d CCK-8 assay showed that the CM from NIH/3T3 cells treated with exosomes extracted from miR-155-mimic-transfected B16 cells promoted MS-1 cell proliferation. Whereas the CM from NIH/3T3 cells treated with exosomes extracted from anti-miR-155-transfected B16F10 cells had the opposite effect. * P < 0.05, ** P < 0.01 vs. the CM from nontreated NIH/3T3 cells. # P < 0.05, ## P < 0.01 vs. the miR-NC-transfected group or anti-NC-transfected group. Student’s t-tests. e, f, and g) Overexpression of miR-155 in exosomes enhanced the promotive effects of the CM from NIH/3T3 cells that treated with miR-155-mimic-transfected B16-secreted exosomes on MS-1 cell proliferation and tube formation. Whereas reduction of miR-155 in exosomes resulted in the opposite effects (h, i, and j). * P < 0.05, ** P < 0.01, *** P < 0.001. Independent experiments performed in triplicate. Values are expressed as means ± SEM. Student’s t-tests. Scale bar, 50 μm. Anti-NC: inhibitor negative control. Anti-miR-155: miR-155 inhibitor. CAFs: cancer-associated fibroblasts. CM: conditioned medium. Exo: exosomes. FGF2: fibroblast growth factor 2. GAPDH: Glyceraldehyde 3-phosphate dehydrogenase. JAK2: Janus kinase 2. MiR-NC: miR-negative control. MMP9: matrix metalloproteinase 9. SEM: standard error of the mean. SOCS1: suppressor of cytokine signaling 1. STAT3: signal transducer and activator of transcription 3. VEGFa: vascular endothelial growth factor A