Fig. 5

Inhibition of YAP1 prevents EBV exosome-induced fibroblast activation. A Assessment of verteporfin- and saracatinib-mediated inhibition of HK1EBV exosome-induced fibroblast contractility. B YAP1 inhibition in fibroblasts decreases EBV exosome-promoted NPC cell proliferation. The culture medium of the fibroblasts treated with inhibitor or vehicle was replaced with fresh medium containing 1% FBS after 5 hours of drug treatment, followed by 3 hours of exosomal stimulation. Fibroblast supernatants were then collected and used to treat NPC cells. Data are presented as the mean and SD of triplicate experiments. C Immunofluorescence staining of active YAP1 (green) and FAPα (red) in the fibroblasts treated with HK1EBV cell-derived exosomes, alone or together with verteporfin or saracatinib. Cells were fixed 3 hours after exosome stimulation. Blue, nuclear staining. Scale bars, 20 μm. D Western blot analysis of active YAP and its downstream target proteins in the fibroblasts treated with HK1EBV-derived exosomes, alone or together with verteporfin (3 μM) or saracatinib. Protein lysates were harvested 3 hours after exosome treatment. GAPDH was used as a loading control. E–G Assessment of verteporfin-mediated suppression of the levels of IL8 (E), CCL2 (F), and IL6 (G) released from the fibroblasts treated under the indicated conditions. H–J, Assessment of saracatinib-mediated suppression of the production of IL8 (H), CCL2 (I), and IL6 (J) released from fibroblasts. Unless otherwise indicated, verteporfin (1 μM) or saracatinib (20 μM) was added to the growth medium of fibroblasts 2 hours prior to exosome (10 μg/ml) treatment. Data are presented as the mean and SD of triplicate experiments (*p < 0.05, **p < 0.01, ***p < 0.001; Bonferroni’s multiple comparison test)