Effect of Human Hepatocellular Carcinoma HepG2 Cell-derived Exosome on the Differentiation of Mesenchymal Stem Cells and Their Interaction.

Objective To investigate the effect of human hepatocellular carcinoma HepG2 cell-derived Exosome on the differentiation of mesenchymal stem cells(MSC)into cancer-associated myofibroblasts(CAF)and the impacts of CAF on liver cancer cell proliferation,migration,and invasion. Methods The protein expression of HepG2 cell-derived Exosome was detected by Western blotting. MSCs were separated from human adipose tissue and cultured with HepG2 cell-derived Exosome(100 ng/nl)to initiate differentiation. The expressions of mesenchymal markers and several interleukins were also detected by Western blotting. HepG2 cells were co-cultured with the conditioned media(CM),in which HepG2 Exosome induced the differentiation of MSC into CAF. The expressions of epithelial and mesenchymal markers were detected by real-time polymerase chain reaction(PCR)and Western blotting. Cell proliferation was assessed using MTS assay. Transwell chambers were used in the in vitro migration and invasion assay. Results HepG2 cell-derived particles expressed CD63,70 kilodalton heat shock proteins,and 90 kilodalton heat shock proteins. With the treatment of HepG2 cell-derived Exosome,the expressions of mesenchymal marker α-smooth muscle actin,fibroblast activation protein α,interleukin(IL)-6,IL-8,and IL-1β were up-regulated,while vascular endothelial growth factor had no significant change. The conditioned media which HepG2 Exosome induced MSC differentiation CAF(CAF-CM)could significantly promote HepG2 cells proliferation(1.075±0.104),compared to BSA control(0.874±0.066,P=0.023)and MSC-CM(0.649±0.034,P=0.0005). CAF-CM could significantly enhance cell migration [(42.5±9.1) cells vs.(18.5±3.1) cells,P=0.001] and invasion [(29.0±3.5) cells vs.(13.1±3.7) cells,P=0.009] compared to its control group. Moreover the conditioned medium which HepG2 Exosome induced MSC to differentiate into CAF could also promote the expressions of mesenchyme-related genes Smad interacting protein 1(P=0.040),β-catenin(P=0.038),fibronectin(P=0.029),and Vimentin(P=0.013)and inhibit the expression of epithelial related genes zonula ocdudens-1(P=0.010).Conclusions Exosome extracted from HepG2 cells can induce human adipose-derived MSC to differentiate into cancer-associated myofibroblasts. CAF-like cells can promote the migration of the liver cancer cell line HepG2.