目的 评估肝癌HepG2细胞分泌的Exosome对间充质干细胞(MSC)分化为肿瘤相关成纤维细胞(CAF)的影响及其相互作用机制.方法 在人脂肪MSC培养体系中加入HepG2细胞分泌的Exosome进行培养,采用Western blot法检测CAF特征性蛋白的表达情况.将已鉴定为CAF样条件培养基(CAF-CM)和牛血清白蛋白对照组分别加至HepG2培养基中,采用Western blot法和定量PCR检测上皮间质转化相关基因的表达,MTS法检测细胞增殖,Transwell法检测HepG2细胞的迁移和侵袭.结果 HepG2细胞分泌的Exosome表达CD63、热休克蛋白(HSP)70和HSP90.将Exosome加入MSC培养体系后14 d,可检测到α平滑肌肌动蛋白、成纤维细胞激活蛋白α、白细胞介素(IL)-6、IL-8和IL-1β等CAF特征性蛋白的表达.MTS法检测CAF-CM组的细胞增殖OD值为1.075±0.104,明显高于对照组的0.874±0.066(P=0.023)和MSC条件培养基组的0.649±0.034(P=0.0005).CAF-CM组迁移的HepG2细胞数为(42.5±9.1)个,明显高于对照组的(18.5±3.1)个(P=0.001);CAF-CM组侵袭细胞数为(29.0±3.5)个,明显高于对照组的(13.1±3.7)个(P=0.009).CAF-CM组Smad交互蛋白1(P=0.040)、β-catenin(P=0.038)、纤连蛋白(P=0.029)和Vimentin(P=0.013)的表达较对照组显著上调;而CAF-CM组的紧密连接蛋白表达显著低于对照组(P=0.010).结论 肝癌HepG2细胞系分泌的Exosome可诱导脂肪组织来源的MSC分化为CAF,后者又可以促进HepG2细胞的增殖、迁移和侵袭.%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.
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