The Study Of Cancer-associated Fibroblast Promotes Tumor Invasion And Metastasis By Inducing Epithelial-mesenchymal Transition Via Activating Thy-1 In Human Gastric Cancer

【AIM】 To investigate the effect and the mechanism of gastric cancer-associated fibroblast(CAFs) in modulating gastric cancer epithelial-mesenchymal transition(EMT).【METHODS】 Separation, purification and identification of primary gastric cancer-associated fibroblast were performed. Co-cultured with CAFs and normal fibroblasts(NFs), migration and invasion abilities of MKN28 cells were investigated. Co-cultured with CAFs and NFs, alterations of EMT markers in MKN28 cells were also investigated; Thy-1 expression was analyzed in gastric cancer tissue chip, together with the isolated CAFs. With si-Thy-1 in CAFs, the effect of Thy-1 in modulating gastric cancer EMT-induced migration and invasion were observed.【RESULTS】 Primary gastric CAFs were successfully separated, purified and identified. The gastric CAFs had a spindle-like shape, which has no significant difference comparing to normal NFs. The expression of α-SMA m RNA in the separated CAFs is significantly higher than the expression in the matched NFs, which indicated the CAFs were identified and can be used for the further study. Co-cultured with CAFs and NFs, migration and invasion abilities of MKN28 cells were enhanced. Co-cultured with CAFs and NFs, E-cadherin expression was decreased, while expressions of Vimentin, Snail, Slug and MMP-9 were decreased in MKN28 gastric cancer cells, which indicated that CAFs promoted the EMT in the co-cultured gastric cancer cells. The immunohistochemistry detection of Thy-1 in 54 gastric cancer cases concluded that Thy-1 was over-expressed in gastric CAFs. Moreover, the m RNA and protein expressions of Thy-1 in 4/5 separated CAFs clones were significantly higher than those in paired NFs. Furthermore, when Thy-1 was knocked-down, the migration, invasion and EMT were reversed in the co-cultured MKN28 cells. The expression of Slug but not snail was partially reversed when Thy-1 was silenced. This indicated that the effect of Thy-1 in CAFs in promoting EMT, migration and invasion in co-cultured gastric cancer cells was probably due to its modulation of Slug-induced signaling pathways.【CONCLUSION】 Our studies demonstrate that gastric CAFs are able to promote EMT and migration and invasion of gastric cancer cells. The enhanced Thy-1 expression in gastric CAFs is a key molecule in the CAFs-mediated EMT process in gastric cancer metastasis.