Osteopontin-mediated gallbladder cancer cell epithelial- mesenchymal transition

Objective To investigate the association between osteopontin(OPN)and the epithelial- mesenchymal transition(EMT)in gallbladder cancer(GBC)and to elucidate the underlying signaling pathway. Methods We evaluated the clinical significance of OPN in 15 GBC patients using real- time quantitative polymerase chain reaction(Real- time PCR).We also investigated the mechanisms of OPN mediating GBC EMT to promote metastasis in GBC cell lines in vitro. Results OPN was up- regulated in the human GBC tissues.The expression of OPN in human GBC tissues was significantly higher than in the cholecystitis tissues(P< 0.01).Clone formation experiment results showed cell clone formation number(59.9±10.3) in pWPI- OPN transfection group was significantly greater than that in control group(23.7±9.2)(P< 0.05).In vitro, the characteristics of EMT were induced by lentivirus transduction of OPN into GBC- SD cells,including the down- regulation of E- cadherin and ZO- 1, and the concomitant up- regulation of N- cadherin and vimentin, whereas the ectopic expression of OPN in the GBC cell line promoted cell motility and invasiveness.The number of migrating cells in OPN over- expression group and control group was 369.3± 23.4 and 84.7±18.7 respectively(P< 0.01).The further functional studies revealed that OPN regulated the activation of ZEB1, which subsequently regulated EMT signaling pathway. Conclusion Our findings have uncovered a novel role for OPN in GBC metastasis, and provide potential therapeutic target for GBC therapy. Key words: Osteopontin; Gallbladder cancer; Epithelial- mesenchymal transition; Metastasis