Background: The precise molecular mechanisms underlying the gallbladder carcinoma (GBC) metastasis has not been fully elucidated.
Methods: In the present study, metastasis-associated proteins were identified by comparative proteomic analysis. The functional study of the candidate protein vimentin was further investigated. First, a pair of higher and lower metastatic sublines (termed GBC-SD/M3 and GBC-SD, respectively), originated from the same parental cell line, was screened by spontaneous tumorigenicity and metastasis in vivo in animal study and further characterized by metastatic phenotypes analysis in vitro. Subsequently, a proteomic approach comprised two-dimensional gel electrophoresis analysis and mass spectroscopy was used to identify and compare the protein expression patterns between higher metastatic GBC-SD/M3 and lower metastatic GBC-SD cell lines. Then twenty-six proteins were identified.
Results: Among the 26 proteins identified, fourteen proteins were up-regulated and 12 proteins were down-regulated in GBC-SD/M3. Vimentin was identified and found to be overexpressed in GBC-SD/M3 as compared with GBC-SD. This result was further confirmed by quantitative PCR and Western blotting analysis. Furthermore, the cell migration and invasion potency of GBC-SD/M3 in vitro was remarkably suppressed after small interference RNA-mediated knockdown of vimentin. Moreover, immunoblot and immunohistochemical analysis on 12 human GBC specimens showed consistently increased vimentin expression in metastases compared with primary tumors.
Conclusion: Tumor vimentin level may reflect the pathological progression in some GBC and may be a useful marker for predicting tumor metastasis and a therapeutic target for the treatment of GBC patients with metastases.