| Objective : Gastric cancer(GC) is now one of the most common malignancies with a relatively high incidence and high mortality rate. The prognosis is closely related to the degree of tumor-metastasis and clinical staging systems, which illustrate depth of wall invasion, local lymph node and distal organ invasion. The survival rates of 5 years is related with tumor metastasis closely. However,the mechanism of metastasis is still unclear. In recent years, proteomics analysis has provided us with a powerful tool to study and evaluate protein expression in tumor tissues. Therefore, investigating the molecular mechanism of gastric cancer metastasis could provide insights to improve diagnosis and therapeutic approaches.Methods: In this study, we collected 15 gastric cancer and adjacent normal gastric tissues and used the isobaric tags for relative and absolute quantitation(iTRAQ) method to identify differentially expressed proteins between them. Several aberrantly expressed proteins were further validated by Western blot, real-time quantitative RT-PCR and immunohistochemical analysis. Furthermore, functional analysis of OLFM4 was carried out with small interfering siRNA-based silencing transfection methods in vitro.Result:A total of 134 proteins were differentially expressed in gastric cancer compared to non-cancerous samples. Among of them, AZU1, CPVL, OLFM4 and VIL1 were up-regulated and confirmed by Western blot, real-time quantitative RT-PCR and immunohistochemical analyses. These results were in accordance with iTRAQ. Furthermore, silencing the OLFM4 expression suppressed the migration, invasion and proliferation of the GC cells in vitro.Conclusion: The iTRAQ method was useful for analyzing the expression levels of thousands of proteins. Over-expression of OLFM4 in gastric cancer may induce the development of gastric cancer. Overall, suppression of OLFM4 expression may be a promising strategy in the development of novel cancer therapeutic drugs. |
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