Eif5a2 Promotes Research The Molecular Mechanism Of Gastric Cancer Cell Proliferation, Invasion

Background Gastric cancer is one of the most common malignancies and the third leading cause of cancer related death in China. The pathogenesis of gastric cancer has not been fully elucidated. Eukaryotic translation initiation factor5A2(EIF5A2), as one of the candidate cancer genes, plays an important role in tumor progression and prognosis evaluation. However, little information is available about the expression of EIF5A2, its clinical/prognostic significance and potential role in human gastric cancer cell proliferation, migration and invasion.Objective(1) To collect the clinicopathological features and follow-up data and investigate the influencing factors of5-year survival time in locally advanced gastric cancer patients after radical resection;⑤(2) To investigate the expression of EIF5A2in human gastric cancer tissues and its clinical/prognostic significance;(3) To investigate the potential role of EIF5A2protein in gastric cancer cell proliferation, migration, and invasion and its potential molecular mechanisms.Material and MethodsThe medical records of patients receiving curative surgery for locally advanced gastric cancer were reviewed. The clinicopathological characteristics, strategies of treatments and follow-up data were collected. Overall survival (OS) and disease-free survival (DFS) curves were constructed using the Kaplan-Meier method, and differences between the curves were compared using the log-rank test. Multivariate analyses were performed with the Cox proportional hazard model. Variables identified as potentially important factors associated with early recurrence by univariate analysis were included in multivariate logistic regression analysis.Paraffin-embedded tumor samples and matched adjacent non-tumor tissues were obtained from111patients who underwent surgical resection for primary gastric cancer at Peking Union Medical College Hospital (PUMCH) from2002to2005. Immunohistochemistry (IHC) staining was performed on5μm sections from paraffin-embedded specimens. The association between EIF5A2expression and clinicopathological features as well as prognosis was assessed subsequently.EIF5A2gene in gastric cancer cell lines was silenced by RNA interference or high expressed by plasmid transfection. Consequently, the ability of cellular proliferation was evaluated by the CCK8methods; the ability of cellular migration and invasion were evaluated by the transwell methods. Western blotting method was used to detect proliferation-related protein (Cyclin D1and Cyclin D3), epithelial-mesenchymal transition associated markers (E-cadherin and vimentin) and c-myc, MTA1, ID1as well as MMP9.Results(1) Lauren classification (P=0.004), tumor location (P=0.030), AJCC pT stage (P=0.020), the AJCC pN stage (P＜0.001), lymphovascular invasion (P=0.022), intra-operative systemic chemotherapy (P=0.037) and postoperative chemotherapy (P<0.001) were independent risk factors for predicting5-year OS of patients receiving curative surgery for locally advanced gastric cancer. Lauren classification (P=0.011), AJCC pT stage (P=0.005), the AJCC pN stage (P<0.001), lymphovascular invasion (P=0.021), intra-operative systemic chemotherapy (P=0.009) and postoperative chemotherapy (P=0.002) were independent risk factors for predicting5-year DFS of patients receiving curative surgery for locally advanced gastric cancer.(2) EIF5A2protein highly expressed in57out of111gastric cancer tissues (51.35%). Overexpression of EIF5A2in gastric carcinoma was closely related to lymph node metastasis (P=0.040) and lymphovascular invasion (P=0.023). The5-year OS for the EIF5A2overexpression group was shorter than that for the normal EIF5A2expression group (31.3%versus60.7%, P＜0.001). The5-year DFS rate for the EIF5A2overexpression group was lower than that for the normal EIF5A2expression group (35.1%vs.64.5%, P=0.001). The overexpression of EIF5A2was an independent predictor for both OS (P=0.006) and DFS (P=0.005) in patients who underwent gastrectomy for gastric cancer.(3) EIF5A2mRNA and protein were positively expressed in seven gastric cancer cell lines. Knockdown of EIF5A2by the siRNA caused an apparent suppression of cell proliferation, migration and invasion in both MKN28and HGC27cells. After the silence of EIF5A2in MKN28and HGC27cells, the levels of the epithelial marker E-cadherin was upregulated, while the levels of mesenchymal marker vimentin was downregulated and accompanied by proliferation-related protein Cyclin D1and Cyclin D3and metastasis-associated genes protein c-myc, MTA1and ID1downregulation. On the other hand, after overexpression of EIF5A2in MKN45cells, we found that the ability of cell proliferation, migration and invasion significantly increased. The expression of E-cadherin was downregulated, while the level of mesenchymal marker vimentin was upregulated and accompanied by proliferation-related protein Cyclin D1and Cyclin D3and metastasis-associated protein c-myc, MTA1and ID1upregulation. Knockdown or overexpression of EIF5A2had no significant effect on MMP9expression in HGC27, MKN28and MKN45cells.Conclusion(1) Lauren classification, tumor location, pT stage, pN stage, lymphovascular invasion, intra-operative systemic chemotherapy and postoperative chemotherapy were closely related OS or DFS of the gastric cancer patients. Intra-operative systemic chemotherapy during curative surgery and postoperative chemotherapy may benefit patients with gastric cancer in terms of both overall survival and disease-free survival.(2) Overexpression of EIF5A2protein in gastric cancer tissues was closely related to lymph node metastasis and lymphovascular invasion. EIF5A2protein was an independent predictor for poor survival in patients undergoing surgery for gastric cancer.(3) Overexpression of EIF5A2may promote gastric cancer cell proliferation by upregulating CyclinD1and Cyclin D3, and promote gastric cancer cell aggressivess by both upregulating MTA1、c-myc and ID1and inducing epithelial-mesenchymal transition.