Abstract: Objective To investigate the expression of Vav1 in gastric cancer(GC), and analyze its potential relevance to clinicopathological characteristics and prognostic significance in GC patients. Methods The mRNA expression level of Vav1 was detected by real-time quantitative PCR in GC cell lines (HGC- 27， SGC7901 and MGC803) and normal gastric mucosa cell line (GES-1). In addition, the protein expression of Vav1 was analyzed by immunohistochemistry in formalinfixed samples from 105 GC patients. The associations between clinical pathological features and Vav1 protein expression were evaluated in GC patients. Kaplan-Meier method and Cox regression analysis were used to analyze the related factors influencing the prognosis of GC. Results The mRNA expression levels of Vav1 were significantly higher in GC cell lines (HGC-27, SGC7901, MGC803) than those in normal gastric mucosa cell line (GES-1, P＜ 0.05). The positive expression of Vav1 in GC tissues was correlated with diameter of tumor and lymph node metastasis (P＜ 0.05). The univariate analysis showed that size of tumor, degree of differentiation, serosal invasion, lymph node metastasis and Vav1 expression were significantly related with prognosis of GC (P＜ 0.05). Results of Cox regression showed that tumor invasion depth (HR=2.764, 95% CI 1.316- 5.817, P=0.007), lymph node metastasis (HR=1.298, 95% CI 1.098- 1.534, P=0.002) and Vav1 expression (HR=2.577, 95% CI 1.066- 3.946, P=0.006) were the risk factors affecting prognosis of patients with gastric cancer.Conclusion Vav1 performs important role in the aggressiveness of GC, and Vav1 may serve as a novel prognostic factor in GC.

Key words: stomach neoplasms, proto-oncogene proteins c-vav, neoplasm invasiveness, neoplasm metastasis, prognosis