Reduced EphB6 protein in gastric carcinoma and associated lymph nodes suggests EphB6 as a gastric tumor and metastasis inhibitor.

BACKGROUND: Eph receptors comprise the largest group of the receptor tyrosine kinase (RTK) family, and Eph receptors interacting with their ligand ephrins play an important role in development and tumorigenesis. EphB6, a special Eph receptor that lacks tyrosine kinase activity, was reported to be expressed in some human cancers. The clinical significance of EphB6 in gastric carcinoma has not been well investigated.

METHODS: In this study, we detected expression of EphB6 protein in four gastric cancer cell lines and a set of gastric carcinoma tissue specimens by using immunohistochemistry. The relationship between EphB6 protein expression and clinicopathological parameters was statistically analyzed.

RESULTS: EphB6 protein was differentially detected in four gastric cancer cell lines. EphB6 protein was low expressed in 52.6%, moderately expressed in 32.59%, and strongly expressed in 14.5% of gastric carcinomas. EphB6 expression was positively associated with tumor differentiation (P< 0.001, rs= 0.476), and negatively associated with lymph node metastasis (P< 0.001, rs=-0.444) and tumor stage (P= 0.001, rs=-0.269). Low EphB6 expression was detected more often in female patients (P= 0.031). No significant relationship between EphB6 expression and patient age, tumor location, or depth of tumor invasion was identified.

CONCLUSION: Our data indicate that EphB6 protein was decreased in gastric carcinoma compared with normal mucosa. Analytic results based on pathological parameters suggests that EphB6 protein may inhibit metastasis of gastric carcinoma and could be a potential therapeutic target for gastric carcinoma.