Purpose: We have previously reported that EPHB2 is overexpressed in gastric cancer; however, the expression profiles of its ligands, EFNB1 and EFNB2, are unknown. This study was designed to investigate the expression of EPHB2 and its ligands, EFNB1 and EFNB2, in human gastric cancer.

Methods: Semi-quantitative RT-PCR using (32)P was performed on human gastric cancer tissues and corresponding normal tissues (29 gastric cancer patients).

Results: EPHB2 was more highly expressed in tumor tissues than in normal tissues in 21 out of 29 (72.4%), in gastric cancer patients ( P = 0.01); EFNB1 and EFNB2 were highly expressed in 21 out of 29 (72.4%) ( P = 0.037) and 14 out of 29 (48.3%) patients, respectively. The overexpression of EPHB2 was frequently detected in both well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma [10/13 (76.9%) and 9/14 (64.3%), respectively]. On the other hand, the overexpression of EFNB1 was more frequently detected in poorly differentiated adenocarcinoma than in well-differentiated adenocarcinoma [12/14 (85.7%) and 7/13 (53.8%), respectively. P =0.027]. Elevated levels of EPHB2 and EFNB1 were detected in substantial subsets of early gastric cancers. Genomic alterations to these three genes in gastric cancer specimens were either not found or rarely found except for several rare variations of EPHB2.

Conclusions: These findings suggest that not only the expression of EPHB2, but the expression of its ligand EFNB1 may have some relation with the oncogenesis of gastric cancer.