Objective  To determine the expression levels of gp78 and KAI1 in human gastric carcinoma tissue and investigate their clinical significance in the development of gastric carcinoma.   Methods  Western blot analysis and immunohistochemical staining were employed to assay gp78 and KAI1 expressions in 18 samples of normal gastric mucosa and 65 samples of gastric carcinoma tissue.   Results  Western blotting results indicated that gp78 protein level was increased in 25 cases (38.5%) and KAI1 protein level was decreased in 27 cases (41.5%). Meanwhile

simultaneous increased gp78 and decreased KAI1 levels were detected in 13 cases (20.0%). Immunohistochemical results showed that gp78 level was up-regulated in 21 cases (32.3%)

and KAI1 level was down-regulated in 22 cases (33.8%). Further

simultaneous increased gp78 and decreased KAI1 levels were found in 10 (15.4%) out of 65 cases. Spearman correlation assay suggested there was a significant negative correlation between gp78 and KAI1 expression (r=－0.908

P0.05). Respectively

the expression level of gp78 and KAI1 was significantly enhanced and reduced along with the aggravation of lymphatic metastasis

tumor infiltration

and vessel infiltration. However

no statistical difference was seen in age and sex between groups (P0.05).   Conclusion  Gp78 and KAI1 play important roles in the genesis and development of gastric carcinoma. Compared with the normal gastric mucosa tissue

the expressions of gp78 and KAI1 are remarkably up-regulated and down-regulated

respectively. In fact

overexpression of gp78 results in more degradation of KAI1

which might be responsible for infiltration and metastasis of gastric carcinoma.