OBJECTIVETo identify the expression of DOG-1 in gastrointestinal stromal tumors (GIST) and to explore its potential association with clinicopathological features of GIST.

METHODSTwo tissue microarrays (TMA) were used for the study. Each TMA contained 80 tissue samples of GIST from 80 different patients, with each tumor represented by one core, and paraffin-embedded sections of 40 samples from normal gastrointestinal tissue were used as control. Immunohistochemistry staining (SABC method) was performed on TMA and paraffin-embedded sections to detected the expression of c-Kit (CD117) and DOG-1.

RESULTSImmunohistochemistry showed that in 80 GIST patients, 76 cases (95.0%) were DOG-1 positive and 67 cases (83.8%) were CD117 positive. The positive rate of DOG-1 was higher than that of CD117 (P<0.05). In 13 GIST samples of negative CD117, the positive rate of DOG-1 was 100%. Expressions of both DOG-1 and CD117 were negative in all the 40 samples of normal gastrointestinal tissue. The positive expression of DOG-1 and CD117 was not significantly different in spindle cell type (96.0% vs. 96.0%, P>0.05) and in mixed cell type (91.7% vs. 75.0%, P>0.05). While in the epithelioid cell type, the DOG-1 expression was higher than CD117 expression (94.1% vs. 52.9%, P<0.05). The positive expression of DOG-1 and CD117 was not associated with age, gender, location and risk stratification of the tumors (all P>0.05).

CONCLUSIONSDOG-1 expression is up-regulated in gastrointestinal stromal tumors, especially in epithelioid cell GIST, and may be used as a new marker in the diagnosis of GIST.