Mutation assay of the novel gene DOG1 in gastrointestinal stromal tumors (GISTs).

Recently, the novel gene DOG1 has been found to be overexpressed in most gastrointestinal stromal tumors (GISTs) specifically within the field of soft tissue tumors. DOG1 might play a role in development of GISTs and have potential as a diagnostic marker and therapeutic target, but the biological function and the overexpression mechanism have not yet been investigated. In this study we examined whether the DOG1 gene mutation occurs as with the KIT gene and PDGFRA gene. We investigated ten resected primary GIST tissues. All cases were examined for immunoreactivity for KIT and DOG1 and screened for mutation in the KIT gene (exons 9, 11, 13, and 17) and the PDGFRA gene (exons 12, 14, and 18) by direct DNA sequencing. Four cases with relatively good quality DNA were analyzed for the DOG1 gene (exons 1-26) mutation. All ten GISTs showed immunoreactivity for KIT. Although all cases expressed DOG1 in immunohistochemistry, we could not find any mutations within all 26 exons (a total of 104 exons) of the DOG1 gene in the four analyzed cases. Based on four cases, the DOG1 gene was found not to be mutated in GISTs.