Expression of adipophilin in gastric epithelial neoplasia is associated with intestinal differentiation and discriminates between adenoma and adenocarcinoma.

Adipophilin, a lipid droplet-associated protein that regulates lipid droplet structure and formation, is expressed in a wide variety of tumors. The aims of this study were to evaluate the frequency and distribution pattern of adipophilin expression in gastric epithelial neoplasia and to correlate these variables with clinicopathological features and the mucin phenotype. We retrospectively examined 159 cases of gastric epithelial neoplasia, which were classified according to the Vienna classification system as 52 noninvasive low-grade adenoma (category 3), 65 noninvasive high-grade neoplasia (category 4), and 42 invasive neoplasia (category 5). Immunohistochemistry for adipophilin was performed, and phenotypic marker expression was determined by immunohistostaining with MUC2, MUC5AC, CD10, MUC6, and villin. Adipophilin was expressed in 41 of the 52 (79 %) category 3 cases, in 42 of the 65 (65 %) category 4 cases, and in 23 of the 42 (55 %) category 5 cases. Expression of adipophilin was only present in lesions with complete or incomplete intestinal phenotypes. Adipophilin was expressed more frequently in the surface epithelium in category 3, whereas there was a stepwise increase in cryptal staining of adipophilin from category 3 to category 5. In conclusion, adipophilin expression is closely related to the intestinal differentiation of the tumor. The pattern of immunostaining for adipophilin might be a useful new marker for discriminating adenomas from adenocarcinomas.