Expression of AGR2 in pituitary adenomas and its association with tumor aggressiveness

The aim of the present study was to study the expression of anterior gradient 2 (AGR2) to determine its clinical significance in pituitary adenoma (PA), and to evaluate the potential effect of AGR2 on the diagnosis, therapy or prognosis of PA. Immunohistochemistry was performed to detect the expression of AGR2 in 117 PA tissue samples. Western blotting was performed to confirm the expression profile of AGR2 in different subtypes of PAs. The data showed that in 117 different histological subtypes of PA, 51.3% exhibited AGR2-positive expression. Although AGR2 expression occurred more frequently in PAs secreting growth hormone (GH; 62.5%), adrenocorticotropic hormone (ACTH; 80.0%) and follicle-stimulating hormone (FSH; 75.0%),the positive expression rate of AGR2 showed no statistically significant differences between PA subtypes (P>0.05). The association between AGR2 expression and clinical parameters was analyzed using a χ² test, or Fisher's exact probability test when appropriate. The result showed that the aggressiveness of PA was significantly associated with AGR2 expression, and that in the majority of aggressive PAs, AGR2 was negative (P<0.001). In conclusion, the current study detected the expression of AGR2 in different subtypes of PAs for the first time. The data indicated that GH-, ACTH- and FSH-secreting PAs present marginally more frequently with AGR2 expression, howeverm the association was not significant (P>0.05). AGR2 may be a target for the study of PA aggressiveness, and a potential index for the diagnosis or prognosis of PAs.