Protein expression of insuline-like growth factor I and II, growth hormone and growth hormone receptor in canine cortisol-producing adrenocortical tumors

Abstract

Cushing’s syndrome is an important endocrinological disorder in dogs. In 15-20% of the cases it is caused by excessive secretion of glucocorticoids by an adrenocortical tumor (AT) that is benign or malignant. It has become clear that the growth hormone-insulin-like growth factor pathway plays a role in the pathogenesis of ATs. In this research we compared the expression of growth hormone (GH), the growth hormone receptor (GHR), insulin-like growth factor I receptor (IGF-IR) and insulin-like growth factor II receptor (IGF-IIR) in normal adrenal tissue, cortisol-producing adrenocortical adenomas (ACAs) and carcinomas (ACCs) of dogs by immonohistochemistry (IHC). A significant higher intensity of staining of GHR was demonstrated in the ACAs as compared to the normal adrenal glands. However, the intensity of staining in ACAs was also stronger than in the ACCs (although not significant). This makes the role of GHR in tumorigenesis less likely. There were no significant differences between the intensity or proportion of staining of GH, IGF-IR and IGF-IIR between the normal adrenal glands and the ATs. Therefore, there also seems to be no roles for GH, IGF-IR and IGF-IIR in tumorigenesis in adrenal tissue.