Immunohistochemical localization of somatostatin receptor subtypes in benign and malignant adrenal tumours.
BACKGROUND
Somatostatin mediates its action through five receptor subtypes (sst1-5) that are widely distributed in various endocrine tissues and tumours. Because of the inhibitory effects of somatostatin, long-acting analogues have been synthesized. In contrast to their well-established use in neuroendocrine and pituitary tumours, little is known about their potential use in adrenal tumours.


OBJECTIVE
We examined somatostatin receptor protein expression in adrenal tumours of various aetiologies. Immunostaining was performed with specific polyclonal antibodies for sst1-5.


METHODS
Seven benign and eight malignant pheochromocytomas (PHEOs), eight aldosterone-secreting adenomas (APAs), nine cortisol-secreting adenomas (CPAs), seven nonfunctioning adrenal tumours (NFAs) and 25 adrenal carcinomas (CAs) as well as eight normal adrenal glands were investigated.


METHODS
Staining pattern, distribution and subcellular localization of the somatostatin receptor subtypes were evaluated.


RESULTS
In the majority of normal cortices the expression of sst1-5 was limited to the reticular zone. The medulla was predominantly positive for sst3. Most cortical adenomas were positive for all five subtypes. However, in the majority of these tumours, less than 30% of cells were positively stained. A high expression of sst4 was found in CPAs but only very few cortical carcinomas exhibited sst immunostaining. All benign PHEOs were positive for sst3. The majority presented with more than 60% of tumour cells stained. By contrast, only six out of eight malignant PHEOs were positive for sst3.


CONCLUSIONS
Somatostatin receptor subtypes are expressed in PHEOs as well as in tumours of the adrenal cortex with tumour-specific distribution patterns. This may offer new diagnostic and therapeutic possibilities.
Unger
Nicole
N
Division of Endocrinology, Medical Centre, University of Duisburg-Essen, Essen, Germany.
Serdiuk
Inna
I
Sheu
Sien-Yi
SY
Walz
Martin K
MK
Schulz
Stefan
S
Saeger
Wolfgang
W
Schmid
Kurt W
KW
Mann
Klaus
K
Petersenn
Stephan
S
D000310:Adrenal Gland Neoplasms / Q000378:metabolism*; D000311:Adrenal Glands / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D017481:Receptors, Somatostatin / Q000145:classification* / Q000378:metabolism*; D013194:Staining and Labeling
D017481:Receptors, Somatostatin