Immunohistochemical detection of FSH receptors in pituitary adenomas and adrenal tumors

Abstract

Objectives. Follicle stimulating hormone (FSH) receptors (FSHR) are physiologically expressed in the ovary and testis. It is well known that FSHR are also expressed in gonadal cancers, but the data on their incidence in extra-gonadal tumors are scarce. Recently, the expression of FSHR in the vascular endothelium within different human cancers was found, but nothing is known on FSHR appearance in non-gonadal endocrine tumors. The present paper reports on the immunohistochemical detection of FSHR in human pituitary adenomas and adrenal tumors.

Materials and methods. The study included samples of 28 pituitary adenomas and 36 adrenal tumors. Moreover, 2 samples of non-tumoral adrenal glands were also studied.

FSH receptor immunostaining was performed on paraffin sections using the rabbit anti-human FSH-R polyclonal antibody raised against 1-190 amino acid sequence from the human FSH-R (sc-13935). The pituitary adenomas were immunostained to reveal the pituitary hormones and the proliferation marker Ki-67.

Results. In the pituitary adenomas, positive immunostaining with anti-FSHR antibody occurred in the adenoma cells cytoplasm and endothelia of the intra- and peritumoral blood vessels. The cytoplasmic immunostaining was found in the majority of investigated tumors but the intensity of staining was weak to moderate. There is some tendency towards the higher cytoplasmic FSHR score in tumors with higher Ki-67 index (atypical adenomas). In contrast to the cytoplasm, the FSHR immunostaining in blood vessels is strong and concerns all the investigated samples. Strong FSHR immunostaining is present in the endothelium of intra- and/or peritumoral blood vessels in the majority of pheochromocytomas, approximatively one half of the adrenocortical adenomas and both cases of the adrenal cancers. The immunostaining is detectable also in the tumoral cell cytoplasm in all but one examined pheochromocytomas.. All the investigated adrenocortical adenomas presented strong immunostaining of cell membranes. No immunostained cell membranes were found. in adrenal cancers. The positive immunostaining was found in glandular cells, but not in blood vessels, of non-tumoral adrenal cortex and medulla.

Conclusions. Immunostaining of FSHR often occurs in the endothelium of intra- and/or peritumoral blood vessels of pituitary adenomas and benign and malignant adrenal tumors. The immunostaining may be also present in tumoral cells. A role of FSHR expression in these tumors (stimulation of angiogenesis? stimulation of cell growth?) needs further studies to be clarified.