Expression of follicle stimulating hormone receptors in pituitary adenomas - a marker of tumour aggressiveness?

Abstract

In our earlier study, we found that pituitary adenomas, like other human tumours, express ectopically follicle stimulating hormone receptors (FSHR) in intratumoural blood vessels endothelia and/or tumoural cells. The aim of the present paper was to provide more detailed data on FSHR expression in different subtypes of pituitary adenomas and to evaluate its possible role as a prognostic and/ or predictive biomarker in these tumours. Forty two pituitary adenomas, surgically removed, were immunostained with antibodies against the pituitary hormones, antigen Ki-67 and 1-190 fragment of FSHR. The positive FSHR immunostaining was found in blood vessels endothelia of 88% of adenomas and in tumoural cells of 40% adenomas. In tumoural cells, the incidence of at least moderate FSHR immunostaining is significantly higher in invasive tumours (68%) compared to non-invasive (12%) ones, and higher (albeit not statistically significantly) in invasive-proliferating adenomas (Ki-67 > 3%, grade 2b) compared to invasive but non-proliferating (Ki-67 < 3%, grade 2a) ones. The present study confirms that pituitary adenomas ectopically express FSHR in intratumoural blood vessels endothelia and tumoural cells. Moreover, the expression in tumoural cells is prevalent in invasive and proliferating adenomas vs. non-invasive and non-proliferating tumours.