Inhibin alpha-subunit and the inhibin coreceptor betaglycan are downregulated in endometrial carcinoma

Objective: In the present study we evaluated the protein distribution and mRNA levels of inhibin α-subunit and its coreceptor betaglycan in endometrial adenocarcinoma. Design: Two groups of postmenopausal women were studied: the first group had recently diagnosed endometrial adenocarcinoma (n = 16; age range 61-79 years), and the second group (n = 12; age range 64-78 years) had undergone hysterectomy for uterine prolapse and served as control. Methods: Inhibin α-subunit and betaglycan gene expression and tissue distribution were evaluated by semiquantitative RT-PCR and immunohistochemistry respectively. Results: Inhibin α-subunit and betaglycan mRNAs were expressed by both healthy and tumoral endometria, but their expression was significantly lower in endometrial carcinoma (P < 0.001, based on Student's t test). Inhibin α-subunit expression was much weaker in the glands of tumours than in non-neoplastic specimens. Betaglycan protein was identified in the epithelial cells lining non-tumoral endometrium, and in endothelial cells of both normal and tumoral endometria. Well-differentiated neoplastic cells had a faint and scarce betaglycan staining, and poorly differentiated cells did not express betaglycan at all. Conclusions: The lower inhibin α and betaglycan expression in endometrial adenocarcinoma suggests that the inhibin action may be disrupted. However, the expression of betaglycan in the endothelia of the tumour vasculature suggests that a selective vascular response to inhibin may be possible in these tumours. © 2005 Society of the European Journal of Endocrinology.