Expression of chorionic gonadotrophin in human pituitary adenomas

Levy A, Biswas S, Burton PA, Lightman SL. Expression of chorionic gonadotrophin in human pituitary adenomas. Eur J Endocrinol 1994;131:615–22. ISSN 0804–4643 In addition to the classical anterior pituitary hormones, many human pituitary adenomas express hormone genes ectopically. Expression of glycoprotein hormone α-subunit and, less commonly, free luteinizing hormone β (LH-β) or follicle-stimulating hormone β is characteristic of endocrinologically inactive adenomas, a subgroup thought to be derived predominantly from the gonadotroph line. Thyrotrophin β expression in these tumours is unusual, and specific chorionic gonadotrophin β (CG-β) expression, identified using oligonucleotide probes that reliably distinguish LH-β and CG-β in situ, is not well described. Using in situ hybridization histochemistry with a CG-β transcript-specific oligonucleotide probe and a non-specific LH/CG-β oligonucleotide and riboprobe, we have demonstrated specific CG-β expression in two of 35 random pituitary adenomas; LH-β expression occurred in a further eight adenomas. Unlike prolactin, growth hormone and proopiomelanocortin, which are transcribed in the vast majority of cells in their respective hormone-positive tumour subtypes, the pattern of LH/CG-β was typically a scattering of single or small clusters of hormone-positive cells in a predominantly LH/CG-β-negative tumour. Finally, although bona fide CG-β expression in human pituitary adenomas does occur, it is only at an incidence similar to that described for carcinomas of other tissues. A Levy, Department of Medicine, University of Bristol, Bristol Royal Infirmary, Marlborough Street, Bristol BS2 8HW, UK