Expression of hypoxia-inducible factor-1a (HIF-1a) in pituitary tumours

S. Vidal1,2, E. Horvath2, K. Kovacs2, T. Kuroki3,4, R.V. Lloyd4 and B.W. Scheithauer4

1Department of Anatomy, Laboratory of Histology, University of Santiago de Compostela, Lugo, Spain,
2Department of Laboratory Medicine and Pathology, St. Michaels Hospital, University of Toronto, Toronto, Canada
3First Department of Neurosurgery, Toho University, School of Medicine, Tokyo, Japan and
4Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, MN, USA

Offprint requests to: B.W. Scheithauer, M.D., Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905, USA. Fax: (507) 284-1599. e-mail: scheithauer.bernd@mayo.edu

 

Summary. The present study was performed to investigate HIF-1a (hypoxia-inducible factor-1a) expression in a large number of immunohistochemically and ultrastructurally characterized surgically removed pituitary tumours. The potential relation of HIF-1a with outcome variables as well as the presence of HIF-1a expression in the tumours treated with dopamine agonists and octreotide, a long-acting somatostatin analogue was also investigated. HIF-1a immunoreactivity was confined to the nucleoplasm whereas the nucleoli were unconspicuous. The distribution of HIF-1a was evident in the tumours whereas normal adenohypophysial cells showed no HIF-1a staining. HIF-1a expression was detected not only in the tumour cells but also in endothelial cells lining the blood vessels within the tumour. ACTH producing adenomas showed the lowest level of HIF-1a expression whereas pituitary carcinomas and GH producing adenomas had the highest counts. The statistical study demonstrated no significant correlation between HIF-1a expression, patient age, gender, tumour, size, invasiveness, cell proliferation rate and vascularity. These results suggest that the behaviour of pituitary tumours does not primarily depend of HIF-1a expression. Our study demonstrated an increase HIF-1a expression in bromocriptine treated PRL producing pituitary adenomas compared with untreated tumours but no increase in octreotide treated tumours. Histol. Histopathol. 18, 679-686 (2003)

Key words: Angiogenesis, Pituitary tumours, Hypoxia, MIB-1, Immunohistochemistry, Hypoxia-inducible factor-1a

DOI: 10.14670/HH-18.679