Expression of an orphan nuclear receptor DAX-1 in human pituitary adenomas

OBJECTIVES An orphan nuclear receptor, DAX-1, is known to be involved in the development and differentiation of anterior pituitary cells, The present study aimed to examine 1) whether DAX-1 is expressed in human pituitary adenomas, and 2) if it is expressed, what types of adenoma express the factor, MATERIALS AND METHODS Adenoma tissues examined included 18 clinically non-functioning adenomas, 14 ON-secreting adenomas and 7 PRL-secreting adenomas. The expression of the following genes were tested by reverse transcription-polymerase chain reaction (RT-PCR): DAX-1, Adrenal-4-binding protein/steroidogenic factor-1 (Ad4BP/SF-1), Pit-1, LH beta, FSH beta, gonadotrophin-releasing hormone receptor (GnRN-R), GN, PRL, and TSH beta, as well as beta-actin as a control, RESULTS Eleven clinically non-functioning adenomas expressed DAX-1, in of which also expressed Ad4BP/ SF-1, Nine out of the ii DAX-1-expressing adenomas also expressed LH beta, FSH beta and GnRN-R as well, indicating that these adenomas possessed gonadotrophic properties. Nine clinically non-functioning adenomas expressed Pit-1 as well as GH, PRL and/or TSH beta, thus having somatomammotrophic or thyrotrophic properties, 3 of which overlapped with the above DAX-1-expressing adenomas. One non-functioning adenoma expressed Ad4BP/SF1 and FSH beta but not DAX-1, and another one expressed DAX-1 and Ad4BP/SE-1 with PRL, On the other hand, all ON-secreting and PRL-secreting adenomas expressed Pit-1 and GH and/or PRL, but neither DAX-1 nor Ad4BP/SF-1, CONCLUSIONS The results shown here indicate that DAX-1 is expressed in the majority of human pituitary adenomas of gonadotrophic origin in parallel with Adrenal-4-binding protein/steroidogenic factor-1.