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, Th e present study aimed to examine 1) whether DAX-1 is expressed in huma n pituitary adenomas, and 2) if it is expressed, what types of adenoma express the factor, MATERIALS AND METHODS Adenoma tissues examined in cluded 18 clinically non-functioning adenomas, 14 ON-secreting adenoma s 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,RE SULTS Eleven clinically non-functioning adenomas expressed DAX-1, in o f which also expressed Ad4BP/ SF-1, Nine out of the ii DAX-1-expressin g adenomas also expressed LH beta, FSH beta and GnRN-R as well, indica ting that these adenomas possessed gonadotrophic properties. Nine clin ically non-functioning adenomas expressed Pit-1 as well as GH, PRL and /or TSH beta, thus having somatomammotrophic or thyrotrophic propertie s, 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 oth er hand, all ON-secreting and PRL-secreting adenomas expressed Pit-1 a nd GH and/or PRL, but neither DAX-1 nor Ad4BP/SF-1, CONCLUSIONS The re sults shown here indicate that DAX-1 is expressed in the majority of h uman pituitary adenomas of gonadotrophic origin in parallel with Adren al-4-binding protein/steroidogenic factor-1.