Pituitary tumor transforming gene (PTTG) expression in pituitary adenomas

We recently cloned a novel pituitary tumor transforming gene (PTTG). Here w e report PTTG expression in human pituitary adenomas and in normal pituitar y tissue. In situ hybridization revealed PTTG expression in nonfunctioning and in GH-secreting adenomas but not in normal pituitary tissue. Using a mo re sensitive detection method, RT-PCR, low level PTTG expression was detect ed in normal pituitary. However, when expression levels in normal pituitary tissue were compared with those in 54 pituitary tumors using comparative r everse transcription polymerase chain reaction (RT-PCR), we found that most tumor samples expressed higher levels of PTTG. More than 50% PTTG increase s were observed in 23 of 30 nonfunctioning pituitary tumors, all 13 GH-prod ucing tumors, 9 of 10 prolactinomas, and I ACTH-secreting tumor, with more than 10-fold increases evident in some tumors. Furthermore, higher PTTG exp ression (P = 0.03) was observed in hormone-secreting tumors that had invade d the sphenoid bone (stages III and IV; 95% CI 3.118 -9.715) compared with hormone-secreting tumors that were confined to the pituitary fossa (stages I and II; 95% CI 1.681-3.051). Therefore, PTTG abundance is a molecular mar ker for invasiveness in hormone-secreting pituitary tumors. The ubiquitous and prevalent expression of pituitary adenoma PTTG suggests that PTTG plays a role in pituitary tumorigenesis and invasiveness.