A specific antibody to detect transcription factor T-Pit: a reliable marker of corticotroph cell differentiation and a tool to improve the classification of pituitary neuroendocrine tumours

Excerpt

Pituitary adenomas, or pituitary neuroendocrine tumours (PitNETs) according to a recent proposal [1], are classified based on expression of the anterior lobe pituitary hormones (ACTH, GH, Prolactin, TSH, FSH, LH and alpha-subunit of the glycoprotein hormones) [2]. Cell differentiation in the adenohypophysis includes three main lineages, each dependent on specific transcription factors: T-Pit (T-box family member TBX19) regulates the proopiomelanocortin (POMC) lineage giving origin to the corticotrophs; Pit-1 determines the fate of somatotroph, lactotroph and thyrotroph cells, while development of FSH- and LH-producing gonadotrophs is regulated by SF-1 (steroidogenic factor-1) and GATA-2 [3, 4]. The nuclear expression of the pituitary specific transcription factors T-Pit, Pit-1 and SF-1 is retained in the pituitary tumour cells that are differentiated towards respective pituitary cell lineages and thus serves as a useful complement in the classification of PitNETs [2]. PitNETs lacking immunolabeling for both adenohypophysial hormones and pituitary transcription factors have been designated as null-cell pituitary adenomas [2]. However, lack of a specific and sensitive antibody towards T-Pit has rendered the classification of pituitary neuroendocrine tumours based on the expression of pituitary transcription factors insufficient. …