Activin, TGF-β and menin in pituitary tumorigenesis

Abstract

Pituitary adenomas are common monoclonal neoplasms accounting for approximately one-fifth ofprimary intracranial tumors. Prolactin-secreting pituitary adenomas (prolactinomas) are the most common form ofpituitary tumors in humans. They are associated with excessive release ofthe hormone prolactin and increased tumor growth, giving rise to severe endocrine disorders and serious clinical concerns for the patients. Recent studies indicated that the activin/TGF-β family ofgrowth factors plays a prominent role in regulating pituitary tumor growth and prolactin secretion from anterior pituitary lactotrope cells. Furthermore, these studies highlighted the tumor suppressor menin and the protein Smads as central regulators ofthese biological processes in the pituitary. Alterations in the activin/TGF-β downstream signaling pathways are critical steps towards tumor formation and progression. Thi s chapter will review the role and intracellular molecular mechanisms ofaction by which activin , TGF-β , Smads and menin act in concert to prevent pituitary tumor cell growth and control hormonal synthesis by the anterior pituitary. © 2009 Landes Bioscience and Springer Science+Business Media.