Open AccessOncogene Activation in Pituitary Tumors
Author(s) -
Yu Run,
Melmed Shlomo
Publication year - 2001
Publication title -
brain pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.986
H-Index - 132
eISSN - 1750-3639
pISSN - 1015-6305
DOI - 10.1111/j.1750-3639.2001.tb00403.x
Subject(s) - pituitary tumors , cyclin d1 , cancer research , oncogene , biology , carcinogenesis , cell cycle , cell growth , cell , gene , endocrinology , genetics
Pituitary tumors constitute 10% of intracranial neoplasms and are mostly benign, monoclonal adenomas derived from single mutant cells. Pituitary oncogenes have been intensively studied and three of them, gsp, ccnd1 , and PTTG are abundant in significant numbers of cases. gsp is present in ∼40% of Caucasian patients with GH‐secreting tumors and results from a mutated, constitutively active α sub‐unit of Gs protein. Persistent activation of the cAMP‐PKA‐CREB pathway may lead to uncontrolled cell proliferation and GH secretion. ccnd1 is overexpressed cyclin D1, and cyclin D1 gene is amplified in some pituitary tumors. PTTG is expressed in most pituitary tumors. PTTG is localized to both the nucleus and cytoplasm and interacts with several protein partners. At least three tumorigenesis mechanisms are proposed for human PTTG. 1) PTTG and FGF form a positive feedback loop and stimulate tumor vascularity. 2) PTTG transactivates c‐myc or other pro‐proliferation genes. 3) PTTG overexpression causes aneuploidy. PTTG expression activates p53 and causes p53‐dependent and ‐independent apoptosis. Due to lack of functional human pituitary cell cultures and appropriate animal models for pituitary tumors, many of the results reviewed here are obtained from heterologous systems.