Pituitary senescence: the evolving role of Pttg.
Despite the high prevalence of pituitary adenomas they are invariably benign, indicative of unique intrinsic mechanisms controlling pituitary cell proliferation. Cellular senescence is characterized by a largely irreversible cell cycle arrest and constitutes a strong anti-proliferative response, which can be triggered by DNA damage, chromosomal instability and aneuploidy, loss of tumor suppressive signaling or oncogene activation. In vivo senescence is an important protective mechanism against cancer. Here we discuss prospective mechanisms underlying senescence-associated molecular pathways activated in benign pituitary adenomas. Both deletion and over-expression of pituitary tumor transforming gene (Pttg) promote chromosomal instability and aneuploidy. Pttg deletion abrogates tumor development by activating p53/p21-dependent senescence pathways. Abundant PTTG in GH-secreting pituitary adenomas also triggers p21-dependent senescence. Pituitary p21 may therefore safeguard against further chromosomal instability by constraining pituitary tumor growth. These observations point to senescence as a target for effective therapy for both tumor silencing and growth restraint towards development of pituitary malignancy.
Department of Medicine, Division of Endocrinology and Metabolism, Cedars Sinai Medical Center-David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90048, USA. chesnokovav@cshs.org
Vera
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Chesnokova
Shlomo
S
Melmed
D000236:Adenoma / Q000378:metabolism*; D000782:Aneuploidy; D000818:Animals; D016922:Cellular Senescence / Q000502:physiology*; D043171:Chromosomal Instability; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000235:genetics; D006801:Humans; D051379:Mice; D009363:Neoplasm Proteins / Q000502:physiology*; D010902:Pituitary Gland / Q000473:pathology; D010911:Pituitary Neoplasms / Q000378:metabolism*; D064249:Securin
D009363:Neoplasm Proteins; D064249:Securin; C578002:pituitary tumor-transforming protein 1, human