title: The expression of AIB1 correlates with cellular proliferation in human prolactinomas.
abstract: Estrogens as well as certain growth factors strongly influence the development and growth of prolactinomas. However, the molecular mechanisms by which extracellular factors trigger prolactinomas are not well known. Amplified in breast cancer 1 (AIB1), also known as steroid receptor co-activator 3 (SRC-3), belongs to the p160/SRC family of nuclear receptor co-activators and is a major co-activator of the estrogen receptor. Here, we report that the estrogen receptor coactivator AIB1 is overexpressed in human prolactinomas and correlates with the detection of aromatase and estrogen receptor α (ERα). Of the 87 pituitary tumors evaluated in women, 56%, corresponding to hyperoprolactinemic women, contained an enriched population of prolactin-positive cells and hence were further classified as prolactinomas. All prolactinomas stained positive for both ERα and AIB1. Moreover, AIB1 sub-cellular distribution was indicative of the cell-cycle status of tumors; the nuclear expression of AIB1 was correlated with proliferative markers whereas the cytoplasmic localization of AIB1 coincided with active caspase-3. Thus, our results demonstrate for the first time that AIB1 is expressed in prolactinomas and suggest its participation in the regulation of proliferation and apoptosis of tumoral cells. Because aromatase expression is also enhanced in these prolactinomas and it is involved in the local production of estradiol, both mechanisms, ER-AIB1 and aromatase could be related.
authors: Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Spain. jcar@usal.es
authors: José
authors: J
authors: Carretero
authors: Enrique J
authors: EJ
authors: Blanco
authors: Manuel
authors: M
authors: Carretero
authors: Marta
authors: M
authors: Carretero-Hernández
authors: Ma José
authors: MJ
authors: García-Barrado
authors: Ma Carmen
authors: MC
authors: Iglesias-Osma
authors: Deborah Jane
authors: DJ
authors: Burks
authors: Jaime
authors: J
authors: Font de Mora
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D056921:Nuclear Receptor Coactivator 3 / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology*; D015175:Prolactinoma / Q000378:metabolism* / Q000473:pathology*; D011960:Receptors, Estrogen / Q000378:metabolism*; D013223:Statistics as Topic
chemical_list: D014408:Biomarkers, Tumor; D011960:Receptors, Estrogen; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3