Effects of an estrogen receptor antagonist on proliferation, prolactin secretion and growth factor expression in the MMQ pituitary prolactinoma cell line.

The aim of this study was to investigate the functional role of estrogen receptor α (ERα) in MMQ pituitary prolactinoma cells in the absence of estrogen with respect to proliferation, prolactin (PRL) secretion, and expression of growth factors. MMQ cells were treated with the ERα antagonist fulvestrant, then proliferation and PRL secretion were measured using MTS and enzyme-linked immunosorbent assays. Levels of ERα, vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9) and B cell leukemia/lymphoma-2 (BCL-2) were measured using quantitative polymerase chain reaction and western blot analysis. Fulvestrant acted as a potent inhibitor of ERα expression, and significantly inhibited cell proliferation (by up to 57.6±2.2%) and PRL secretion (by up to 81.0%). Fulvestrant also significantly altered the expression levels of VEGF, MMP-9 and BCL-2. We conclude that ERα plays an important functional role in pituitary prolactinomas and is also involved in the expression of particular growth factors, even in the absence of estrogen. Fulvestrant treatment may be an effective therapy for such tumors.