Figure 1.

The probable role of estrogens in the pathogenesis of parathyroid adenomas. (A) In normal parathyroid cells, estrogen signaling through ERα and ERβ1 exerts its genomic and non-genomic effects by increasing PTH secretion and release, and controlling proliferation. (B) In parathyroid tumors, the low expression of ERβ1 and the absence of ERα attenuates the protective antiproliferative effect of estrogens and enhances tumor growth. ERα and ERβ1, estrogen receptor alpha and beta 1; GPR30, G protein-coupled receptor for estrogens; ERE/AP1, estrogen responsive element/activating protein 1; mERα and β1, membrane estrogen receptor alpha and beta 1; MAPK, mitogen-activated protein kinase; cAMP, cyclic adenosine monophosphate.