GPER (G protein-coupled estrogen receptor)

Class

GPER agonist (oral, enantiomerically pure small molecule)

Pathway

GPER activation drives rapid non-genomic G-protein signaling (cAMP/CREB), proteasomal c-Myc degradation, and mitotic arrest

GPER, also called GPR30, is a G protein-coupled receptor that responds to estrogen but functions independently of the classical nuclear estrogen receptors (ER-alpha and ER-beta) that drive gene transcription over hours to days. Instead, GPER sits at the cell membrane and triggers rapid, non-genomic signaling through G proteins, generating second messengers such as cyclic AMP that activate the transcription factor CREB. In some cancer cell types, this signaling cascade leads to degradation of the c-Myc protein, a key driver of cell division, and results in arrest of the cell cycle at mitosis. This makes GPER of interest as an anticancer target, particularly in tumors that no longer depend on, or have become resistant to, classical estrogen receptor signaling, including some tumors that lack ER-alpha altogether. Because GPER operates through a distinct pathway from nuclear estrogen receptors, agonists directed at it are being explored as a mechanistically differentiated approach to hormone-responsive and hormone-independent malignancies alike. More broadly, GPER biology also intersects with cardiovascular, metabolic, and immune physiology, since estrogen signaling through this receptor is present in tissues beyond the reproductive system, a consideration relevant to understanding the full physiological footprint of modulating it.