Differential expression of G-protein-coupled estrogen receptor-30 in human myometrial and uterine leiomyoma smooth muscle

OBJECTIVE:To determine differential expression of G-protein-coupled receptor 30 (GPR30) in uterine leiomyoma and its matched myometrium. DESIGN:GPR30 expression examined in both tissues and cultured cells. SETTING:Research laboratories. PATIENT(S):Women 35 to 50 years old with uterine leiomyomas. INTERVENTION(S):Hysterectomy. MAIN OUTCOME MEASURE(S):GPR30 expression profile. RESULT(S):Using Western blot and real-time quantitative polymerase chain reaction analyses, we found that GPR30 was highly expressed in uterine leiomyomas compared with their matched myometrium. In only three out of nine patients examined was GPR30 protein detectable by Western blot analysis in myometrial tissues, but at statistically significantly lower levels than in their leiomyomas. Confocal microscopy revealed the nuclear localization of GPR30 in leiomyoma tissues and cultured leiomyoma smooth muscle cells (SMCs). Treatment with 0.1 μM 17β-estradiol increased mRNA expression of GPR30 in leiomyoma SMCs but decreased expression in myometrial SMCs. Treatment with G-1, a GPR30 agonist, stimulated phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) in both SMC types. PD98059, the MEK inhibitor, completely inhibited G-1-induced phosphorylation of p44/42 in myometrium SMCs, but not in SMCs from leiomyoma. CONCLUSION(S):GPR30 is abundantly expressed in uterine leiomyomas, likely resulting from estrogen stimulation.