Geburtshilfe Frauenheilkd 2014; 74 - PO_Onko04_12
DOI: 10.1055/s-0034-1388395

GPER-1 acts as a tumor suppressor in ovarian cancer

L Seiz 1, T Ignatov 2, S Modl 2, 3, C Weißenborn 2, 3, A Zenclussen 3, SD Costa 2, O Ortmann 1, A Ignatov 1, 2
  • 1Department of Obstetrics and Gynecology, University Medical Center Regensburg, Regensburg, Germany
  • 2Department of Obstetrics and Genecology, University Clinic, Magdeburg, Germany
  • 3Department of Experimental Obstetrics and Gynecology, University Clinic, Magdeburg, Germany

Background: It is known that the new membrane-bound estrogen receptor GPER-1 acts suppressive in breast cancer cells and its expression decreases during disease progression. This study was conducted to evaluate the GPER-1 expression in ovarian cancer and its correlation with progression. Its function was tested in vitro in ovarian cancer cells.

Patients and methods: GPER-1 expression was analyzed by immunohistochemistry in 35 benign ovarian tumors, 35 tumors of low-malignant potential and in 124 ovarian cancers. GPER-1 expression was correlated to the prospectively evaluated disease-free survival of ovarian cancer patients. We also tested GPER-1 expression in ovarian cancer cells and the effect of GPER-1 stimulation on cell growth.

Results: GPER-1 expression was significantly lower in ovarian cancer tissue than in benign and low-malignant ovarian tumors. GPER-1 expression was observed in 83.1% of malignant tumors and was higher in early stage cancers and tumors with high histological differentiation. GPER-1 expression was associated with favourable clinical outcome. The difference in 2-year disease-free survival by GPER-1 expression was significant, 28.6% for GPER-1 negative and 59.2% for GPER-1 positive cases (p = 0.002). GPER-1 expression was observed in SKOV-3 and OVCAR-3 ovarian cancer cell lines. G-1, a selective GPER-1 agonist, suppressed proliferation of the two cell types via inhibition of cell cycle progression in G2/M phase and stimulation of caspase-dependent apoptosis. The blockade in G2/M phase was associated with increased expression of cyclin B1 and Cdc2 and phosphorylation of histone 3.

Conclusion: GPER-1 emerges as a new tumor suppressor with unsuspected therapeutic potential for ovarian cancer.