Expression And Significance Of GPER, ER_αand ER_βin Primary Breast Cancer

Objective: To evaluate the expression and tissue distribution of Gprotein-coupled receptors (GPER), estrogen receptor-α (ERα) and estrogenreceptor-β (ERβ) in vasive ductal breast cancer.Methods: The expressions of GPER, ERα and ERβ were detected byimmunohistochemistry in135cases of invasive ductal breast cancer. Thecorrelation among the three ERs, as well as the association between each ofthem, and the clinicopathological variables of tumors were analyzed.Results: GPER was positively stained in the cytoplasm but not inmembrane and nucleus. GPER was detected in74.8%of all the tumors;there was no correlation between GPER expression and clinicopathologicvariables (such as age, human epidermal growth factor receptor-2, lymphnode metastasis, TNM stage, tumor size, histological grade menstruation).ERα only expressed in the nucleus and the positive ratio was53.3%. Theexpression of ERα was significantly related to the expression of theprogesterone receptor and human epidermal growth factor receptor-2buthad no correlation with other clinicopathological variables of tumor. ERβexpressed mainly in the nucleus, little in cytoplasm and stroma, with positive ratio of63.7%, whose expression also had no correlation withclinicopathological variables of tumor. Co-expression of GPER and ERαwas presented in40.7%of all the samples. The ratio of co-expression ofERα and ERβ was28.9%in135patients. Only5.2%of samples presentednone of any ERs and27.4%of them were triple positive in ERs. GPER andERβ were detected in73%and65.3%of ERα-tumors respectively. Theexpression of the three ER subtypes had no significant relationship amongthem each other. The average Nottingham prognostic index (NPI) of ERα+/ERβ+/GPER-and ERα+/ERβ+/GPER+tumors were higher thanERα-/ERβ-/GPER-tumors, with statistical significance (P values were0.046,0.022respectively).Conclusion: GPER, ERα and ERβ were widely expressed in breast cancer,thus, all of them may be involved in estrogenic effects. GPER, ERα andERβ were independent of each other, the expression ratio of GPER andERβ were high the ERα positive breast cancer patients, drugs targeting atGPER and ERβ may be the complement of endocrine treatment to breastcancer and provided research foundation to expand the field of clinicalendocrine therapy. GPER and ERβ may be the independent prognosticfactors, which had no significant relationships with clinical pathologicalprognostic indicators. However, further follow-up studies need to determinethe specific features and the effect of them on breast cancer prognosis. ERsphenotypic analysis is of great significance for understanding the influence of estrogen on breast cancer.