The interactions between GPR30 and the major biomarkers in infiltrating ductal carcinoma of the breast in an asian population

Objective: G-protein-coupled receptor 30 (GPR30) has been reported to be a novel estrogen receptor α (ERα) in vitro. Therefore, the Interactions among GPR30, ERα, progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER-2/neu), and their prognostic utilities in the infiltrating ductal carcinoma (IDC) of the breast were evaluated. Materials and Methods: Messenger RNA (mRNA) levels of GPR30, ERα, PR and HER-2/neu in the tumor samples of 118 Taiwanese IDC patients and 27 non-tumor mammary tissues were measured via quantitative polymerase chain reaction analyses. The correlations of GPR30 mRNA levels with clinical parameters, i.e. tumor/non-tumor, ERα, PR, HER-2/neu, age, lymph node metastasis, lymph-vascular invasion, grade, stage and patient survival, were assessed by using appropriate statistical analyses. Results: GPR30 expression was observed to be lower in IDC (p < 0.001) than in non-tumor mammary tissues. Importantly, GPR30 mRNA level was positively correlated with that of ERα (p = 0.001) and PR (p = 0.001) but not correlated with that of HER-2/neu when they were analyzed as continuous variables. However, lower GPR30 was noticed in tumors with HER-2/neu protein overexpression. GPR30 expression was not correlated with age, lymph node metastasis, lymph-vascular invasion, grade and stage in IDC. GPR30 expression was not an independent prognostic factor for patient survival. Conclusion: GPR30 expression is downregulated in IDC. GPR30 is preferentially co-expressed with ER and/or PR but is lowly expressed in HER-2/neu(+) tumors. The correlation of GPR30 expression with clinical parameters, including patient survival, was not evident in this cohort.