The cooperation and communication between different cell signaling transduction pathways are considered critical in the development of various types of cancer as well as drug resistance. There is evidence of crosstalk between the G protein-coupled receptor 30 (GPR30), the newly discovered estrogen receptor (ER), and the ErbB family. Heregulin (HRG)-β1, the ligand for ErbB3 and ErbB4, upregulates GPR30 expression in MCF-7, T-47D and BT-474 breast cancer cell lines that express ERα. In the present study, recombinant human HRG-β1 was used to investigate the upregulation of GPR30 expression by HRGs in MCF-7 breast cancer cells which were ERα-positive. In MCF-7 cells, the ErbB2 inhibitor, AG825, the MAPK inhibitor, PD98059, and the MEK1/2 inhibitor, U0126, blocked the HRG-β1-induced GPR30 expression. 17-β-estradiol (E2) boosted the HRG-β1-induced proliferation, migration and invasion of MCF-7 cells. Similar to E2, the specific GPR30 agonist, G-1, promoted HRG-β1-induced migration and invasion, but inhibited growth. Using the specific GPR30 antagonist, G-15, or the small interfering RNA for GPR30, the functions of GPR30 after treatment with HRG-β1 were further investegated. The results from our study indicate that the interruption between GPR30 signaling and the ErbB family system may serve as a promising therapeutic strategy for breast cancer.

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