1-(4-(6-bromobenzo(1-3)dioxol-5-yl)-3a-4-5-9b-tetrahydro-3h-cyclopenta(c)quinolin-8-yl)ethanone and Triple-Negative-Breast-Neoplasms

Triple-negative breast cancer (TNBC) is characterized by high vascularity and frequent metastasis. Here, we found that activation of G protein-coupled estrogen receptor (GPER) by its specific agonist G-1 can significantly inhibit interleukin 6 (IL-6) and vascular endothelial growth factor A (VEGF-A). TNBC tissue microarrays from 100 TNBC patients revealed GPER is negatively associated with IL-6 levels and higher grade and stage. Activation of GPER or anti-IL-6 antibody can inhibit both in vitro tube formation of human umbilical vein endothelial cells (HUVECs) and migration of TNBC cells. While recombinant IL-6 supplementary can significantly reverse the inhibitory effects of G-1, suggesting the essential role of IL-6 in G-1 induced suppression of angiogenesis and invasiveness of TNBC cells. G-1 treatment decreased the phosphorylation, nuclear localization, transcriptional activities of NF-κB and suppressed its binding with IL-6 promoter. BAY11-7028, the inhibitor of NF-κB, can mimic the effect of G-1 to suppression of IL-6 and VEGF-A. While over expression of p65 can attenuate the inhibitory effects of G-1 on IL-6 and VEGF expression. The suppression of IL-6 by G-1 can further inhibit HIF-1α and STAT3 signals in TNBC cells by inhibition their expression, phosphorylation and/or nuclear localization. Moreover, G-1 also inhibited the in vivo NF-κB/IL-6 signals and angiogenesis and metastasis of MDA-MB-231 xenograft tumors. In conclusion, our study demonstrated that activation of GPER can suppress migration and angiogenesis of TNBC via inhibition of NF-κB/IL-6 signals, therefore it maybe act as an important target for TNBC treatment.

Topics: Animals; Antibodies; Antineoplastic Agents; Binding Sites; Cell Line, Tumor; Cell Movement; Cyclopentanes; Dose-Response Relationship, Drug; Female; Human Umbilical Vein Endothelial Cells; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Interleukin-6; Mice, Nude; Middle Aged; Neoplasm Invasiveness; Neovascularization, Pathologic; Neovascularization, Physiologic; NF-kappa B; Phosphorylation; Promoter Regions, Genetic; Quinolines; Receptors, Estrogen; Receptors, G-Protein-Coupled; Signal Transduction; STAT3 Transcription Factor; Time Factors; Triple Negative Breast Neoplasms; Tumor Burden; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

The orphan, membrane-bound estrogen receptor (GPER) is expressed at high levels in a large fraction of breast cancer patients and its expression is favorable for patients' survival.. We investigated the role of GPER as a potential tumor suppressor in triple-negative breast cancer cells MDA-MB-231 and MDA-MB-468 using cell cycle analysis and apoptosis assay. The constitutive activity of GPER was investigated.. GPER-specific activation with G-1 agonist inhibited breast cancer cell growth in concentration-dependent manner via induction of the cell cycle arrest in G2/M phase, enhanced phosphorylation of histone H3 and caspase-3-mediated apoptosis. Analysis of the methylation status of the GPER promoter in the triple-negative breast cancer cells and in tissues derived from breast cancer patients revealed that GPER amount is regulated by epigenetic mechanisms and GPER expression is inactivated by promoter methylation. Furthermore, GPER expression was induced by stress factors, such as radiation, and GPER amount inversely correlated with the p53 expression level.. Overall, our results establish the protective role in breast cancer tumorigenesis, and the cell surface expression of GPER makes it an excellent potential therapeutic target for triple-negative breast cancer.

Topics: Apoptosis; Carcinogenesis; Caspase 3; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cyclopentanes; Female; G2 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Humans; Quinolines; Receptors, Estrogen; Receptors, G-Protein-Coupled; RNA, Small Interfering; Triple Negative Breast Neoplasms