Estrogen receptor a enhances the transcriptional activity of ETS-1 and promotes the proliferation, migration and invasion of neuroblastoma cell in a ligand dependent manner

Background: It is well known that estrogen receptor alpha (ER alpha) participates in the pathogenic progress of breast cancer, hepatocellular carcinoma and head and neck squamous cell carcinoma. In neuroblastoma cells and related cancer clinical specimens, moreover, the ectopic expression of ER alpha has been identified. However, the detailed function of ER alpha in the proliferation of neuroblastoma cell is yet unclear. Methods: The transcriptional activity of ETS-1 (E26 transformation specific sequence 1) was measured by luciferase analysis. Western blot assays and Real-time RT-PCR were used to examine the expression of ER alpha, ETS-1 and its targeted genes. The protein-protein interaction between ER alpha and ETS-1 was determined by co-IP and GST-Pull down assays. The accumulation of ETS-1 in nuclear was detected by western blot assays, and the recruitment of ETS-1 to its targeted gene's promoter was tested by ChIP assays. Moreover, SH-SY5Y cells' proliferation, anchor-independent growth, migration and invasion were quantified using the MTT, soft agar or Trans-well assay, respectively. Results: The transcriptional activity of ETS-1 was significantly increased following estrogen treatment, and this effect was related to ligand-mediated activation of ER alpha. The interaction between the ER alpha and ETS-1 was identified, and enhancement of ER alpha activation would up-regulate the ETS-1 transcription factor activity via modulating its cytoplasm/nucleus translocation and the recruitment of ETS-1 to its target gene's promoter. Furthermore, treatment of estrogen increased proliferation, migration and invasion of neuroblastoma cells, whereas the antagonist of ER alpha reduced those effects. Conclusions: In this study, we provided evidences that activation of ER alpha promoted neuroblastoma cells proliferation and up-regulated the transcriptional activity of ETS-1. By investigating the role of ER alpha in the ETS-1 activity regulation, we demonstrated that ER alpha may be a novel ETS-1 co-activator and thus a potential therapeutic target in human neuroblastoma treatment.