The Molecular Mechanism Research Of Ovol2Inhibit TGF-βSignaling Pathway In Human Breast Cancer Cell

The transforming growth factor-β(TGF-β) signaling pathway plays a critical role in the progression of human breast cancer. During the early phase of tumor progression, TGF-P acts as a tumor suppressor, exemplified by deletions or mutations in the core components of the TGF-β signaling pathway, it can repress cell progression and proliferation, promote the apoptosis.On the contrary, TGF-β also promotes processes that support tumor progression such as tumor cell EMT, invasion, dissemination, and immune evasion. Ovol2is a transcription factor, who can regulate gene expression through binding to DNA directly by its zinc finger domain. Recently, it have been demonstrated that ovol2can decrease the invasion and dissemination ability of tumor cell. Ovo12can decrease the expression of mesenchymal markers Vimentin and the protein that is required when cell undergo EMT, zebl,while at the same time acquiring the expression of epithelial cell-cell junction proteins, E-cadherin, and reverse EMT into MET. The opposite function of ovo12and TGF-P signaling pathway in breast cancer cell EMT catches our eye in the connection between them.In our study, we found that over express ovo12in the breast cancer cell can repress the activity of TGF-P signaling pathway and expression of genes involved in TGF-P signaling pathway. We demonstrated that ovol2could repress the expression of smad4by realtime PCR, western blotting and luciferase activity reporter, and then used electrophoretic mobility shift assay and Chromatin immunoprecipitation assay to prove that ovol2can bind directly to the smad4promoter by5’-GGTAACGG-3’.At the same time, the zinc fingers of ovo12could bind directly to the MH1domain of smad4detected by GST-pull down and co-immunoprecipitation, and then electrophoretic mobility shift assay found ovo12can reduce the DNA binding ability of smad4. In this paper, we revealed the relationship between ovol2and TGF-P signaling pathway, and found the molecular mechanism how ovo12suppress TGF-P signaling pathway. Our finding is significant for the research about ovo12function, TGF-β signaling pathway and human breast cancer.