1. The Cdc42/Rac1 regulator CdGAP is a novel E-cadherin transcriptional co-repressor with Zeb2 in breast cancer.
- Author
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He, Y, Northey, J, Pelletier, A, Kos, Z, Meunier, L, Haibe-Kains, B, Mes-Masson, A-M, Côté, J-F, Siegel, P, and Lamarche-Vane, N
- Subjects
Animals ,Antigens ,CD ,Breast Neoplasms ,Cadherins ,Cell Line ,Tumor ,Epithelial-Mesenchymal Transition ,Female ,GTPase-Activating Proteins ,Gene Expression Profiling ,Gene Expression Regulation ,Neoplastic ,Gene Knockdown Techniques ,Homeodomain Proteins ,Humans ,Intercellular Junctions ,MCF-7 Cells ,Mice ,Phosphoproteins ,Prognosis ,Repressor Proteins ,Signal Transduction ,Zinc Finger E-box Binding Homeobox 2 - Abstract
The loss of E-cadherin causes dysfunction of the cell-cell junction machinery, which is an initial step in epithelial-to-mesenchymal transition (EMT), facilitating cancer cell invasion and the formation of metastases. A set of transcriptional repressors of E-cadherin (CDH1) gene expression, including Snail1, Snail2 and Zeb2 mediate E-cadherin downregulation in breast cancer. However, the molecular mechanisms underlying the control of E-cadherin expression in breast cancer progression remain largely unknown. Here, by using global gene expression approaches, we uncover a novel function for Cdc42 GTPase-activating protein (CdGAP) in the regulation of expression of genes involved in EMT. We found that CdGAP used its proline-rich domain to form a functional complex with Zeb2 to mediate the repression of E-cadherin expression in ErbB2-transformed breast cancer cells. Conversely, knockdown of CdGAP expression led to a decrease of the transcriptional repressors Snail1 and Zeb2, and this correlated with an increase in E-cadherin levels, restoration of cell-cell junctions, and epithelial-like morphological changes. In vivo, loss of CdGAP in ErbB2-transformed breast cancer cells impaired tumor growth and suppressed metastasis to lungs. Finally, CdGAP was highly expressed in basal-type breast cancer cells, and its strong expression correlated with poor prognosis in breast cancer patients. Together, these data support a previously unknown nuclear function for CdGAP where it cooperates in a GAP-independent manner with transcriptional repressors to function as a critical modulator of breast cancer through repression of E-cadherin transcription. Targeting Zeb2-CdGAP interactions may represent novel therapeutic opportunities for breast cancer treatment.
- Published
- 2017