Inactivation of the Tumor Suppressor CYLD Sensitizes Mice to Breast Cancer Development.

Background/aim: Breast cancer is a leading cause of cancer-related deaths among women. Down-regulation of the tumor suppressor gene Cyld in breast cancer has been linked to a poor prognosis. This study investigated the role of Cyld in breast cancer using conditional mutant mouse models carrying a Cyld mutation, which inactivates the deubiquitinating activity of its protein product CYLD in mammary epithelial cells.

The Tumor Suppressor CYLD Inhibits Mammary Epithelial to Mesenchymal Transition by the Coordinated Inhibition of YAP/TAZ and TGF Signaling.

Downregulation of the cylindromatosis (CYLD) tumor suppressor has been associated with breast cancer development and progression. Here, we report a critical role for CYLD in maintaining the phenotype of mammary epithelial cells in vitro and in vivo. CYLD downregulation or inactivation induced an epithelial to mesenchymal transition of mammary epithelial cells that was dependent on the concomitant activation of the transcription factors Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) and transforming growth factor beta (TGF)signaling.

Activation of peroxisome proliferator-activated receptor gamma in mammary epithelial cells upregulates the expression of tumor suppressor Cyld to mediate growth inhibition and anti-inflammatory effects.

Several studies have implicated the downregulation of the tumor suppressor Cyld expression in breast cancer development. However, the mechanisms that regulate Cyld expression in mammary epithelial cells are largely unknown. In order to investigate them, a bioinformatic analysis of the promoter region of Cyld was performed and identified putative nuclear hormone receptor response elements that included peroxisome proliferator-activated receptor gamma (PPAR-γ)-responsive elements.