CCN6 (WISP3) decreases ZEB1-mediated EMT and invasion by attenuation of IGF-1 receptor signaling in breast cancer

• Published in: Journal of cell science Vol. 124; no. Pt 10; pp. 1752 - 1758
• Main Authors: Lorenzatti, Guadalupe, Huang, Wei, Pal, Anupama, Cabanillas, Ana M, Kleer, Celina G
• Format: Journal Article
• Language: English
• Published: England Company of Biologists 15.05.2011
• Subjects: Breast Neoplasms - metabolism; Breast Neoplasms - pathology; CCN Intercellular Signaling Proteins; Cell Dedifferentiation - drug effects; Cell Line, Tumor; Down-Regulation; Epithelial-Mesenchymal Transition - drug effects; Female; Fluorescent Antibody Technique; Gene Knockdown Techniques; Homeodomain Proteins - biosynthesis; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Insulin-Like Growth Factor Binding Proteins - deficiency; Insulin-Like Growth Factor Binding Proteins - genetics; Insulin-Like Growth Factor Binding Proteins - metabolism; Insulin-Like Growth Factor Binding Proteins - pharmacology; Insulin-Like Growth Factor I - metabolism; Receptor, IGF Type 1 - antagonists & inhibitors; Receptor, IGF Type 1 - metabolism; Recombinant Proteins - pharmacology; RNA, Messenger - genetics; RNA, Messenger - metabolism; Signal Transduction - drug effects; Transcription Factors - biosynthesis; Transcription Factors - genetics; Transcription Factors - metabolism; Up-Regulation; Zinc Finger E-box-Binding Homeobox 1
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.084194

During progression of breast cancer, CCN6 protein exerts tumor inhibitory functions. CCN6 is a secreted protein that modulates the insulin-like growth factor-1 (IGF-1) signaling pathway. Knockdown of CCN6 in benign mammary epithelial cells triggers an epithelial to mesenchymal transition (EMT), with upregulation of the transcription factor ZEB1/δEF1. How CCN6 regulates ZEB1 expression is unknown. We hypothesized that CCN6 might regulate ZEB1, EMT and breast cancer invasion by modulating IGF-1 signaling. Exogenously added human recombinant CCN6 protein was sufficient to downregulate ZEB1 mRNA and protein levels in CCN6-deficient (CCN6 KD) HME cells and MDA-MB-231 breast cancer cells. Recombinant CCN6 protein decreased invasion of CCN6 KD cells compared with controls. We discovered that knockdown of CCN6 induced IGF-1 secretion in HME cells cultivated in serum-free medium to higher concentrations than found in MDA-MB-231 cells. Treatment with recombinant CCN6 protein was sufficient to decrease IGF-1 protein and mRNA to control levels, rescuing the effect of CCN6 knockdown. Specific inhibition of IGF-1 receptors using the pharmacological inhibitor NVP-AE541 or short hairpin shRNAs revealed that ZEB1 upregulation due to knockdown of CCN6 requires activation of IGF-1 receptor signaling. Recombinant CCN6 blunted IGF-1-induced ZEB1 upregulation in MDA-MB-231 cells. Our data define a pathway in which CCN6 attenuates IGF-1 signaling to decrease ZEB1 expression and invasion in breast cancer. These results suggest that CCN6 could be a target to prevent or halt breast cancer invasion.