Activation-induced cytidine deaminase (AID) is necessary for the epithelial–mesenchymal transition in mammary epithelial cells

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 32; pp. E2977 - E2986
• Main Authors: Muñoz, Denise P, Lee, Elbert L, Takayama, Sachiko, Coppé, Jean-Philippe, Heo, Seok-Jin, Boffelli, Dario, Di Noia, Javier M, Martin, David I K
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 06-08-2013; National Acad Sciences
• Series: PNAS Plus
• Subjects: Animals; Azacitidine - analogs & derivatives; Azacitidine - pharmacology; Biological Sciences; Blotting, Western; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cell Line; Cell Line, Tumor; Cell Movement - genetics; Cells; CpG Islands - genetics; Cytidine Deaminase - genetics; Cytidine Deaminase - metabolism; Deoxyribonucleic acid; DNA; DNA Methylation; Epigenetics; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Epithelial-Mesenchymal Transition - genetics; Gene expression; Gene Expression Regulation; Genetic Complementation Test; HEK293 Cells; Humans; Mammary Glands, Human - cytology; Mammary Glands, Human - metabolism; Matrix Metalloproteinases - genetics; Metastasis; Mice; PNAS Plus; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Transforming Growth Factor beta - pharmacology; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1301021110

Activation-induced cytidine deaminase (AID), which functions in antibody diversification, is also expressed in a variety of germ and somatic cells. Evidence that AID promotes DNA demethylation in epigenetic reprogramming phenomena, and that it is induced by inflammatory signals, led us to investigate its role in the epithelial–mesenchymal transition (EMT), a critical process in normal morphogenesis and tumor metastasis. We find that expression of AID is induced by inflammatory signals that induce the EMT in nontransformed mammary epithelial cells and in ZR75.1 breast cancer cells. shRNA–mediated knockdown of AID blocks induction of the EMT and prevents cells from acquiring invasive properties. Knockdown of AID suppresses expression of several key EMT transcriptional regulators and is associated with increased methylation of CpG islands proximal to the promoters of these genes; furthermore, the DNA demethylating agent 5 aza-2'deoxycytidine (5-Aza-dC) antagonizes the effects of AID knockdown on the expression of EMT factors. We conclude that AID is necessary for the EMT in this breast cancer cell model and in nontransformed mammary epithelial cells. Our results suggest that AID may act near the apex of a hierarchy of regulatory steps that drive the EMT, and are consistent with this effect being mediated by cytosine demethylation. This evidence links our findings to other reports of a role for AID in epigenetic reprogramming and control of gene expression.