An epithelial-mesenchymal transition (EMT) represents a basic morphogenetic process of high cell plasticity underlying embryogenesis, wound healing, cancer metastasis and drug resistance. It involves a profound transcriptional and epigenetic reprogramming of cells. A critical role of epigenetic modifiers and their specific chromatin modifications has been demonstrated during EMT. However, it has remained elusive whether epigenetic control differs between the dynamic cell state transitions of reversible EMT and the fixed differentiation status of irreversible EMT. We have employed varying EMT models of murine breast cancer cells to identify the key players establishing epithelial-mesenchymal cell plasticity during reversible and irreversible EMT. We demonstrate that the Mbd3/NuRD complex and the activities of histone deacetylases (HDACs), and Tet2 hydroxylase play a critical role in keeping cancer cells in a highly metastatic mesenchymal state. Combinatorial interference with their functions leads to mesenchymal-epithelial transition (MET) and efficiently represses metastasis formation by invasive murine and human breast cancer cells in vivo.