The organization of animal cells in vivo can be categorized as being either epithelial or mesenchymal. Inter-conversions between these two states, epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET), often represent key events in animal development and pathogenesis. The molecular and cellular mechanisms by which cell-cell and cell-substrate interactions are governed during EMT/MET have been examined extensively. Recent studies have also shown that EMT/MET is implicated in the acquisition of stemness in cancer cells and is accompanied by changes in epigenetic modifications. Ongoing progresses in regenerative medicine suggest that morphological and physical changes can facilitate somatic cell reprogramming and help achieve stemness. In this review, we will describe the principles of EMT/MET, their roles in cancer and normal animal development, and their relationship to stemness. We will conclude by emphasizing that studying cell shape changes in development is important for mechanistic understanding of how EMT/MET contributes to cell lineage conversion in cancer research and therapeutic medicine.
2014 by Japan Poultry Science Association