Intermediate filament vimentin and potential role in epithelial mesenchymal transition (EMT)

Epithelial mesenchymal transition (EMT) is a biological process in which epithelial cells undergo extensive molecular reprogramming allowing these cells to undergo numerous biochemical changes and acquire a mesenchymal phenotype. This is accompanied by progressive loss of epithelial markers, gain in migratory potential and invasiveness, and enhanced capacity to produce extracellular matrix components. The digestion of underlying basement membrane facilitates the process of EMT and the fragmented anatomical appearance of the reticular basement membrane (Rbm) has been reported as a marker of completion of the process. EMT is considered critical during cancer metastasis and fibrosis. The intermediate filament protein vimentin is also an important marker of EMT and increases in abundance in epithelial cells undergoing EMT. It is also seen in tumour invasion, suggesting a particular role in cell migration. Vimentin has been most commonly used as marker to identify cells undergoing EMT in cancers; a positive correlation has been reported between vimentin and increased metastatic potential in breast cancer. This chapter reviews these issues, and highlights recent advances in understanding the role of vimentin in EMT as part of disease processes.