Scanning Electron Microscopy With an Ionic Liquid Reveals the Loss of Mitotic Protrusions of Cells During the Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a key event in cancer metastasis and is characterized by increase in cell motility, increase in expression of mesenchymal cell markers, loss of proteins from cell-to-cell junction complexes, and changes in cell morphology. Here, the morphological effects of a representative EMT inducer, transforming growth factor (TGF)-beta 1, were investigated in human lung adenocarcinoma (A549) cells and pancreatic carcinoma (Panc-1) cells. TGF-beta 1 caused morphological changes characteristic of EMT, and immunostaining showed loss of E-cadherin from cell-to-cell junction complexes in addition to the upregulation of the mesenchymal marker vimentin. During scanning electron microscopy (SEM) with an ionic liquid, we observed EMT-specific morphological changes, including the formation of various cell protrusions. Interestingly, filopodia in mitotic cells were clearly observed by SEM, and the number of these filopodia in TFG-beta 1-treated mitotic cells was reduced significantly. We conclude that this reduction in such mitotic protrusions is a novel effect of TGF-beta 1 and may contribute to EMT. Microsc. Res. Tech. 74: 1024-1031, 2011. (C) 2011 Wiley Periodicals, Inc.