The F-actin and adherence-dependent mechanical differentiation of normal epithelial cells after TGF-β1-induced EMT...

The epithelial to mesenchymal transition (EMT) is known to involve several physiological and pathological phenomena. In this study, we utilized a microplate measurement system (MMS) approach based on the deflection of a flexible micro-cantilever to measure cell stiffness (in Pa) and adhesion force (in nN) of a single cell during EMT with nN resolution. Our results demonstrated that after transforming growth factor-β1 (TGF-β1) induced EMT (tEMT), NMuMG cells became stiffer due to thicker and more abundant F-actin and displayed stronger vinculin accumulation after long-term cell-substrate adhesion. The MMS could distinguish differences in compressive stiffness (219 ± 10 and 287 ± 14 Pa), tensile stiffness (114 ± 14 and 132 ± 12 Pa), and adhesion force (150 ± 42 and 192 ± 31 nN) between cells before and after tEMT. However, without proper development of the F-actin structure and adequate adherent time, the mechanical differences were diminished. After tEMT, the cells with increased stiffness and a cell-substrate adhesion force benefited by migrating more rapidly and had more invasiveness. Thus, this technology has the potential to benefit research focused on cancer diagnosis, drug development, and cell-substrate interactions.