EMT changes actin cortex rheology in a cell-cycle dependent manner
The actin cortex is a key structure for cellular mechanics and cellular migration. Accordingly, cancer cells were shown to change their mechanical properties based on different degrees of malignancy and metastatic potential. Epithelial-Mesenchymal transition (EMT) is a cellular transformation associated with cancer progression and malignancy. To date, a detailed study of the effects of EMT on the frequency-dependent viscoelastic mechanics of the actin cortex is still lacking. In this work, we have used an established AFM-based method of cell confinement to quantify the rheology of the actin cortex of human breast, lung and prostate epithelial cells before and after EMT in a frequency range of 0.02 − 2 Hz. Interestingly, we find for all cell lines opposite EMT-induced changes in interphase and mitosis; while the actin cortex softens upon EMT in interphase, it stiffens in mitosis. Our rheological data can be accounted for by a rheological model with a characteristic time scale of slowest relaxation. In conclusion, our study discloses a consistent rheological trend induced by EMT in human cells of diverse tissue origin reflecting major structural changes of the actin cytoskeleton upon EMT.