The Epithelial to mesenchymal transition (EMT) is the process that drives epithelial tumor cells to acquire an invasive phenotype. The role of transforming growth factor-β1 (TGF-β1) in EMT is still debated. We used confocal laser scanning microscopy and scanning force spectroscopy to perform a morphomechanical analysis on epithelial breast cancer cells (MCF-7), comparing them before and after TGF-β1 exogenous stimulation (5 ng/mL for 48 h). After TGF-β1 treatment, loss of cell⁻cell adherence (mainly due to the reduction of E-cadherin expression of about 24%) and disaggregation of actin cortical fibers were observed in treated MCF-7. In addition, TGF-β1 induced an alteration of MCF-7 nuclei morphology as well as a decrease in the Young's modulus, owing to a rearrangement that involved the cytoskeletal networks and the nuclear region. These relevant variations in morphological features and mechanical properties, elicited by TGF-β1, suggested an increased capacity of MCF-7 to migrate, which was confirmed by a wound healing assay. By means of our biophysical approach, we highlighted the malignant progression of breast cancer cells induced by TGF-β1 exposure. We are confirming TGF-β1's role in EMT by means of morphomechanical evidence that could represent a turning point in understanding the molecular mechanisms involved in cancer progression.
Keywords: TGF-β1; cytomechanics; epithelial to mesenchymal transition (EMT).