Effects of substrate stiffness on the viscoelasticity and migration of prostate cancer cells by atomic force microscopy

The stiffness of the extracellular matrix of tumour cells plays a key role in tumour cell metastasis. However, it is unclear how mechanical properties regulate the cellular response to the matrix environmental. In this study, atomic force microscopy and laser confocal imaging were used to qualitatively quantify the relationship between substrate stiffness and the migration of prostate cancer (PCa) cells. Cells cultured on stiff substrate (35kPa) undergone severval interesting phenomena compared to soft substrate (3kPa). Here, the stimulation of the stiff substrate promoted the F-actin skeleton filaments into bundles and increased the polarity index of the external contour of PCa cells. Analysis of AFM force distance curves indicated that the elasticity of cell cultured on 35kpa increased while the viscosity decreased. Wound-healing experiments showed that PCa cells cultured on 35kpa have higher potential of migration. These phenomena suggested that the mechanical properties may correlate to the migration of PCa cells. After depolymerization of actin, the elasticity of PCa cell decreased while the viscosity increased, and the migration ability was correspondingly weakened. In conclusion, this study clearly demonstrated the relationship between substrate stiffness and the mechanical properties of cells in prostate tumor metastasis which provides a basis for understanding the changes in the biomechanical properties at the single-cell level.