Exploration of Curvature and Stiffness Dual-Regulated Breast Cancer Cell Motility by a Motor-Clutch Model and Cell Traction Force Characterization.

The migration of breast cancer cells is the main cause of death and significantly regulated by physical factors of the extracellular matrix (ECM). To be specific, the curvature and stiffness of the ECM were discovered to effectively guide cell migration in velocity and direction. However, it is not clear what the extent of effect is when these dual-physical factors regulate cell migration. Moreover, the mechanobiology mechanism of breast cancer cell migration in the molecular level and analysis of cell traction force (CTF) are also important, but there is a lack of systematic investigation. Therefore, we employed a microfluidic platform to construct hydrogel microspheres with an independently adjustable curvature and stiffness as a three-dimensional substrate for breast cancer cell migration. We found that the cell migration velocity was negatively correlated to curvature and positively correlated to stiffness. In addition, curvature was investigated to influence the focal adhesion expression as well as the assignment of F-actin at the molecular level. Further, with the help of a motor-clutch mathematical model and hydrogel microsphere stress sensors, it was concluded that cells perceived physical factors (curvature and stiffness) to cause changes in CTF, which ultimately regulated cell motility. In summary, we employed a theoretical model (motor-clutch) and experimental strategy (stress sensors) to understand the mechanism of curvature and stiffness regulating breast cancer cell motility. These results provide evidence of force driven cancer cell migration by ECM physical factors and explain the mechanism from the perspective of mechanobiology.