Investigating Cell Substrate Stiffness and its Effects on Morphology, Gene Expression, and Motility

Epithelial cells line organ surfaces throughout the body and perform vital physiological functions including adsorption of solutes and ions, secretion of biochemical factors, barrier protection against foreign bodies, and sensory reception. They are also the source of a wide variety of diseases from skin disorders to polycystic disease to 90% of cancer types. Due to their wide influence, it is important to fully understand epithelial cell behaviour. However, previous works have analyzed cell phenotype of single cells or colonies, which is not reflected in in vivo biological systems. Additionally, traditional biological studies place a heavy significance on the biochemical interactions of cells and their surroundings. This approach often does not acknowledge the contribution of the mechanical interactions between the substrate on which cells are grown on and the biomechanical signaling resulting from physical adhesions between neighbouring cells. Here, we elucidate the individual and combined effects of cell-substrate and cell-cell adhesions on fully confluent epithelium to reveal a more physiologically relevant model of study. To perform this study, we manufacture polydimethylsiloxane substrates of varying stiffness to map the phenotypical contribution from substrate stiffness. Additionally, we use a variety of mechanisms to inhibit or degrade intercellular adhesion proteins such as e-cadherin to modulate cell-cell interactions. We use these two methods to comprehensively study morphology, gene expression, and cell motility.