Mechanical regulation of shape deformation by matrix viscoelasticity in breast tissues

The shape change is one of the phenomena seen in cancerous tissue and the physical mechanism that allows this process to take place has not been clear. The synthetic extracellular matrix (ECM) are typically almost purely elastic. In contrast, the physiological ECM in various tissues, such as brain, liver, adipose tissue, and coagulated bone marrow, etc. are all viscoelastic. Most of the studies to date have focussed largely on elastic properties of ECM. Recently synthetic ECMs have been developed which closely mimic the natural viscoelastic ECMs. In this study, we are further looking into the role of such mechanical properties in inducing the malignant phenotype in normal mammary epithelium MCF10A cell line. Based on these experimental findings we have proposed a mathematical model to capture the qualitative results. This is the first mechanical model to capture this epithelial to mesenchymal transition by changing the viscoelastic properties of ECM. We observe that as you increase the fluidic nature of the ECM, the cell proliferation rate increases, loses its spherical shape, the interface becomes rough and for small viscosities leads to the formation of fingers. We show it in the model that this finger formation can be arrested either by increasing the viscosity or elasticity.