Mechanical Responses of Cancer Cells to Different Matrices Measured by AFM and FRET

Abstract

Integrin-based focal adhesions matured at the front of the migrating cells and dissembled at the retracting edge of cells. In the formation, maturation and disassembly of focal adhesions, talin play an import role as a mediator between mechanosensitive membrane protein, integrin, and actin cytoskeleton. It is known that talin undergo conformational changes when they are stretched with higher force. Vinculin binding sites and actin binding domains is known to be exposed when talin are stretched. Matrix can impact cellular functions, such as cell growth and migration. However, how the physical properties of cancer cells change with the extracellular matrix remains to be an open question. Here, we measured the rigidities of cancer cells at different matrix using AFM and force transduction of cancer cells using a new Forster resonance energy transfer (FRET) tension sensor. Measurements the force changes on talin were conducted in normal cells (MCF10A), non-invasive cancerous cell (MCF7), and invasive cancerous human breast cells (MDA-MB-231). Using atomic force microscopy (AFM), rigidity-based mechanical properties of these three different cell lines under six different substrate stiffnesses are measured and quantified. Magnetic tweezers are used to apply force directly to integrins at focal adhesions. The correlation between the mechanical properties and forces on talin which are showed in our data reveal the different mechanisms adopted by normal and cancerous human breast cells. Our results indicate that the response of cancer cells to matrix is significantly different from that of normal cells, which provide an insight about the properties of cancer cells during the metastasis.