Characterization of mechanical behavior of an epithelial monolayer in response to epidermal growth factor stimulation

Abstract

Cell signaling often causes changes in cellular mechanical properties. Knowledge of such changes can ultimately lead to insight into the complex network of cell signaling. In the current study, we employed a combination of atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D) to characterize the mechanical behavior of A431 cells in response to epidermal growth factor receptor (EGFR) signaling. From AFM, which probes the upper portion of an individual cell in a monolayer of cells, we observed increases in energy dissipation, Young’s modulus, and hysteresivity. Increases in hysteresivity imply a shift toward a more fluid-like mechanical ordering state in the bodies of the cells. From QCM-D, which probes the basal area of the monolayer of cells collectively, we observed decreases in energy dissipation factor. This result suggests a shift toward a more solid-like state in the basal areas of the cells. The comparative analysis of these results indicates a regionally specific mechanical behavior of the cell in response to EGFR signaling and suggests a correlation between the time-dependent mechanical responses and the dynamic process of EGFR signaling. This study also demonstrates that a combination of AFM and QCM-D is able to provide a more complete and refined mechanical profile of the cells during cell signaling.

Dynamic Mechanical Response of Epithelial Cells to Epidermal Growth Factor

“…This interpretation is consistent with morphological changes observed in A431 cells responding to EGF stimulation, where the cells undergo cell rounding, membrane ruffling, and filopodia extension, all of which might be facilitated by a more fluid-like state of the cells (Chinkers et al, 1981). (Yang et al, 2012). A 30-min baseline was established for each measurement prior to the addition of EGF.…”

“…This manuscript recapitulates some information from original works that have previously been published in Analytical Chemistry (Chen et al, 2011) and Experimental Cell Research (Yang et al, 2012). This work was supported in part by NSF Grants IIS-0713346 and DMI-0500372, ONR Grants N00014-04-1-0799 and N00014-07-1-0935, and NIH Grant R43 GM084520.…”

“…Figure 3 shows the Young's moduli, obtained at a probe speed of 5.8 µm/s and indentation depth of ~500 nm, for two hundred randomly selected A431 cells before and after the treatment with a 40-nM EGF solution (Yang et al, 2012). The focus is on the comparison, rather than on the modulus values themselves.…”

“…The actin filaments of the cytoskeleton were then stained with fluorescently labeled phalloidin and imaged with an inverted fluorescence microscope. (Yang et al, 2012).…”

Nano-biomechanical investigation of living endothelial cells

“…Cell shape and elasticity depend on cytoskeletal networks and contractile systems (Levayer and Lecuit 2012), and external factors surely influence cell stiffness as well (Yang et al 2012). Water soluble salts do have considerable influence on endothelial cell stiffness (Oberleithner et al 2009;Oberleithner et al 2007), not to speak of osmotic parameters (Bálint et al 2007a).…”