Myosin phosphorylation on stress fibers predicts contact guidance behavior across diverse breast cancer cells

Abstract

During cancer progression the extracellular matrix is remodeled, forming aligned collagen fibers that proceed radially from the tumor, resulting in invasion. We have recently shown that different invasive breast cancer cells respond to epitaxially grown, aligned collagen fibrils differently. This article develops insight into why these cells differ in their contact guidance fidelity. Small changes in contractility or adhesion dramatically alter directional persistence on aligned collagen fibrils, while migration speed remains constant. The directionality of highly contractile and adhesive MDA-MB-231 cells can be diminished by inhibiting Rho kinase or β1 integrin binding. Inversely, the directionality of less contractile and adhesive MTLn3 cells can be enhanced by activating contractility or integrins. Subtle, but quantifiable alterations in myosin II regulatory light chain phosphorylation on stress fibers explain the tuning of contact guidance fidelity, separate from migration per se indicating that the contractile and adhesive state of the cell in combination with collagen organization in the tumor microenvironment determine the efficiency of migration. Understanding how distinct cells respond to contact guidance cues will not only illuminate mechanisms for cancer invasion, but will also allow for the design of environments to separate specific subpopulations of cells from patient-derived tissues by leveraging differences in responses to directional migration cues.

Degradation and Remodeling of Epitaxially Grown Collagen Fibrils

“…MDA-MB-231 cells robustly engage in contact guidance and take migration steps primarily in directions along the long axis of the collagen fibrils over the first 10 h. 52,53 However, we observed that for longer times (12–24 h), cells pull (using contractility) and potentially degrade (using MMP activity) the collagen fibrils to such a large extent that the cells detach. This detachment phenotype is robust and is not seen in MTLn3 cells.…”

“…52 In addition, turning cell contractility either up or down can correspondingly alter contact guidance efficiency in a dose dependent manner. 53 MDA-MB-231 cells move on these substrates along the collagen fibrils (Fig. 1b).…”

“…Inhibition of contractility retains collagen alignment constant over time as it appears to block large changes in collagen density, but cells are disordered, presumably due to the direct affect that contractility inhibitors have on the cells ability to engage in contact guidance. Contractility appears to modulate contact guidance, 53 but not spreading on contact guidance cues. 47 However, inhibition of degradation appears to act differently.…”

“…52 This diversity in response to this 2D contact guidance cue mimics behavior seen in 3D contact guidance cues 38 and in mouse models for invasion and metastasis 58 and has been used as a substrate by which to assess the role of adhesion and contractility in tuning contact guidance fidelity. 53 …”

“…25 In addition, they may reveal differences in contact guidance due to collagen fiber deformation that are not revealed by other contact guidance systems (electrospinning, fiber drawing, microcontact printing, and generating grooves or gratings). 53 …”