Three-dimensional matrix fiber alignment modulates cell migration and MT1-MMP utility by spatially and temporally directing protrusions

Abstract

Multiple attributes of the three-dimensional (3D) extracellular matrix (ECM) have been independently implicated as regulators of cell motility, including pore size, crosslink density, structural organization, and stiffness. However, these parameters cannot be independently varied within a complex 3D ECM protein network. We present an integrated, quantitative study of these parameters across a broad range of complex matrix configurations using self-assembling 3D collagen and show how each parameter relates to the others and to cell motility. Increasing collagen density resulted in a decrease and then an increase in both pore size and fiber alignment, which both correlated significantly with cell motility but not bulk matrix stiffness within the range tested. However, using the crosslinking enzyme Transglutaminase II to alter microstructure independently of density revealed that motility is most significantly predicted by fiber alignment. Cellular protrusion rate, protrusion orientation, speed of migration, and invasion distance showed coupled biphasic responses to increasing collagen density not predicted by 2D models or by stiffness, but instead by fiber alignment. The requirement of matrix metalloproteinase (MMP) activity was also observed to depend on microstructure, and a threshold of MMP utility was identified. Our results suggest that fiber topography guides protrusions and thereby MMP activity and motility.

Modeling the two-way feedback between contractility and matrix realignment reveals a nonlinear mode of cancer cell invasion

“…Cells secrete metalloproteinase enzymes (such as MMPs) to dilute the concentration of collagen and increase the size of the pores to facilitate cell invasion. This effect is more pronounced when the density of the fibers is high and the voids between the fibers are significantly smaller than the cell body (5). Including the effect of the MMPs in our model results in an increase in the cell invasion at higher collagen densities, in agreement with our melanoma observations (Fig.…”

“…For example, the comparison between cell contractility in malignant and normal tissues has shown that the cells with malignant phenotype have a higher level of contractility (1)(2)(3)(4). This elevated contractility is directly proportional to factors such as the stiffness of the extracellular matrix (ECM) and the fiber realignment (5)(6)(7), suggesting that the cross talk between ECM and intracellular contractility mediated by mechanosensory signaling pathways is also implicated in metastasis. Specifically, the activity of Rho, a myosin GTPase that regulates the activity of myosins, is elevated in proportion to the stiffness of the surrounding matrix (1,8,9), and inhibition of Rho-associated protein kinase (ROCK) has been known to reduce the invasiveness of the tumor (1,10), demonstrating that the Rho pathway is a key promoter of cell invasion (11,12).…”

“…At the periphery of the spheroid, cells can sense and respond to the stiffness of the matrix by forming actin-rich focal adhesions with the matrix ligands. The cell-matrix interactions depend on the mechanical and microstructural properties of the matrix such as matrix rigidity (13,14), fiber alignment (5,6,15,16), interfibrillar pore size (17), and density of cell-adhesive ligands (18). Previous computational models of cell invasion have examined cellular interactions (19,20) and the interplay between protrusion forces (generated due to the polymerization of actin), traction forces (at the cell-matrix adhesions), and resisting forces (mostly the drag force caused by the viscosity of the matrix) (19,(21)(22)(23)(24).…”

The extracellular matrix in breast cancer predicts prognosis through composition, splicing, and crosslinking

“…In mesenchymal cells, organization of fibriliar matrices is the major determinant of migration patterns, such that cell migration persistence tends to be highest in aligned matrices [97,[99][100][101]. Both non-malignant and malignant epithelial cells respond to the biomechanics of their surrounding matrix [35], through multiple mechanisms [6,33,35,102].…”

Automated analysis of collagen networks via microscopy

“…It is mainly composed by collagen [1] and for this reason, collagen-based networks are widely employed as three-dimensional environments to study cell motility and tumor invasion [2]. Moreover, recent works reflect that the composition and mechanical properties of these threedimensional environments affect cellular phenotypes and migratory patterns [3,4,5].…”