Mechanotransduction of mesenchymal melanoma cell invasion into 3D collagen lattices: Filopod-mediated extension–relaxation cycles and force anisotropy

Abstract

a b s t r a c tMesenchymal cell migration in interstitial tissue is a cyclic process of coordinated leading edge protrusion, adhesive interaction with extracellular matrix (ECM) ligands, cell contraction followed by retraction and movement of the cell rear. During migration through 3D tissue, the force fields generated by moving cells are non-isotropic and polarized between leading and trailing edge, however the integration of protrusion formation, cell-substrate adhesion, traction force generation and cell translocation in time and space remain unclear. Using high-resolution 3D confocal reflectance and fluorescence microscopy in GFP/actin expressing melanoma cells, we here employ time-resolved subcellular coregistration of cell morphology, interaction and alignment of actin-rich protrusions engaged with individual collagen fibrils. Using single fibril displacement as sensitive measure for force generated by the leading edge, we show how a dominant protrusion generates extension-retraction cycles transmitted through multiple actin-rich filopods that move along the scaffold in a hand-overhand manner. The resulting traction force is oscillatory, occurs in parallel to cell elongation and, with maximum elongation reached, is followed by rear retraction and movement of the cell body. Combined live-cell fluorescence and reflection microscopy of the leading edge thus reveals step-wise caterpillarlike extension-retraction cycles that underlie mesenchymal migration in 3D tissue.

Force Engages Vinculin and Promotes Tumor Progression by Enhancing PI3K Activation of Phosphatidylinositol (3,4,5)-Triphosphate

“…At the tissue level, our data suggest that cells migrating as a collective also likely employ vinculin as a force sensor at cell-cell junctions, and force responsive actin cross-linking proteins; including CAS and FERM family proteins (44,58). More broadly, our results confirm the existence of focal adhesions and focal adhesion activity in 3D and in vivo and demonstrate their functional importance by showing that they are instrumental in regulating growth factor receptor signaling (11,13,59,60). Indeed, our data showed that neither matrix stiffness nor oncogenic transformation are sufficient for malignant transformation and tumor cell invasion, suggesting ECM stiffness collaborates with key oncogenic pathways to exacerbate the potentiating mutations found in cancer.…”

A cytoskeletal clutch mediates cellular force transmission in a soft, three-dimensional extracellular matrix

“…Parallel studies have quantified matrix deformations using a variety of techniques ( Bloom et al. , 2008 ; Starke et al. , 2013 ; Notbohm et al.…”

The Mechanics of Single Cell and Collective Migration of Tumor Cells

“…As a result, numerous 3D models have been developed to address these and other shortcomings of 2D systems. Confocal microscopy has been integral in the translation of 2D mechanics measurements into 3D as it allows for 3D imaging of the cell and its surroundings [45,46].…”