Contractility of the cell rear drives invasion of breast tumor cells in 3D Matrigel

Abstract

Cancer cells use different modes of migration, including integrindependent mesenchymal migration of elongated cells along elements of the 3D matrix as opposed to low-adhesion-, contractionbased amoeboid motility of rounded cells. We report that MDA-MB-231 human breast adenocarcinoma cells invade 3D Matrigel with a characteristic rounded morphology and with F-actin and myosin-IIa accumulating at the cell rear in a uropod-like structure. MDA-MB-231 cells display neither lamellipodia nor bleb extensions at the leading edge and do not require Arp2/3 complex activity for 3D invasion in Matrigel. Accumulation of phospho-MLC and blebbing activity were restricted to the uropod as reporters of actomyosin contractility, and velocimetric analysis of fluorescent beads embedded within the 3D matrix showed that pulling forces exerted to the matrix are restricted to the side and rear of cells. Inhibition of actomyosin contractility or β1 integrin function interferes with uropod formation, matrix deformation, and invasion through Matrigel. These findings support a model whereby actomyosin-based uropod contractility generates traction forces on the β1 integrin adhesion system to drive cell propulsion within the 3D matrix, with no contribution of lamellipodia extension or blebbing to movement.uring metastasis, tumor cells encounter various extracellular matrix (ECM) environments with distinct composition and architecture, including basement membrane (BM) and interstitial collagen networks (1-3). Although basic mechanisms of cell motility on 2D substrata are generally well understood, much less is known regarding the mechanics of cell migration in 3D matrix environments (1, 4-7). Recent evidence supports the conclusions that 2D and 3D migration can differ considerably and that different types of 3D motility exist depending on the biophysical properties of the 3D environment (viscoelasticity, confinement, porosity) (8-15). Understanding the mechanics of cancer cell migration in these different 3D environments is therefore of paramount importance.Schematically, two modes of 3D migration of invasive cells have been described; the models differ by the dependency on actomyosin contractility, requirement for integrin adhesion, and matrix remodeling. In the mesenchymal mode, which has some parallel with 2D migration of fibroblasts (1), invasive cells are elongated and require pericellular matrix proteolysis for extending Racdependent F-actin-based leading pseudopodia in an integrindependent manner (16)(17)(18)(19)(20). In contrast, some carcinoma cells invade with a low-adhesion amoeboid mode of migration, characterized by a round morphology, no stable intrinsic cell polarity, and a required high level of RhoA/ROCK-driven actomyosin contractility (17, 18). Amoeboid cell motility, which is typically associated with bleb formation, is independent of proteases, and it is generally thought that by forming blebs, tumor cells can squeeze themselves through preexisting voids in the matrix (5, 21). In vivo, bleb-based motility has been implicate...

The Rho family GEF Asef2 regulates cell migration in three dimensional (3D) collagen matrices through myosin II

“…5,31 The migration speed of human foreskin fibroblasts in cell-derived 3D matrices and human breast adenocarcinoma cells in 3D Matrigel were reduced following blebbistatin treatment. 5,31 Our studies were performed with HT1080 cells migrating in 3D collagen I matrices, whereas the previous experiments were done with other cell types migrating in 3D cell-derived matrices or 3D Matrigel. Therefore, the differences in matrices as well as cell types could contribute to the differential effect observed on migration with blebbistatin treatment.…”

Regulation of local expression of cell adhesion and motility-related mRNAs in breast cancer cells by IMP1/ZBP1

“…Moreover, ZBP1 is broadly expressed in non-metastatic breast cell lines and human tumors, but is downregulated in metastatic cells (Gu et al, 2009). A recent study reported that human metastatic MDA231 cells, which do not express IMP1/ZBP1, display neither lamellipodia nor bleb extensions at the leading edge and invade 3D Matrigel with a characteristic rounded morphology using a uropod-like structure (Poincloix et al, 2011). It is suggested that cells that are able to localize b-actin mRNA retain a stable and persistent polarity, leading to reduced responsiveness to orient towards exogenous chemotactic gradients; such responsiveness is required for cellular invasiveness and hence reduced metastatic potential (Lapidus et al, 2007).…”

Mechanochemical actuators of embryonic epithelial contractility

“…One such strategy involves the actuation of nonmuscle cell contractility to drive a wide range of developmental processes as well as normal physiological and pathological disease states (1-5). The contractile behaviors of cells and their interactions in multicellular arrays are not only critical in shaping and guiding tissue formation (e.g., epithelial folding) for the successful outcome of development programs (6, 7), but also play a major role in the pathology of tumor growth, the invasionmetastasis cascade, wound healing, and tissue regeneration (8,9).…”

“…One such strategy involves the actuation of nonmuscle cell contractility to drive a wide range of developmental processes as well as normal physiological and pathological disease states (1-5). The contractile behaviors of cells and their interactions in multicellular arrays are not only critical in shaping and guiding tissue formation (e.g., epithelial folding) for the successful outcome of development programs (6, 7), but also play a major role in the pathology of tumor growth, the invasionmetastasis cascade, wound healing, and tissue regeneration (8,9).From a signaling standpoint, embryonic development is a dynamic process where cells interact and coordinate force generation as their identities are patterned by spatiotemporally applied chemical stimuli. There has been considerable debate over the effectiveness of intra-versus intercellular signaling during development (10, 11); nevertheless, the cell-cell signaling and the coordination of a variety of multicellular responses are known to be mediated by gap-junction-dependent intercellular communication (12, 13).…”