title: ROCK- and myosin-dependent matrix deformation enables protease-independent tumor-cell invasion in vivo.
abstract: Tumor cells invading three-dimensional matrices need to remodel the extracellular matrix (ECM) in their path. Many studies have focused on the role of extracellular proteases; however, cells with amoeboid or rounded morphologies are able to invade even when these enzymes are inhibited. Here, we describe the mechanism by which cells move through a dense ECM without proteolysis. Amoeboid tumor cells generate sufficient actomyosin force to deform collagen fibers and are able to push through the ECM. Force generation is elevated in metastatic MTLn3E cells, and this correlates with increased invasion and altered myosin light chain (MLC) organization. In metastatic cells, MLC is organized perpendicularly to the direction of movement behind the invading edge. Both the organization of MLC and force generation are dependent upon ROCK function. We demonstrate that ROCK regulates the phosphorylation of MLC just behind the invading margin of the cell. Imaging of live tumors shows that MLC is organized in a similar ROCK-dependent fashion in vivo and that inhibition of ROCK but not matrix-metalloproteases reduces cancer cell motility in vivo.
authors.affiliation: Analytical Imaging Facility, Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Wyckoff
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Pinner
authors.forename: Steve
authors.initials: S
authors.lastname: Gschmeissner
authors.forename: John S
authors.initials: JS
authors.lastname: Condeelis
authors.forename: Erik
authors.initials: E
authors.lastname: Sahai
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D018994:Myosin Light Chains / Q000378:metabolism*; D009361:Neoplasm Invasiveness / Q000503:physiopathology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D054460:rho-Associated Kinases
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases