Abstract
The three-step model of cell migration consisting of protrusion of a leading lamella, attachment to the substrate, and contraction of the cell body is well established for fibroblasts migrating across planar surfaces. However, it is not resolved to what extent the migration of cancer cells in a 3-dimensional tissue environment follows similar principles. Here, we present evidence that the migration of highly invasive MV3 melanoma cells in 3-dimensional collagen matrices follows the three-step concept of migration but also results in characteristic reorganization of the extracellular matrix. After incorporation in the lattice, MV3 cells spontaneously developed a slow type of migration (mean velocity, 0.19 µm/min), leading to alignment of collagen fibers at attachment sites, as detected from unfixed and fixed samples by confocal reflection contrast in combination with immunofluorescence staining. In the process of migration, the formation of focal clusters or stripes of α2 and β1 integrins colocalized with binding sites to collagen fibrils at the leading as well as the trailing edge. In contrast, CD44 was nonclustered and redistributed toward the rear end of the cell. At detachment sites, dynamic fiber traction, localized fiber disruption, and the release of cell surface determinants, including α2β1 integrins and CD44, resulted in circumscribed matrix reorganization. Not infrequently, these emerging tube-like paths of least resistance bordered by a dense fiber network facilitated the reorientation and contact guidance of proximate MV3 cells to migrate along the preexisting path. In conclusion, the migration of MV3 cells in 3-dimensional collagen lattices resulted in dynamic tissue reorganization and receptor shedding the consequences of which were directly visualized by combining confocal reflection imaging with immunofluorescence.
Footnotes
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↵1 Supported by Grants FR 1155/1-1 and KL 510/3-2 from the Deutsche Forschungs-gemeinschaft and by a grant from the Fritz-Bender-Foundation. Munich, Germany. Essential sequences of videorecordings and confocal time series analyses depicting migrating MV3 melanoma cells reorganizing 3-dimensional collagen lattices and releasing cell surface determinants were submitted with this manuscript and can be downloaded from our web site (http://natwi.natwi.uni-uwh.de).
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↵2 To whom requests for reprints should be addressed.
- Received September 18, 1996.
- Accepted April 2, 1997.
- ©1997 American Association for Cancer Research.