6th Annual Symposium
Physics of Cancer
Leipzig, Germany
September 7-9, 2015
Contributed Talk
Cytoskeletal architecture of cancer cells during invasion through three dimensional microchannels
Andrew Holle1, Kim Clar2, Anthony Fan3, Ralf Kemkemer2, Joachim Spatz1,4
1Max Planck Institute for Intelligent Systems, Stuttgart, Germany
2University of Reutlingen, Reutlingen, Germany
3University of Illinois, Champagne, Illinois, USA
4University of Heidelberg, Heidelberg, Germany
Cancer cell invasion is a complex, multifaceted process in which a cancer cell breaks free from its tumor environment and invades the surrounding stromal tissue. In order to do this, it must synergistically combine biochemical degradation of ECM with physical traction force generation and cytoskeletal rearrangement. While much attention has been focused on the mechanical nature of this process, more work is needed to fully understand the role of the cytoskeleton and the bulk material properties of the cell during its invasive journey. Using microchannels fabricated via lithography and replica molding featuring widths between 3 and 10 microns, MDA MB-231 basal breast cancer cells were analyzed for multiple invasion metrics in conjunction with cytoskeletal inhibitor treatment. To image the cytoskeleton during this process, confocal laser scanning microscopy was combined with SiR-Actin and SiR-Tubulin labeling. The MDA MB-231 cells exhibited adhesion dependent mesenchymal-like behavior in 10 μm channels, including stop-and-go leading edge profiles and relatively lower cell speeds. Of the cells that interacted with the 3 μm channels, a higher percentage permeated to the other side of the chip, moved faster, produced blebs, and exhibited smooth leading edge profiles, which is more characteristic of amoeboid invasion. Subsequent confocal imaging revealed distinctly different patterns of actin microfilament and tubulin microtubule organization inside these wide and narrow channels, providing new information about the role of the cytoskeleton in three-dimensional invasion. An optical cell stretching device was then used to compare the stiffness of a cell line that was more likely to move through the narrow channels with that of one that preferred the wide channels, allowing for a correlation between bulk material characteristics and metastatic potential. Finally, chemical inhibitors for the Rho/ROCK and Rac pathways were found to disrupt the actin and microtubule organization and inhibit confinement-dependent invasion behavior.
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