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Mechanobiology of Disease
Thursday Speaker Abstracts
32
Cancer Cells Sense and Respond to Their Mechanical Environment during Confined
Invasion
Andrew W. Holle
1
, Kim Clar
1
, Neethu Govindankutty Devi
1,2
, Ralf Kemkemer
1,3
, Joachim P.
Spatz
1,4
.
1
Max Planck Institute for Medical Research, Stuttgart, Germany,
2
University of Ulm, Ulm,
Germany,
3
Reutlingen University, Reutlingen, Germany,
4
University of Heidelberg, Heidelberg,
Germany.
Cancer metastasis is dependent upon individual cancer cells to invade through physical tissue
barriers when escaping the tumor microenvironment. This process requires traction force
generation, mechanotransduction, and subsequent cytoskeletal rearrangement. Two distinct
modes of cancer cell invasion, mesenchymal and amoeboid, have been identified, and plasticity
of invasion mode can limit the effectiveness of targeted chemotherapy. Microchannels with
widths between 3 and 10 μm and lengths over 150 μm were fabricated, necessitating complete
movement of the cell into the channel. Nine different cancer cell lines from three different tissue
origins were observed interacting with the channels. Of these lines, five were found to
successfully permeate from one side of the channel to the other. In four of these lines, migration
was faster in narrow 3 μm channels than in wide 10 μm channels. Furthermore, cells navigating
narrow channels exhibited blebs and had smooth leading edge profiles, suggesting a transition
from mesenchymal invasion to amoeboid invasion. To better understand the role of the
cytoskeleton in this process, highly invasive MDA MB-231 breast cancer cells were analyzed
individually. Consistent with the hypothesis of a mesenchymal-to-amoeboid transition, a
reduction in focal adhesion protein localization was observed in narrow channels, and cells were
found to permeate narrow channels even in the absence of cell-binding ECM proteins. Chemical
inhibition of the Rho/ROCK and Rac pathways, which underlie amoeboid and mesenchymal
invasion respectively, revealed that amoeboid invasion through confined environments may rely
on both pathways in a time-dependent manner. SiR-Actin live cell labeling was used to reveal
distinct patterns of cytoskeletal organization inside wide and narrow channels. A
mechanosensing period was identified in which the cell determines the channel to be too narrow
for mesenchymal-based migration, reorganizes its cytoskeleton, and proceeds using an amoeboid
phenotype.