Cell News 04/2018
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function. By analyzing cell behavior on ex vivo tissue samples
obtained from various laminin-knockout mouse models, she
demonstrated that the presence of a certain type of laminin
(511) decreases flexibility of the basement membrane, impli-
cating this protein in mechanical-based signaling of cells such
as leukocytes.
Ending the morning session,
Alison Patteson
(Syracuse Univer-
sity), demonstrated how the intermediate filament vimentin
acts as a self-imposed safety mechanism for invading cells.
While the loss of vimentin expression greatly increase the
motility of cells through small constrictions like microfluidic
channels or collagen networks, this comes with the unwant-
ed effect of significant damage to the nucleus, indicating
that vimentin has an important role in keeping the cells from
self-destruction.
Following a short coffee break,
Daniel Riveline
(Institut de
Génétique et de Biologie Moléculaire et Cellulaire) presented
biophysical investigations of two type of active biomechanical
cell phenomena: so-called rachetaxis and the more well-known
cytokinesis. Contrary to chemotaxis or mechanotaxis where
cells direct their motion based on chemical gradients or the
mechanical profile of their surroundings, rachetaxis is a more
locally driven mode of stimulated cell movement. Here, cells
are found to follow local features of their surroundings as well
as short-range periodicity of their substrate structure. In the
case of cytokinesis, or the assembly of the cortical ring essen-
tial for cell division, periodic distributions of myosin on the
ring-shaped actin structure is a key feature.
Afterwards,
Bob Austin
(Princeton University) explained in a
highly entertaining and illuminating lecture what krummholz
(yes, that is – like rucksack - an English word!) may have to do
with malignant transformation and the emergence of cancer
drug resistance. Krummholz are the millennium-old pine (and
other) trees that grow in gnarled shapes at the timberline of
mountains. Just like krummholz at the timberline, some few
selected cancer cells may survive in the presence of cytostatic
drug gradient, barely surviving due to some genetic or epigene-
tic advantage, but able to transmit this advantage to offspring
in evolutionary cycles so that the frontier of surviving cancer
cells travels further and further uphill against the cytostatic
drug gradient. Impressive time-lapse images from a microfluid-
ic platform that recapitulates the heterogeneous environment
in a tumor showed the emergence of drug-resistant polyploid
giant prostate cancer cells (hence the term krummholz) that
survived in increasingly higher concentrations of docetaxel, a
chemotherapeutic agent.
Dapeng Bi
(Northeastern University) subsequently discussed
a topic of growing popularity within the physics of cancer
community: the role of jammed configurations and unjamming
transitions in tissues and metastasis. Importantly, he showed
how collections of epithelial cells - arranged in a stable
jammed configuration - can be induced via biochemical sig-
naling to undergo an unjamming transition to a more fluid-like
state. In contrast to the epithelial to mesenchymal transition
(EMT), these cells do not express typical mesenchymal markers,
but instead seem to adopt a collectively fluid state due more to
changes in their shape.
Participants of the 9th POC in the Felix Klein Lecture Hall in the Paulinum, University of Leipzig
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