|
|
| Invited Talk, Thursday, 14:15 – 14:45 |
|
|
|
| Mechanobiology of the Cytoskeleton
and How it Impacts on Cell and Tissue Plasticity
U. Aebi1, M. Plodinec1,
E. Obermann2, R. Suetterlin1, G. Schweighauser1,
R. Zanetti3, C.-A. Schoenenberger1
|
1
|
|
M.E. Müller Institute for Structural
Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056
Basel, Switzerland |
|
|
|
|
2
|
|
Department of Pathology, University
of Basel, Switzerland |
|
|
|
| 3 |
|
Department of Obstetrics & Gynecology,
University of Basel, Switzerland |
|
|
|
| Contact:
| Website |
|
|
To probe the nanomechanical properties of cells and tissues in relation
to changes in cytoarchitecture and microenvironmental conditions, we have
been employing atomic force microscopy (AFM) complemented by light microscopy.
To this end, we have manipulated the vimentin filament network of Rat2
fibroblasts, i.e. by transient transfection with mutant desmin variants,
in order to examine the contribution of the intermediate filament (IF)
cytoskeleton to cell stiffness. In contrast to the stiffness changes that
accompanied interference with the IF system, expression of a mutant actin
variant that renders Rat2 cells tumorigenic, did not alter the stiffness
of cells cultured on solid substrates.
To exclude impacts of substrate attachment on the organization of the
cytoskeleton, we probed the stiffness of normal and tumorigenic Rat2 cells
grown as 3D spheroids. On day 3, tumor spheroids exhibited a gradual softening
from the periphery to the core accompanied by hypoxia. Low oxygen differentially
affected the mechanical properties of tumor versus normal spheroids.
To account for cell heterogeneity and complex 3D cytoarchitecture,
we further explored the correlation of tissue plasticity and hypoxia in
human breast biopsies. AFM stiffness maps complemented with histopathological
examination revealed malignant lesions to be characterized by a stiffness
gradient. Interestingly, a high ratio of soft versus stiff areas seemed
to be indicative of a more aggressive tumor. As in spheroids, biopsy softening
was associated with hypoxia. In contrast, benign lesions typically showed
a uniform stiffness, which is consistent with the fairly homogenous morphology.
We conclude that AFM stiffness testing might prove a valuable prognostic
marker for cancer progression with significant implications for treatment. |
|
