Scientific Program - 2nd Physics of Cancer Symposium

PoC - Physics of Cancer - Annual Symposium

Poster, Friday, 19:00

Local membrane mechanical probing of neoplastic and non-neoplastic human cells

Federica Tavano^1,2, Serena Bonin¹, Elisa D'Este², Giulietta Pinato², Giorgio Stanta¹, Dan Cojoc^1,2

¹
ACADEM Department University of Trieste / Cattinara Hospital, Italy

²
CNR-IOM, Istituto Officina dei Materiali, Area Science Park – Basovizza, Trieste, Italy

Contact: | Website

Metastasis, the spread of malignant cells from a primary tumor to a distant organ, represents the most common cause of death in cancer patients and the main problem for cancer treatment. Metastasis is accompanied by several processes as epithelial-mesenchymal transition, loss of cell polarity, alteration of the cytoskeleton structure and membrane modifications. These processes lead to changes in cell stiffness and the ability of cells to attach, move and spread. The mechanical properties of the cell membranes contribute to the cell deformability and movement. Therefore, characterizing these properties in connection with the cytoskeleton organization is very important for understanding better the migration mechanisms. The general statement for metastasis prone cells is to become softer [1,2].
In this study we analyse the viscoelastic properties of the cell membranes belonging to three different types of breast cell lines: MDA-MB-231, MCF-7, and HBL-100, characterised by different metastatic potential. We use optical tweezers to extract tethers from the cell membrane and measure the pulling force versus tether elongation [3,4]. From the force-elongation curve we extract three viscoelastic parameters: tether stiffness, membrane rigidity and viscosity and analyse the differences between the neoplastic and non-neoplastic cell lines. The tether stiffenss and the membrane rigidity of neoplastic cells are significantly lower than those of the non-neoplastic cells, while the viscosity has an inverse tendency, less significant.
Using the immunofluorescence assay we analyze also the actin organization within the cytoskeleton and observe that neoplastic cells present a disordered network with rather thick actin drifts, while non-neoplastic cells have a more regular structure with thin actin filaments.
Our results are in line with those obtained for other cells using AFM, in which the cell is considered as a whole body [5]. We are going to perform AFM probing on the same cell lines we have studied with OT to get complementary mechanical properties, as the elastic modulus of the cell, and correlate the results of the two techniques.
The immunofluorescence imaging suggests the progressive dysregulation of the actin cytoskeleton as one of the main causes of changes in the cells biomechanical properties. Beside microscopy we are applying proteomic analysis to investigate possible correlations between changes in cell biomechanical properties and expression of breast cancer molecular markers.

[1]		L. Banks et al., Oncogene 27 (55): 6876 (2008).

[2]		S. Suresh, Acta Biomaterialia 3: 413 (2007).

[3]		F. Tavano et al., Int. J. Optomech., in print (2011).

[4]		R. M. Hochmuth et al., Biophys. J. 70: 358 (1996).

[5]		J. Schmitz et. al., Biophys. J. 95: 1448 (2008).

University of Leipzig | Faculty of Physics and Earth Sciences | Institute of Experimental Physics I | Soft Matter Physics Division