12th Annual Symposium
Physics of Cancer
Leipzig, Germany
Aug 30 - Sept 1, 2021
Contributed Talk
3D multicellular spheroids as an in vitro model for bladder cancer: a mechanical and microrheological study by means of atomic force microscopy.
Kajangi Gnanachandran1, Joanna Pabijan1, Grażyna Pyka-Fościak2, Malgorzata Lekka1
1Department of Biophysical Microstructures Institute of Nuclear Physics, Polish Academy of Sciences, Krakòw, Poland
2Histological Department Collegium Medicum, Jagiellonian University, Krakòw, Poland
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3D cell cultures are known to better mimic the natural environment of cells and some characteristics of the solid tumours, such as the structural organization, cellular layered assembling, physiological responses, gene expression and drug resistance mechanism. Therefore, they have been widely used as new potential in vitro models for finding new biological features of cancer cells and anticancer drug discovery.
In this study, three different cell lines from bladder cancer were used to form the multicellular spheroids: HCV29 (non-malignant cancer), HT1376 (grade III carcinoma), T24 (grade IV transitional cell carcinoma). Firstly, we show that these cell lines have distinct proliferation rate, and they form spheroids in dissimilar ways as they require different amount of initial cell numbers to form spheroids of similar diameter. Secondly, we observe the differences in their morphology by using live/dead staining at different days of growth.
Knowing that cancer progression is associated with changes in the mechanical properties of cells and that Atomic Force Microscopy (AFM) is a versatile tool used to study cell elastic and rheological properties, we decided to investigate biomechanics of the spheroids at these two time points, 3 and 14 days respectively. Three parameters were compared: Young’s (compression), storage and loss (shear stress) moduli. We made the mechanical experiments at three different complexity levels: single cells, cell monolayers and 3D spheroids. Our results show that under compression, HCV29 is stiffer than HT1376 and T24. Thus, cancer cells are softer than non-malignant ones. HCV29 and T24 rigidity increases when cells are grown as monolayer. Similar relation is observed for cells undergoing shear stress. The elastic properties of HT1376 cells in monolayer are of the same order as for single HT1376 cells regardless of the type of applied deformation. The mechanical and rheological properties of bladder cancer cells are related to actin filament organisation as stress fibres are present in HCV29 and T24 cells, not in HT1376 ones.
Regarding the spheroids, even though all three cell lines form spheroids diversely and change biomechanics at the 3D level, cancer cells were still softer. These changes seem to be related to their cytoskeleton organization, presence/absence of actin fibers and the amount of extracellular matrix component. These results were confirmed by the histological images of spheroids. Therefore, we conclude that both mechanical (compression) and rheological (shear stress) properties may serve as a biophysical cancer marker.

This project has received funding from European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement N° 812772.
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