Abstract 1409: Whole-cell and local viscoelasticity of stem-like and non-stem-like breast cancer cells

Abstract

Abstract It has been shown that the mechanical properties of pathological cells are different from healthy ones. Therefore, mechanical characterization of cells may be useful for investigating mechanisms and progression of diseases. In the case of cancer, the finding that cancerous cells are considerably more deformable than normal ones provides the motivation for investigating rheological differences between stem-like and non-stem-like cancer cells. In this study, the viscoelastic properties of six breast cancer cell lines, three of which have been regarded (based on surface markers) as stem-like and three considered less stem-like, were measured using micropipette aspiration and particle tracking microrheology. In micropipette experiments, cancer cells were aspirated one-by-one at controlled pressures into small glass micropipettes and the length of the aspirated section of the cells was tracked as a function of time. The applied pressure was either increased linearly or increased suddenly to different levels and then held constant. The homogeneous elastic half-space model was used to interpret the viscoelastic properties of the different cell lines. The effect of pressure loading rate on cell viscoelasticity was examined by applying three different aspiration pressure rates of 9, 6, and 3 Pa/s. The apparent Young's modulus was found to depend on pressure loading rate, which suggests a more complex rheology than a standard viscoelastic solid. Above a threshold force level, cells were also found to enter the micropipette continuously in a fashion that is analogous to white blood cells, i.e. as a liquid drop with constant cortical tension. A comparison between the Young's moduli showed that at least some of the stem-like breast cancer cell lines were less stiff than less stem-like cell lines and more likely to exhibit the liquid drop-like behavior. The reduction in stiffness and change in rheological regime might be the result of lower actin filament density which allowed the stem-like cancer cells to be more deformable while undergoing extravasation and intravasation during the metastatic process. Regional rheological differences were also found using particle tracking microrheology. Our hypothesis is that the differences in the rheological properties might help to distinguish between stem-like cancer cells and non-stem-like ones, which could eventually lead to a new detection and diagnostic method in cancer research. Citation Format: Amina Alipour, Monica M. Burdick, David F.J. Tees. Whole-cell and local viscoelasticity of stem-like and non-stem-like breast cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1409. doi:10.1158/1538-7445.AM2015-1409