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Mechanical properties of normal versus cancerous breast cells.

ABSTRACT: A cell's mechanical properties are important in determining its adhesion, migration, and response to the mechanical properties of its microenvironment and may help explain behavioral differences between normal and cancerous cells. Using fluorescently labeled peroxisomes as microrheological probes, the interior mechanical properties of normal breast cells were compared to a metastatic breast cell line, MDA-MB-231. To estimate the mechanical properties of cell cytoplasms from the motions of their peroxisomes, it was necessary to reduce the contribution of active cytoskeletal motions to peroxisome motion. This was done by treating the cells with blebbistatin, to inhibit myosin II, or with sodium azide and 2-deoxy-D-glucose, to reduce intracellular ATP. Using either treatment, the peroxisomes exhibited normal diffusion or subdiffusion, and their mean squared displacements (MSDs) showed that the MDA-MB-231 cells were significantly softer than normal cells. For these two cell types, peroxisome MSDs in treated and untreated cells converged at high frequencies, indicating that cytoskeletal structure was not altered by the drug treatment. The MSDs from ATP-depleted cells were analyzed by the generalized Stokes-Einstein relation to estimate the interior viscoelastic modulus G* and its components, the elastic shear modulus G' and viscous shear modulus G", at angular frequencies between 0.126 and 628 rad/s. These moduli are the material coefficients that enter into stress-strain relations and relaxation times in quantitative mechanical models such as the poroelastic model of the interior regions of cancerous and non-cancerous cells.

SUBMITTER: Smelser AM

PROVIDER: S-EPMC4984850 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Mechanical properties of normal versus cancerous breast cells.

Smelser Amanda M AM Macosko Jed C JC O'Dell Adam P AP Smyre Scott S Bonin Keith K Holzwarth George G

Biomechanics and modeling in mechanobiology 20150501 6

A cell's mechanical properties are important in determining its adhesion, migration, and response to the mechanical properties of its microenvironment and may help explain behavioral differences between normal and cancerous cells. Using fluorescently labeled peroxisomes as microrheological probes, the interior mechanical properties of normal breast cells were compared to a metastatic breast cell line, MDA-MB-231. To estimate the mechanical properties of cell cytoplasms from the motions of their ...[more]

PMID: 25929519

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Project description:BackgroundTechnologies for quick and label-free diagnosis of malignancies from breast tissues have the potential to be a significant adjunct to routine diagnostics. The biophysical phenotypes of breast tissues, such as its electrical, thermal, and mechanical properties (ETM), have the potential to serve as novel markers to differentiate between normal, benign, and malignant tissue.ResultsWe report a system-of-biochips (SoB) integrated into a semi-automated mechatronic system that can characterize breast biopsy tissues using electro-thermo-mechanical sensing. The SoB, fabricated on silicon using microfabrication techniques, can measure the electrical impedance (Z), thermal conductivity (K), mechanical stiffness (k), and viscoelastic stress relaxation (%R) of the samples. The key sensing elements of the biochips include interdigitated electrodes, resistance temperature detectors, microheaters, and a micromachined diaphragm with piezoresistive bridges. Multi-modal ETM measurements performed on formalin-fixed tumour and adjacent normal breast biopsy samples from N = 14 subjects were able to differentiate between invasive ductal carcinoma (malignant), fibroadenoma (benign), and adjacent normal (healthy) tissues with a root mean square error of 0.2419 using a Gaussian process classifier. Carcinoma tissues were observed to have the highest mean impedance (110018.8 ± 20293.8 Ω) and stiffness (0.076 ± 0.009 kNm-1) and the lowest thermal conductivity (0.189 ± 0.019 Wm-1 K-1) amongst the three groups, while the fibroadenoma samples had the highest percentage relaxation in normalized load (47.8 ± 5.12%).ConclusionsThe work presents a novel strategy to characterize the multi-modal biophysical phenotype of breast biopsy tissues to aid in cancer diagnosis from small-sized tumour samples. The methodology envisions to supplement the existing technology gap in the analysis of breast tissue samples in the pathology laboratories to aid the diagnostic workflow.

Project description:The bodys elemental/ metal loads are known to exert essential influence in maintaining normal and abnormal metabolism leading to eventual pathology of some forms of cancer phenotypes. Accumulation of potentially toxic or nonessential trace metals has been observed but not highly noted as an active factor in toxicogenesis and in the development of many diseases including cancers. The compositional balance and distribution of trace metals in various body tissues are essential key players in homeostasis in life. To this end the etiology of diseases including cancer has been linked with the accumulation of potentially toxic or nonessential trace metals. However, scarce literature / experimental evidence exist as a scientific proof that metal concentrations play important role in the etiology and development of cancer phenotypes. The aim of this study was to investigate the differential relationship of metal concentrations and profiles in cancer and normal tissues from cadavers of humans. The originated hypothesis was that elemental / metal concentrations and profiles seen in post mortem will show significant differences between normal and cancer-derived tissues as well as between various tissue types in humans. This study also establishes critical elemental /metal profiles that may be relevant in providing correlations with the development of three major cancers. Normal human and tumor tissues of cadaverous lung, breast and liver tissues used in this study were obtained from US Biomax Company. Tissue samples were prepared using standardized digestion procedures necessary for use with the Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). This equipment was utilized to determine the concentrations and profiles of 21 elements including Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Tl, V, and Zn. Twelve major elements of Al, Ba, Ca, Cr, Cu, Fe, Mg, Na, Pb, Se, Sr, and Zn were found to be significantly different in term of their concentrations / profiles in normal and tumor tissues of human lung, breast and liver. These critical elements appeared to be respectively five to ten times more abundant in human lung and breast tumor than in their respective normal tissues. In contrast Ba, Cr, Cu, Fe, Zn, concentrations were shown to be lower in liver tumors than in normal liver tissues, and that Ca and Na appeared to be higher in human liver tumors than in normal liver tissues. Data analysis showed significant variations in elemental concentrations and profiles consistent with the hypothesis. It is concluded that metal / elemental homeostasis is essential for normal tissue function and that elemental variations and distributions are tissue specific as well as carcinoma specific. These results are promising and warrant further studies to confirm / exploit the possibility of manipulating elemental distribution and content as means for diagnosing / utility as therapeutic modalities in chronic human disease as well as cancer management.

Project description:The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell's cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

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Mechanical properties of normal versus cancerous breast cells.

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Mechanical properties of normal versus cancerous breast cells.

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