Cancer cells are mechanically sensitive to physical properties of the microenvironment, which can affect downstream signaling to promote malignancy, in part through the modulation of metabolic pathways. Fluorescence Lifetime Imaging Microscopy (FLIM) can be used to measure the fluorescence lifetime of endogenous fluorophores, such as the metabolic co-factors NAD(P)H and FAD, in live samples. We used multiphoton FLIM to investigate the changes in cellular metabolism of 3D breast spheroids derived from MCF-10A and MD-MB-231 cell lines embedded in collagen with varying densities (1 vs. 4 mg/ml) over time (Day 0 vs. Day 3). MCF-10A spheroids demonstrated spatial gradients, with the cells closest to the spheroid edge exhibiting FLIM changes consistent with a shift towards oxidative phosphorylation (OXPHOS) while the spheroid core had changes consistent with a shift towards glycolysis. The MDA-MB-231 spheroids had a large shift consistent with increased OXPHOS with a more pronounced change at the higher collagen concentration. The MDA-MB-231 spheroids invaded into the collagen gel over time and cells that traveled the farthest had the largest changes consistent with a shift towards OXPHOS. Overall, these results suggest that the cells in contact with the extracellular matrix (ECM) and those that migrated the farthest had changes consistent with a metabolic shift towards OXPHOS. More generally, these results demonstrate the ability of multiphoton FLIM to characterize how spheroids metabolism and spatial metabolic gradients are modified by physical properties of the 3D ECM.
Aromatic carbohydrate amphiphile disrupts cancer spheroids and prevents relapse
Spheroids recapitulate the organization, heterogeneity and microenvironment of solid tumors. Herein, we targeted spatiotemporally the accelerated metabolism of proliferative cells located on the spheroid surface that ensure structure maintenance and/or growth. We demonstrate that phosphorylated carbohydrate amphiphile acts as a potent antimetabolite due to glycolysis inhibition and to in situ formation of supramolecular net around spheroid surface where alkaline phosphatase is overexpressed. The efficiency of the treatment is higher in spheroids as compared to the conventional 2D cultures because of the 2-fold higher expression of glucose transporter 1 (GLUT1). Moreover, treated spheroids do not undergo following relapse.
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- Award ID(s):
- 1808143
- NSF-PAR ID:
- 10382292
- Date Published:
- Journal Name:
- Nanoscale
- Volume:
- 12
- Issue:
- 37
- ISSN:
- 2040-3364
- Page Range / eLocation ID:
- 19088 to 19092
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
Three-dimensional (3D) dried blood spheroids form when whole blood is deposited onto hydrophobic paper and allowed to dry in ambient air. The adsorbed 3D dried blood spheroid present at the surface of the hydrophobic paper is observed to offer enhanced stability for labile analytes that would otherwise degrade if stored in the traditional two-dimensional (2D) dried blood spot method. The protective mechanism for the dried blood spheroid microsampling platform was studied using scanning electron microscopy (SEM), which revealed the presence of a passivation thin film at the surface of the spheroid that serves to stabilize the interior of the spheroid against environmental stressors. Through time-course experiments based on sequential SEM analyses, we discovered that the surface protective thin film forms through the self-assembly of red blood cells following the evaporation of water from the blood sample. The bridging mechanism of red blood cell aggregation is evident in our experiments, which leads to the distinct rouleau conformation of stacked red blood cells in less than 60 min after creating the blood spheroid. The stack of self-assembled red blood cells at the exterior of the spheroid subsequently lyse to afford the surface protective layer detected to be approximately 30 μm in thickness after three weeks of storage in ambient air. We applied this mechanistic insight to plasma and serum to enhance stability when stored under ambient conditions. In addition to physical characterization of these thin biofilms, we also used paper spray (PS) mass spectrometry (MS) to examine chemical changes that occur in the stored biofluid. For example, we present stability data for cocaine spiked in whole blood, plasma, and serum when stored under ambient conditions on hydrophilic and hydrophobic paper substrates.more » « less
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Through high-fidelity numerical simulation based on the lattice Boltzmann method, we have conducted an in-depth study on the heat and mass transport from an oblate spheroid neutrally suspended in a simple shear flow. In the simulation, the temperature and mass concentration are modeled as a passive scalar released at the surface of the spheroid. The fluid dynamics induced by the interaction between the carrier fluid and the suspended spheroid, as well as the resultant scalar transport process, have been extensively investigated. A coupled transport mechanism comprising several components of the flow around the oblate spheroid has been identified. The effects of the Reynolds number and the aspect ratio of the spheroid on the flow characteristics and scalar transport rate are examined. The variation of the nondimensional scalar transport rate suggests that the effect of spheroid shape on scalar transfer rate can be decoupled from the effects of Peclet and Reynolds numbers, which facilitates the development of a correlation of scalar transfer rate for oblate spheroids based on the well-developed correlations for a sphere.
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null (Ed.)Breast cancer cells can metastasize either as single cells or as clusters to distant organs from the primary tumor site. Cell clusters have been shown to possess higher metastatic potential compared to single cells. The organ microenvironment is critical in regulating the ultimate phenotype, specifically, the dormant versus proliferative phenotypes, of these clusters. In the context of breast cancer brain metastasis (BCBM), tumor cell cluster–organ microenvironment interactions are not well understood, in part, due to the lack of suitable biomimetic in vitro models. To address this need, herein, we report a biomaterial-based model, utilizing hyaluronic acid (HA) hydrogels with varying stiffnesses to mimic the brain microenvironment. Cell spheroids were used to mimic cell clusters. Using 100–10 000 MDA-MB-231Br BCBM cells, six different sizes of cell spheroids were prepared to study the impact of cluster size on dormancy. On soft HA hydrogels (∼0.4 kPa), irrespective of spheroid size, all cell spheroids attained a dormant phenotype, whereas on stiff HA hydrogels (∼4.5 kPa), size dependent switch between the dormant and proliferative phenotypes was noted ( i.e. , proliferative phenotype ≥5000 cell clusters < dormant phenotype), as tested via EdU and Ki67 staining. Furthermore, we demonstrated that the matrix stiffness driven dormancy was reversible. Such biomaterial systems provide useful tools to probe cell cluster–matrix interactions in BCBM.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0nr05008c
