Biology subjects

Boukany, P.

Publications and source records attributed to Boukany, P..

5 recordsLinked to original sources

bioRxiv2025

Inter-Spheroid Proximity and Matrix Remodeling Determine CAF-Mediated Cancer Cell Invasion

Breast cancer is the most commonly diagnosed malignancy worldwide, with molecular subtypes following distinct clinical trajectories. While Luminal A breast cancers are typically indolent, a subset enriched in -smooth muscle actin (-SMA)-positive cancer-associated fibroblasts (CAFs) exhibits aggressive behavior, facilitating tumor invasion. However, the biophysical mechanisms by which CAFs drive invasion and extracellular matrix (ECM) remodeling remain unclear. Furthermore, the temporal and spatial dynamics of CAF interactions with the collagen matrix and cancer cell spheroids remain unknown, raising the question of whether these processes follow a deterministic sequence or occur stochastically. To address this, we conduct histological analysis of Luminal A tumors, revealing variation in CAF, cancer cell, and ECM organization at tumor boundaries. To assess the impact of CAF on cancer cell invasion, we use a 3D in-vitro model co-embedding 19TT breast CAF and MCF7 luminal breast cancer spheroids within a three-dimensional (3D) collagen-I hydrogel and perform time-lapse imaging. We demonstrate that inter-spheroid distance critically determines 19TT CAF-induced MCF7 spheroid behavior. Furthermore, we show that CAF-mediated collagen matrix remodeling and degradation precedes MCF7 spheroid disruption and is critical in promoting cancer cell spheroid expansion and cell dissemination. While broad-spectrum matrix metalloproteinase inhibition suppresses CAF-driven collagen degradation and MCF7 spheroid expansion, it does not prevent ECM remodeling, CAF migration, or single-cell dissemination of cancer cell spheroids. Furthermore, a complementary heterospheroid model reveals similar ECM remodeling and invasion dynamics despite altered cellular arrangement of cancer cells and CAFs. These findings enhance our understanding of the relationship between CAF activity and collagen matrix remodeling processes that promote cancer cell invasion, providing insights into the potential therapeutic benefits of targeting CAFs in breast cancer treatment.

cancer biology↗

bioRxiv2025

Actin and vimentin jointly control cell viscoelasticity and compression stiffening

AbstractThe mechanical properties of cells are governed by the cytoskeleton, a dynamic network of actin filaments, intermediate filaments, and microtubules. Understanding the individual and collective mechanical contributions of these three different cytoskeletal elements is essential to elucidate how cells maintain mechanical integrity during deformation. Here we use a custom single-cell rheometer to identify the distinct contributions of actin and vimentin to the viscoelastic and nonlinear elastic response of cells to uniaxial compression. We used mouse embryonic fibroblasts (MEFs) isolated from wild type (WT) and vimentin knockout (vim -/-) mice in combination with chemical treatments to manipulate actin polymerization and contractility. We show through small amplitude oscillatory measurements and strain ramp tests that vimentin, often overlooked in cellular mechanics, plays a role comparable to actin in maintaining cell stiffness and resisting large compressive forces. However, actin appears to be more important than vimentin in determining cellular energy dissipation. Finally we show by comparing wild type and enucleated cells that compression stiffening originates from the actin and vimentin cytoskeleton, while the nucleus appears to play little role in this. Our findings provide insight into how cytoskeletal networks collectively determine the mechanical properties of cells, providing a basis to understand the role of the cytoskeleton in the ability of cells to resist external as well as internal forces. Significance statementO_LIA cells response to mechanical stress is largely governed by the actin and vimentin cytoskeletal networks, but their relative contribution to cell viscoelasticity and response to large deformations are poorly characterized. C_LIO_LIWe reveal that actin and vimentin networks have an almost equal contribution to cellular stiffness and the cells ability to strain-stiffen under uniaxial compression. C_LIO_LIThis work underscores the cytoskeletons central role in cellular mechanics and the mechanical synergy between the cytoskeletal networks, providing a framework for understanding how cellular components coordinate to maintain structural integrity and respond to different mechanical environments. C_LI

biophysics↗

bioRxiv2024

Linking metastatic potential and viscoelastic properties of breast cancer spheroids via dynamics compression and relaxation in microfluidics

The growth and invasion of solid tumors are associated with changes in their viscoelastic properties, influenced by both internal cellular factors and physical forces in the tumor microenvironment. Due to the lack of a comprehensive investigation of tumor tissue viscoelasticity, the relationship between such physical properties and cancer malignancy remains poorly understood. Here, the viscoelastic properties of breast cancer spheroids, 3D (in vitro) tumor models, are studied in relation to their metastatic potentials by imposing controlled, dynamic compression within a microfluidic constriction, and subsequently monitoring the relaxation of the imposed deformation. By adopting a modified Maxwell model to extract viscoelastic properties from the compression data, the benign (MCF-10A) spheroids are found to have higher bulk elastic modulus and viscosity compared to malignant spheroids (MCF-7 and MDA-MB-231). The relaxation is characterized by two timescales, captured by a double exponential fitting function, which reveals a similar fast rebound for MCF-7 and MCF-10A. Both the malignant spheroids exhibit similar long-term relaxation and display residual deformation. However, they differ significantly in morphology, particularly in intercellular movements. These differences between malignant spheroids are demonstrated to be linked to their cytoskeletal organization, by microscopic imaging of F-actin within the spheroids, together with cell-cell adhesion strength.

biophysics↗

bioRxiv2024

EMT-dependent cell-matrix interactions are linked to unjamming transitions in cancer spheroid invasion

The plasticity of cancer cells allows them to switch between different migration modes, promoting their invasion into the extracellular matrix (ECM) and hence increasing the risks of metastasis. Epithelial-to-mesenchymal transitions (EMT) and unjamming transitions provide two distinct pathways for cancer cells to become invasive, but it is still unclear to what extent these pathways are connected. Here we addressed this question by performing 3D spheroid invasion assays of lung adenocarcinoma (A549, epithelial) and melanoma (MV3, mesenchymal-like) cancer cell lines in collagen-based hydrogels, where we varied both the invasive character of the cells (using Transforming Growth Factor (TGF)-{beta} to promote EMT and matrix metalloprotease (MMP) inhibition to block cell-mediated matrix degradation) and the porosity of the matrix. Using a quantitative image analysis method to track spheroid invasion, we discovered that the onset time of invasion mostly depended on the matrix porosity and corresponded with vimentin levels, while the subsequent spheroid expansion rate mostly depended on metalloprotease MMP1 levels and thus cell-matrix interaction. Morphological analysis revealed that spheroids displayed solid-like (non-invasive) behavior in small-pore hydrogels and switched to fluid-like (strand-based) or gas-like (disseminating cells) phases in large-pore hydrogels and when cells were more mesenchymal-like. Our findings are consistent with unjamming transitions as a function of cell motility and matrix confinement predicted in recent models for cancer invasion, but show that cell motility and matrix confinement are coupled via EMT-dependent matrix degradation.

cancer biology↗

bioRxiv2018

Unravelling the response of the actin cortex to electric pulses in vesicles

We study the role of a biomimetic actin cortex during the application of electric pulses that induce electroporation or electropermeabilization, using giant unilamellar vesicles (GUVs) as a model system. The actin cortex, a subjacently attached interconnected network of actin filaments, regulates the shape and mechanical properties of the plasma membrane of mammalian cells, and is a major factor influencing the mechanical response of the cell to external physical cues. We demonstrate that the presence of an actin shell inhibits the formation of macropores in the electroporated GUVs. Additionally, experiments on the uptake of dye molecules after electroporation show that the actin network slows down the resealing process of the permeabilized membrane. We further analyze the stability of the actin network inside the GUVs exposed to high electric pulses. We find disruption of the actin layer that is likely due to the electrophoretic forces acting on the actin filaments during the permeabilization of the GUVs. Our findings on the GUVs containing a biomimetic cortex provide a step towards understanding the discrepancies between the electroporation mechanism of a living cell and its simplified model of the empty GUV.

biophysics↗