Biology subjects

Chavrier, P.

Publications and source records attributed to Chavrier, P..

7 recordsLinked to original sources

bioRxiv2025

SPARC is a new driver of early breast tumor progression via TGF-β -dependent mechanism.

Ductal carcinoma in situ (DCIS) is a pre-invasive lesion that is thought to be a precursor of invasive ductal carcinoma (IDC). The challenge lies in discriminating between DCIS progressors and DCIS non-progressors, often resulting in over- or under-treatment in many cases. Membrane type 1 (MT1)-matrix metalloproteinase (MMP) has been previously identified as an essential gene involved in DCIS progression. Here, RNA-sequencing analysis of MT1-MMPhigh subpopulation derived from invasive breast tumors in the intraductal xenograft model was compared against a dataset of human high-grade DCIS, and Secreted Protein Acidic and Cysteine Rich (SPARC) has emerged as a master candidate involved in early breast tumor progression. We report that SPARC is up-regulated in DCIS as compared to normal breast epithelial tissues, and further increased in IDC relative to synchronous DCIS foci. We found a positive correlation between SPARC and MT1-MMP expression in DCIS lesions. At the mechanistic level, depletion of SPARC reduced MT1-MMP expression, the degradative capacity of the cells and the activation of the TGF-{beta} signalling canonical pathway. Pharmacological inhibition of the TGF-{beta} signalling pathway decreased SPARC and MT1-MMP at the mRNA and protein level, and concomitantly the cell degradative capacity and 3D cell migration. Strikingly, inhibition of the TGF-{beta} signalling pathway limits the invasive transition of breast tumors in a new triple-negative mouse intraductal syngeneic xenograft model. Moreover, high SPARC expression was positively correlated with both, TGF-{beta} and its receptor, TGFBRI, in a basal type of breast cancer collection supporting our findings. This study identifies SPARC as a new driver of early breast tumor progression via a TGF-{beta}-dependent mechanism, suggesting TGF-{beta} signaling pathway as a potential target for patients with high SPARC expression.

cancer biology↗

bioRxiv2024

Force transmission is a master regulator of mechanical cell competition

Cell competition is a tissue surveillance mechanism for eliminating unwanted cells and as such is indispensable in development, infection and tumorigenesis. Although different biochemical mechanisms are proposed, due to the dearth of direct force measurements, how mechanical forces determine the competition outcome remains unclear. Here, using ex vivo tissues and different cell lines, we have discovered an unknown form of cell competition that is regulated by differences in force transmission capabilities, favoring cell types with stronger intercellular adhesion. Direct force measurements reveal increased mechanical activity at the interface of the two competing cell types in the form of large stress fluctuations which can lead to upward forces and cell elimination. We show how a winning cell type endowed with a stronger intercellular adhesion exhibits a higher resistance to elimination while benefiting from efficient force transmission to neighboring cells. This cell elimination mechanism could have broad implications of keeping strong force transmission ability for maintaining tissue boundaries and cell invasion pathology.

biophysics↗

bioRxiv2022

Multiscale model of the different modes of cancer cell invasion

Mathematical models of biological processes implicated in cancer are built using the knowledge of complex networks of signaling pathways, describing the molecular regulations inside different cell types, such as tumor cells, immune and other stromal cells. If these models mainly focus on intracellular information, they often omit a description of the spatial organization among cells and their interactions, and with the tumoral microenvironment. We present here a model of tumor cell invasion simulated with PhysiBoSS, a multiscale framework which combines agent-based modeling and continuous time Markov processes applied on Boolean network models. With this model, we aim to study the different modes of cell migration by considering both spatial information obtained from the agent-based simulation and intracellular regulation obtained from the Boolean model. Our multiscale model integrates the impact of gene mutations with the perturbation of the environmental conditions and allows the visualization of the results with 2D and 3D representations. The model successfully reproduces single and collective migration processes and is validated on published experiments on cell invasion. In silico experiments are suggested to search for possible targets that can block the more invasive tumoral phenotypes.

bioinformatics↗

bioRxiv2021

A new approach to measure forces at junction vertices in an epithelium

The mechanical properties of cell-cell junctions are critical for the stability of an epithelium. Cell-cell junction ablation experiments are classically used as a readout for junctional mechanics. However, without the knowledge of the viscoelastic properties of the microenvironment of the ablated junction, tensile junctional forces cannot be measured. Here we combine laser ablation with intracellular microrheology and develop a model to measure tensile forces exerted on cell-cell junctions. We show that the overexpression of the proto-oncogene atypical Protein Kinase C iota (aPKCi) in a single cell within a normal epithelium induces a gradient of junctional tension with neighbouring cells. Our method allows us to demonstrate that junctions contacting the aPKCi-overexpressing cell display a mechanical asymmetry which correlates with the levels of E-cadherin and P-MLC2. Measuring intracellular viscoelasticity is crucial for accurate measurements of cell-cell junction mechanics in the context of development or cancer research. TeaserWe combine cytoplasmic and junctional mechanics to detect asymmetry in forces exerted on cell-cell junctions.

cell biology↗

bioRxiv2021

mTOR repression in response to amino acid starvation promotes ECM degradation through MT1-MMP endocytosis arrest

Under conditions of starvation, normal and tumor epithelial cells can rewire their metabolism towards the consumption of extracellular matrix-derived components as nutrient sources. The mechanism of pericellular matrix degradation by starved cells has been largely overlooked. Here we show that matrix degradation by breast and pancreatic tumor cells and patient-derived xenograft explants increases by one order of magnitude upon amino acid and growth factor deprivation. In addition, we found that collagenolysis requires the invadopodia components, TKS5 and the transmembrane metalloproteinase, MT1-MMP, which are key to the tumor invasion program. Increased collagenolysis is controlled by mTOR repression upon nutrient depletion or pharmacological inhibition by rapamycin. Our results reveal that starvation hampers clathrin-mediated endocytosis, resulting in MT1-MMP accumulation in arrested clathrin-coated pits. Our study uncovers a new mechanism whereby mTOR repression in starved cells leads to the repurposing of abundant plasma membrane clathrin-coated pits into robust ECM-degradative assemblies.

cancer biology↗

bioRxiv2020

Compromised nuclear envelope integrity drives tumor cell invasion

While mutations leading to a fragile envelope of the cell nucleus are well known to cause diseases such as muscular dystrophies or accelerated aging, the pathophysiological consequences of the recently discovered mechanically induced nuclear envelope ruptures in cells harboring no mutation are less known. Here we show that repeated loss of nuclear envelope integrity in nuclei experiencing mechanical constraints promotes senescence in nontransformed cells, and induces an invasive phenotype including increased collagen degradation in human breast cancer cells, both in vitro and in a mouse xenograft model of breast cancer progression. We show that these phenotypic changes are due to the presence of chronic DNA damage and activation of the ATM kinase. In addition, we found that depletion of the cytoplasmic exonuclease TREX1 is sufficient to abolish the DNA damage in mechanically challenged nuclei and to suppress the phenotypes associated with the loss of nuclear envelope integrity. Our results also show that TREX1-dependent DNA damage induced by physical confinement of tumor cells inside the mammary duct drives the progression of in situ breast carcinoma to the invasive stage. We propose that DNA damage in mechanically challenged nuclei could affect the pathophysiology of crowded tissues by modulating proliferation and extracellular matrix degradation of normal and transformed cells.

cell biology↗

bioRxiv2019

A new analytical pipeline for the study of the onset of mammary gland oncogenesis based on mammary organoid transplantation and organ clearing

Metastasis formation is a multi-step process starting from the dissemination of transformed carcinomatous cells from the primary tumor and could occur at a very early stage of oncogenesis, before primary tumor detection. The adult mammary gland provides a unique model to investigate epithelial cell dissemination processes. Tissue clearing techniques allow imaging samples of large volume. uDSICO clearing, one of the latest tissue clearing technique developed, provides optical imaging of whole organ due to organ clearing and tissue size reduction. We wanted to take advantage of this technique to study rare events occurring in vivo. Here, we have established a new analytical pipeline exploiting the regenerative properties of the mammary epithelium following orthotropic transplantation of organoids together with the uDISCO organ size reduction and clearing method to study early cell dissemination in the mammary gland. As proof of concept, we analyzed the localization of epithelial cells overexpressing the oncogenic protein atypical protein kinase C iota (aPKCi+) in the normal mammary gland and we were able to visualize epithelial aPKCi+ cells, surrounded by normal epithelial cells, escaping from the normal mammary epithelium and disseminating into the surrounding stroma.

cell biology↗