Biology subjects

Luton, F.

Publications and source records attributed to Luton, F..

6 recordsLinked to original sources

bioRxiv2026

Basement membrane turnover drives filopodial protease-independent invasion

The basement membrane is a specialised nanoporous extracellular matrix mainly composed of collagen IV fibres and laminins. As collagen IV fibres form covalent cross-links, cells cannot freely cross it. Basement membrane breaching marks the transition from in situ to invasive carcinoma, commonly attributed to protease activity. Yet, recent data show that tumour cells can cross basement membranes through protease-independent mechanisms. Experimental evidence suggests that filopodia can play an active role in pore enlargement in extracellular matrices by generating plastic mechanical deformation. Moreover, plasticity can be regulated by covalent cross-link concentration, which we hypothesise can be responsive to collagen IV turnover, thus generating transient weak spots. To test this, we developed a quantitative, biophysical mathematical model describing the interaction between a tumour-cell cluster and a basement membrane using relevant biological assumptions and parameters. The cluster is represented as an evolving, energetic surface and the basement membrane is described as a set of points representing active and inactive links. Simulations show that synchronisation of collagen IV turnover coupled with filopodium extension drives pore enlargement, providing a mechanistic basis for protease-independent invasion. Consistent with experiments, simulations identify two complementary filopodium groups: one driving global degradation and the other promoting local pore enlargement.

biophysics↗

bioRxiv2025

Inhibition of PTCH1 drug efflux activity enhances chemotherapy efficacy against triple negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subgroup characterized by a high risk of resistance to chemotherapies and high relapse potential. High levels of mRNA from the Hedgehog receptor PTCH1 are associated with poor prognosis in TNBC. PTCH1 is overexpressed in many aggressive cancers. We previously reported that PTCH1 is a multidrug transporter that triggers resistance to chemotherapy of adrenocortical carcinoma and melanoma cells, and that inhibiting PTCH1 drug efflux strongly enhanced chemotherapy efficacy on these cell lines both in vitro and in vivo. In the present study, we found that PTCH1 inhibition also significantly inhibited doxorubicin efflux in three TNBC cell lines leading to a strong increase of the cytotoxic effect of doxorubicin and docetaxel, and an inhibition of cell migration. Altogether, our data highlight the therapeutic potential of targeting PTCH1 drug efflux activity using drug association strategies for the treatment of TNBC patients.

cancer biology↗

bioRxiv2025

Human mammary 3D spheroid models uncover the role of filopodia in breaching the basement membrane to facilitate invasion

Basement membranes (BM) are thin, nanoporous sheets of specialized extracellular matrix (ECM) that line epithelial tissues. They are dynamic structures that serve multiple key functions, as evidenced by numerous diseases, including cancer progression, that are associated with their alterations. Our understanding of the BM and its communication with adjoining epithelial cells remains highly fragmented due to the BMs complex molecular architecture, the lack of molecular tools, limitations in utilizing high-resolution imaging techniques to BMs assembled on tissues, and the difficulty of assessing their functional contributions in vivo. Here, by combining multiple -omics analyses and advanced microscopy methodologies, we characterized the BM from two normal human mammary epithelial cell lines, MCF10 and HMLE, grown as spheroids in 3D matrices. Our findings indicate that the spheroids autonomously assemble a BM exhibiting all the molecular, structural, and biophysical characteristics of physiological BM. Using these minimalist model systems, we show for the first time that the laminins, perlecan, and the hemidesmosomes are all arranged along a shared porous lattice defined by the collagen IV molecular network. Next, we demonstrate that the invasion-promoting PSD4/EFA6B knockout, found in patients with breast cancer, decreases the expression of BM components and their assembly on the spheroid surface. We then show that invasive spheroids develop enlarged pores in the BM via filopodia-like plasma membrane extensions, which further expand in a protease-dependent manner, thereby facilitating the passage of invasive cells. Significance StatementThe basement membrane (BM) directs epithelial tissue architecture and behavior. How tumor cells breach this barrier during invasion remains poorly understood. Using minimalist 3D spheroid models mimicking physiological BM assembly, we reveal a novel infiltration mechanism. Filopodia-like protrusions perforate and widen BM pores. This facilitates cell dissemination through sequential protease-independent and -dependent steps.

cell biology↗

bioRxiv2021

OSBP-mediated cholesterol transfer determines epithelial polarity and associated cargo secretion

Golgi lipid environment regulates sorting and cargo secretion. However, the mechanisms that spatiotemporally control the lipid composition of the secretory membranes to drive cargo trafficking are poorly understood. Lipid transfer proteins regulate the concentration of specific lipids at membrane contact sites. We hypothesised that by catalysing cholesterol/PI(4)P exchange at ER-trans-Golgi membrane contact sites the lipid transfer protein oxysterol binding protein (OSBP) affects the secretion of a subset of cargoes. Here, we report that OSBP is a major epithelial protein as its inhibition leads to complete loss of apico-basal polarity. By mapping the OSBP proximity proteome with the biotin ligase TurboID, we found that OSBP controls the secretion of multiple membrane associated proteins, including key polarity determinants such as E-cadherin. Mechanistically, we established that OSBP contributes to E-cadherin secretion by supplying cholesterol to post-Golgi membranes. Importantly, when cells downregulate cell-cell junctions upon epithelial-to-mesenchymal transition, they re-wire their lipid homeostasis and downregulate OSBP as well, thus altering the trafficking of the OSBP-dependent secretory cargoes.

cell biology↗

bioRxiv2021

Arf6 is necessary for high level Wingless signalling during Drosophila wing development

Wnt signalling is a core pathway involved in a wide range of developmental processes throughout the metazoa. In vitro studies have suggested that the small GTP binding protein Arf6 regulates upstream steps of Wnt transduction, by promoting the phosphorylation of the Wnt co-receptor, LRP6, and the release of {beta}-catenin from the adherens junctions. To assess the relevance of these previous findings in vivo, we analyse the consequence of the absence of Arf6 activity on Drosophila wing patterning, a developmental model of Wnt/Wingless signalling. We observed a dominant loss of wing margin bristles and Senseless expression in Arf6 mutant flies, phenotypes characteristic of a defect in high level Wingless signalling. In contrast to previous findings, we show that Arf6 is required downstream of Armadillo/{beta}-catenin stabilisation in Wingless signal transduction. Our data suggest that Arf6 modulates the activity of a downstream nuclear regulator of Pangolin activity in order to control the induction of high level Wingless signalling. Our findings represent a novel regulatory role for Arf6 in Wingless signalling.

developmental biology↗

bioRxiv2020

EFA6B regulates a stop signal for collective invasion in breast cancer

Cancer is initiated by somatic mutations in oncogenes or tumor suppressor genes, however additional mutations provide selective advantages to the tumor cells to resist treatment and develop metastases, therefore identification of secondary mutations is of paramount importance. EFA6B (Exchange Factor for ARF6, B) expression is reduced in breast cancer. To study the pro-tumoral impact of the loss of EFA6B we have invalidated its gene in normal human mammary cells. We found that EFA6B knock-out triggers a transcriptional reprogramming of the cell-to-ECM interaction machinery and unleashes CDC42-dependent collective invasion in collagen. In addition, invasive and metastatic tumors isolated from patients have lower expression of EFA6B and display gene ontology signatures identical to those of EFA6B knock-out cells. Thus, we reveal a new EFA6B-regulated molecular mechanism that controls the invasive potential of mammary cells; this finding opens up new avenues for the treatment of invasive breast cancer.

cancer biology↗