46 results found
Lachowski D, Cortes E, Rice A, et al., Matrix stiffness modulates the activity of MMP-9 and TIMP-1 in hepatic stellate cells to perpetuate fibrosis, Scientific Reports, ISSN: 2045-2322
Liver fibrosis is characterised by a dense and highly cross-linked extracellular matrix (ECM) which promotes progression of diseases such as hepatocellular carcinoma. The fibrotic microenvironment is characterised by an increased stiffness, with rigidity associated with disease progression. External stiffness is known to promote hepatic stellate cell (HSC) activation through mechanotransduction, leading to increased secretion of ECM components. HSCs are key effector cells which maintain the composition of the ECM in health and disease, not only by regulating secretion of ECM proteins such as collagen, but also ECM-degrading enzymes called matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Uninhibited MMPs degrade ECM proteins to reduce external rigidity. Using fibronectin-coated polyacrylamide gels to alter substrate rigidity without altering ligand density, we show that fibrotic rigidities downregulate MMP-9 expression and secretion, and also upregulate secretion of TIMP-1, though not its expression. Using tissue immunofluorescence studies, we also report that the expression of MMP-9 is significantly decreased in activated HSCs in fibrotic tissues associated with hepatocellular carcinoma. This suggests the presence of a mechanical network that allows HSCs to maintain a fibrotic ECM, with external rigidity providing feedback which affects MMP-9 and TIMP-1 secretion, which may become dysregulated in fibrosis.
Perone Y, Farrugia AJ, Meira AR, et al., 2019, SREBP1 drives Keratin 80-dependent cytoskeletal changes and invasive behavior in endocrine resistant ERα breast cancer, Nature Communications, Vol: 10, ISSN: 2041-1723
Approximately 30% of ERα breast cancer patients relapse with metastatic disease following adjuvant endocrine therapies. The connection between acquisition of drug resistance and invasive potential is poorly understood. In this study, we demonstrate that the type II keratin topological associating domain undergoes epigenetic reprogramming in aromatase inhibitors (AI)-resistant cells, leading to Keratin-80 (KRT80) upregulation. KRT80 expression is driven by de novo enhancer activation by sterol regulatory element-binding protein 1 (SREBP1). KRT80 upregulation directly promotes cytoskeletal rearrangements at the leading edge, increased focal adhesion and cellular stiffening, collectively promoting cancer cell invasion. Shearwave elasticity imaging performed on prospectively recruited patients confirms KRT80 levels correlate with stiffer tumors. Immunohistochemistry showed increased KRT80-positive cells at relapse and, using several clinical endpoints, KRT80 expression associates with poor survival. Collectively, our data uncover an unpredicted and potentially targetable direct link between epigenetic and cytoskeletal reprogramming promoting cell invasion in response to chronic AI treatment.
Matellan C, Del Río Hernández AE, 2019, Engineering the cellular mechanical microenvironment - from bulk mechanics to the nanoscale., J Cell Sci, Vol: 132
The field of mechanobiology studies how mechanical properties of the extracellular matrix (ECM), such as stiffness, and other mechanical stimuli regulate cell behaviour. Recent advancements in the field and the development of novel biomaterials and nanofabrication techniques have enabled researchers to recapitulate the mechanical properties of the microenvironment with an increasing degree of complexity on more biologically relevant dimensions and time scales. In this Review, we discuss different strategies to engineer substrates that mimic the mechanical properties of the ECM and outline how these substrates have been applied to gain further insight into the biomechanical interaction between the cell and its microenvironment.
Cortes E, Lachowski D, Robinson B, et al., 2019, Tamoxifen mechanically reprograms the tumor microenvironment via HIF-1A and reduces cancer cell survival, EMBO Reports, Vol: 20, ISSN: 1469-221X
The tumor microenvironment is fundamental to cancer progression, and the influence of its mechanical properties is increasingly being appreciated. Tamoxifen has been used for many years to treat estrogen-positive breast cancer. Here we report that tamoxifen regulates the level and activity of collagen cross-linking and degradative enzymes, and hence the organization of the extracellular matrix, via a mechanism involving both the G protein-coupled estrogen receptor (GPER) and hypoxia-inducible factor-1 alpha (HIF-1A). We show that tamoxifen reduces HIF-1A levels by suppressing myosin-dependent contractility and matrix stiffness mechanosensing. Tamoxifen also downregulates hypoxia-regulated genes and increases vascularization in PDAC tissues. Our findings implicate the GPER/HIF-1A axis as a master regulator of peri-tumoral stromal remodeling and the fibrovascular tumor microenvironment and offer a paradigm shift for tamoxifen from a well-established drug in breast cancer hormonal therapy to an alternative candidate for stromal targeting strategies in PDAC and possibly other cancers.
Cortes E, Sarper M, Robinson B, et al., 2019, GPER is a mechanoregulator of pancreatic stellate cells and the tumor microenvironment, EMBO Reports, Vol: 20, ISSN: 1469-221X
The mechanical properties of the tumor microenvironment are emerging as attractive targets for the development of therapies. Tamoxifen, an agonist of the G protein-coupled estrogen receptor (GPER), is widely used to treat estrogen-positive breast cancer. Here, we show that tamoxifen mechanically reprograms the tumor microenvironment through a newly identified GPER-mediated mechanism. Tamoxifen inhibits the myofibroblastic differentiation of pancreatic stellate cells (PSCs) in the tumor microenvironment of pancreatic cancer in an acto-myosin-dependent manner via RhoA-mediated contractility, YAP deactivation, and GPER signaling. This hampers the ability of PSCs to remodel the extracellular matrix and to promote cancer cell invasion. Tamoxifen also reduces the recruitment and polarization to the M2 phenotype of tumor-associated macrophages. Our results highlight GPER as a mechanical regulator of the tumor microenvironment that targets the three hallmarks of pancreatic cancer: desmoplasia, inflammation, and immune suppression. The well-established safety of tamoxifen in clinics may offer the possibility to redirect the singular focus of tamoxifen on the cancer cells to the greater tumor microenvironment and lead a new strategy of drug repurposing.
Cortes E, Lachowski D, Rice A, et al., 2018, Tamoxifen mechanically deactivates hepatic stellate cells via the G protein-coupled estrogen receptor, Oncogene, ISSN: 0950-9232
Tamoxifen has been used for many years to target estrogen receptor signalling in breast cancer cells. Tamoxifen is also an agonist of the G protein-coupled estrogen receptor (GPER), a GPCR ubiquitously expressed in tissues that mediates the acute response to estrogens. Here we report that tamoxifen promotes mechanical quiescence in hepatic stellate cells (HSCs), stromal fibroblast-like cells whose activation triggers and perpetuates liver fibrosis in hepatocellular carcinomas. This mechanical deactivation is mediated by the GPER/RhoA/myosin axis and induces YAP deactivation. We report that tamoxifen decreases the levels of hypoxia-inducible factor-1 alpha (HIF-1α) and the synthesis of extracellular matrix proteins through a mechanical mechanism that involves actomyosin-dependent contractility and mechanosensing of tissue stiffness. Our results implicate GPER-mediated estrogen signalling in the mechanosensory-driven activation of HSCs and put forward estrogenic signalling as an option for mechanical reprogramming of myofibroblast-like cells in the tumour microenvironment. Tamoxifen, with half a century of safe clinical use, might lead this strategy of drug repositioning.
Yeldag G, Rice A, Del Rio Hernandez A, 2018, Chemoresistance and the self-maintaining tumor microenvironment, Cancers, Vol: 10, ISSN: 2072-6694
The progression of cancer is associated with alterations in the tumor microenvironment, including changes in extracellular matrix (ECM) composition, matrix rigidity, hypervascularization, hypoxia, and paracrine factors. One key malignant phenotype of cancer cells is their ability to resist chemotherapeutics, and elements of the ECM can promote chemoresistance in cancer cells through a variety of signaling pathways, inducing changes in gene expression and protein activity that allow resistance. Furthermore, the ECM is maintained as an environment that facilitates chemoresistance, since its constitution modulates the phenotype of cancer-associated cells, which themselves affect the microenvironment. In this review, we discuss how the properties of the tumor microenvironment promote chemoresistance in cancer cells, and the interplay between these external stimuli. We focus on both the response of cancer cells to the external environment, as well as the maintenance of the external environment, and how a chemoresistant phenotype emerges from the complex signaling network present.
Samandari M, Julia MG, Rice A, et al., 2018, Liquid biopsies for management of pancreatic cancer, TRANSLATIONAL RESEARCH, Vol: 201, Pages: 98-127, ISSN: 1931-5244
Cameron W, Elijah M, Del Rio Hernandez A, 2018, Role of extracellular matrix in development and cancer progression, International Journal of Molecular Sciences, Vol: 19, ISSN: 1422-0067
The immense diversity of extracellular matrix (ECM) proteins confers distinct biochemical and biophysical properties that influence cell phenotype. The ECM is highly dynamic as it is constantly deposited, remodelled, and degraded during development until maturity to maintain tissue homeostasis. The ECM’s composition and organization are spatiotemporally regulated to control cell behaviour and differentiation, but dysregulation of ECM dynamics leads to the development of diseases such as cancer. The chemical cues presented by the ECM have been appreciated as key drivers for both development and cancer progression. However, the mechanical forces present due to the ECM have been largely ignored but recently recognized to play critical roles in disease progression and malignant cell behaviour. Here, we review the ways in which biophysical forces of the microenvironment influence biochemical regulation and cell phenotype during key stages of human development and cancer progression.
Cortes E, Lachowski D, Rice A, et al., 2018, RAR-β is downregulated in HCC & cirrhosis and its expression inhibits myosin-driven activation and durotaxis in hepatic stellate cells, Hepatology, ISSN: 0270-9139
Hepatic stellate cells (HSCs) are essential perisinusoidal cells in the healthy and diseased liver. HSCs modulate extracellular matrix (ECM) homeostasis when quiescent, but in liver fibrosis, HSCs become activated and promote excess deposition of ECM molecules and tissue stiffening via force generation and mechanosensing. In hepatocellular carcinoma (HCC), activated HSCs infiltrate the stroma and migrate to the tumor core to facilitate paracrine signalling with cancer cells. Since the function of HSCs is known to be modulated by retinoids, we investigated the expression profile of retinoic acid receptor beta (RAR-β) in cirrhotic and HCC patients, as well as the effects of RAR-β activation in HSCs. We found that RAR-β expression is significantly reduced in cirrhotic and HCC tissues. Using a comprehensive set of biophysical methods combined with cellular and molecular biology, we have elucidated the biomechanical mechanism by which all trans-retinoic acid (ATRA) promotes HSC deactivation via RAR-β-dependent transcriptional downregulation of myosin light chain 2 (MLC-2) expression. Furthermore, this also abrogated mechanically driven migration towards stiffer substrates. CONCLUSION: Targeting mechanotransduction in HSCs at the transcriptional level may offer new therapeutic options for a range of liver diseases. This article is protected by copyright. All rights reserved.
Haining AWM, Rahikainen R, Cortes E, et al., 2018, Mechanotransduction in talin through the interaction of the R8 domain with DLC1, PLoS Biology, Vol: 16, ISSN: 1544-9173
The mechanical unfolding of proteins is a cellular mechanism for force transduction with potentially broad implications in cell fate. Despite this, the mechanism by which protein unfolding elicits differential downstream signalling pathways remains poorly understood. Here, we used protein engineering, atomic force microscopy, and biophysical tools to delineate how protein unfolding controls cell mechanics. Deleted in liver cancer 1 (DLC1) is a negative regulator of Ras homolog family member A (RhoA) and cell contractility that regulates cell behaviour when localised to focal adhesions bound to folded talin. Using a talin mutant resistant to force-induced unfolding of R8 domain, we show that talin unfolding determines DLC1 downstream signalling and, consequently, cell mechanics. We propose that this new mechanism of mechanotransduction may have implications for a wide variety of associated cellular processes.
Elsharkawy S, Al-Jawad M, Pantano MF, et al., 2018, Protein disorder-order interplay to guide the growth of hierarchical mineralized structures, Nature Communications, Vol: 9, ISSN: 2041-1723
Del Rio Hernandez AE, Matellan C, 2018, Cost-effective rapid prototyping and assembly of poly(methyl methacrylate)microfluidic devices., Scientific Reports, Vol: 8, ISSN: 2045-2322
The difficulty in translating conventional microfluidics from laboratory prototypes to commercial products has shifted research efforts towards thermoplastic materials for their higher translational potential and amenability to industrial manufacturing. Here, we present an accessible method to fabricate and assemble polymethyl methacrylate (PMMA) microfluidic devices in a “mask-less” and cost-effective manner that can be applied to manufacture a wide range of designs due to its versatility. Laser micromachining offers high flexibility in channel dimensions and morphology by controlling the laser properties, while our two-step surface treatment based on exposure to acetone vapour and low-temperature annealing enables improvement of the surface quality without deformation of the device. Finally, we demonstrate a capillarity-driven adhesive delivery bonding method that can produce an effective seal between PMMA devices and a variety of substrates, including glass, silicon and LiNbO3. We illustrate the potential of this technique with two microfluidic devices, an H-filter and a droplet generator. The technique proposed here offers a low entry barrier for the rapid prototyping of thermoplastic microfluidics, enabling iterative design for laboratories without access to conventional microfabrication equipment.
Mykuliak V, Haining A, von Essen M, et al., 2018, Mechanical unfolding reveals stable 3-helix intermediates in talin and α-catenin, PLoS Computational Biology, Vol: 14, ISSN: 1553-734X
Mechanical stability is a key feature in the regulation of structural scaffolding proteins and their functions. Despite the abundance of α-helical structures among the human proteome and their undisputed importance in health and disease, the fundamental principles of their behavior under mechanical load are poorly understood. Talin and α-catenin are two key molecules in focal adhesions and adherens junctions, respectively. In this study, we used a combination of atomistic steered molecular dynamics (SMD) simulations, polyprotein engineering, and single-molecule atomic force microscopy (smAFM) to investigate unfolding of these proteins. SMD simulations revealed that talin rod α-helix bundles as well as α-catenin α-helix domains unfold through stable 3-helix intermediates. While the 5-helix bundles were found to be mechanically stable, a second stable conformation corresponding to the 3-helix state was revealed. Mechanically weaker 4-helix bundles easily unfolded into a stable 3-helix conformation. The results of smAFM experiments were in agreement with the findings of the computational simulations. The disulfide clamp mutants, designed to protect the stable state, support the 3-helix intermediate model in both experimental and computational setups. As a result, multiple discrete unfolding intermediate states in the talin and α-catenin unfolding pathway were discovered. Better understanding of the mechanical unfolding mechanism of α-helix proteins is a key step towards comprehensive models describing the mechanoregulation of proteins.
von Erlach T, Bertazzo S, Wozniak MA, et al., 2018, Cell geometry dependent changes in plasma membrane order direct stem cell signalling and fate, Nature Materials, Vol: 17, Pages: 237-242, ISSN: 1476-1122
Cell size and shape affect cellular processes such as cell survival, growth and differentiation1,2,3,4, thus establishing cell geometry as a fundamental regulator of cell physiology. The contributions of the cytoskeleton, specifically actomyosin tension, to these effects have been described, but the exact biophysical mechanisms that translate changes in cell geometry to changes in cell behaviour remain mostly unresolved. Using a variety of innovative materials techniques, we demonstrate that the nanostructure and lipid assembly within the cell plasma membrane are regulated by cell geometry in a ligand-independent manner. These biophysical changes trigger signalling events involving the serine/threonine kinase Akt/protein kinase B (PKB) that direct cell-geometry-dependent mesenchymal stem cell differentiation. Our study defines a central regulatory role by plasma membrane ordered lipid raft microdomains in modulating stem cell differentiation with potential translational applications.
Lachowski D, Cortes E, Robinson B, et al., 2018, FAK controls the mechanical activation of YAP, a transcriptional regulator required for durotaxis, FASEB JOURNAL, Vol: 32, Pages: 1099-1107, ISSN: 0892-6638
Inostroza-Brito KE, Collin EC, Majkowska A, et al., 2017, Cross-linking of a biopolymer-peptide co-assembling system, ACTA BIOMATERIALIA, Vol: 58, Pages: 80-89, ISSN: 1742-7061
Rice AJ, Cortes E, Lachowski D, et al., 2017, Matrix stiffness induces epithelial-mesenchymal transition and promotes chemoresistance in pancreatic cancer cells, Oncogenesis, Vol: 6, Pages: e352-e352, ISSN: 2157-9024
Increased matrix rigidity associated with the fibrotic reaction is documented to stimulate intracellular signalling pathways that promote cancer cell survival and tumour growth. Pancreatic cancer is one of the stiffest of all human solid carcinomas and is characterised by a remarkable desmoplastic reaction. Here we use mouse models, genetically engineered to recapitulate human pancreatic cancer, and several pancreatic cancer cell lines as a model to investigate the effect of matrix stiffness in epithelial-mesenchymal transition (EMT) and resistance to chemotherapeutics. We found that recapitulation of the fibrotic rigidities found in pancreatic cancer tissues promote elements of EMT, including increases in vimentin expression, decreases in E-cadherin expression, nuclear localisation of β-catenin, YAP and TAZ and changes in cell shape towards a mesenchymal phenotype. We also report that stiffness induces chemoresistance to paclitaxel, but not to gemcitabine, both commonly used therapeutics, suggesting that environmental rigidity underlies an aspect of chemoresistance.
Lachowski D, Cortes E, Pink D, et al., 2017, Substrate rigidity controls activation and durotaxis in pancreatic stellate cells, Scientific Reports, Vol: 7, ISSN: 2045-2322
Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive malignancy characterised by the presence of extensive desmoplasia, thought to be responsible for the poor response of patients to systemic therapies. Pancreatic stellate cells (PSCs) are key mediators in the production of this fibrotic stroma, upon activation transitioning to a myofibroblast-like, high matrix secreting phenotype. Given their importance in disease progression, characterisation of PSC activation has been extensive, however one aspect that has been overlooked is the mechano-sensing properties of the cell. Here, through the use of a physiomimetic system that recapitulates the mechanical microenvironment found within healthy and fibrotic pancreas, we demonstrate that matrix stiffness regulates activation and mechanotaxis in PSCs. We show the ability of PSCs to undergo phenotypic transition solely as a result of changes in extracellular matrix stiffness, whilst observing the ability of PSCs to durotactically respond to stiffness variations within their local environment. Our findings implicate the mechanical microenvironment as a potent contributor to PDAC progression and survival via induction of PSC activation and fibrosis, suggesting that direct mechanical reprogramming of PSCs may be a viable alternative in the treatment of this lethal disease.
Chronopoulos A, Lieberthal TJ, del Río Hernández AE, 2017, Pancreatic cancer: a mechanobiology approach, Convergent Science Physical Oncology, Vol: 3, Pages: 013001-013001
Chronopoulos A, Lieberthal TJ, del Río Hernández AE, 2017, Exosomes as a platform for ‘liquid biopsy’ in pancreatic cancer, Convergent Science Physical Oncology, Vol: 3, Pages: 013005-013005
Attwood S, Cortes E, Haining, et al., 2016, Adhesive ligand tether length affects the size and length of focal adhesions and influences cell spreading and attachment, Scientific Reports, Vol: 6, ISSN: 2045-2322
Cells are known to respond to physical cues from their microenvironment such as matrix rigidity.Discrete adhesive ligands within flexible strands of fibronectin connect cell surface integrins to thebroader extracellular matrix and are thought to mediate mechanosensing through the cytoskeletonintegrin-ECMlinkage. We set out to determine if adhesive ligand tether length is another physical cuethat cells can sense. Substrates were covalently modified with adhesive arginylglycylaspartic acid (RGD)ligands coupled with short (9.5nm), medium (38.2nm) and long (318nm) length inert polyethyleneglycol tethers. The size and length of focal adhesions of human foreskin fibroblasts gradually decreasedfrom short to long tethers. Furthermore, we found cell adhesion varies in a linker length dependentmanner with a remarkable 75% reduction in the density of cells on the surface and a 50% reduction incell area between the shortest and longest linkers. We also report the interplay between RGD ligandconcentration and tether length in determining cellular spread area. Our findings show that withoutvarying substrate rigidity or ligand density, tether length alone can modulate cellular behaviour.
Lachowski D, Cortes E, Robinson B, et al., 2016, SAT-402 - Elucidating the Biomechanical Response of Human Hepatic Stellate Cells on Substrates Mimicking Healthy and Fibrotic Matrix Rigidity, EASL International Liver Congress, Publisher: Elsevier, Pages: S706-S706, ISSN: 0168-8278
Chronopoulos A, Robinson B, Sarper M, et al., 2016, ATRA mechanically reprograms pancreatic stellatecells to suppress matrix remodelling and inhibitcancer cell invasion, Nature Communications, Vol: 7, ISSN: 2041-1723
Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a dismalsurvival rate. Persistent activation of pancreatic stellate cells (PSCs) can perturb thebiomechanical homoeostasis of the tumour microenvironment to favour cancer cell invasion.Here we report that ATRA, an active metabolite of vitamin A, restores mechanical quiescencein PSCs via a mechanism involving a retinoic acid receptor beta (RAR-b)-dependentdownregulation of actomyosin (MLC-2) contractility. We show that ATRA reduces the abilityof PSCs to generate high traction forces and adapt to extracellular mechanical cues(mechanosensing), as well as suppresses force-mediated extracellular matrix remodelling toinhibit local cancer cell invasion in 3D organotypic models. Our findings implicate aRAR-b/MLC-2 pathway in peritumoural stromal remodelling and mechanosensory-drivenactivation of PSCs, and further suggest that mechanical reprogramming of PSCs with retinoicacid derivatives might be a viable alternative to stromal ablation strategies for the treatmentof PDAC.
Robinson B, Rice A, Cortes E, et al., Assessment of extracellular matrix remodeling using 3D Matrigel/collagen matrices and second harmonic generation microscopy, Jove-Journal of Visualized Experiments, ISSN: 1940-087X
Sarper M, Lieberthal T, Del Rio Hernandez AE, Elucidating the Effect of Extracellular Matrix Remodeling by Stromal Cells on Pancreatic Cancer Cell Invasion in 3D Organotypic Systems, Jove-Journal of Visualized Experiments, ISSN: 1940-087X
Kis Z, Rodin T, Zafar A, et al., 2016, Development of a synthetic gene network to module gene expression by mechanical forces, Scientific Reports, Vol: 6, ISSN: 2045-2322
The majority of (mammalian) cells in our body are sensitive to mechanical forces, but little work hasbeen done to develop assays to monitor mechanosensor activity. Furthermore, it is currently impossibleto use mechanosensor activity to drive gene expression. To address these needs, we developed thefrst mammalian mechanosensitive synthetic gene network to monitor endothelial cell shear stresslevels and directly modulate expression of an atheroprotective transcription factor by shear stress. Thetechnique is highly modular, easily scalable and allows graded control of gene expression by mechanicalstimuli in hard-to-transfect mammalian cells. We call this new approach mechanosyngenetics. To insertthe gene network into a high proportion of cells, a hybrid transfection procedure was developed thatinvolves electroporation, plasmids replication in mammalian cells, mammalian antibiotic selection,a second electroporation and gene network activation. This procedure takes 1 week and yielded over60% of cells with a functional gene network. To test gene network functionality, we developed a fowsetup that exposes cells to linearly increasing shear stress along the length of the fow channel foor.Activation of the gene network varied logarithmically as a function of shear stress magnitude.
Haining AW, von Essen M, Attwood SJ, et al., 2016, All Subdomains of the Talin Rod Are Mechanically Vulnerable and May Contribute to Cellular Mechanosensing, ACS Nano, Vol: 10, Pages: 6648-6658, ISSN: 1936-086X
Although the relevance of mechanotransduction in cell signalling is currently appreciated, themechanisms that drive this process remain largely unknown. Mechanical unfolding of proteins maytrigger distinct downstream signals in cells, providing a mechanism for cellular mechanotransduction.Force-induced unfolding of talin, a prominent focal adhesion protein, has been demonstrated previouslyfor a small portion of its rod domain. Here, using single-molecule atomic force microscopy (smAFM), weshow that the entire talin rod can be unfolded by mechanical extension, over a physiological range offorces between 10 – 40 pN. We also demonstrate, through a combination of smAFM and steeredmolecular dynamics (SMD), that the different bundles within the talin rod exhibit a distinct hierarchy ofmechanical stability. These results provide a mechanism by which different force conditions within thecell control a graduated unfolding of the talin rod. Mechanical unfolding of the rod subdomains, and thesubsequent effect on talin’s binding interactions, would allow for a finely-tuned cellular response tointernally or externally applied forces.
Sarper M, Cortes E, Lieberthal T, et al., 2016, ATRA modulates mechanical activation of TGF-β by pancreatic stellate cells, Scientific Reports, Vol: 6, ISSN: 2045-2322
The hallmark of pancreatic ductal adenocarcinoma (PDAC) is abundant desmoplasia, which is orchestrated by pancreatic stellate cells (PSCs) and accounts for the majority of the stroma surrounding the tumour. Healthy PSCs are quiescent, but upon activation during disease progression, they adopt a myofibroblast-contractile phenotype and secrete and concomitantly reorganise the stiff extracellular matrix (ECM). Transforming growth factor β (TGF-β) is a potent activator of PSCs, and its activation requires spatiotemporal organisation of cellular and extracellular cues to liberate it from an inactive complex with latent TGF-β binding protein (LTBP). Here we study the mechanical activation of TGF-β by PSCs in vitro by investigating LTBP-1 organisation with fibrillar fibronectin and show that all trans-retinoic acid (ATRA), which induces PSC quiescence, down-regulates the ability of PSCs to mechanically organise LTBP-1 and activate TGF-β through a mechanism involving myosin II dependent contractility. Therefore, ATRA inhibits the ability of PSCs to mechanically release active TGF-β, which might otherwise act in an autocrine manner to sustain PSCs in an active state and a tumour-favouring stiff microenvironment.
Robinson BK, Cortes E, Rice AJ, et al., 2016, Quantitative analysis of 3D extracellular matrix remodelling bypancreatic stellate cells, Biology Open, Vol: 5, Pages: 875-882, ISSN: 2046-6390
Extracellular matrix (ECM) remodelling is integral to numerousphysiological and pathological processes in biology, such asembryogenesis, wound healing, fibrosis and cancer. Until recently,most cellular studies have been conducted on 2D environmentswhere mechanical cues significantly differ from physiologicallyrelevant 3D environments, impacting cellular behaviour andmasking the interpretation of cellular function in health and disease.We present an integrated methodology where cell-ECM interactionscan be investigated in 3D environments via ECM remodelling.Monitoring and quantification of collagen-I structure in remodelledmatrices, through designated algorithms, show that 3D matrices canbe used to correlate remodelling with increased ECM stiffnessobserved in fibrosis. Pancreatic stellate cells (PSCs) are the keyeffectors of the stromal fibrosis associated to pancreatic cancer. Weuse PSCs to implement our methodology and demonstrate that PSCmatrix remodelling capabilities depend on their contractile machineryand β1 integrin-mediated cell-ECM attachment.
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