Biology subjects

Kopecky, C.

Publications and source records attributed to Kopecky, C..

6 recordsLinked to original sources

bioRxiv2025

Capillary constrictions prime cancer cell tumorigenicity through PIEZO1

Metastasis is a hallmark of cancer and is responsible for the majority of cancer-related deaths. Evidence suggests that even a single cancer cell can spread and seed a secondary tumour. However, not all circulating tumour cells have this ability, which implies that dissemination and distal growth require adaptative mechanisms during circulation. Here we report that constriction during microcapillary transit will trigger reprogramming of melanoma cells to a tumorigenic cancer stem cell-like state. Using a microfluidic device mimicking physiological flow rates and gradual capillary narrowing, we showed that compression through narrow channels lead to cell and nuclear deformation, rapid changes in chromatin state and increased calcium handling through the mechanosensor PIEZO1. Within minutes of microcapillary transit, cells show increased regulation of transcripts associated with metabolic reprogramming and metastatic processes, which culminates in the adoption of cancer stem cell-like properties. Squeezed cells displayed elevated melanoma stem cell markers, increased propensity for trans-endothelium invasion, and characteristics of enhanced tumorigenicity in vitro and in vivo. Pharmacological disruption of channel activity inhibited the stem cell-like state, while the selective PIEZO1 activator Yoda1 primed this state irrespective of constriction. Finally, deletion of PIEZO1 led to complete abrogation of the constriction-induced stem cell-like state. Together, this work demonstrates that compressive forces during circulation can reprogram circulating cancer cells to tumorigenic stem cell-like states that are primed for extravasation and metastatic colonization.

cancer biology↗

bioRxiv2022

Effect of insulin insufficiency on ultrastructure and function in skeletal muscle

BackgroundDecreased insulin availability and high blood glucose levels, the hallmark features of poorly controlled diabetes, drive disease progression and are associated with decreased skeletal muscle mass. We have shown that mice with {beta}-cell dysfunction and normal insulin sensitivity have decreased skeletal muscle mass. This project asks how insulin deficiency impacts on the structure and function of the remaining skeletal muscle in these animals. MethodsSkeletal muscle function was determined by measuring exercise capacity and specific muscle strength prior to and after insulin supplementation for 28 days in 12-week-old mice with conditional {beta}-cell deletion of the ATP binding cassette transporters ABCA1 and ABCG1 ({beta}-DKO mice). Abca1 and Abcg1 floxed (fl/fl) mice were used as controls. RNAseq was used to quantify changes in transcripts in soleus and extensor digitorum longus muscles. Skeletal muscle and mitochondrial morphology were assessed by transmission electron microscopy. Myofibrillar Ca2+ sensitivity and maximum isometric single muscle fibre force were assessed using MyoRobot biomechatronics technology. ResultsRNA transcripts were significantly altered in {beta}-DKO mice compared to fl/fl controls (32 in extensor digitorum longus and 412 in soleus). Exercise capacity and muscle strength were significantly decreased in {beta}-DKO mice compared to fl/fl controls (p = 0.012), and a loss of structural integrity was also observed in skeletal muscle from the {beta}-DKO mice. Supplementation of {beta}-DKO mice with insulin restored muscle integrity, strength and expression of 13 and 16 of the dysregulated transcripts in and extensor digitorum longus and soleus muscles, respectively. ConclusionsInsulin insufficiency due to {beta}-cell dysfunction perturbs the structure and function of skeletal muscle. These adverse effects are rectified by insulin supplementation.

physiology↗

bioRxiv2022

βIII-Tubulin is a Brake on Extrinsic Cell-Death in Pancreatic Cancer

The microtubule protein, {beta}III-tubulin, has been implicated as a prognostic, pro-survival, and chemoresistance factor in some of the most lethal malignancies including pancreatic ductal adenocarcinoma (PDAC). However, precise survival mechanisms controlled by {beta}III-tubulin in cancer cells are unknown. Here, we report an unexpected role of {beta}III-tubulin as a brake on extrinsic caspase 8-dependent apoptosis in PDAC. We show that {beta}III-tubulin knockdown frees death-receptor DR5 to increase its membrane diffusion, clustering, and activation of cell-death. We demonstrate that {beta}III-ubulin silencing increases sensitivity of PDAC cells to chemotherapeutic and microenvironment-derived extrinsic cell-death signals including TRAIL, TNF, and FasL. Finally, nanoparticle delivery of {beta}III-tubulin siRNA to mouse orthotopic PDAC tumours in vivo and human patient-derived PDAC tumour explants ex vivo increases extrinsic apoptosis and reduces tumour progression. Thus, silencing of {beta}III-tubulin represents an innovative strategy to unleash a suicide signal in PDAC cells and render them sensitive to microenvironment and chemotherapy-derived death signals.

cancer biology↗

bioRxiv2022

Gas modulating microcapsules for spatiotemporal control of hypoxia

Oxygen is a vital molecule involved in regulating development, homeostasis, and disease. The oxygen levels in tissue vary from 1 to 8% with deviations having major biological consequences. In this work, we developed an approach to encapsulate enzymes and nanozymes, at an unprecedented loading capacity, which precisely controls the oxygen content in cell culture. Here, a single microcapsule is able to locally perturb the oxygen balance, and varying the concentration and distribution of matrix embedded microcapsules provides spatiotemporal control. We demonstrate attenuation of hypoxia signaling in populations of stem cells, cancer cells, endothelial cells, and cancer spheroids. Capsule containing hydrogel films applied to chick chorioallantoic membranes encourage neovascularization, providing scope for topical treatments or hydrogel wound dressings. We further demonstrate versatility by loading capsules with ceria nanorods as "nanozymes" to modulate active oxygen species with potential as a cytoprotective treatment. The approach can be used in multiple formats, including deposition in hydrogels, as granular solids for 3D bioprinting, and as injectable biomaterials. Overall, this platforms simplicity and flexibility will prove useful for fundamental studies of oxygen-mediated processes in virtually any in vitro or in vivo format, with scope for inclusion in biomedical materials where controlling hypoxia may be clinically advantageous.

bioengineering↗

bioRxiv2020

Bringing the pancreas patient back to the bench: Ex vivo culture of intact human patient derived pancreatic tumour tissue

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is attributed to the highly fibrotic stroma and complex multi-cellular microenvironment that is difficult to fully recapitulate in pre-clinical human models. To fast-track translation of therapies and to inform personalised medicine, we aimed to develop a whole-tissue ex vivo explant model that maintains viability, 3D multicellular architecture, and microenvironmental cues present in human pancreatic tumours. Patient-derived surgically-resected PDAC tissue was cut into 2 mm explants, cultured on gelatin sponges, and grown for 12 days. Immunohistochemistry revealed that human PDAC tissue explants were viable for 12 days and maintained their original tumour, stromal and extracellular matrix architecture. As proof-of-principle, human PDAC tissue explants responded to Abraxane(R) treatment with a 3.7-fold increase in cell-death (p=0.0007). PDAC explants were also transfected with polymeric nanoparticles+Cy5-siRNA and we observed abundant cytoplasmic distribution of nanoparticle+Cy5-siRNA throughout the PDAC explant tissue. Our novel model retains the 3D architecture of human pancreatic tumours and has several advantages over standard organoids: presence of functional multi-cellular stroma and fibrosis and no tissue manipulation, digestion, or artificial propagation of organoids. This provides an unprecedented opportunity to study PDAC biology, tumour-stromal interactions and rapidly assess therapeutic response that could drive personalised treatment for PDAC.

cancer biology↗

bioRxiv2018

Translocator Protein Localises To CD11b+ Macrophages In Atherosclerosis

BackgroundAtherosclerosis is characterized by lipid deposition, monocyte infiltration and foam cell formation in the artery wall. Translocator protein (TSPO) is abundantly expressed in lipid rich tissues. Recently, TSPO has been identified as a potential diagnostic tool in cardiovascular disease. The purpose of this study was to determine if the TSPO ligand, 18F-PBR111, can identify early atherosclerotic lesions and if TSPO expression can be used to identify distinct macrophage populations during lesion progression.\n\nMethods and ResultsApoE-/- mice were maintained on a high-fat diet for 3 or 12 weeks. C57BL/6J mice maintained on chow diet served as controls. Mice were administered 18F-PBR111 intravenously and PET/CT imaged. After euthanasia, aortas were isolated, fixed and optically cleared. Cleared aortas were immunostained with DAPI, and fluorescently labelled with antibodies to-TSPO, the tissue resident macrophage marker F4/80 and the monocyte-derived macrophage marker CD11b. TSPO expression and the macrophage markers were visualised in fatty streaks and mature lesions by light sheet microscopy. While tissue resident F4/80+ macrophages were evident in the arteries of animals without atherosclerosis, no CD11b+ macrophages were observed in these animals. In contrast, mature plaques had high CD11b and low F4/80 expression. A ~3-fold increase in the uptake of 18F-PBR111 was observed in the aortas of atherosclerotic mice relative to controls.\n\nConclusionsImaging of TSPO expression is a new approach for studying atherosclerotic lesion progression and inflammatory cell infiltration. The TSPO ligand, 18F-PBR111, is a potential clinical diagnostic tool for the detection and quantification of atherosclerotic lesion progression in humans.

pathology↗