37 research outputs found
Therapeutic Targeting of Fibrotic Epithelial-Mesenchymal Transition–An Outstanding Challenge
Back in 1995, a landmark paper was published, which shaped the fibrosis literature for many years to come. During the characterization of a fibroblast-specific marker (FSP1) in the kidneys, an observation was made, which gave rise to the hypothesis that “fibroblasts in some cases arise from the local conversion of epithelium.” In the following years, epithelial-mesenchymal transition was in the spotlight of fibrosis research, especially in the kidney. However, the hypothesis came under scrutiny following some discouraging findings from lineage tracing experiments and clinical observations. In this review, we provide a timely overview of the current position of the epithelial-mesenchymal transition hypothesis in the context of fibrosis (with a certain focus on renal fibrosis) and highlight some of the potential hurdles and pitfalls preventing therapeutic breakthroughs targeting fibrotic epithelial-mesenchymal transition
Endothelial-Mesenchymal Transition of Brain Endothelial Cells: Possible Role during Metastatic Extravasation
Cancer progression towards metastasis follows a defined sequence of events described as the metastatic cascade. For extravasation and transendothelial migration metastatic cells interact first with endothelial cells. Yet the role of endothelial cells during the process of metastasis formation and extravasation is still unclear, and the interaction between metastatic and endothelial cells during transendothelial migration is poorly understood. Since tumor cells are well known to express TGF-beta, and the compact endothelial layer undergoes a series of changes during metastatic extravasation (cell contact disruption, cytoskeletal reorganization, enhanced contractility), we hypothesized that an EndMT may be necessary for metastatic extravasation. We demonstrate that primary cultured rat brain endothelial cells (BEC) undergo EndMT upon TGF-beta 1 treatment, characterized by the loss of tight and adherens junction proteins, expression of fibronectin, beta 1-integrin, calponin and a-smooth muscle actin (SMA). B16/F10 cell line conditioned and activated medium (ACM) had similar effects: claudin-5 down-regulation, fibronectin and SMA expression. Inhibition of TGF-beta signaling during B16/F10 ACM stimulation using SB-431542 maintained claudin-5 levels and mitigated fibronectin and SMA expression. B16/F10 ACM stimulation of BECs led to phosphorylation of Smad2 and Smad3. SB-431542 prevented SMA up-regulation upon stimulation of BECs with A2058, MCF-7 and MDA-MB231 ACM as well. Moreover, B16/F10 ACM caused a reduction in trans-endothelial electrical resistance, enhanced the number of melanoma cells adhering to and transmigrating through the endothelial layer, in a TGF-beta-dependent manner. These effects were not confined to BECs: HUVECs showed TGF-beta-dependent SMA expression when stimulated with breast cancer cell line ACM. Our results indicate that an EndMT may be necessary for metastatic transendothelial migration, and this transition may be one of the potential mechanisms occurring during the complex phenomenon known as metastatic extravasation
Sleeping Beauty transposon-based system for cellular reprogramming and targeted gene insertion in induced pluripotent stem cells.
The discovery of direct cell reprogramming and induced
pluripotent stem (iPS) cell technology opened up new avenues for
the application of non-viral, transposon-based gene delivery
systems. The Sleeping Beauty (SB) transposon is highly advanced
for versatile genetic manipulations in mammalian cells. We
established iPS cell reprogramming of mouse embryonic
fibroblasts and human foreskin fibroblasts by transposition of
OSKM (Oct4, Sox2, Klf4 and c-Myc) and OSKML (OSKM + Lin28)
expression cassettes mobilized by the SB100X hyperactive
transposase. The efficiency of iPS cell derivation with SB
transposon system was in the range of that obtained with
retroviral vectors. Co-expression of the miRNA302/367 cluster
together with OSKM significantly improved reprogramming
efficiency and accelerated the temporal kinetics of
reprogramming. The iPS cells displayed a stable karyotype, and
hallmarks of pluripotency including expression of stem cell
markers and the ability to differentiate into embryoid bodies in
vitro. We demonstrate Cre recombinase-mediated exchange allowing
simultaneous removal of the reprogramming cassette and targeted
knock-in of an expression cassette of interest into the
transposon-tagged locus in mouse iPS cells. This strategy would
allow correction of a genetic defect by site-specific insertion
of a therapeutic gene construct into 'safe harbor' sites in the
genomes of autologous, patient-derived iPS cells
Forward Genetic Screens as Tools to Investigate Role and Mechanisms of EMT in Cancer
Epithelial–mesenchymal transition (EMT) is a process of cellular plasticity regulated by complex signaling networks. Under physiological conditions, it plays an important role in wound healing and organ repair. Its importance for human disease is given by its central role in chronic fibroproliferative diseases and cancer, which represent leading causes of death worldwide. In tumors, EMT is involved in primary tumor growth, metastasis and therapy resistance. It is therefore a major requisite to investigate and understand the role of EMT and the mechanisms leading to EMT in order to tackle these diseases therapeutically. Forward genetic screens link genome modifications to phenotypes, and have been successfully employed to identify oncogenes, tumor suppressor genes and genes involved in metastasis or therapy resistance. In particular, transposon-based insertional mutagenesis screens and CRISPR-based screens are versatile and easy-to-use tools applied in recent years to discover and identify novel cancer-related mechanisms. Here, we review the contribution of forward genetic screens to our understanding of how EMT is regulated and how it is involved in various aspects of cancer. Based on the current literature, we propose these methods as additional tools to investigate EMT
MIDDLE TRIASSIC (ANISIAN) CEPHALOPODS FROM THE MECSEK MOUNTAINS, HUNGARY
Recent nautiloid and ammonoid finds from the Middle Triassic Zuhánya Limestone Formation in the Mecsek Mountains (south Hungary) proved that the formation encompasses the whole Pelsonian and the lower Illyrian substages of the Anisian Stage. On the basis of 11 identified ammonoid species, the Balatonicus and Trinodosus zones have a complete record. The stratigraphical position of the Zuhánya Limestone on the whole corresponds to the Felsőörs Limestone in the Balaton Highland. The palaeobiogeographical evaluation of the cephalopod fauna showed that the elements of the nautilid fauna point mostly to Germanic and partly to Sephardic affinity. On the other hand, the ammonoid fauna has no Germanic elements; most of the species are Alpine in character, while the species Procladiscites brancoi indicates Dinaridic connection, or at least an occasional appearance of pelagic organisms. These results endorse the previous palaeogeographical assumption and suggest that during the Middle Triassic the Mecsek succession was situated along the European shelf, between the Vindelician-Bohemian Land and the open Tethyan Ocean
Genetisch modifizierte regulatorische T-Zellen: Therapiekonzepte und ihr regulatorischer Rahmen
Adoptive T‑cell therapies are emerging tools to combat various human diseases. CAR‑T cells are approved and marketed as last line therapeutics in advanced B‑cell lymphomas and leukemias. TCR-engineered T cells are being evaluated in clinical trials for a variety of hematological and solid tumors. Genetically modified regulatory T cells, however, are still in the initial stages of clinical development for the induction of immune tolerance in various indications.Here we outline the general role of regulatory T cells in establishing self-tolerance and the mechanisms by which these suppress the effector immune cells. Further, the role of regulatory T cells in the pathomechanism of certain immune diseases is presented, and the current status of clinical developments of genetically modified Treg cells is discussed. We also present the regulatory framework for genetically modified regulatory T cells as advanced therapy medicinal products, including aspects of manufacture and quality control, as well as nonclinical and clinical development requirements
When the endothelium scores an own goal: endothelial cells actively augment metastatic extravasation through endothelial-mesenchymal transition
Endothelial-mesenchymal transition (EndMT) is an important mechanism during organ development and in certain pathological conditions. For example, EndMT contributes to myofibroblast formation during organ fibrosis, and it has been identified as an important source of cancer-associated fibroblasts, facilitating tumor progression. Recently, EndMT was proposed to modulate endothelial function during intravasation and extravasation of metastatic tumor cells. Evidence suggests that endothelial cells are not passive actors during transendothelial migration (TEM) of cancer cells, as there are profound changes in endothelial junctional protein expression, signaling, permeability, and contractility. This review describes these alterations in endothelial characteristics during TEM of metastatic tumor cells and discusses them in the context of EndMT. EndMT could play an important role during metastatic intravasation and extravasation, a novel hypothesis that may lead to new therapeutic approaches to tackle metastatic disease. </jats:p