Onkogenomikai kutatás melanomában génexpresszió és a nem kódoló microRNS profil meghatározása alapján = Oncogenomic studies in melanoma through gene expression and non-coding microRNA profiling

Kutatásukban mikroRNS (miRNS) expressziót vizsgáltak a melanoma sejtvonalakban, szövetmintákban és melanocyta sejtekben. Céluk a melanoma komplex keletkezési és fennmaradási mechanizmusában a miRNS profil felvételével új, melanomában eddig még nem leírt, a normáltól eltérő expresszió –szabályozási hálózat keresése, amely a daganat biológiai viselkedésének hátterében állhat, tükrözve a genetikai és epigenetikai tényezők komplexitását. A talált miRNS-ek lehetőséget adhatnak a célzott génterápia bevezetésére. Eredmények: 1. A melanoma sejtvonalak miRNS összetétele eltér a normál bőr melanocitáiktól 2. Egy, sok tumorban megtalálható miRNS, a miR21 bejuttatása sejtekbe önmagában nem okoz lényeges funkcionális hatást 3. Eltérést találtak a melanoma szövetminták és a melanoma vonalak miRNS mintázatában 4. Útvonalanalízis eredményeképpen egyes molekuláris jelutak (génhálózatok) kiemelt jelentőségét ismerték fel melanomában (elsősorban a p53 út) 5. Informatikai eszközökkel célpont predikciót végeztek. Kimutatták, hogy a melanoma szövet közelében található hízósejtekben a miRNS- 132 nagyon erősen gátló hatású, amely egy új génterápia lehetőségét veti fel. | In the present research mikroRNA (miRNA) expression was analysed in melanoma cell lines, tissue and melanocytes. Our goal was to uncover the complex mechanism of the miRNA action, specific on the regulatory network of the tumor reflecting the underlying epigenetic factors. Based on these findings a novel miRNA-targeted gene therapy may provide new opportunities. Results: 1. The melanoma cell lines differ in the composition of the miRNA from that of the melanocytes of healthy skin 2. A common miRNAs, miR21 transfected alone into cells does not cause a significant functional effect 3. Differences were found in the pattern of miRNA between melanoma tissue samples and established melanoma cell lines 4. The pathway analysis of the molecular signal processes proved the utmost importance of p53 pathway. 5. Mast cells occur in close vicinity of melanoma. Based on target prediciton screening miRNA-132 was selected. This miRNA reveals a very strong inhibitory effect, which raises the possibility of a new gene therapy

Characterization of the in vitro gene response of chicken cells to Salmonella Enteritidis

Salmonella Enteritidis (SE) is one of the most frequently reported causative agent of human gastroenteritis, originating mainly from poultry. Pathogenesis of SE infection in poultry is well-elucidated, but the complexity of the host cell response, and its relation to differring pathogenic potential of various strains is much less understood. Therefore we intended to provide a genome-wide comparative characterization of the gene expression profiles of chicken cells to wild type strains and virulence-related mutants of Salmonella Enteritidis. Freshly isolated chicken embryo fibroblast (CEF) cells co-incubated with Salmonella for 4 hrs were used to model gene response of young chickens to Salmonella infection and to measure the invasiveness of wild type strains SE147, SE11 and non-motile mutants of SE11 lacking the fliD gene and/or the virulence plasmid. Agilent custom 8×15K microarray was designed to profile the expression of 13741 chicken genes, with emphasis to those related to immune response. Significant gene expression changes with fold change ≥3 (in total of 31 genes) were verified by real-time PCR. Expression profile of infected CEF cells resulted in 314 genes significantly misregulated by the infection with the wild type strain SE147 (206 up-/108 down-regulations) while only 135 genes were significantly expressed as a result to SE11 infection (74 up-/61 down-regulations). There were 100 genes induced by both wild strains, among them CSF3 (colony-stimulating factor), IL-1β and IL-8 showing the highest upregulations. In contrast to this, infection with non-motile mutants lacking fliD gene and/or the virulence plasmid, did not cause any significant change in host gene expression. However real-time PCR results indicated that the cell cycle-related G0S2 switch-, and the enolase ENO2 genes were highly induced by the mutant strains, indicating that the reduced invasiveness of the mutants might have stimulated cell division and/or metabolism of the host cells. Results suggest that fliD gene plays a key role in the invasiveness of Salmonella strains, and could be considered as an important modulator of the chicken response to Salmonella infection. This work was supported by the EU FP6 NoE MedVetNet and OTKA 105635. Ama Szmolka is a holder of János Bolyai Research Scholarship of HAS

Low-density lipoprotein mimics blood plasma-derived exosomes and microvesicles during isolation and detection

Circulating extracellular vesicles have emerged as potential new biomarkers in a wide variety of diseases. Despite the increasing interest, their isolation and purification from body fluids remains challenging. Here we studied human pre-prandial and 4 hours postprandial platelet-free blood plasma samples as well as human platelet concentrates. Using flow cytometry, we found that the majority of circulating particles within the size range of extracellular vesicles lacked common vesicular markers. We identified most of these particles as lipoproteins (predominantly low-density lipoprotein, LDL) which mimicked the characteristics of extracellular vesicles and also co-purified with them. Based on biophysical properties of LDL this finding was highly unexpected. Current state-of-the-art extracellular vesicle isolation and purification methods did not result in lipoprotein-free vesicle preparations from blood plasma or from platelet concentrates. Furthermore, transmission electron microscopy showed an association of LDL with isolated vesicles upon in vitro mixing. This is the first study to show co-purification and in vitro association of LDL with extracellular vesicles and its interference with vesicle analysis. Our data point to the importance of careful study design and data interpretation in studies using blood-derived extracellular vesicles with special focus on potentially co-purified LDL

Transcription factor PROX1 suppresses Notch pathway activation via the nucleosome remodeling and deacetylase complex in colorectal cancer stem-like cells

The homeobox transcription factor PROX1 is induced by high Wnt/ß-catenin activity in intestinal adenomas and colorectal cancer (CRC), where it promotes tumor progression. Here we report that in LGR5+ CRC cells, PROX1 suppresses the Notch pathway, which is essential for cell fate in intestinal stem cells. Pharmacological inhibition of Notch in ex vivo 3D organoid cultures from transgenic mouse intestinal adenoma models increased Prox1 expression and the number of PROX1-positive cells. Notch inhibition led to increased proliferation of the PROX1-positive CRC cells but did not affect their ability to give rise to PROX1-negative secretory cells. Conversely, PROX1 deletion increased Notch target gene expression and NOTCH1 promoter activity, indicating reciprocal regulation between PROX1 and the Notch pathway in CRC. PROX1 interacted with the nucleosome remodeling and deacetylase (NuRD) complex to suppress the Notch pathway. Thus, our data suggests that PROX1 and Notch suppress each other and that PROX1-mediated suppression of Notch mediates its stem cell function in CRC

Antibiotic-induced release of small extracellular vesicles (exosomes) with surface-associated DNA

Recently, biological roles of extracellular vesicles (which include among others exosomes, microvesicles and apoptotic bodies) have attracted substantial attention in various fields of biomedicine. Here we investigated the impact of sustained exposure of cells to the fluoroquinolone antibiotic ciprofloxacin on the released extracellular vesicles. Ciprofloxacin is widely used in humans against bacterial infections as well as in cell cultures against Mycoplasma contamination. However, ciprofloxacin is an inducer of oxidative stress and mitochondrial dysfunction of mammalian cells. Unexpectedly, here we found that ciprofloxacin induced the release of both DNA (mitochondrial and chromosomal sequences) and DNA-binding proteins on the exofacial surfaces of small extracellular vesicles referred to in this paper as exosomes. Furthermore, a label-free optical biosensor analysis revealed DNA-dependent binding of exosomes to fibronectin. DNA release on the surface of exosomes was not affected any further by cellular activation or apoptosis induction. Our results reveal for the first time that prolonged low-dose ciprofloxacin exposure leads to the release of DNA associated with the external surface of exosomes

Skin-homing CD8+ T cells preferentially express GPI-anchored peptidase inhibitor 16, an inhibitor of cathepsin K

This study sought to identify novel CD8+ T cell homing markers by studying acute graft versus host disease (aGvHD), typically involving increased T cell homing to the skin and gut. FACS-sorted skin-homing (CD8β+ /CLA+ ), gut-homing (CD8β+ /integrinβ7+ ), and reference (CD8β+ /CLA- /integrinβ7- ) T cells were compared in patients affected by cutaneous and/or gastrointestinal aGVHD. Microarray analysis, qPCR, and flow cytometry revealed increased expression of peptidase inhibitor 16 (PI16) in skin-homing CD8+ T cells. Robust association of PI16 with skin homing was confirmed in all types of aGvHD and in healthy controls, too. PI16 was not observed on CLA+ leukocytes other than T cells. Induction of PI16 expression on skin-homing T cells occurred independently of vitamin D3. Among skin-homing T cells, PI16 expression was most pronounced in memory-like CD45RO+ /CD127+ /CD25+ /CD69- /granzyme B- cells. PI16 was confined to the plasma membrane, was GPI-anchored, and was lost upon restimulation of memory CD8+ T cells. Loss of PI16 occurred by downregulation of PI16 transcription, and not by Phospholipase C (PLC)- or Angiotensin-converting enzyme (ACE)-mediated shedding, or by protein recycling. Inhibitor screening and pull-down experiments confirmed that PI16 inhibits cathepsin K, but may not bind to other skin proteases. These data link PI16 to skin-homing CD8+ T cells, and raise the possibility that PI16 may regulate cutaneous cathepsin K

CD44 Expression Intensity Marks Colorectal Cancer Cell Subpopulations with Different Extracellular Vesicle Release Capacity

Extracellular vesicles (EV) are released by virtually all cells and they transport biologically important molecules from the release site to target cells. Colorectal cancer (CRC) is a leading cause of cancer-related death cases, thus, it represents a major health issue. Although the EV cargo may reflect the molecular composition of the releasing cells and thus, EVs may hold a great promise for tumor diagnostics, the impact of intratumoral heterogeneity on the intensity of EV release is still largely unknown. By using CRC patient-derived organoids that maintain the cellular and molecular heterogeneity of the original epithelial tumor tissue, we proved that CD44(high) cells produce more organoids with a higher proliferation intensity, as compared to CD44(low) cells. Interestingly, we detected an increased EV release by CD44(high) CRC cells. In addition, we found that the miRNA cargos of CD44(high) and CD44(low) cell derived EVs largely overlapped and only four miRNAs were specific for one of the above subpopulations. We observed that EVs released by CD44(high) cells induced the proliferation and activation of colon fibroblasts more strongly than CD44(low) cells. However, this effect was due to the higher EV number rather than to the miRNA cargo of EVs. Collectively, we identified CRC subpopulations with different EV releasing capabilities and we proved that CRC cell-released EVs have a miRNA-independent effect on fibroblast proliferation and activation