Publications by authors named "L Kos"

63 Publications

The immunosuppressive role of Edn3 overexpression in the melanoma microenvironment.

Pigment Cell Melanoma Res 2021 Jul 20. Epub 2021 Jul 20.

Department of Biological Sciences, Florida International University, Miami, FL, USA.

Endothelins are cytokines expressed in the microenvironment of several tumors. To identify which stromal cells in the melanoma microenvironment respond to endothelin, we injected murine melanoma cell lines B16F10, YUMM1.7, and YUMMER1.7 in a transgenic mouse that overexpresses endothelin 3 (Edn3) under the control of the keratin 5 promoter in the skin (K5-Edn3). All cell lines developed larger tumors in K5-Edn3 mice than in control animals. In YUMM1.7 tumors, the Edn3 receptor, endothelin receptor B (Ednrb), was expressed in several stromal cell types including immune cells. This result was validated by the identification of Ednrb-positive stromal cells in human melanoma from previously published RNA-seq data. Regulatory T cells (Tregs) and dendritic cell numbers were significantly higher in K5-Edn3 tumors when compared to control tumors. Edn3 increased Treg proliferation in vitro and the expression of FOXP3. YUMM1.7-GFP tumors in K5-Edn3 mice were sensitive to immune checkpoint inhibitor (anti-CTLA-4) as well as to Ednrb blockage (BQ-788). Our results indicate that Ednrb signaling has an important role in the melanoma microenvironment where it mediates immunosuppression resulting in escape from tumor immunity.
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http://dx.doi.org/10.1111/pcmr.13002DOI Listing
July 2021

Elastogenesis Correlates With Pigment Production in Murine Aortic Valve Leaflets.

Front Cardiovasc Med 2021 22;8:678401. Epub 2021 Jun 22.

Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.

Aortic valve (AV) leaflets rely on a precise extracellular matrix (ECM) microarchitecture for appropriate biomechanical performance. The ECM structure is maintained by valvular interstitial cells (VICs), which reside within the leaflets. The presence of pigment produced by a melanocytic population of VICs in mice with dark coats has been generally regarded as a nuisance, as it interferes with histological analysis of the AV leaflets. However, our previous studies have shown that the presence of pigment correlates with increased mechanical stiffness within the leaflets as measured by nanoindentation analyses. In the current study, we seek to better characterize the phenotype of understudied melanocytic VICs, explore the role of these VICs in ECM patterning, and assess the presence of these VICs in human aortic valve tissues. Immunofluorescence and immunohistochemistry revealed that melanocytes within murine AV leaflets express phenotypic markers of either neuronal or glial cells. These VIC subpopulations exhibited regional patterns that corresponded to the distribution of elastin and glycosaminoglycan ECM proteins, respectively. VICs with neuronal and glial phenotypes were also found in human AV leaflets and showed ECM associations similar to those observed in murine leaflets. A subset of VICs within human AV leaflets also expressed dopachrome tautomerase, a common melanocyte marker. A spontaneous mouse mutant with no aortic valve pigmentation lacked elastic fibers and had reduced elastin gene expression within AV leaflets. A hyperpigmented transgenic mouse exhibited increased AV leaflet elastic fibers and elastin gene expression. Melanocytic VIC subpopulations appear critical for appropriate elastogenesis in mouse AVs, providing new insight into the regulation of AV ECM homeostasis. The identification of a similar VIC population in human AVs suggests conservation across species.
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http://dx.doi.org/10.3389/fcvm.2021.678401DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8257952PMC
June 2021

Identification of HMGA2 inhibitors by AlphaScreen-based ultra-high-throughput screening assays.

Sci Rep 2020 11 2;10(1):18850. Epub 2020 Nov 2.

Biomolecular Sciences Institute, Florida International University, Miami, FL, 33199, USA.

The mammalian high mobility group protein AT-hook 2 (HMGA2) is a multi-functional DNA-binding protein that plays important roles in tumorigenesis and adipogenesis. Previous results showed that HMGA2 is a potential therapeutic target of anticancer and anti-obesity drugs by inhibiting its DNA-binding activities. Here we report the development of a miniaturized, automated AlphaScreen ultra-high-throughput screening assay to identify inhibitors targeting HMGA2-DNA interactions. After screening the LOPAC1280 compound library, we identified several compounds that strongly inhibit HMGA2-DNA interactions including suramin, a century-old, negatively charged antiparasitic drug. Our results show that the inhibition is likely through suramin binding to the "AT-hook" DNA-binding motifs and therefore preventing HMGA2 from binding to the minor groove of AT-rich DNA sequences. Since HMGA1 proteins also carry multiple "AT-hook" DNA-binding motifs, suramin is expected to inhibit HMGA1-DNA interactions as well. Biochemical and biophysical studies show that charge-charge interactions and hydrogen bonding between the suramin sulfonated groups and Arg/Lys residues play critical roles in the binding of suramin to the "AT-hook" DNA-binding motifs. Furthermore, our results suggest that HMGA2 may be one of suramin's cellular targets.
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http://dx.doi.org/10.1038/s41598-020-75890-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7606612PMC
November 2020

Simultaneous mapping of nanoscale topography and surface potential of charged surfaces by scanning ion conductance microscopy.

Nanoscale 2020 Oct;12(40):20737-20748

Physics Department, Florida International University, Miami, FL 33199, USA. and Biomolecular Science Institute, Florida International University, Miami, FL 33199, USA.

Scanning ion conductance microscopy (SICM) offers the ability to obtain nanoscale resolution images of the membranes of living cells. Here, we show that a dual-barrel nanopipette probe based potentiometric SICM (P-SICM) can simultaneously map the topography and surface potential of soft, rough and heterogeneously charged surfaces under physiological conditions. This technique was validated and tested by systematic studies on model samples, and the finite element method (FEM) based simulations confirmed its surface potential sensing capability. Using the P-SICM method, we compared both the topography and extracellular potential distributions of the membranes of normal (Mela-A) and cancerous (B16) skin cells. We further monitored the structural and electrical changes of the membranes of both types of cells after exposing them to the elevated potassium ion concentration in extracellular solution, known to depolarize and damage the cell. From surface potential imaging, we revealed the dynamic appearance of heterogeneity of the surface potential of the individual cell membrane. This P-SICM method provides new opportunities to study the structural and electrical properties of cell membrane at the nanoscale.
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http://dx.doi.org/10.1039/d0nr04555aDOI Listing
October 2020

ApPropRiateness of myOcardial revascUlarization assessed by SYNTAX Scores in patients with type 2 diabetes melliTus: the PROUST study.

Postepy Kardiol Interwencyjnej 2020 Jun 23;16(2):153-161. Epub 2020 Jun 23.

Wilhelminenspital, 3 Medical Department-Cardiology, Vienna, Austria.

Introduction: Results of currently available trials have shown divergent outcomes in diabetic patients undergoing percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Current guidelines do not recommend PCI in patients with diabetes and a SYNTAX score ≥ 23.

Aim: To compare all-cause 4-year mortality after revascularization for complex coronary artery disease (CAD) in diabetics.

Material And Methods: The study group comprised consecutive patients with three-vessel CAD and/or unprotected left main CAD (≥ 50% diameter stenosis) without major hemodynamic instability, who were treated in two institutions with PCI or referred for CABG.

Results: Out of 342 diabetics, 177 patients underwent PCI and 165 patients were referred for CABG. The incidence of all-cause death was different between diabetics treated with PCI or CABG at 4 years (16/177, 9.0% vs. 26/165, 15.8%, respectively, = 0.03). The difference was not evident in non-diabetics (PCI: 41/450, 9.1% vs. CABG: 19/249, 7.6%, = 0.173). In diabetics, there was a higher incidence of all-cause mortality in PCI patients with intermediate-high (≥ 23) SYNTAX scores compared with those with low (0-22) SYNTAX scores (10/56, 17.9% vs. 6/121, 5.0%, respectively, < 0.01). On the other hand, diabetics who underwent CABG showed similar mortality rates irrespective of the SYNTAX scores (SYNTAX 0-22: 3/29, 10.3%; SYNTAX ≥ 23: 23/136, 11.9%, = 0.46). In the subgroup analysis, there was no interaction according to presence or absence of left main CAD ( for interaction = 0.12) as well as according to diabetes status ( for interaction = 0.38), whereas gender and SYNTAX scores were differentiators between PCI and CABG with a for interaction < 0.1.

Conclusions: Our analysis supports recent evidence that diabetes is not a differentiator between PCI and CABG.
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http://dx.doi.org/10.5114/aic.2020.96058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7333192PMC
June 2020
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