Publications by authors named "Ernest Duah"

11 Publications

  • Page 1 of 1

XRCC1-mediated DNA repair is associated with progression-free survival of multiple myeloma patients after autologous stem cell transplant.

Mol Carcinog 2019 12 22;58(12):2327-2339. Epub 2019 Sep 22.

Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio.

Autologous stem cell transplant (ASCT) with high-dose melphalan (HDM) is the standard treatment for fit multiple myeloma (MM) patients. It is generally believed that some DNA repair proteins impact the activity to repair melphalan-induced DNA damage, thus potentially contributing to the patient's clinical response. However, knowledge of these proteins is limited. In the current study, we investigated the roles of XRCC1, a protein involved in base excision repair and single-strand break repair, in melphalan response in MM cells. Small interfering RNA knockdown of XRCC1 significantly increased the accumulation of melphalan-induced DNA damage in MM cells and sensitized them to melphalan treatment, indicating that genetic variation in XRCC1 may impact response to melphalan treatment. We then evaluated the association between an XRCC1 variant with reduced activity, rs25487 (R399Q), and clinical outcomes of 108 MM patients with melphalan therapy. Our results showed that XRCC1 rs25487 was associated with prolonged progression-free survival (PFS) in MM patients. The adjusted hazard ratio for PFS between patients carrying rs25487 AA/AG and GG was 0.42 (95% confidence interval: 0.25, 0.84, P = .014). Taken together, these results indicate that XRCC1 is involved in the repair of melphalan-induced DNA damage and XRCC1 rs25487 variant with impaired DNA repair function influences the clinical responses of HDM in MM patients.
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http://dx.doi.org/10.1002/mc.23121DOI Listing
December 2019

An efficient and quantitative assay for epitope-tagged therapeutic protein development with a capillary western system.

Bioanalysis 2019 Mar 20;11(6):471-483. Epub 2019 Mar 20.

Division of Pharmacy Practice & Science, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.

To develop and validate a reliable, robust and efficient assay to detect and quantify biologic compounds and during early stage of a biotherapeutic agent discovery. An enrichment-free immunoassay method was developed to quantify a polyhistidine N- and FLAG C-terminally-tagged recombinant protein of ∼55 kDa. The target proteins were purified by a nickel-based matrix via tag affinity, followed by probing with biotinylated antitag antibody and subsequently detected by streptavidin-horseradish peroxidase conjugate using an automated capillary-based western system. A simple, highly sensitive and efficient immunoassay protocol was established to assess the stability and pharmacokinetic properties of propitious recombinant proteins in mouse to support early stage development of a biotherapeutic lead.
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http://dx.doi.org/10.4155/bio-2018-0248DOI Listing
March 2019

Cysteinyl leukotriene 2 receptor promotes endothelial permeability, tumor angiogenesis, and metastasis.

Proc Natl Acad Sci U S A 2019 01 17;116(1):199-204. Epub 2018 Dec 17.

Department of Chemistry, University of Akron, Akron, OH 44325;

Cysteinyl leukotrienes (cys-LTs) are proinflammatory mediators that enhance vascular permeability through distinct receptors (CysLTRs). We found that CysLTR regulates angiogenesis in isolated mouse endothelial cells (ECs) and in Matrigel implants in WT mice and enhances EC contraction and permeability via the Rho-dependent myosin light chain 2 and vascular endothelial (VE)-cadherin axis. Since solid tumors utilize aberrant angiogenesis for their growth and metastasis and their vessels exhibit vascular hyperpermeability, we hypothesized that CysLTR, via its actions on the endothelium, might regulate tumor growth. Both tumor growth and metastases of adoptively transferred syngeneic Lewis lung carcinoma (LLC) cells are significantly reduced in CysLTR-null mice () compared with WT and CysLTR-null mice (). In WT recipients of LLC cells, CysLTR expression is significantly increased in the tumor vasculature, compared with CysLTR. Further, the tumor vasculature in recipients exhibited significantly improved integrity, as revealed by increased pericyte coverage and decreased leakage of i.v.-administered Texas Red-conjugated dextran. Administration of a selective CysLTR antagonist significantly reduced LLC tumor volume, vessel density, dextran leakage, and metastases in WT mice, highlighting CysLTR as a VEGF-independent regulator of the vasculature promoting risk of metastasis. Thus, both genetic and pharmacological findings establish CysLTR as a gateway for angiogenesis and EC dysregulation in vitro and ex vivo and in an in vivo model with a mouse tumor. Our data suggest CysLTR as a possible target for intervention.
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http://dx.doi.org/10.1073/pnas.1817325115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6320507PMC
January 2019

Mechanosensitive transient receptor potential vanilloid 4 regulates -induced airway remodeling 2 distinct pathways modulating matrix synthesis and degradation.

FASEB J 2017 04 10;31(4):1556-1570. Epub 2017 Jan 10.

Department of Chemistry, University of Akron, Akron, Ohio, USA; and

Contributions of mechanical signals to airway remodeling during asthma are poorly understood. Transient receptor potential vanilloid 4 (TRPV4), a mechanosensitive ion channel, has been implicated in cardiac and pulmonary fibrosis; however, its role in asthma remains elusive. Employing a -induced asthma model, we report here that TRPV4-knockout mice were protected from -induced airway remodeling. Furthermore, lung fibroblasts that were isolated from TRPV4-knockout mice showed diminished differentiation potential compared with wild-type mice. Fibroblasts from asthmatic lung exhibited increased TRPV4 activity and enhanced differentiation potential compared with normal human lung fibroblasts. Of interest, TGF-β1 treatment enhanced TRPV4 activation in a PI3K-dependent manner in normal human lung fibroblasts Mechanistically, TRPV4 modulated matrix remodeling in the lung 2 distinct but dependent pathways: one enhances matrix deposition by fibrotic gene activation, whereas the other slows down matrix degradation by increased plasminogen activator inhibitor 1. Of importance, both pathways are regulated by Rho/myocardin-related transcription factor-A and contribute to fibroblast differentiation and matrix remodeling in the lung. Thus, our results support a unique role for TRPV4 in -induced airway remodeling and warrant further studies in humans for it to be used as a novel therapeutic target in the treatment of asthma.-Gombedza, F., Kondeti, V., Al-Azzam, N., Koppes, S., Duah, E., Patil, P., Hexter, M., Phillips, D., Thodeti, C. K., Paruchuri, S. Mechanosensitive transient receptor potential vanilloid 4 regulates -induced airway remodeling 2 distinct pathways modulating matrix synthesis and degradation.
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http://dx.doi.org/10.1096/fj.201601045RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5349793PMC
April 2017

Anti-tumor activity of lipophilic imidazolium salts on select NSCLC cell lines.

Med Chem Res 2015 Jul 13;24(7):2838-2861. Epub 2015 Feb 13.

Department of Chemistry, The University of Akron, Akron, OH 44325-3601, USA.

The anti-tumor activity of imidazolium salts is highly dependent upon the substituents on the nitrogen atoms of the imidazolium cation. We have synthesized and characterized a series of naphthalene-substituted imidazolium salts and tested them against a variety of non-smallcell lung cancer cell lines. Several of these complexes displayed anticancer activity comparable to cisplatin. These compounds induced apoptosis in the NCI-H460 cell line as determined by Annexin V staining, caspase-3, and PARP cleavage. These results strongly suggest that this class of compounds can serve as potent chemotherapeutic agents.
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http://dx.doi.org/10.1007/s00044-015-1330-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593509PMC
July 2015

Leukotriene D4 and prostaglandin E2 signals synergize and potentiate vascular inflammation in a mast cell-dependent manner through cysteinyl leukotriene receptor 1 and E-prostanoid receptor 3.

J Allergy Clin Immunol 2016 Jan 5;137(1):289-298. Epub 2015 Aug 5.

Department of Chemistry, University of Akron, Akron, Ohio. Electronic address:

Background: Although arachidonic acid metabolites, cysteinyl leukotrienes (cys-LTs; leukotriene [LT] C4, LTD4, and LTE4), and prostaglandin (PG) E2 are generated at the site of inflammation, it is not known whether crosstalk exists between these 2 classes of inflammatory mediators.

Objective: We sought to determine the role of LTD4-PGE2 crosstalk in inducing vascular inflammation in vivo, identify effector cells, and ascertain specific receptors and pathways involved in vitro.

Methods: Vascular (ear) inflammation was assessed by injecting agonists into mouse ears, followed by measuring ear thickness and histology, calcium influx with Fura-2, phosphorylation and expression of signaling molecules by means of immunoblotting, PGD2 and macrophage inflammatory protein 1β generation by using ELISA, and expression of transcripts by using RT-PCR. Candidate receptors and signaling molecules were identified by using antagonists and inhibitors and confirmed by using small interfering RNA.

Results: LTD4 plus PGE2 potentiated vascular permeability and edema, gearing the system toward proinflammation in wild-type mice but not in Kit(W-sh) mice. Furthermore, LTD4 plus PGE2, through cysteinyl leukotriene receptor 1 (CysLT1R) and E-prostanoid receptor (EP) 3, enhanced extracellular signal-regulated kinase (Erk) and c-fos phosphorylation, inflammatory gene expression, macrophage inflammatory protein 1β secretion, COX-2 upregulation, and PGD2 generation in mast cells. Additionally, we uncovered that this synergism is mediated through Gi, protein kinase G, and Erk signaling. LTD4 plus PGE2-potentiated effects are partially sensitive to CysLT1R or EP3 antagonists but completely abolished by simultaneous treatment both in vitro and in vivo.

Conclusions: Our results unravel a unique LTD4-PGE2 interaction affecting mast cells through CysLT1R and EP3 involving Gi, protein kinase G, and Erk and contributing to vascular inflammation in vivo. Furthermore, current results also suggest an advantage of targeting both CysLT1R and EP3 in attenuating inflammation.
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http://dx.doi.org/10.1016/j.jaci.2015.06.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5839097PMC
January 2016

A step toward simplified detection of serum albumin on SDS-PAGE using an environment-sensitive flavone sensor.

Chem Commun (Camb) 2015 Jul;51(55):11060-3

Department of Chemistry, University of Akron, Akron, Ohio 44325, USA.

In this study, we report a series of novel flavone-based sensors that exhibit a superior fluorescence response when interacting with serum albumin in real serum samples and in acrylamide gels. The detection limit of probe 4 for serum albumin solution is 0.09 μg mL(-1), and the detectable volume for monkey serum reaches as low as 0.03 μL.
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http://dx.doi.org/10.1039/c5cc03516cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4512168PMC
July 2015

A selective NIR-emitting zinc sensor by using Schiff base binding to turn-on excited-state intramolecular proton transfer.

J Mater Chem B 2014 ;2(14):2008-2012

Department of Chemistry, The University of Akron, Akron, Ohio 44325, USA ; Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325, USA.

A rational design has led to a highly selective and cell-permeable zinc sensor, which exhibits a large fluorescence turn-on at ~545 nm the desirable NIR emission (~720 nm) with a large Stokes' shift, providing a practical sensor platform with two emission channels for reliable zinc detection.
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http://dx.doi.org/10.1039/C3TB21339KDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4233661PMC
January 2014

Modulation of mast cell proliferative and inflammatory responses by leukotriene d4 and stem cell factor signaling interactions.

J Cell Physiol 2015 Mar;230(3):595-602

Department of Chemistry, University of Akron, Akron, Ohio.

Mast cells (MCs) are important effector cells in asthma and pulmonary inflammation, and their proliferation and maturation is maintained by stem cell factor (SCF) via its receptor, c-Kit. Cysteinyl leukotrienes (cys-LTs) are potent inflammatory mediators that signal through CysLT1 R and CysLT2 R located on the MC surface, and they enhance MC inflammatory responses. However, it is not known if SCF and cys-LTs cross-talk and influence MC hyperplasia and activation in inflammation. Here, we report the concerted effort of the growth factor SCF and the inflammatory mediator LTD4 in MC activation. Stimulation of MCs by LTD4 in the presence of SCF enhances c-Kit-mediated proliferative responses. Similarly, SCF synergistically enhances LTD4 -induced calcium, c-fos expression and phosphorylation, as well as MIP1β generation in MCs. These findings suggest that integration of SCF and LTD4 signals may contribute to MC hyperplasia and hyper-reactivity during airway hyper-response and inflammation.
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http://dx.doi.org/10.1002/jcp.24777DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4244248PMC
March 2015

Cysteinyl leukotrienes regulate endothelial cell inflammatory and proliferative signals through CysLT₂ and CysLT₁ receptors.

Sci Rep 2013 Nov 20;3:3274. Epub 2013 Nov 20.

Department of Chemistry, University of Akron, OH 44325.

Cysteinyl leukotrienes (cys-LTs), LTC₄, LTD₄, LTE₄ are potent inflammatory lipid mediators that act through two distinct G-protein-coupled receptors, CysLT₁R and CysLT₂R. Although cys-LTs are shown to induce vascular leakage and atherosclerosis, the molecular mechanism by which cys-LTs modulate endothelial function is not known. Here, we show that cys-LTs (LTC₄ and LTD₄) induce robust calcium influx in human umbilical vein endothelial cells (HUVECs) through CysLT₂R, but not CysLT₁R. Further, cys-LT treatment induced endothelial cell (EC) contraction leading to monolayer disruption via CysLT₂R/Rho kinase dependent pathway. Furthermore, stimulation with cys-LTs potentiated TNFα-induced VCAM-1 expression and leukocyte recruitment to ECs through CysLT₂R. In contrast, we found that both LTC₄ and LTD₄ stimulated EC proliferation through CysLT₁R. Taken together, these results suggest that cys-LTs induce endothelial inflammation and proliferation via CysLT₂R/Rho kinase and CysLT₁R/Erk dependent pathways, respectively, which play critical role in the etiology of cardiovascular diseases such as atherosclerosis and myocardial infarction.
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http://dx.doi.org/10.1038/srep03274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834363PMC
November 2013

Differential regulation of cysteinyl leukotriene receptor signaling by protein kinase C in human mast cells.

PLoS One 2013 15;8(8):e71536. Epub 2013 Aug 15.

Department of Chemistry, University of Akron, Akron, Ohio, United States of America.

Cysteinyl leukotrienes (cys-LTs) are a group of lipid mediators that are potent bronchoconstrictors, powerful inducers of vascular leakage and potentiators of airway hyperresponsiveness. Cys-LTs play an essential role in asthma and are synthesized as well as activated in mast cells (MCs). Cys-LTs relay their effects mainly through two known GPCRs, CysLT1R and CysLT2R. Although protein kinase C (PKC) isoforms are implicated in the regulation of CysLT1R function, neither the role of PKCs in cys-LT-dependent MC inflammatory signaling nor the involvement of specific isoforms in MC function are known. Here, we show that PKC inhibition augmented LTD4 and LTE4-induced calcium influx through CysLT1R in MCs. In contrast, inhibition of PKCs suppressed c-fos expression as well MIP1β generation by cys-LTs. Interestingly, cys-LTs activated both PKCα and PKCε isoforms in MC. However, knockdown of PKCα augmented cys-LT mediated calcium flux, while knockdown of PKCε attenuated cys-LT induced c-fos expression and MIP1β generation. Taken together, these results demonstrate for the first time that cys-LT signaling downstream of CysLT1R in MCs is differentially regulated by two distinct PKCs which modulate inflammatory signals that have significant pathobiologic implications in allergic reactions and asthma pathology.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0071536PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744564PMC
April 2014