Screening Assay For Compounds Research Articles

Development and utility of a SARS-CoV-2 pseudovirus assay for compound screening and antibody neutralization assays

BackgroundThe highly infectious nature of SARS-CoV-2 necessitates using bio-containment facilities to study viral pathogenesis and identify potent antivirals. However, the lack of high-level bio-containment laboratories across the world has limited research efforts into SARS-CoV-2 pathogenesis and the discovery of drug candidates. Previous research has reported that non-replicating SARS-CoV-2 Spike-pseudotyped viral particles are effective tools to screen for and identify entry inhibitors and neutralizing antibodies. MethodsTo generate SARS-CoV-2 pseudovirus, a lentiviral packaging plasmid p8.91, a luciferase expression plasmid pCSFLW, and SARS-CoV-2 Spike expression plasmids (Wild-type (D614G) or Delta strain) were co-transfected into HEK293 cells to produce a luciferase-expressing non-replicating pseudovirus which expresses SARS-CoV-2 spike protein on the surface. For relative quantitation, HEK293 cells expressing ACE2 (ACE2-HEK293) were infected with the pseudovirus, after which luciferase activity in the cells was measured as a relative luminescence unit. The ACE2-HEK293/Pseudovirus infection system was used to assess the antiviral effects of some compounds and plasma from COVID-19 patients to demonstrate the utility of this assay for drug discovery and neutralizing antibody screening. ResultsWe successfully produced lentiviral-based SARS-CoV2 pseudoviruses and ACE2-expressing HEK293 cells. The system was used to screen compounds for SARS-CoV-2 entry inhibitors and identified two compounds with potent activity against SARS-CoV-2 pseudovirus entry into cells. The assay was also employed to screen patient plasma for neutralizing antibodies against SARS-CoV-2, as a precursor to live virus screening, using successful hits. SignificanceThis assay is scalable and can perform medium-to high-throughput screening of antiviral compounds with neither severe biohazard risks nor the need for higher-level containment facilities. Now fully deployed in our resource-limited laboratory, this system can be applied to other highly infectious viruses by swapping out the envelope proteins in the plasmids used in pseudovirus production.

Abstract 2060: Automation of 3D cancer spheroid assay for compound screening

Abstract Finding efficient drug combinations to treat cancer patients is critical for therapy success. Accordingly, there is a critical need to develop methods for efficient testing drug efficacy to discover new therapeutic targets. 3D cancer models are highly valuable tools for cancer research and drug development. However, the complexity of performing 3D assays remains a hurdle for adopting these methods for compound screening. To alleviate the bottlenecks that come with labor-intensive manual protocols we developed cell culture automation methods using CellXpress.ai instrument. The instrument enables automation of 2D or 3D culture for prolonged complex workflows. The CellXpress.ai provides automated plating, passaging, media exchanges, monitoring organoids, alone with compound treatment and the end point assays with high content image analysis. In the present study we describe full automation of imaging, analysis, and cell culture process which enables scaling up complex 3D cell-based assays and compound screening. As an example of 3D protocol, we automated culture and imaging of colorectal cancer 3D spheroids formed from HCT116 cell line in U-shape low attachment plates. HCT116 cells were expanded in 2D, then spheroids were formed after automated dispensing of cell suspension into U-shape 96 or 384 plates. After 48h spheroids were treated with 12 anti-cancer compounds, at multiple concentrations for 3-5 days, then stained and imaged. Cell plating, compound additions, media exchange, and staining were performed automatically by CellXpressAI instrument. During the culture spheroids were monitored using transmitted light, with immediate analysis of phenotypic changes, including inhibition of growth or spheroid disintegration. For endpoint assay spheroids were stained with combination of Hoechst nuclear stain and viability dyes Calcein AM and EtHD, then imaged, and analyzed for multiple read-outs including spheroid size, marker intensities, and live-dead cell scoring. We observed concentration-dependent inhibition of spheroid growth and cell death in response to anti-cancer compounds and evaluated effective compound concentrations for cytotoxic or cytostatic effects. Cell culture process automation for 3D assays, powered by imaging and image analysis has a potential to bring 3D biology into another level, allowing to increase throughput and reproducibility, and enabling variety of high throughput drug discovery and precision medicine applications. Citation Format: Oksana Sirenko, Angeline Lim, Astrid Michlmayr, Zhisong Tong, Emilie Keidel, Felix Spira. Automation of 3D cancer spheroid assay for compound screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2060.

A Viral Attachment Assay for Screening of Antiviral Compounds

A Viral Attachment Assay for Screening of Antiviral Compounds

A Viral Attachment Assay for Screening of Antiviral Compounds

A Viral Attachment Assay for Screening of Antiviral Compounds

A Neurofilament-L reporter cell line for the quantification of early neuronal differentiation: A Bioassay for neurotrophic activities

BackgroundNeurotrophic activity constitutes a crucial factor in the recovery from neurological injuries and is impaired in neurodegenerative disorders. Preclinical studies of neurotrophic factors to improve outcome of neurodegenerative diseases have yielded promising results. However, due to the complexity of these therapies, the clinical translation of this approach was so far not successful and more feasible treatments with neurotrophic activity may be promising alternatives. Therefore, highly sensitive and robust assays for compound screening are required. New methodNerve growth factor is known to induce Neurofilament-L (NF-L) expression in a rat pheochromocytoma cell line (PC12 cells) during early neuronal differentiation. We generated and characterized an enhanced green fluorescent protein (EGFP)-NF-L reporter PC12 cell line for the development of a cell-based assay (designated Neurofilament-L Bioassay) that allows straightforward quantification of early neuronal differentiation based on NF-L expression. ResultsUsing Cerebrolysin® as a role model for a pharmacological compound that stimulates neurotrophic activity in the central nervous system, the Neurofilament-L Bioassay was proved to be a robust, specific, and reproducible method. Comparison with existing method(s)It was already shown that NF-L expression correlates with neurite outgrowth in PC12 cells. Currently, quantification of neurite outgrowth is the most commonly used method to evaluate neuronal differentiation in PC12 cells, an approach that is time-consuming and of high variability. ConclusionsThis work describes the development of an EGFP-NF-L reporter PC12 cell-based assay as a robust and reproducible tool for “high throughput” compound screening for neurotrophic activity.

Drosophila CASK regulates brain size and neuronal morphogenesis, providing a genetic model of postnatal microcephaly suitable for drug discovery

BackgroundCASK-related neurodevelopmental disorders are untreatable. Affected children show variable severity, with microcephaly, intellectual disability (ID), and short stature as common features. X-linked human CASK shows dosage sensitivity with haploinsufficiency in females. CASK protein has multiple domains, binding partners, and proposed functions at synapses and in the nucleus. Human and Drosophila CASK show high amino-acid-sequence similarity in all functional domains. Flies homozygous for a hypomorphic CASK mutation (∆18) have motor and cognitive deficits. A Drosophila genetic model of CASK-related disorders could have great scientific and translational value.MethodsWe assessed the effects of CASK loss of function on morphological phenotypes in Drosophila using established genetic, histological, and primary neuronal culture approaches. NeuronMetrics software was used to quantify neurite-arbor morphology. Standard nonparametric statistics methods were supplemented by linear mixed effects modeling in some cases. Microfluidic devices of varied dimensions were fabricated and numerous fluid-flow parameters were used to induce oscillatory stress fields on CNS tissue. Dissociation into viable neurons and neurite outgrowth in vitro were assessed.ResultsWe demonstrated that ∆18 homozygous flies have small brains, small heads, and short bodies. When neurons from developing CASK-mutant CNS were cultured in vitro, they grew small neurite arbors with a distinctive, quantifiable “bushy” morphology that was significantly rescued by transgenic CASK+. As in humans, the bushy phenotype showed dosage-sensitive severity. To overcome the limitations of manual tissue trituration for neuronal culture, we optimized the design and operation of a microfluidic system for standardized, automated dissociation of CNS tissue into individual viable neurons. Neurons from CASK-mutant CNS dissociated in the microfluidic system recapitulate the bushy morphology. Moreover, for any given genotype, device-dissociated neurons grew larger arbors than did manually dissociated neurons. This automated dissociation method is also effective for rodent CNS.ConclusionsThese biological and engineering advances set the stage for drug discovery using the Drosophila model of CASK-related disorders. The bushy phenotype provides a cell-based assay for compound screening. Nearly a dozen genes encoding CASK-binding proteins or transcriptional targets also have brain-development mutant phenotypes, including ID. Hence, drugs that improve CASK phenotypes might also benefit children with disorders due to mutant CASK partners.

KDOAM-25 Overcomes Resistance to MEK Inhibitors by Targeting KDM5B in Uveal Melanoma.

Background Uveal Melanoma (UM) is a potentially lethal cancer, and epigenetics may participate in the regulation of MEK resistance. This study is aimed at targeting the epigenetic kinase to overcome the resistance to MEK inhibitor. Method We developed the 92.1 and OMM1 MEK-inhibitor resistant cell lines by culturing them in the trametinib (Tra) mixed medium. We utilized CCK8 analysis for detecting the viability of the cell. Western blot was used to determine the ERK1/2 and Akt phosphorylation. Small compound library screening assays were carried out by CCK8 analysis. To test the apoptosis, we employed flow cytometric analysis with Annexin-V/PI. Western blot and CCK8 were used to explore the epigenetic regulation of KDM5B in MEK-resistance cell lines. To knock out the expression level of KDM5B, we used the CRISPR/Cas9 by lentivirus delivering well-validated shRNAs in pLKO.1 vector. The directly binding affinity of KDOAM-25 to KDM5B was determined by drug affinity responsive target stability (DARTS) and microscale thermophoresis (MST). Results The phosphorylation of ERK1/2 and Akt (T308) was inhibited in OMM1 cell lines. However, inhibition of Tra was abolished in OMM1-R cell lines. From a compound screening assay, we identified that KDOAM-25 robustly inhibited the viability and colony formation of MEK-resistance cell lines. Furthermore, KDOAM-25 significantly promoted cell death in OMM1-R cells. H3K4me3 (tri-methylation of lysine 4 on histone H3) and H3K27ac (acetyl of lysine 27 on histone H3) were both upregulated in OMM1-R cells. Tra significantly inhibited the expression of KDM5B in OMM1-P cells. However, the effect on KDM5B was abolished in OMM1-R cells. Knockdown of KDM5B robustly suppressed the cell viability in OMM1-R cells. KDOAM-25 directly interacted with KDM5B. Conclusion KDOAM-25 inhibited the viability and colony formation and promoted cell death of MEK-resistance cell lines through H3K4me3 and H3K27ac, indicating that KDOAM-25 may be a potential therapeutic agent for MEK resistance in UM patients.

A multiplexable microfluidic injector for versatile encoding of droplets

While droplet microfluidics brings paradigm shifts in biological and chemical studies due to its unprecedented precision, throughput and cost-effectiveness, the colossal number of droplets required makes their identification and tracking a challenging task, hindering the application of droplets as individual bioreactors. Herein, we develop a multiplexable injector which exploits a distinctive design comprising a circular electrode and a concentric fluidic channel to accommodate multiple injection ports for on-demand droplet injection and encoding. Droplet ingredients can be precisely injected via pressure pulse regulation. Through varying the fluorescence in droplets, binary coding and gradient coding are successfully demonstrated with droplet sequences. Additionally, a device with three individually controllable injectors is exploited to form color-encoded droplets via various single or combinatorial injection modes. We also demonstrate that these color-coded droplets can be further collected and identified via an image analysis algorithm. As the developed platform is versatile, compact, and easy to integrate, we foresee it can potentially be used in applications such as multiplexed compound screening, combinatorial synthesis, or other multistep assays.

Abstract 180: Automation and high content imaging of 3D triple negative breast cancer patient-derived tumoroids assay for compound screening

Abstract Introduction: Currently there are no clinically approved small molecule targeted therapies for triple negative breast cancer, underlining the critical need to discover new therapeutic targets. Patient-derived cell-based 3D cancer models are highly valuable tools for cancer research and drug development. Primary tumor-derived models can recapitulate tumor heterogeneity and morphology, as well as complex genetic and molecular composition accelerating drug development and drug testing. However, the complexity of performing 3D assays remains a hurdle for adopting these methods for compound screening. In the present study we describe automation of imaging and cell culture methods that enables scaling up complex 3D cell-based assays and compound screening. Methods: We developed an integrated workcell that includes a confocal imaging system, an automated CO2 incubator, an automated liquid handler, and a Collaborative Robot combining different instruments. Workcell allows automation of compound testing, culture monitoring, and evaluation of phenotypic effects of drugs with high content imaging. Tumoroids were formed from primary cells isolated from a patient-derived tumor explant, TU-BcX-4IC, that represents metaplastic breast cancer with a triple-negative breast cancer subtype. Cells were expanded in 2D format, then tumoroids were formed by plating 2,000 cells per well in U-shape low attachment 384 plates. Tumoroids (200 μm in diameter) were formed 48 hr after plating and were treated with 165 compounds of approved cancer drugs from the NCI library at multiple concentrations (10 nM to 100 μM). Compound dilutions, additions, media additions, and staining were performed using liquid handler. During incubation with compounds, tumoroids were monitored daily using transmitted light imaging. For end point assay tumoroids were stained with viability dyes and imaged using automated confocal imaging system. Advanced image analysis included 3D reconstitution and complex phenotypic evaluation of tumoroids. Results: We characterized multiple quantitative descriptors that can be used for studying tumor phenotypes and compound effects including characterization of size and integrity, cell morphology and viability, as well as determining presence and expression levels for various cell markers. Concentration-dependent effects of numerous compounds were observed across multiple read-outs that indicate cytotoxic effects, with 8 compounds demonstrating effects at 10 nM (e.g, romidepsin, trametinib, bortezomib, carfilzomib, and panobinostat). These compounds include HDAC inhibitors and proteosome inhibitors. Conclusions: We demonstrated methods for increased throughput and automation in 3D cancer assays and compound screening, and also analysis approaches and descriptors that provide information about cell phenotypes and compound effects. Citation Format: Oksana Sirenko, Angeline Lim, Courtney K. Brock, Katya Nikolov, Cathy Olsen, Evan F. Cromwell, Margarite D. Matossian, Matthew E. Burow. Automation and high content imaging of 3D triple negative breast cancer patient-derived tumoroids assay for compound screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 180.

Label-free cell assays to determine compound uptake or drug action using MALDI-TOF mass spectrometry.

Cell-based assays for compound screening and profiling are fundamentally important in life sciences, chemical biology and pharmaceutical research. Most cell assays measure the amount of a single reporter molecule or cellular endpoint, and require the use of fluorescence or other labeled materials. Consequently, there is high demand for label-free technologies that enable multiple biomolecules or endpoints to be measured simultaneously. Here, we describe how to develop, optimize and validate MALDI-TOF mass spectrometry (MS) cell assays that can be used to measure cellular uptake of transporter substrates, to monitor cellular drug target engagement or to discover cellular drug-response markers. In uptake assays, intracellular accumulation of a transporter substrate and its inhibition by test compounds is measured. In drug response assays, changes to multiple cellular metabolites or to abundant posttranslational protein modifications are monitored as reporters of drug activity. We detail a ten-part optimization protocol with every part taking 1-2 d that leads to a final 2 d optimized procedure, which includes cell treatment, transfer, MALDI MS-specific sample preparation, quantification using stable-isotope-labeled standards, MALDI-TOF MS data acquisition, data processing and analysis. Key considerations for validation and automation of MALDI-TOF MS cell assays are outlined. Overall, label-free MS cell-based assays offer speed, sensitivity, accuracy and versatility in drug research.

The ATP bioluminescence assay: a new application and optimization for viability testing in the parasitic nematode Haemonchus contortus

The parasitic gastrointestinal nematode Haemonchus contortus causes serious economic losses to agriculture due to infection and disease in small ruminant livestock. The development of new therapies requires appropriate viability testing, with methods nowadays relying on larval motility or development using procedures that involve microscopy. None of the existing biochemical methods, however, are performed in adults, the target stage of the anthelmintic compounds. Here we present a new test for the viability of H. contortus adults and exsheathed third-stage larvae which is based on a bioluminescent assay of ATP content normalized to total protein concentration measured using bicinchoninic acid. All the procedure steps were optimized to achieve maximal sensitivity and robustness. This novel method can be used as a complementary assay for the phenotypic screening of new compounds with potential antinematode activity in exsheathed third-stage larvae and in adult males. Additionally, it might be used for the detection of drug-resistant isolates.

Test-system in vitro for screening of therapeutic drugs with IL-17A inhibitory activity

To achieve greater clinical relevance of the newly discovered compounds, modern drug discovery requires disease-targeted assays based on human cells. The specific aim of this study was to design and develop a new cell-based assay for screening of compounds with IL-17A inhibitory activity. Human foreskin fibroblasts (HFF) were treated with IL-17A alone (experimental conditions I) or a mixture of IL-17A inhibitor netakimab and IL-17A (experimental conditions II). IL-17A - dependent production of inflammatory mediators IL-6, IL-8, MCP-1 was evaluated by ELISA (enzyme-linked immunosorbent assay). The study demonstrated the ability of HFF subcultured in vitro for a long time (>20 passages) to respond to IL-17A treatment by increased production of inflammatory cytokines IL-6, IL-8, MCP-1. Neutralization of IL-17A by netakimab (IL-17A inhibitor) resulted in a dose-dependent decrease of inflammatory cytokines production into cell growth medium. Thus, a new cell-based assay to evaluate the biological activity of Il-17A inhibitors has been developed and tested. The assay is based on the analysis of IL-17A-dependent production of inflammatory cytokines synthesized by human dermal fibroblasts. Netakimab has been shown to be a highly potent inhibitor of IL-17A.

A novel 3D polycaprolactone high-throughput system for evaluation of toxicity in normoxia and hypoxia.

Two-dimensional (2D) culturing of cancer cells has been indispensable for the development of anti-cancer drugs. Drug development, however, is lengthy and costly with a high attrition rate, calling to mind that 2D culturing does not mimic the three-dimensional (3D) tumour microenvironment in vivo. Thus, began the development of 3D culture models for cancer research. We have constructed a 3D 96-well plate using electrospun fibres made of biocompatible polycaprolactone (PCL). Finely-cut PCL fibre pieces in water/ethanol solution was pipetted to the wells of hydrophobic 96-well plates. A fibrous network of approximately 200 μm thickness and high porosity was formed after crosslinking and drying. Human JIMT-1 breast cancer cells or fibroblasts were seeded into the network. Confocal microscopy shows that the cells grow throughout the fibre network. The toxicity of paclitaxel and an experimental salinomycin analogue was assessed and compared in 2D and 3D cultures incubated under conditions of normoxia and hypoxia often found in tumours. The toxicity of both compounds is lower when the cells are cultured in 3D compared to 2D in either normoxia or hypoxia. We conclude that our 96-well assay is a cost-efficient tool that may be used for high-throughput pre-clinical screening of potential anti-cancer compounds.

Advancing Marburg virus antiviral screening: Optimization of a novel T7 polymerase-independent minigenome system

Marburg virus (MARV) is the only known pathogenic filovirus not belonging to the genus Ebolavirus. Minigenomes have proven a useful tool to study MARV, but all existing MARV minigenomes are dependent on the addition of an exogenous T7 RNA polymerase to drive minigenome expression. However, exogenous expression of a T7 polymerase is not always feasible and can act as a confounding factor in compound screening assays. We have developed an alternative minigenome that is controlled by the natively expressed RNA polymerase II. We demonstrate here the characteristics of this new system and its applicability in a wide range of cell types. Our system shows a clear concentration-dependent activity and shows comparable activity to the existing T7 polymerase-based system at higher concentrations, also in difficult-to-transfect cell lines. In addition, we show that our system can be used for compound screening in a 96-well format, thereby providing an attractive alternative to previously developed MARV minigenomes.

Abstract 705: A cell-based screening assay to identify agents interfering protein-protein interaction of MAPKAPK2 and OCT4

Abstract c-MYC overexpression plays an important role in tumorigenesis as well as in the progression of tumors. Historically, direct targeting strategies have been challenging due to c-MYC being a transcription factor. Our observation demonstrated that MAPKAPK2 as one of the two major protein kinases involved in binding and phosphorylating OCT4 at serine 111 residue to induce c-MYC activation in progressive disease neuroblastoma. In targeting this novel pathway of c-MYC activation, we considered two options: direct inhibition of MAPKAPK2 or inhibition of MAPKAPK2-OCT4 protein-protein interaction. Given the limitations of direct targeting kinases, namely resistance and off-target effect, we pursued the inhibition of the protein-protein interaction. The purpose of this study is to introduce a novel cell-based assay for compound screening and validation steps to identify compounds that inhibit OCT4-MAPKAPK2 interaction. First, OCT4 (NTD and POUs: the domains critical for c-MYC activation) and MAPKAPK2 were exogenously expressed by a single vector with CMV promoter using a lentiviral vector system in NCI-H82, a small cell lung cancer cell line. Upon the optimization of the assay, we screened approximately 100,000 compounds to identify “hits” by statistically analyzing the reduction in luminescence. Seventy-six compounds were found to inhibit the interaction of MAPKAPK2-OCT4. Subsequently, we have used a two-step hit validation for the 76 compounds: 1) the decrease in pOCT4S111 expression along with the reduction in c-MYC expression by immunoblotting: 2) and the inhibition of binding between MAPKAPK2 and OCT4 by co-immunoprecipitation. The validation step further narrowed down the hits to three compounds that reduced the phosphorylation of OCT4 at S111 and inhibited the MAPKAPK2-OCT4 interaction. To verify the compounds interfering the MAPKAPK2-OCT4 interaction, we used in vitro assay using recombinant human MAPKAPK2 kinase and OCT4 and all three compounds inhibited phosphorylation of OCT4S111. These all compounds also tested minimally affected ATP-dependent MAPKAPK2 kinase relative to the known MAPKAPK2 inhibitor (PF3644022). In conclusion, our screening assay and validation experiments was successfully implemented in identifying hits and the validation step confirmed three novel compounds that demonstrated: 1) impairment of MAPKAPK2-mediated phosphorylation of OCT4; and 2) inhibition of the MAPKAPK2-OCT4 kinase-substrate interaction. These compounds may be further optimized to minimize systemic toxicities and improve the anti-cancer activity for the treatment of neuroblastoma or small cell lung cancer with high c-MYC expression. Citation Format: Inhyoung Yang, Sung-Jen Wei, Ismail Mohiuddin, Gloria M. Martinez, Min H. Kang. A cell-based screening assay to identify agents interfering protein-protein interaction of MAPKAPK2 and OCT4 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 705.

A Neurite Outgrowth Assay and Neurotoxicity Assessment with Human Neural Progenitor Cell-Derived Neurons.

Neurite outgrowth assay and neurotoxicity assessment are two major studies that can be performed using the presented method herein. This protocol provides reliable analysis of neuronal morphology together with quantitative measurements of modifications on neurite length and synaptic protein localization and abundance upon treatment with small molecule compounds. In addition to the application of the presented method in neurite outgrowth studies, neurotoxicity assessment can be performed to assess, distinguish and rank commercial chemical compounds based on their potential developmental neurotoxicity effect. Even though cell lines are nowadays widely used in compound screening assays in neuroscience, they often differ genetically and phenotypically from their tissue origin. Primary cells, on the other hand, maintain important markers and functions observed in vivo. Therefore, due to the translation potential and physiological relevance that these cells could offer neurite outgrowth assay and neurotoxicity assessment can considerably benefit from using human neural progenitor cells (hNPCs) as the primary human cell model. The presented method herein can be utilized to screen for the ability of compounds to induce neurite outgrowth and neurotoxicity by taking advantage of the human neural progenitor cell-derived neurons, a cell model closely representing human biology."

High-content screening assay for compounds that enhance or inhibit leukocyte superoxide production to identify drugs for treating immune-mediated diseases

Abstract Reactive oxygen species (ROS) are produced by cells to play important roles in the effector and regulatory functions of immune cells. Our previous studies revealed that ROS act as negative regulators in IL-1β-mediated inflammation. Enhanced severity of inflammation in immune-mediated arthritis was noted when leukocyte NADPH oxidase (NOX2), which mediates the production of ROS, was defective. We hence hypothesized that drugs that modulate the leukocyte ROS production may regulate the pathogenicity of immune-mediated arthritis. Here, we devised a high-content image assay using the dye H2DCF-DA for identifying LOPAC 1280 library compounds that may facilitate or suppress superoxide production in differentiated HL-60 (dHL-60) cells. ROS levels were measured after the cells were treated with phorbol 12-myristate 13-acetate (PMA) or menadione which may induce ROS production from NOX2 or mitochondria. From a screening of 640 compounds in a 3-point interpolate titration in cell-based imaging analysis, we identified 74 drugs that may enhance the ROS production and 72 compounds that may inhibit ROS production by PMA-stimulated-dHL-60 cells. The drugs that we identified included the agonist/antagonist of neurotransmitters and their receptors, ion channel blockers, serotonin antagonists, cell stress modulators and cell cycle inhibitors. To further clarified our hypothesis, we treated NOX2-deficient mice with menadione, which tended to increase the oxidant stress in the joint tissue. The severity of the immune-mediated arthritic joint was significantly suppressed after the treatment. This novel screening method hence may be used to identify potential drugs for treating redox-related inflammatory diseases.

Development of a Cell-Based Immunodetection Assay for Simultaneous Screening of Antiviral Compounds Inhibiting Zika and Dengue Virus Replication.

Practical cell-based assays can accelerate anti-Zika (ZIKV) and anti-dengue (DENV) virus drug discovery. We developed an immunodetection assay (IA), using a pan-flaviviral monoclonal antibody recognizing a conserved envelope domain. The final protocol includes a direct virus yield reduction assay (YRA) carried out in the human Huh7 cell line, followed by transfer of the supernatant to a secondary Huh7 culture to characterize late antiviral effects. Sofosbuvir and ribavirin were used to validate the assay, while celgosivir was used to evaluate the ability to discriminate between early and late antiviral activity. In the direct YRA, at 100, 50, and 25 TCID50, sofosbuvir IC50 values were 5.0 ± 1.5, 2.7 ± 0.5, 2.5 ± 1.1 µM against ZIKV and 16.6 ± 2.8, 4.6 ± 1.4, 2.6 ± 2.2 µM against DENV; ribavirin IC50 values were 6.8 ± 4.0, 3.8 ± 0.6, 4.5 ± 1.4 µM against ZIKV and 17.3 ± 4.6, 7.6 ± 1.2, 4.1 ± 2.3 µM against DENV. Sofosbuvir and ribavirin IC50 values determined in the secondary YRA were reproducible and comparable with those obtained by direct YRA and plaque reduction assay (PRA). In agreement with the proposed mechanism of late action, celgosivir was active against DENV only in the secondary YRA (IC50 11.0 ± 1.0 µM) and in PRA (IC50 10.1 ± 1.1 µM). The assay format overcomes relevant limitations of the gold standard PRA, allowing concurrent analysis of candidate antiviral compounds against different viruses and providing preliminary information about early versus late antiviral activity.

Comparative analysis of myometrial and vascular smooth muscle cells to determine optimal cells for use in drug discovery

Novel therapeutic regulators of uterine contractility are needed to manage preterm labor, induce labor and control postpartum hemorrhage. Therefore, we previously developed a high-throughput assay for large-scale screening of small molecular compounds to regulate calcium-mobilization in primary mouse uterine myometrial cells. The goal of this study was to select the optimal myometrial cells for our high-throughput drug discovery assay, as well as determine the similarity or differences of myometrial cells to vascular smooth muscle cells (VSMCs)-the most common off-target of current myometrial therapeutics. Molecular and pharmacological assays were used to compare myometrial cells from four sources: primary cells isolated from term pregnant human and murine myometrium, immortalized pregnant human myometrial (PHM-1) cells and immortalized non-pregnant human myometrial (hTERT-HM) cells. In addition, myometrial cells were compared to vascular SMCs. We found that the transcriptome profiles of hTERT-HM and PHM1 cells were most similar (r = 0.93 and 0.90, respectively) to human primary myometrial cells. Comparative transcriptome profiling of primary human myometrial transcriptome and VSMCs revealed 498 upregulated (p ≤ 0.01, log2FC≥1) genes, of which 142 can serve as uterine-selective druggable targets. In the high-throughput Ca2+-assay, PHM1 cells had the most similar response to primary human myometrial cells in OT-induced Ca2+-release (Emax = 195% and 143%, EC50 = 30 nM and 120 nM, respectively), while all sources of myometrial cells showed excellent and similar robustness and reproducibility (Z’ = 0.52 to 0.77). After testing a panel of 61 compounds, we found that the stimulatory and inhibitory responses of hTERT-HM cells were highly-correlated (r = 0.94 and 0.95, respectively) to human primary cells. Moreover, ten compounds were identified that displayed uterine-selectivity (≥5-fold Emax or EC50 compared to VSMCs). Collectively, this study found that hTERT-HM cells exhibited the most similarity to primary human myometrial cells and, therefore, is an optimal substitute for large-scale screening to identify novel therapeutic regulators of myometrial contractility. Moreover, VSMCs can serve as an important counter-screening tool to assess uterine-selectivity of targets and drugs given the similarity observed in the transcriptome and response to compounds.

Calcium/Calmodulin Dependent Protein Kinase 2 Gamma Is Identified As a Potential Therapeutic Target of Myelofibrosis Using Disease-Specific Induced Pluripotent Stem Cells

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by megakaryocytic atypia, fibrosis in bone marrow, and extramedullary hematopoiesis. Although mutational analyses reveal that about 90% of patients with primary MF harbor JAK2, CALR or MPL mutation that constitutively activates JAK-STAT pathway, the outcome of JAK2 inhibitor treatment for MF patients still remains to be improved. However, only a limited number of humanized disease-models are currently available to develop a novel therapeutic strategy for MF. We have previously reported that induced pluripotent stem cells (iPSCs) established from MF patients (MF-iPSCs) by using retroviral vectors recapitulated the disease phenotype (Hosoi et al. 2014), indicating that MF-iPSCs are one of the useful humanized disease-models of MF.We established iPSCs from three MF patients harboring a JAK2 V617F, CALR type 1, or CALR type 2 mutations by using integration-free episomal vectors and confirmed that established MF-iPSCs harbored the identical mutations to parental cells. After hematopoietic differentiation, we obtained hematopoietic progenitor cells (HPCs) immunophenotypically defined as CD34+/CD43+ cells. Viability assays revealed that JAK2 inhibitors (Ruxolitinib and HSP90) impaired cell survival of MF-HPCs compared to normal-HPCs, suggesting that MF-HPCs also reproduce drug-sensitivity.To investigate therapeutic targets of MF, we optimized culture condition of HPCs to perform compound screening. By the use of small chemical library containing 192 compounds and two MF-iPSCs harboring a JAK2 or CALR mutation, we identified KN93, calcium/calmodulin dependent protein kinase (CAMK) 2 inhibitor, as a compound which inhibited the viability of MF-HPCs from all three patients in dose-dependent manner, compared to normal-HPCs. For validation, we used Trifluoperazine (TFP), another CAMK inhibitor and TFP had similar inhibitory effects on MF-HPCs. In Ba/F3 mouse cell line ectopically expressing MPL W515L mutant (Ba/F3 MPLmu ;IC50 of ruxolitinib = 112 nM) as other models mimicking MF than that using JAK2 mutant and CALR mutant, KN93 and TFP decreased cell growth, induced apoptosis, and suppressed the phosphorylation of Stat5, a major signaling event in MF, indicating that CAMK2 is a candidate of therapeutic target for MF.To determine the critical subtype of CAMK2 in MF, we assessed the expression of CAMK2 subtypes. In Ba/F3 MPLmu, Camk2 gamma subtype (Camk2g) was detectable among all Camk2 subtypes in mRNA levels and phosphorylation of CAMK2G protein was enhanced at the absence of interluekin-3. Knock down of CAMK2G by short-hairpin RNA decreased cell growth of Ba/F3 MPLmu. Moreover, berbamine, a CAMK2G inhibitor, also inhibited the viability of Ba/F3 MPLmu and colony forming capacity of c-kit+ primary mouse bone marrow ectopically expressing MPLW515L compared to that of expressing wild type MPL at dose-dependent manner, suggesting that CAMK2G is a critical subtype of CAMK2 in MF.To address whether CAMK2 inhibition overcome the JAK2 inhibitor-resistance, one of the reason why JAK2 inhibitor is not efficient in clinical setting, we established ruxolitinib-resistant Ba/F3_MPLmu (Ba/F3_MPLmu_R; IC50 of ruxolitinib = 642 nM) cells through one-month exposure to ruxolitinib. KN93 and TFP decreased cell growth, induced apoptosis, and suppressed the phosphorylation of Stat5 in Ba/F3_MPLmu_R and combination of CAMK2 inhibitors and ruxolitinib exhibited inhibitory effects more efficiently than single agent, suggesting that CAMK2 inhibitors show a cooperative effect with ruxolitinib against MF cells and have the potential to overcome JAK2 inhibitor-resistance.To address the effectiveness of CAMK2 inhibition in primary samples, we used CD34+ cells isolated from peripheral blood mononuclear cells of MF patients. Although either KN93 or ruxolitinib inhibited the colony forming capacity of primary MF cells with similar efficiency, combination of KN93 with ruxolitinib showed cooperative inhibition. Taken together, these findings indicate that CAMK2G would be a therapeutic target of MF patients.In conclusion, MF-iPSCs enable comparable compound screening assay and identify CAMK2G as a potential therapeutic target of MF. Our results revealed that CAMK2G inhibition could lead the novel therapeutic strategies to combine with JAK2 inhibitors and to overcome the resistance against JAK2 inhibitors. DisclosuresArai:Novartis: Research Funding. Kurokawa:Kyowa Hakko Kirin: Honoraria, Research Funding; Astellas Pharma: Research Funding; Sumitomo Dainippon Pharma: Research Funding; Takeda Pharmaceutical: Research Funding; Eizai: Research Funding; Pfizer: Research Funding; Nippon Sinyaku: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Chugai Pharmaceutical: Research Funding; MSD: Honoraria, Research Funding; Otsuka Pharmaceutical: Research Funding; Teijin Pharma: Research Funding.