Activity In Cell-based Assays Research Articles

L-Carnitine Reduces Oxidative Stress and Promotes Cells Differentiation and Bone Matrix Proteins Expression in Human Osteoblast-Like Cells.

Bone fragility and associated fracture risk are major problems in aging. Oxidative stress and mitochondrial dysfunction play a key role in the development of bone fragility. Mitochondrial dysfunction is closely associated with excessive production of reactive oxygen species (ROS). L-Carnitine (L-C), a fundamental cofactor in lipid metabolism, has an important antioxidant property. Several studies have shown how L-C enhances osteoblastic proliferation and activity. In the current study, we investigated the potential effects of L-C on mitochondrial activity, ROS production, and gene expression involved in osteoblastic differentiation using osteoblast-like cells (hOBs) derived from elderly patients. The effect of 5mM L-C treatment on mitochondrial activity and L-C antioxidant activity was studied by ROS production evaluation and cell-based antioxidant activity assay. The possible effects of L-C on hOBs differentiation were assessed by analyzing gene and protein expression by Real Time PCR and western blotting, respectively. L-C enhanced mitochondrial activity and improved antioxidant defense of hOBs. Furthermore, L-C increased the phosphorylation of Ca2+/calmodulin-dependent protein kinase II. Additionally, L-C induced the phosphorylation of ERK1/2 and AKT and the main kinases involved in osteoblastic differentiation and upregulated the expression of osteogenic related genes, RUNX2, osterix (OSX), bone sialoprotein (BSP), and osteopontin (OPN) as well as OPN protein synthesis, suggesting that L-C exerts a positive modulation of key osteogenic factors. In conclusion, L-C supplementation could represent a possible adjuvant in the treatment of bone fragility, counteracting oxidative phenomena and promoting bone quality maintenance.

Evaluation of oral anticoagulants with vitamin K epoxide reductase in its native milieu

AbstractWarfarin, acenocoumarol, phenprocoumon, and fluindione are commonly prescribed oral anticoagulants for the prevention and treatment of thromboembolic disorders. These anticoagulants function by impairing the biosynthesis of active vitamin K–dependent coagulation factors through the inhibition of vitamin K epoxide reductase (VKOR). Genetic variations in VKOR have been closely associated with the resistant phenotype of oral anticoagulation therapy. However, the relative efficacy of these anticoagulants, their mechanisms of action, and their resistance variations among naturally occurring VKOR mutations remain elusive. Here, we explored these questions using our recently established cell-based VKOR activity assay with the endogenous VKOR function ablated. Our results show that the efficacy of these anticoagulants on VKOR inactivation, from most to least, is: acenocoumarol > phenprocoumon > warfarin > fluindione. This is consistent with their effective clinical dosages for stable anticoagulation control. Cell-based functional studies of how each of the 27 naturally occurring VKOR mutations responds to these 4 oral anticoagulants indicate that phenprocoumon has the largest resistance variation (up to 199-fold), whereas the resistance of acenocoumarol varies the least (<14-fold). Cell-based kinetics studies show that fluindione appears to be a competitive inhibitor of VKOR, whereas warfarin is likely to be a mixed-type inhibitor of VKOR. The anticoagulation effect of these oral anticoagulants can be reversed by the administration of a high dose of vitamin K, apparently due to the existence of a different enzyme that can directly reduce vitamin K. These findings provide new insights into the selection of oral anticoagulants, their effective dosage management, and their mechanisms of anticoagulation.

Optimization of Phenyl Indole Inhibitors of the AAA+ ATPase p97

Optimization of the side-chain of a phenyl indole scaffold identified from a high-throughput screening campaign for inhibitors of the AAA+ ATPase p97 is reported. The addition of an N-alkyl piperazine led to high potency of this series in a biochemical assay, activity in cell-based assays, and excellent pharmaceutical properties. Molecular modeling based on a subsequently obtained cryo-EM structure of p97 in complex with a phenyl indole was used to rationalize the potency of these allosteric inhibitors.

Design and Characterization of Novel Covalent Bromodomain and Extra-Terminal Domain (BET) Inhibitors Targeting a Methionine.

BET proteins are key epigenetic regulators that regulate transcription through binding to acetylated lysine (AcLys) residues of histones and transcription factors through bromodomains (BDs). The disruption of this interaction with small molecule bromodomain inhibitors is a promising approach to treat various diseases including cancer, autoimmune and cardiovascular diseases. Covalent inhibitors can potentially offer a more durable target inhibition leading to improved in vivo pharmacology. Here we describe the design of covalent inhibitors of BRD4(BD1) that target a methionine in the binding pocket by attaching an epoxide warhead to a suitably oriented noncovalent inhibitor. Using thermal denaturation, MALDI-TOF mass spectrometry, and an X-ray crystal structure, we demonstrate that these inhibitors selectively form a covalent bond with Met149 in BRD4(BD1) but not other bromodomains and provide durable transcriptional and antiproliferative activity in cell based assays. Covalent targeting of methionine offers a novel approach to drug discovery for BET proteins and other targets.

Abstract 3446: Deciphering key cancer and inflammation signaling pathways with homogeneous bioluminescent cell-based kinase activity assays

Abstract Signaling pathways activation leads to a multitude of cellular responses including modulation of enzyme activity, altered gene expression, and protein translocation or degradation. Specific phosphorylation events by specific kinases in the cell constitute important nodes in signaling pathways. Altered normal kinase activity leads to several undesirable consequences, causing diseases such as cancer and inflammation. Thus, monitoring these signaling events is essential to better understand normal cell behavior and disease states. Current assays to analyze cellular kinase activities can be tedious, nonhomogeneous, and not easily adaptable to HTS or suffer from generation of false hits due to fluorescence interference, signal quenching, or require special instruments for detection. To overcome these shortcomings, we developed a simple homogeneous assay platform to detect phosphorylation of specific endogenous proteins in cells. We took advantage of the NanoLuc Binary Technology (NanoBiT), a two-subunit system based on NanoLuc luciferase that was successfully demonstrated for protein-protein interaction (PPI) detection. We generated a detection system containing secondary antibody pairs linked to the two Nanoluc components, NanoBiT small and large fragments (11 aa peptide and 18 kDa). Cell lysate containing the phosphorylated protein is incubated with two primary antibodies that recognize separate epitopes on a single protein. These will bring NanoBiT secondary antibodies into proximity to form an active NanoLuc luciferase that makes light in proportion to the amount of target protein. When the primary antibody pair includes a phosphospecific antibody, the luminescence reflects the level of target protein phosphorylation. We tested this system by monitoring the activation of signaling pathways involved in cancer, immune and inflammatory responses (NF-κB, BTK and JAK/STAT). In very few steps we detected the expected biologic response of these pathways either by monitoring BTK autophosphorylation, assessing phosphorylation and degradation of IκB or phosphorylation of STAT3 upon activation of the cells with TNFα, or IL6, respectively. We also tested different small- or large-molecule inhibitors of these pathways or their corresponding node kinase (BTK, IKK, or JAKs) and obtained the expected pharmacology. The bioluminescent system presented here has many advantages including “Add and Read” format, no cell engineering required as the phosphorylation of endogenous substrate is detected in any cell type, and only a simple luminometer is required for detection. Our results demonstrate that this technology can be adapted to any signaling pathway analysis, allowing scientists to analyze signaling pathways of interest, study the kinase cellular activity and regulation or identify specific kinase or pathway inhibitors. Citation Format: Hicham Zegzouti, Brian Hwang, Nidhi Nath, Said Goueli. Deciphering key cancer and inflammation signaling pathways with homogeneous bioluminescent cell-based kinase activity assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3446.

Delivery system for budesonide based on lipid-DNA

Budesonide is a hydrophobic glucocorticoid with high anti-inflammatory activity for the treatment of asthma, inflammatory bowel disease and rheumatoid arthritis. A micellar drug-delivery system based on lipid-DNA may provide a strategy to maximize its drug efficacy and reduce adverse effects. In this work, we report the use of lipid-DNAA (UU11mer), featuring two hydrophobic alkyl chains and forming micelles at a comparatively low critical micelle concentration, to render budesonide water-soluble with a high loading capacity (LC). The inhibition of interleukin-8 (IL-8) release shows that the new delivery system retains the inhibitory activity in cell-based assays. In conclusion, this research provides a novel approach to formulate and administer budesonide in a non-invasive manner, which dramatically improves its water-solubility while retaining its bioavailability.

Antiviral activities of 5-chlorobenzotriazole derivatives

In this study, we designed and synthesized a series of new 5-chlorobenzotriazole derivatives. Compounds were tested for cytotoxicity and antiviral activity in cell-based assays against several positive single-stranded RNA viruses: BVDV, YFV, CVB-5, and Sb-1; two negative single-stranded RNA viruses: RSV and VSV; a double-stranded RNA virus (Reo-1); and two DNA viruses: VV and HSV-1. N-[4-(5-Chloro-2H-benzo[d][1,2,3]triazol-2-yl)phenyl]-3,4,5-trimethoxybenzamide turned out to be the most potent compound against bovine viral diarrhea virus (BVDV). Its activity was shown to be comparable to the activity of the reference drug NM 107 (EC50 3.0 vs. 1.7 μM). It is going to be used as a lead compound for future antiviral drug developments.

Stabilization of warfarin‐binding pocket of VKORC1 and VKORL1 by a peripheral region determines their different sensitivity to warfarin inhibition

Background The human genome encodes two paralogs of vitamin-K-epoxide reductase, VKORC1 and VKORL1, that support blood coagulation and other vitamin-K-dependent processes. Warfarin inhibits both enzymes, but VKORL1 is relatively resistant to warfarin. Objectives To understand the difference between VKORL1 and VKORC1, and the cause of warfarin-resistant (WR) mutations in VKORC1. Methods We performed systematic mutagenesis and analyzed warfarin responses with a cell-based activity assay. Mass spectrometry analyses were used to detect cellular redox state. Results VKORC1 and VKORL1 adopt a similar intracellular redox state with four-transmembrane-helix topology. Most WR mutations identified in VKORC1 also confer resistance in VKORL1, indicating that warfarin inhibits these paralogs at a common binding site. A group of WR mutations, distant from the warfarin-binding site, show significantly less resistance in VKORL1 than in VKORC1, implying that their different warfarin responses are determined by peripheral interactions. Remarkably, we identify a critical peripheral region in which single mutations, Glu37Lys or His46Tyr, drastically increase the warfarin sensitivity of VKORL1. In the background of these warfarin-sensitive VKORL1 mutants, WR mutations showing relative less resistance in wild-type VKORL1 become much more resistant, suggesting a structural conversion to resemble VKORC1. At this peripheral region, we also identified a human single nucleotide polymorphism that confers warfarin sensitivity of VKORL1. Conclusions Peripheral regions of VKORC1 and VKORL1 primarily maintain the stability of their common warfarin-binding pocket, and differences of such interactions determine their relative sensitivity to warfarin inhibition. This new model also explains most WR mutations located at the peripheral regions of VKORC1.

Development and validation of a targeted affinity-enrichment and LC–MS/MS proteomics approach for the therapeutic monitoring of adalimumab

BackgroundThe anti-tumor necrosis factor alpha (TNFα) therapeutic monoclonal antibodies (mAbs), such as adalimumab, are widely used in the treatment of rheumatoid arthritis, inflammatory bowel diseases, and other auto-immune diseases. The administration of adalimumab can elicit the immune responses from some patients, resulting in the formation of anti-drug antibodies (ADAbs). The ADAbs can diminish the therapeutic effects of adalimumab by neutralizing the TNFα binding site or increasing its clearance from circulation. MethodsTo effectively monitor the therapeutic concentrations of adalimumab, we developed and validated a targeted quantitative proteomic assay to determine the circulating concentrations of adalimumab. Since drug effects can be attenuated by ADAbs, the method adopted an affinity-enrichment step to selectively quantify the bioavailable forms of adalimumab in patient serum samples. ResultsThe performance of the LC–MS/MS based assay provides the analytical measuring range and precisions applicable for the therapeutic monitoring of adalimumab. It also provides comparable results to a cell-based activity assay when evaluating patient samples with different concentrations of adalimumab. ConclusionOur assay can quantify both sub-therapeutic and therapeutic concentrations of bioavailable adalimumab in patient serum samples. This assay design provides an alternative to isotope-labeled peptides approach currently adopted in targeted proteomics methods.

Evaluation of Teneligliptin Effects on Transcriptional Activity of PPARγ in Cell-Based Assays.

The antidiabetic drug teneligliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor with a thiazolidine-specific structure. This study aimed to investigate whether teneligliptin can activate PPARγ directly and/or indirectly in cell-based assays. Promoter assays using the reporter construct driven under the control of the SV40 promoter and the PPAR response element (PPRE) were performed. Luciferase activity was measured after a 3-day incubation of vector-transduced cells with various concentrations of teneligliptin. Treatment of the cells with 50 μM teneligliptin significantly transactivated a reporter gene. The presence of the PPARγ antagonist, GW9662, did not affect the activation of PPRE-reporter expression by teneligliptin. We found that teneligliptin could increase PPARγ activity in cell-based assays irrespective of the PPARγ ligand-binding domain.

Synthesis, Biological Investigation, and Structural Revision of Sielboldianin A.

The two ar-bisabol sesquiterpenoids (+)-sielboldianin A (1) and (+)-sielboldianin B (2) were isolated from the stem bark of the plant Fraxinus sielboldiana and belong to a medicinally interesting class of natural products used in traditional Chinese medicine. Herein the total synthesis of the proposed structure of (+)-sielboldianin A (1) is reported using an organocatalyzed enantioselective bromolactonization protocol. X-ray analysis of a key intermediate together with specific rotation values and NOESY data of the synthesized product enabled the revision of the absolute configuration of the natural product (+)-sielboldianin A to (7 R,10 R). Studies on the antioxidant effects using two cell-based assays were conducted. These studies revealed that the enantiomer of 1 exhibited antioxidant effects with IC50 values of 18 ± 3 μM in a cellular lipid peroxidation antioxidant activity assay. Moreover, (-)-1 showed strong protective effects against reactive oxygen species in a cell-based antioxidant activity assay (IC50 = 31 ± 5 μM). In addition, the two ar-sesquiterpenoids (-)-boivinianin B and (-)-gossoronol showed no effect in either assay. No cytotoxic activity in the K562 cancer cell line was observed for the three sesquiterpenoids tested (IC50 > 50 μM).

Variant in human POFUT1 reduces enzymatic activity and likely causes a recessive microcephaly, global developmental delay with cardiac and vascular features

Protein O-fucosyltransferase-1 (POFUT1) adds O-fucose monosaccharides to epidermal growth factor-like (EGF) repeats found on approximately 100 mammalian proteins, including Notch receptors. Haploinsufficiency of POFUT1 has been linked to adult-onset Dowling Degos Disease (DDD) with hyperpigmentation defects. Homozygous deletion of mouse Pofut1 results in embryonic lethality with severe Notch-like phenotypes including defects in somitogenesis, cardiogenesis, vasculogenesis and neurogenesis, but the extent to which POFUT1 is required for normal human development is not yet understood. Here we report a patient with a congenital syndrome consisting of severe global developmental delay, microcephaly, heart defects, failure to thrive and liver disease with a previously unreported homozygous NM_015352.1: c.485C>T variant (p.Ser162Leu) in POFUT1 detected by exome sequencing. Both parents are heterozygotes and neither manifests any signs of DDD. No other detected variant explained the phenotype. This variant eliminated a conserved N-glycosylation sequon at Asn160 in POFUT1 and profoundly decreased POFUT1 activity in patient fibroblasts compared to control fibroblasts. Purified p.Ser162Leu mutant protein also showed much lower POFUT1 activity with a lower affinity for EGF acceptor substrate than wild type POFUT1. Eliminating the N-glycan sequon by replacing Asn160 with Gln had little effect on POFUT1 activity, suggesting that loss of the glycan is not responsible for the defect. Furthermore, the p.Ser162Leu mutant showed weaker ability to rescue Notch activity in cell-based assays. These results suggest that this N-glycan of POFUT1 is not required for its proper enzymatic function, and that the p.Ser162Leu mutation of POFUT1 likely causes global developmental delay, microcephaly with vascular and cardiac defects.

Discovery and characterization of an iminocoumarin scaffold as an inhibitor of MEKK2 (MAP3K2)

The kinase MEKK2 (MAP3K2) activates the MEK5/ERK5 cell signaling pathway and may play an important role in tumor growth and metastasis. Thus, MEKK2 may represent a novel kinase target for cancer. In order to identify inhibitors of MEKK2, we screened a library of compounds using a high throughput MEKK2 intrinsic ATPase enzyme assay. We identified two hits with validated structures and confirmed activity in the primary assay (IC50 values = 322 nM and 7.7 μM) and two orthogonal MEKK2 biochemical assays. Compound 1, the more potent hit, was the subject of further investigation. Limited structure-activity relationship (SAR) studies were performed on this iminocoumarin hit which resulted in ≥20-fold more potent analogs (e.g. 8 and 16 nM IC50). Two analogs had improved selectivity in a 50-member kinase profiling panel compared to the hit. These studies suggested that substitutions around the phenoxy ring of this scaffold can impart improved potency and selectivity for MEKK2. Analog Compound 1s (16 nM IC50) was further verified by external testing to inhibit MEKK2 and MEKK3 with similar potencies. Compound 1s displayed activity in cell-based assays in which it inhibited ERK5 pathway activation in cells and inhibited cell migration in a scratch assay. Thus, we have identified a scaffold that has promising potential to be developed into a highly selective and potent inhibitor of MEKK2. Information from these SAR studies provides specific guidance for the future design of MEKK2 inhibitor probes.

Inhibitors of LexA Autoproteolysis and the Bacterial SOS Response Discovered by an Academic-Industry Partnership.

The RecA/LexA axis of the bacterial DNA damage (SOS) response is a promising, yet nontraditional, drug target. The SOS response is initiated upon genotoxic stress, when RecA, a DNA damage sensor, induces LexA, the SOS repressor, to undergo autoproteolysis, thereby derepressing downstream genes that can mediate DNA repair and accelerate mutagenesis. As genetic inhibition of the SOS response sensitizes bacteria to DNA damaging antibiotics and decreases acquired resistance, inhibitors of the RecA/LexA axis could potentiate our current antibiotic arsenal. Compounds targeting RecA, which has many mammalian homologues, have been reported; however, small-molecules targeting LexA autoproteolysis, a reaction unique to the prokaryotic SOS response, have remained elusive. Here, we describe the logistics and accomplishments of an academic-industry partnership formed to pursue inhibitors against the RecA/LexA axis. A novel fluorescence polarization assay reporting on RecA-induced self-cleavage of LexA enabled the screening of 1.8 million compounds. Follow-up studies on select leads show distinct activity patterns in orthogonal assays, including several with activity in cell-based assays reporting on SOS activation. Mechanistic assays demonstrate that we have identified first-in-class small molecules that specifically target the LexA autoproteolysis step in SOS activation. Our efforts establish a realistic example for navigating academic-industry partnerships in pursuit of anti-infective drugs and offer starting points for dedicated lead optimization of SOS inhibitors that could act as adjuvants for current antibiotics.

Methylisoindigo and Its Bromo-Derivatives Are Selective Tyrosine Kinase Inhibitors, Repressing Cellular Stat3 Activity, and Target CD133+ Cancer Stem Cells in PDAC.

Indirubin is an active component of the herbal ingredient ‘Danggui Longhui wan’, which was used for the treatment of inflammation and chronic myeloid leukemia in China. The recent study showed its derivative methylisoindigo (also known as meisoindigo) preferentially targeting cancer stem cells (CSCs) in interference with AMPK and LKB1, the cellular metabolic sensors. In this study, we screened the effect of meisoindigo on a panel of 300 protein kinases and found that it selectively inhibited Stat3-associated tyrosine kinases and further confirmed its activity in cell based assays. To gain a deeper insight into the structure–activity relationship we produced 7 bromo-derivatives exhausting the accessible positions on the bisindole backbone except for in the 4-position due to the space limitation. We compared their anti-proliferative effects on tumor cells. We found that 6-bromomeisoindigo showed improved toxicity in company with increased Stat3 inhibition. Moreover, we detected that 6-bromomeisoindigo induced apoptosis of 95% of CD133+ pancreatic cancer cells. Considering that CD133 is a common marker highly expressed in a range of CSCs, our results imply the potential application of 6-bromomeisoindigo for the treatment of CSCs in different types of cancers.

A high-throughput chemical screen identifies novel inhibitors and enhancers of anti-inflammatory functions of the glucocorticoid receptor

Glucocorticoids (GCs)—ligands of the glucocorticoid receptor (GR)—are widely used to treat inflammatory diseases, but suffer from significant side effects and poor responsiveness in certain patient populations. Identification of chemical GR modulators may provide insights into the regulatory mechanisms of anti-inflammatory functions of GR and help improve GC-based therapy. Here we report the development and application of a high-throughput screening to identify compounds that either enhance or suppress the anti-inflammatory effect of GR function. Using a cell-based GR activity assay that measures Dexamethasone (Dex)-mediated NF-κB repression, we have screened ~8,000 compounds and identified several compounds that suppressed GR activity, including multiple GSK3β inhibitors and anti-cancer agent camptothecin. Notably, we also identified two kinase IKK2 inhibitors, including TPCA-1, as GR enhancers that improve the anti-inflammatory effect of GR. In particular, TPCA-1 augmented the activity of Dex in NF-κB repression by attenuating GR down-regulation. Consistent with the observation, siRNA-mediated IKK2 knockdown decreased GR down-regulation and increased GR expression. Together, our results identified chemical compounds as novel modulators of GR and revealed an unexpected role for IKK2 in GR down-regulation. Furthermore, we have established a high-throughput screening platform for discovering GR-modulating compounds that may be repurposed to improve current GC-based therapies.

Small molecule metalloprotease inhibitor with in vitro, ex vivo and in vivo efficacy against botulinum neurotoxin serotype A

Botulinum neurotoxins (BoNTs) are the most toxic substances known to mankind and are the causative agents of the neuroparalytic disease botulism. Their ease of production and extreme toxicity have caused these neurotoxins to be classified as Tier 1 bioterrorist threat agents and have led to a sustained effort to develop countermeasures to treat intoxication in case of a bioterrorist attack. While timely administration of an approved antitoxin is effective in reducing the severity of botulism, reversing intoxication requires different strategies. In the present study, we evaluated ABS 252 and other mercaptoacetamide small molecule active-site inhibitors of BoNT/A light chain using an integrated multi-assay approach. ABS 252 showed inhibitory activity in enzymatic, cell-based and muscle activity assays, and importantly, produced a marked delay in time-to-death in mice. The results suggest that a multi-assay approach is an effective strategy for discovery of potential BoNT therapeutic candidates.

Abstract LB-305: Development and pre-clinical assessment of a first-in-class small molecule inhibitor of FLIP

Abstract Background Evasion of cell death is a major cause of resistance to anti-cancer therapies, making proteins that regulate cell death clinically relevant therapeutic targets. The anti-apoptotic protein FLIP is frequently overexpressed in a number of cancers, including non-small cell lung cancer (NSCLC) and colorectal cancer (CRC), and has been shown by us and others to be a major mediator of drug resistance. FLIP and procaspase-8 form complexes with the adaptor protein FADD in response to a variety of clinically relevant stimuli, including ligation of death receptors, such as TRAIL-R1 and R2, and treatment with chemotherapeutic agents. In these complexes, FLIP modulates the activation of procaspase-8, and thereby apoptosis and necroptosis - two major cell death mechanisms. We have found that there are important differences between FLIP and procaspase-8 in terms of their preferred modes of interaction with FADD that are potentially therapeutically exploitable [1]. Herein, we report the development and pre-clinical characterization of first-in-class inhibitors of FLIP. Methods Molecular modelling of the FLIP-FADD interaction; cell-free screening assays; cell-based activity assays; biophysical binding assays; on-target mechanism-of-action studies, in vivo studies. Results Molecular modelling of the FLIP-FADD interaction identified a putative drug-binding pocket on FLIP against which a virtual small-molecule screen was carried out. Subsequent biochemical screening of selected compounds using a FLIP-FADD protein-protein interaction assay identified hits with on-target activity. Medicinal chemistry optimization of these hits identified a series of compounds that are able to disrupt FLIP’s interaction with the DISC and display nanomolar activity in NSCLC and CRC cell-based assays (i.e. caspase activation, cell death and cell survival), which is in line with their binding affinity in an orthogonal biophysical assay (isothermal calorimetry). The pro-apoptotic effects of these FLIP inhibitors were enhanced upon addition of death ligands, such as TRAIL, and lead-molecules have been shown to potentiate the effects of the standard-of-care chemotherapeutics such as e.g. cisplatin (NSCLC) or 5FU (CRC). FLIP overexpression and CRISPR-mediated procaspase-8 deletion abrogated the effects of these novel inhibitors consistent with the expected mechanism-of-action. In addition, using peripheral blood mononuclear cells (PBMCs), we demonstrate that FLIP inhibitors have selectivity against cancer cells. Finally, we identified lead molecules with ADME profiles suitable for in vivo evaluation and using these compounds, single-agent anti-tumor effects have been demonstrated in xenograft models. Conclusions The first-in-class inhibitors of FLIP developed in this study have the potential for broad application in treatment of cancer, either as monotherapy or in combination with other agents. Acknowledgements This work was supported by a Seeding Drug Discovery award from the Wellcome Trust. 1. Majkut, J., et al., Differential affinity of FLIP and procaspase 8 for FADD's DED binding surfaces regulates DISC assembly. Nat Commun, 2014. 5: p. 3350. Citation Format: Joanna Majkut, Catherine Higgins, Jennifer Fox, Greti E. Fiedler, Timothy Harrison, Daniel B. Longley. Development and pre-clinical assessment of a first-in-class small molecule inhibitor of FLIP [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-305. doi:10.1158/1538-7445.AM2017-LB-305

Anemone rivularis inhibits pyruvate dehydrogenase kinase activity and tumor growth

Ethnopharmacological relevanceAnemone rivularis Buch.-Ham. ex DC. (Ranunculaceae) have been used as a traditional remedy for treatment of inflammation and cancer. However, there is no report demonstrating experimental evidence on anti-tumor action of A. rivularis. Aim of studyThe Warburg's effect, preference of aerobic glycolysis rather than oxidative phosphorylation (OXPHOS) even in oxygen rich condition, is focused as one of major characteristics of malignant tumor. Thus, we investigated the effect of A. rivularis on the Pyruvate dehydrogenase (PDH) kinases (PDHKs), a major molecular targets for reducing aerobic glycolysis. Materials and methodsThe ethanol extract of whole plant of A. rivularis (ARE), fingerprinted by high performance liquid chromatography (HPLC), was applied to in vitro and cell-based PDHK activity assays. The effect of ARE on cell viabilities of several tumor cells was estimated by MTT assay. The expression of phosphor-PDH, PDH and PDHK1 were measured by Western blot analysis. The production of reactive oxygen species (ROS) and apoptosis was measured by fluorescence-activated cell sorting analysis, using 5-(and-6)-carboxy-2′,7′-dichlorodihydrofluorescein diacetate (carboxy-H2DCFDA) and Annexin V/propidium iodide (PI) staining, respectively. Mitochondrial membrane potential was examined by tetramethylrhodamine methyl ester (TMRM) staining. In vivo anti-tumor efficacy of ARE was estimated by means of tumor volume and weight using allograft injection of murine Lewis lung carcinoma (LLC) cells to dorsa of C57BL/6 mice. ResultsARE inhibited the viabilities of several cancer cells, including MDA-MB321, K562, HT29, Hep3B, DLD-1, and LLC. ARE suppressed PDHK activity in in vitro kinase assay, and also inhibited aerobic glycolysis by reducing phosphorylation of PDHA in human DLD-1 colon cancer and murine LLC cells. The expression of PDHK1, a major isoform of PDHKs in cancer, was not affected by ARE treatment. Moreover, ARE increased the both ROS production and mitochondrial damage. In addition, ARE suppressed the in vitro tumor growth through mitochondria-mediated apoptosis. The growth rates of allograft LLC cells were also reduced by ARE treatment. ConclusionsHere, we firstly report that ARE inhibits PDHK activity and growth of tumor in both in vitro and in vivo experiments. Therefore, we suggest ARE as a potential candidate for developing anti-cancer drugs.

Clinical immunogenicity of the d-amino acid peptide therapeutic etelcalcetide: Method development challenges and anti-drug antibody clinical impact assessments

The immunogenicity risk assessment and bioanalytical strategy for novel therapeutics should account for both unique biophysical properties and potential consequences of immunogenicity. When assessing the immunogenicity risk of etelcalcetide, a peptide agonist of the calcium-sensing receptor, we considered the potential that the d-amino acid ‘backbone’ and biotransformation of etelcalcetide could allow the drug to act as a hapten. As a consequence, we validated and implemented a surface plasmon resonance immunoassay platform with both etelcalcetide and etelcalcetide-‘carrier’ surfaces to detect anti-drug antibodies (ADA). No evidence of in-vitro neutralizing activity with surrogate controls was detected despite multiple immunization approaches and a sensitive cell-based activity assay. Therefore, a neutralizing assay was not implemented for clinical support. We conducted an integrated analysis of immunogenicity data pooled from two pivotal placebo-controlled trials to define the clinical impact of anti-etelcalcetide antibodies. While both pre-existing and developing anti-etelcalcetide antibodies were detected, we show here that they have no consequences for clinical exposure, efficacy, or safety of etelcalcetide.