Triazoloacridone C-1305 impairs XBP1 splicing by acting as a potential IRE1α endoribonuclease inhibitor.

Inositol requiring enzyme 1 alpha (IRE1α) is one of three signaling sensors in the unfolding protein response (UPR) that alleviates endoplasmic reticulum (ER) stress in cells and functions to promote cell survival. During conditions of irrevocable stress, proapoptotic gene expression is induced to promote cell death. One of the three signaling stressors, IRE1α is an serine/threonine-protein kinase/endoribonuclease (RNase) that promotes nonconventional splicing of XBP1 mRNA that is translated to spliced XBP1 (XBP1s), an active prosurvival transcription factor. Interestingly, elevated IRE1α and XBP1s are both associated with poor cancer survival and drug resistance. In this study, we used next-generation sequencing analyses to demonstrate that triazoloacridone C-1305, a microtubule stabilizing agent that also has topoisomerase II inhibitory activity, dramatically decreases XBP1s mRNA levels and protein production during ER stress conditions, suggesting that C-1305 does this by decreasing IRE1α's endonuclease activity.

Non-targeted detection and differentiation of agonists versus antagonists, directly in bioprofiles of everyday products.

Xenoestrogens exert antiandrogenic effects on the human androgen receptor. In the analytical field, such antagonists block the detection of testosterone and falsify results obtained by sum parameter assays. Currently, such agonistic versus antagonistic effects are not differentiated in complex mixtures. Oppositely acting hormonal effects present in products of everyday use can only be differentiated after tedious fractionation and isolation of the individual compounds along with subjection of each fraction/compound to the status quo bioassay testing. However, such long-lasting procedures are not suited for routine. Hence, we developed a fast bioanalytical tool that figures out agonists versus antagonists directly in complex mixtures. Exemplarily, 8 cosmetics and 15 thermal papers were analyzed. The determined antagonistic potentials of active compounds found were comparable to the ones of known antagonists (in reference shown for bisphenol A, 4-n-nonylphenol and four parabens). Relevant biological/chromatographic parameters such as cell viability, culture conditions, dose response curves, limits of biological detection/quantification and working range (shown for testosterone, dihydrotestosterone, nandrolone and trenbolone) were investigated to obtain the best sensitivity of the biological detection. The developed and validated method was newly termed reversed phase high-performance thin-layer chromatography planar yeast ant-/agonistic androgen screen (RP-HPTLC-pYAAS bioassay). Results were also compared with the RP-HPTLC-Aliivibrio fischeri bioassay (applied on RP plates for the first time). As proof-of-concept, the transfer to another bioassay (RP-HPTLC-pYES) was successfully demonstrated, analogously termed RP-HPTLC-pYAES bioassay detecting anti-/estrogens (exemplarily shown for evaluation of 4 pharmaceuticals used in breast cancer treatment). The new imaging concept provides (1) detection and differentiation of individual agonistic versus antagonistic effects in the bioprofiles, (2) bioanalytical quantification of their activity potential by scanning densitometry and (3) characterization of unknown bioactive compound zones by hyphenation to high-resolution mass spectrometry. Depending on the hormonal bioassay, 15 samples were analyzed in parallel within 5 h or 6 h (calculated as 20 or 24 min per sample). For the first time, piezoelectric spraying of the yeast cells was successfully demonstrated for the planar yeast-based bioassays.

Lysosomal acid lipase does not have a propeptide and should not be considered being a proprotein.

Lysosomal acid lipase (LAL) plays an important role in lipid metabolism by performing hydrolysis of triglycerides and cholesteryl esters in the lysosome. Based upon characteristics of LAL purified from human liver, it has been proposed that LAL is a proprotein with a 55 residue propeptide that may be essential for proper folding, intracellular transport, or enzymatic function. However, the biological significance of such a propeptide has not been fully elucidated. In this study, we have performed a series of studies in cultured HepG2 and HeLa cells to determine the role of the putative propeptide. However, by Western blot analysis and subcellular fractionation, we have not been able to identify a cleaved LAL lacking the N-terminal 55 residues. Moreover, mutating residues surrounding the putative cleavage site at Lys76 ↓ in order to disrupt a proteinase recognition sequence, did not affect LAL activity. Furthermore, forcing cleavage at Lys76 ↓ by introducing the optimal furin cleavage site RRRR↓EL between residues 76 and 77, did not affect LAL activity. These data, in addition to bioinformatics analyses, indicate that LAL is not a proprotein. Thus, it is possible that the previously reported cleavage at Lys76 ↓ could have resulted from exposure to proteolytic enzymes during the multistep purification procedure.

In vitro elucidation of the role of pericellular matrix in metastatic extravasation and invasion of breast carcinoma cells.

Numerous studies have demonstrated the importance of altered hyaluronan metabolism to malignant progression of multiple tumor types, including breast carcinomas. Increased hyaluronan (HA) metabolism in the stroma of primary tumors promotes activation of oncogenic signaling pathways that impact tumor initiation, growth, and invasion. Carcinoma cell synthesis and assembly of HA-rich pericellular matrices induces a stromal-independent phenotype, which is associated with cancer progression. Although the pro-tumorigenic role of stromal HA is well established, a novel but unexplored hypothesis is that carcinoma cell-associated HA pericellular matrices promote metastasis of circulating tumor cells. Here, we report the development of an in vitro assay that employs microfluidic techniques to directly measure the importance of an HA-rich pericellular matrix in the entry of carcinoma cells into ectopic sites. This model provides the capability to visualize specific steps in metastasis, which is difficult using animal models. The results show that the presence of a HA-rich pericellular matrix correlates to the invasive and metastatic potential of breast carcinoma cells. Furthermore, enzymatic removal or pharmacologic inhibition of HA synthesis significantly inhibits carcinoma cell extravasation and invasion in this model system. These results implicate pericellular HA-rich carcinoma cell associated pericellular matrices in colonization of ectopic sites by circulating tumor cells and support specific targeting of this matrix to limit metastasis in patients.

Amentoflavone is a potent broad-spectrum inhibitor of human UDP-glucuronosyltransferases.

Amentoflavone (AMF), an abundant natural biflavonoid found in many medicinal plants, displays various beneficial effects including anti-inflammatory, anti-oxidative and anti-cancer. Despite the extensive studies on pharmacological activities, the toxicity or undesirable effects of AMF are rarely reported. In this study, the inhibitory effects of AMF on human UDP-glucuronosyltransferases (UGTs) were carefully investigated. AMF displayed strong inhibition towards most of human UGTs including UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4 and 2B17, with the IC50 values ranging from 0.12 µM to 16.81 µM. Inhibition constants (Ki) of AMF against various human UGTs varied from 0.29 µM to 11.51 µM. Further investigation demonstrated that AMF was a noncompetitive inhibitor of UGT1A1 mediated NCHN-O-glucuronidation but functioned as a competitive inhibitor of UGT1A1 mediated 4-MU-O-glucuronidation. In addition, AMF was a competitive inhibitor of UGT1A4 mediated TFP-N-glucuronidation in both UGT1A4 and human liver microsomes, while functioned as a competitive inhibitor of UGT1A9 mediated propofol or 4-MU-O-glucuronidation. These findings demonstrated that AMF was a strong and broad-spectrum natural inhibitor of most human UGTs, which might bring potential risks of herb-drug interactions (HDIs) via UGT inhibition. Additionally, this study provided novel insights into the underlying mechanism of AMF-associated toxicity from the perspective of UGT inhibition.

An improved cell-permeable fluorogenic substrate as the basis for a highly sensitive test for NAD(P)H quinone oxidoreductase 1 (NQO1) in living cells.

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a flavoenzyme upregulated in response to oxidative stress and in some cancers. Its upregulation by compounds has been used as an indicator of their potential anti-cancer properties. In this study we have designed, produced and tested a fluorogenic coumarin conjugate which selectively releases highly fluorescent 4-methylumbelliferone (4-MU) in the presence of NQO1. It was found that measuring 4-MU release rapidly and specifically quantitated NQO1 levels in vitro and in live cells. Both the substrate and its products freely perfused through cell membranes and were non-toxic. The substrate was very specific with low background, and the assay itself could be done in less than 10minutes. This is the first assay to allow the quantitation of NQO1 in live cells which can then be retained for further experiments.

4-Methylumbelliferones Analogues as Anticancer Agents: Synthesis and in Cell Pharmacological Studies.

BACKGROUND: Cancer is one of the most serious clinical problems worldwide, and considerable efforts have been devoted to discovering therapeutic agents with novel modes of action. Natural and synthetic coumarin derivatives have attracted intense research interest due to their diverse structural features and remarkable array of biological properties. OBJECTIVE: In the present study, we synthesized a series of 4-MU derivatives containing urea-piperazine and thioureapiperazine moieties and evaluated their antitumor activities to find efficacy antitumor drugs. METHOD: Cell proliferation, apoptosis, cell cycle, the generation of reactive oxygen species and calcium were measured using MTT assay and flow cytometry, respectively. The expression of apoptosis- and proliferation-related proteins was determined by western blotting. The effect of 4l on apoptosis-related mRNA expression in NCI-H460 cells was detected by RT-PCR. RESULTS: Most of the target compounds exhibited potential anticancer activities against tested cancer cells but had low cytotoxicity to normal cells. Compound 4l inhibited the growth and proliferation of NCI-H460 cells and resulted in apoptosis. Successive studies conducted with 4l in NCI-H460 cells demonstrated that this compound induced the intracellular reactive oxygen species generation and calcium overload, suppressed nuclear factor-κB (NF-κB) activity and regulated anti- and pro-apoptotic proteins. In addition, compound 4l effectively arrested NCI-H460 cells in G2 phase and altered the cell cycle regulatory proteins especially cyclin B1. CONCLUSION: Compound 4l exerts significant anticancer effects on NCI-H460 cells in vitro through targeting of mitochondria-dependent apoptotic pathway. These results indicate that the strategy for rational design of 4-MU derivatives may identify potential anticancer agents.

A light-up imaging protocol for neutral pH-enhanced fluorescence detection of lysosomal neuraminidase activity in living cells.

A lysosome-accessing nanoprobe is designed for recognition of lysosomal neuraminidases (Lyso-Neus), which can cleave the 4-methylumbelliferone moieties of the substrate from the nanoprobe, and lead to the escape of the moieties from acidic lysosomes into the neutral cytosol assisted by cationic poly(ethyleneimine) to light up the pH-responsive fluorescence for visual detection and dynamic tracking of Lyso-Neu activity in living cells.

Near-IR Light-Mediated Cleavage of Antibody-Drug Conjugates Using Cyanine Photocages.

Despite significant progress in the clinical application of antibody drug conjugates (ADCs), novel cleavage strategies that provide improved selectivity are still needed. Herein is reported the first approach that uses near-IR light to cleave a small molecule from a biomacromolecule, and its application to the problem of ADC linkage. The preparation of cyanine antibody conjugates, drug cleavage mediated by 690 nm light, and initial in vitro and in vivo evaluation is described. These studies provide the critical chemical underpinning from which to develop this near-IR light cleavable linker strategy.

Real-time assays for monitoring the influence of sulfide and sulfane sulfur species on protein thiol redox states.

Hydrogen sulfide (H2S) is known to induce persulfidation of protein thiols. However, the process of H2S-induced persulfidation is not fully understood as it requires an additional oxidant. There are several mechanistic possibilities and it is of interest to determine which pathway is kinetically most relevant. Here, we detail in vitro assays for the real-time monitoring of thiol redox states in two model proteins with oxidizable cysteines, PTEN, and roGFP2. These allow kinetic measurements of the response of defined protein thiols (or disulfides) to sulfide and sulfane sulfur species. The combination of these assays with cold cyanolysis reveals the role of intermediary sulfane sulfur species in H2S-induced protein thiol oxidation.

Synthesis, structural studies and biological activity of new Cu(II) complexes with acetyl derivatives of 7-hydroxy-4-methylcoumarin.

The new Cu(II) complexes with 6-acetyl-7-hydroxy-4-methylcoumarin (HL1) and 8-acetyl-7-hydroxy-4-methylcoumarin (HL2) have been obtained by the electrochemical method. The density functional theory calculations and X-ray absorption spectroscopy techniques have been used to geometrically describe a series of new compounds. The studies have been focused on the coordination mode of the hydroxy ligands to the metallic centre. The complexes, Cu(HL1)2 and Cu(HL2)2⋅0.5H2O, have flat square geometry with oxygen atoms in the first coordination sphere. Two bidentate anionic coumarins are bonded to the metal cation via the acetyl and deprotonated hydroxyl O atoms. Biological activity, including microbiological and cytotoxic, has been evaluated and found to be enhanced in comparison with the parent ligands. Moreover, the Cu(II) complex with 8-acetyl-7-hydroxy-4-methylcoumarin shows similar antifungal activity as commercially used fluconazole.

Improved solubility and stability of 7-hydroxy-4-methylcoumarin at different temperatures and pH values through complexation with sulfobutyl ether-ß-cyclodextrin.

The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) was investigated by means of UV-vis, circular dichroism and (1)H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ΔG(o), enthalpy change, ΔH(o), and entropy change, ΔS(o), for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ΔH(o) and the small negative or positive ΔS(o) (|ΔH(o)|>|TΔS(o)|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-ß-CD cavity. Moreover, the (1)H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-ß-CD cavity.

Ratiometric measurement of hydrogen sulfide and cysteine/homocysteine ratios using a dual-fluorophore fragmentation strategy.

Hydrogen sulfide (H2S) is an integral signaling molecule in biology with complex generation, translocation, and metabolism processes that are intertwined with cellular thiols. Differentiating the complex interplay between H2S and biological thiols, however, remains challenging due to the difficulty of monitoring H2S and thiol levels simultaneously in complex redox environments. As a step toward unraveling the complexities of H2S and thiols in sulfur redox homeostasis, we present a dual-fluorophore fragmentation strategy that allows for the ratiometric determination of relative H2S and cysteine (Cys) or homocysteine (Hcy) concentrations, two important metabolites in H2S biosynthesis. The key design principle is based on a nitrobenzofurazan-coumarin (NBD-Coum) construct, which fragments into spectroscopically differentiable products upon nucleophilic aromatic substitution with either H2S or Cys/Hcy. Measurement of the ratio of fluorescence intensities from coumarin and the NBD-Cys or NBD-Hcy adducts generates a sigmoidal response with a dynamic range of 3 orders of magnitude. The developed scaffold displays a rapid response (<1 min) and is selective for sulfhydryl-containing nucleophiles over other reactive sulfur, oxygen, and nitrogen species, including alcohol- and amine-functionalized amino acids, polyatomic anionic sulfur species, NO, and HNO. Additionally, NBD-Coum is demonstrated to differentiate and report on different oxidative stress stimuli in simulated sulfur pools containing H2S, Cys, and cystine.

Improving the distribution of Doxil® in the tumor matrix by depletion of tumor hyaluronan.

Liposomes improve the pharmacokinetics and safety of rapidly cleared drugs, but have not yet improved the clinical efficacy compared to the non-encapsulated drug. This inability to improve efficacy may be partially due to the non-uniform distribution of liposomes in solid tumors. The tumor extra-cellular matrix is a barrier to distribution and includes the high molecular weight glycosaminoglycan, hyaluronan (HA). Strategies to remove HA or block its synthesis may improve drug delivery into solid tumors. Orally administered methylumbelliferone (MU) is an inhibitor of HA synthesis, but it is limited by low potency and limited solubility. In this study, we encapsulate a water-soluble phosphorylated prodrug of MU (MU-P) in a liposome (L-MU-P). We demonstrate that L-MU-P is a more potent inhibitor of HA synthesis than oral MU in the 4T1 murine mammary carcinoma model using both a quantitative ELISA and histochemistry. We show that HA depletion improves the tumor distribution of liposomes computed using Mander's colocalization analysis of liposomes with the tumor vasculature. Hyaluronan depletion also increases the fraction of the tumor area positive for liposomes. This improved distribution extends the overall survival of mice treated with Doxil®.

A practical fluorometric assay method to measure lysosomal acid lipase activity in dried blood spots for the screening of cholesteryl ester storage disease and Wolman disease.

Fluorometric measurements of 4-methylumbelliferone (4-MU) are generally used to screen lysosomal storage diseases (LSDs) using dried blood spots (DBSs). However, in DBS, it is difficult to measure lysosomal acid lipase (LAL) activity due to the influence of other lipases in whole blood. Recently, Hamilton used a fluorometric enzyme assay with 4-MU derivatives to measure the LAL activity in DBS. This method requires mercury chloride as stopping reagent, and the fluorescence intensity of 4-MU was measured at an acidic pH. We report a revised method to measure the LAL activity without using toxic mercury chloride and to measure the fluorescence intensity of 4-MU at a basic pH. For this measurement, we established a more practical method that does not require mercury chloride. The LAL activity in DBS was measured in 51 normal controls, seven obligate carriers and seven patients with CESD. The average LAL activities ± SD in the DBS from the normal, obligate carriers and CESD patients were 0.68 ± 0.2 (range: 0.3-1.08), 0.21 ± 0.1 (range: 0.11-0.41) and 0.02 ± 0.02 (range: 0-0.06) nmol/punch/h, respectively. There was a significant difference between the normal and the CESD. Our method does not require toxic mercury chloride and is an appropriate revised enzyme assay using DBS for screening patients with CESD.

Elucidation of the binding mechanism of coumarin derivatives with human serum albumin.

Coumarin is a benzopyrone which is widely used as an anti-coagulant, anti-oxidant, anti-cancer and also to cure arthritis, herpes, asthma and inflammation. Here, we studied the binding of synthesized coumarin derivatives with human serum albumin (HSA) at physiological pH 7.2 by using fluorescence spectroscopy, circular dichroism spectroscopy, molecular docking and molecular dynamics simulation studies. By addition of coumarin derivatives to HSA the maximum fluorescence intensity was reduced due to quenching of intrinsic fluorescence upon binding of coumarin derivatives to HSA. The binding constant and free energy were found to be 1.957±0.01×10(5) M(-1), -7.175 Kcal M(-1) for coumarin derivative (CD) enamide; 0.837±0.01×10(5) M(-1), -6.685 Kcal M(-1) for coumarin derivative (CD) enoate, and 0.606±0.01×10(5) M(-1), -6.49 Kcal M(-1) for coumarin derivative methylprop (CDM) enamide. The CD spectroscopy showed that the protein secondary structure was partially unfolded upon binding of coumarin derivatives. Further, the molecular docking studies showed that coumarin derivatives were binding to HSA at sub-domain IB with the hydrophobic interactions and also with hydrogen bond interactions. Additionally, the molecular dynamics simulations studies contributed in understanding the stability of protein-drug complex system in the aqueous solution and the conformational changes in HSA upon binding of coumarin derivatives. This study will provide insights into designing of the new inspired coumarin derivatives as therapeutic agents against many life threatening diseases.

Photoresponsive coumarin-tethered multifunctional magnetic nanoparticles for release of anticancer drug.

Recently, photoresponsive nanoparticles have received significant attention because of their ability to provide spatial and temporal control over the drug release. In the present work, we report for the first time photoresponsive multifunctional magnetic nanoparticles (MNPs) fabricated using coumarin-based phototrigger and Fe/Si MNPs for controlled delivery of anticancer drug chlorambucil. Further, newly fabricated photoresponsive multifunctional MNPs were also explored for cell luminescence imaging. In vitro biological studies revealed that coumarin tethered Fe/Si MNPs of ~9 nm size efficiently delivered the anticancer drug chlorambucil into cancer cells and thereby improving the drug action to kill the cancer cells upon irradiation. Such multifunctional MNPs with strong fluorescence, good biocompatibility and efficient photocontrolled drug release ability will be of great benefit in the construction of light-activated multifunctional nano drug delivery systems.

FAK and HAS inhibition synergistically decrease colon cancer cell viability and affect expression of critical genes.

Focal adhesion kinase (FAK), hyaluronan (HA), and hyaluronan synthase-3 (HAS3) have been implicated in cancer growth and progression. FAK inhibition with the small molecule inhibitor Y15 decreases colon cancer cell growth in vitro and in vivo. HAS3 inhibition in colon cancer cells decreases FAK expression and activation, and exogenous HA increases FAK activation. We sought to determine the genes affected by HAS and FAK inhibition and hypothesized that dual inhibition would synergistically inhibit viability. Y15 (FAK inhibitor) and the HAS inhibitor 4-methylumbelliferone (4-MU) decreased viability in a dose dependent manner; viability was further inhibited by treatment with Y15 and 4-MU in colon cancer cells. HAS inhibited cells treated with 2 µM of Y15 showed significantly decreased viability compared to HAS scrambled cells treated with the same dose (p < 0.05) demonstrating synergistic inhibition of viability with dual FAK/HAS inhibition. Microarray analysis showed more than 2-fold up- or down-regulation of 121 genes by HAS inhibition, and 696 genes by FAK inhibition (p < 0.05) and revealed 29 common genes affected by both signaling. Among the genes affected by FAK or HAS3 inhibition were genes, playing role in apoptosis, cell cycle regulation, adhesion, transcription, heatshock and WNT pathways. Thus, FAK or HAS inhibition decreases SW620 viability and affects several similar genes, which are involved in the regulation of tumor survival. Dual inhibition of FAK and HAS3 decreases viability to a greater degree than with either agent alone, and suggests that synergistic inhibition of colon cancer cell growth can result from affecting similar genetic pathways.

Comparative study of amplification systems in immunoenzyme assays for the diagnosis of American tegumentary leishmaniasis.

We compared the accuracy and reliability of three amplification systems for enzyme immunoassays in the detection of specific IgG antibodies for the diagnosis of cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis in patients from an endemic area in Rio de Janeiro, Brazil. Partially soluble antigens obtained from the promastigote forms of L. (V.) braziliensis were used. For development of the reaction, two chromogens, 1,2-orthophenylenediamine (OPD) and 3,3',5,5'-tetramethylbenzidine (TMB), and a fluorogen, 4-methylumbelliferylphosphate (MUP), were tested. The performance of each system was compared using the following parameters: accuracy, intraclass correlation coefficient (ICC), and area under the receiver operating characteristic (ROC) curve. Sensitivity was the same (97.4%) for all systems. The reliability was excellent (ICC = 98.6, 98.7, and 99.1%) and specificity was 93.7, 95.8, and 97.4% for OPD, MUP, and TMB, respectively, showing no statistical significance. Despite the absence of differences in the performance of the three systems, the use of TMB is suggested because of its operational advantages, such as low cost compared with fluorogens, easy manipulation, greater stability, and lower toxicity.

Potentiometric enzyme immunoassay using miniaturized anion-selective electrodes for detection.

An enzyme-linked immunosorbent assay (ELISA) for prostate specific antigen (PSA) detection in human serum was developed based on the potentiometric detection of 6,8-difluoro-4-methylumbelliferone (DiFMU). The assays were carried out in anti-human PSA capture antibody modified microtiter plates (150 microL volume). After incubation in the PSA-containing serum samples, beta-galactosidase-labeled PSA tracer antibody was added. The beta-galactosidase label catalyzed the hydrolysis of 6,8-difluoro-4-methylumbelliferyl-beta-D-galactopyranoside (DiFMUG) and the resulting DiFMU(-) anion was detected by potentiometric microelectrodes with anion-exchanger membrane. The selectivity of the anion-exchanger electrode is governed by the lipophilicity of the anions in the sample. Since DiFMU(-) is much more lipophilic (log P = 1.83) than any of the inorganic anions normally present in the working buffers and occurs in its anionic form at the physiological pH (pK(a) = 4.19), it was chosen as the species to be detected. The potentiometric ELISA-based method detects PSA in serum with a linear concentration range of 0.1-50 ng/mL. These results confirm the applicability of potentiometric detection in diagnostic PSA assays. Owing to simple methodology and low cost, potentiometric immunoassays seem to offer a feasible alternative to the development of in vitro diagnostic platforms.