Intravesical instillation of c-MYC inhibitor KSI-3716 suppresses orthotopic bladder tumor growth.

PURPOSE: c-MYC is a promising target for cancer therapy but its use is restricted by unwanted, devastating side effects. We explored whether intravesical instillation of the c-MYC inhibitor KSI-3716 could suppress tumor growth in murine orthotopic bladder xenografts. MATERIALS AND METHODS: The small molecule KSI-3716, which blocks c-MYC/MAX binding to target gene promoters, was used as an intravesical chemotherapy agent. KSI-3716 action was assessed by electrophoretic mobility shift assay, chromatin immunoprecipitation, transcription reporter assay and quantitative reverse transcriptase-polymerase chain reaction. Inhibition of cell proliferation and its mechanism was monitored by cell cytotoxicity assay, EdU incorporation assay and flow cytometry. The in vivo efficacy of KSI-3716 was examined by noninvasive luminescence imaging and histological analysis after intravesical instillation of KSI-3716 in murine orthotopic bladder xenografts. RESULTS: KSI-3716 blocked c-MYC/MAX from forming a complex with target gene promoters. c-MYC mediated transcriptional activity was inhibited by KSI-3716 at concentrations as low as 1 µM. The expression of c-MYC target genes, such as cyclin D2, CDK4 and hTERT, was markedly decreased. KSI-3716 exerted cytotoxic effects on bladder cancer cells by inducing cell cycle arrest and apoptosis. Intravesical instillation of KSI-3716 at a dose of 5 mg/kg significantly suppressed tumor growth with minimal systemic toxicity. CONCLUSIONS: The c-MYC inhibitor KSI-3716 could be developed as an effective intravesical chemotherapy agent for bladder cancer.

Assessing and Grouping Chemicals Applying Partial Ordering Alkyl Anilines as an Illustrative Example.

AIM AND OBJECTIVE: In chemistry, there is a long tradition in classification. Usually, methods are adopted from the wide field of cluster analysis. The present study focusses on the application of partial ordering methodology for the classification of 21 alkyl substituted anilines. MATERIALS AND METHODS: The analyses are based on the concepts from partial order methodology and cluster analyses. Here, with the example of 21 alkyl anilines, we show that concepts taken out from the mathematical discipline of partially ordered sets may be applied for classification. The chemical compounds are described by a multi-indicator system. For the present study four indicators, mainly taken from the field of environmental chemistry were applied and a graph of the ordering (Hasse diagram) was constructed. RESULTS: A Hasse diagram is an acyclic, transitively reduced, triangle-free graph that may have several graph-theoretical components. The Hasse diagram has been directed from a structural chemical point of view. Two cluster analysis methods are applied (K-means and a hierarchical cluster method) and compared with the results from the Hasse diagram. In both cases, the partitioning of the set of 21 compounds by the component structure of the Hasse diagram appears to be better interpretable. CONCLUSION: It is shown that the partial ordering approach indeed can be used for classification in the present case. However, it must be clearly stated that a guarantee for meaningful results, in general, cannot be given. For that, further theoretical work is needed.

Antioxidant effcacy of unripe banana (Musa acuminata Colla) peel extracts in sunflower oil during accelerated storage.

BACKGROUND: Sunflower oil is prone to oxidation during storage time, leading to production of toxic compounds that might affect human health. Synthetic antioxidants are used to prevent lipid oxidation. Spreading interest in the replacement of synthetic food antioxidants by natural ones has fostered research on fruit and vegetables for new antioxidants. METHODS: In this study, the efficacy of unripe banana peel extracts (100, 200 and 300 ppm)  in stabilizing sunflower oil was tested under accelerated storage (65°C) for a period of 24 days. BHA and α-tocopherol served as comparative standards besides the control. Established parameters such as peroxide value (PV), iodine value (IV), p-anisidine value (p-AnV), total oxidation value (TOTOX), thiobarbituric acid reactive substances (TBARS) and free fatty acid (FFA) content were used to assess the extent of oil deterioration. RESULTS: After 24 days storage at 65°C, sunflower oil containing 200 and 300 ppm extract of unripe banana peel showed significantly lower PV and TOTOX compared to BHA and α-tocopherol. TBARS, p-AnV and FFA values of sunflower oil containing 200 and 300 ppm of unripe banana peel extract exhibited comparable inhibitory effects with BHA. Unripe banana peel extract at 200 and 300 ppm demonstrated inhibitory effect against both primary and secondary oxidation up to 24 days under accelerated storage conditions. CONCLUSIONS: Unripe banana peel extract may be used as a potential source of natural antioxidants in the application of food industry to suppress lipid oxidation.

Inhibition of smooth muscle cell proliferation in vitro by leflunomide, a new immunosuppressant, is antagonized by uridine.

Chronic rejection in the form of graft vascular disease (GVD) continues to plague clinical transplantation of vascularized organs. The histopathology of this lesion is characterized by neointimal hyperplasia, smooth muscle cell proliferation, and obliterative arteriopathy. Due to the lack of effective medical therapy for preventing or reversing these chronic vascular changes, retransplantation remains the final resort in treatment. Some of the newer immunosuppressive agents, including the new isoxazole derivative leflunomide (LFM), have shown efficacy in preventing chronic rejection in animal models of transplantation. Although its mechanism of action remains incompletely elucidated, previous work using lymphocytes in vitro suggests that the drug might act as a tyrosine kinase inhibitor, an inhibitor of de novo pyrimidine biosynthesis, or both. In order to elucidate whether the efficacy of LFM in vivo is attributable not only to anti-proliferative effects on the recipient immune system but also to direct effects on mesenchymal cells in the donor organ, we examined the effects of LFM on a transformed 9E11G murine smooth muscle cell (M-SMC) line in vitro. We demonstrate here that the active metabolite of LFM, A77 1726, dose-dependently inhibits the constitutive and growth-factor stimulated proliferation of M-SMC in vitro. Furthermore, the anti-proliferative effect of the drug can be reversed by the addition of uridine to the culture medium. These results suggest that inhibition of uridine biosynthesis appears to be a mechanism by which LFM exerts anti-proliferative effects on both lymphocytes and smooth muscle cells, and this dual action may be responsible for its efficacy in preventing GVD in vivo.

Mechanism of the antiproliferative action of leflunomide. A77 1726, the active metabolite of leflunomide, does not block T-cell receptor-mediated signal transduction but its antiproliferative effects are antagonized by pyrimidine nucleosides.

BACKGROUND: Leflunomide, a novel immunosuppressive drug, prolongs experimental graft survival effectively and has been well tolerated in patients with rheumatoid arthritis. A77 1726, the active metabolite of leflunomide, inhibits lymphocyte proliferation in vitro. This study was conducted in Jurkat T cells to investigate the effects of A77 1726 on signal transduction pathways initiated by ligands of the T-cell receptor CD3 complex and to evaluate the effects of A77 1726 on nucleotide biosynthesis. METHODS: Tritiated thymidine incorporation and cell counts quantitated cell proliferation. Spectrofluorescence of Indo/AM dye measured intracellular Ca2+ mobilization. A luciferase assay quantitated interleukin-2 gene promoter activity in stimulated cells transfected with an interleukin-2 promoter-luciferase gene construct. Pyrimidine and purine nucleosides were used to assess antagonism of the antiproliferative activity of A77 1726. RESULTS: (1) A77 1726 dose-dependently inhibited the proliferation of Jurkat T cells (inhibitory concentration of 50% = 6 mumol/L); (2) A77 1726 did not decrease mobilization of intracellular Ca2+ stimulated by phytohemagglutinin or anti-CD3 monoclonal antibody; (3) A77 1726 did not inhibit interleukin-2 gene promoter activity in cells stimulated with ionomycin plus phorbol myristate acetate; (4) inhibition of cell proliferation by A77 1726 was antagonized by addition of uridine, cytidine, or 2(+)-deoxycytidine; (5) addition of uridine 24 hours after treatment with A77 1726 antagonized inhibition of proliferation; (6) A77 1726 was not antagonized by 2'-deoxyuridine, thymidine, adenosine, or guanosine. CONCLUSIONS: (1) A77 1726 inhibited Jurkat T-cell proliferation without inhibiting T-cell receptor-mediated signal transduction events, including tyrosine kinase-dependent intracellular Ca2+ mobilization and activation of the interleukin-2 gene promoter; (2) the antiproliferative effects of A77 1726 on Jurkat T cells are primarily due to interruption of de novo pyrimidine nucleotide biosynthesis. These data provide evidence for a novel in vitro mechanism of the antiproliferative action of this immunosuppressant.

Dietary selenium and aniline-induced methemoglobinemia in rats.

Depletion of selenium from rats for 8 weeks decreased blood glutathione peroxidase activity to 5.7% of that in selenium-supplemented (0.5 ppm selenium as Na2SeO3) rats. Aniline (60 mg/kg, i.p.) resulted in no significant difference in methemoglobin and blood reduced glutathione (GSH) levels between Se-deficient and Se-supplemented rats. A lowered aniline dose (36 mg/kg, i.p.) also resulted in no difference in methemoglobin levels. The selenium-deficient rat was able to reduce methemoglobin induced by aniline as efficiently as the selenium-sufficient rat.

Effect of Japanese seaweed (Laminaria angustata) extracts on the mutagenicity of 7,12-dimethylbenz[a]anthracene, a breast carcinogen, and of 3,2'-dimethyl-4-aminobiphenyl, a colon and breast carcinogen.

Animal model studies suggest that diets containing Laminaria angustata, a brown seaweed commonly eaten in Japan, inhibit breast carcinogenesis. In order to identify the compound(s) in the seaweed responsible for tumor-inhibiting activity, we used Ames/mammalian microsome assay system to determine the antimutagenic (or anticarcinogenic) effect of various solvents and water extracts of Laminaria angustata. The antimutagenic effects of acetone, ether, chloroform, chloroform + methanol, hot water and cold water extracts on the mutagenicity induced by 7,12-dimethylbenz[a]anthracene (DMBA), a breast carcinogen, and 3,2'-dimethyl-4-aminobiphenyl (DMAB), a colon and breast carcinogen, was studied using the Salmonella typhimurium strains TA98 and TA100. All extracts were nonmutagenic in both bacterial tester strains. The addition of 10-100 mg solvent extracts of seaweed/plate greatly inhibited DMAB-induced mutagenicity in both tester strains (80-96% inhibition) and DMBA-induced mutagenicity in TA100 (about 82%), whereas hot and cold water extracts produced a moderate inhibition in a dose-related manner in both strains.

Effect of micronutrients, antioxidants and related compounds on the mutagenicity of 3,2'-dimethyl-4-aminobiphenyl, a colon and breast carcinogen.

The possible antimutagenic effects of butylated hydroxytoluene (BHT), ethoxyquin, disulfiram, indole-3-carbinol, indole-3-acetonitrile, sodium selenite and alpha-tocopherol on 3,2'-dimethyl-4-aminobiphenyl-induced mutagenicity were studied using the Ames Salmonella/mammalian microsome assay system with strains TA98 and TA100. All seven compounds were nonmutagenic in both bacterial tester strains. The addition of or 50-250 micrograms of sodium selenite, 5-50 mg of alpha-tocopherol or 50-250 microgram of BHT per plate inhibited DMAB-induced mutagenicity in TA98 and/or TA100. Ethoxyquin, disulfiram and indole-3-carbinol increased DMAB-induced mutagenicity in TA100, whereas these compounds had little or no effect in TA98-3-acetonitrile had very little effect in either strain.

[Metabolic activation and the mutagenic properties of carcinogenic N-nitramines in a liquid incubation test]. / Metabolicheskaia aktivatsiia i mutagennye svoistva kantserogennykh N-nitraminov v zhidkostno-inkubatsionnoi probe.

The study established the mutagenicity of carcinogenic dimethylnitramine and nitromorpholine in a liquid-incubation system using Salmonella typhimurium TA 100 and TA 1530 as indicator, in the presence of hepatic postmitochondrial supernatant obtained from 1254 aroclor-treated rats, oxygen and NADP+--generating system. Synthesis of mutagenic metabolites of nitramines was in correlation with the level of N-dimethylase activity. Ascorbic acid and disulfiram efficiently inhibited intramune-induced mutagenesis. Metabolic activation of nitramines involves (a) conversion of nitramines to nitrosoamines due to reduction of a nitro group, (b) hydroxylation by means of multi-function oxydases, and (c) heterolysis resulting in the formation of an end metabolite which is actually responsible for carcinogenicity and mutagenicity.

Role of the 5-HT2A receptor in the locomotor hyperactivity produced by phenylalkylamine hallucinogens in mice.

The 5-HT2A receptor mediates the effects of serotonergic hallucinogens and may play a role in the pathophysiology of certain psychiatric disorders, including schizophrenia. Given these findings, there is a need for animal models to assess the behavioral effects of 5-HT2A receptor activation. Our previous studies demonstrated that the phenylalkylamine hallucinogen and 5-HT2A/2C agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) produces dose-dependent effects on locomotor activity in C57BL/6J mice, increasing activity at low to moderate doses and reducing activity at high doses. DOI did not increase locomotor activity in 5-HT2A knockout mice, indicating the effect is a consequence of 5-HT2A receptor activation. Here, we tested a series of phenylalkylamine hallucinogens in C57BL/6J mice using the Behavioral Pattern Monitor (BPM) to determine whether these compounds increase locomotor activity by activating the 5-HT2A receptor. Low doses of mescaline, 2,5-dimethoxy-4-ethylamphetamine (DOET), 2,5-dimethoxy-4-propylamphetamine (DOPR), 2,4,5-trimethoxyamphetamine (TMA-2), and the conformationally restricted phenethylamine (4-bromo-3,6-dimethoxybenzocyclobuten-1-yl)methylamine (TCB-2) increased locomotor activity. By contrast, the non-hallucinogenic phenylalkylamine 2,5-dimethoxy-4-tert-butylamphetamine (DOTB) did not alter locomotor activity at any dose tested (0.1-10 mg/kg i.p.). The selective 5-HT2A antagonist M100907 blocked the locomotor hyperactivity induced by mescaline and TCB-2. Similarly, mescaline and TCB-2 did not increase locomotor activity in 5-HT2A knockout mice. These results confirm that phenylalkylamine hallucinogens increase locomotor activity in mice and demonstrate that this effect is mediated by 5-HT2A receptor activation. Thus, locomotor hyperactivity in mice can be used to assess phenylalkylamines for 5-HT2A agonist activity and hallucinogen-like behavioral effects. These studies provide additional support for the link between 5-HT2A activation and hallucinogenesis.

Anxiolytic effects of the melatonin MT(2) receptor partial agonist UCM765: comparison with melatonin and diazepam.

Melatonin (MLT) is a neurohormone known to be involved in the regulation of anxiety. Most of the physiological actions of MLT in the brain are mediated by two high-affinity G-protein-coupled receptors, denoted MT(1) and MT(2). However, the particular role of these receptors in anxiety remains to be defined. Here we used a novel MT(2)-selective partial agonist, UCM765 to evaluate the involvement of MT(2) receptors in anxiety. Adult male rats were acutely injected with UCM765 (5-10-20mg/kg), MLT (20mg/kg) or diazepam (DZ, 1mg/kg). Anxiety-related behaviors were assessed in the elevated plus maze test (EPMT), novelty suppressed feeding test (NSFT) and open field test (OFT). UCM765 at the dose of 10mg/kg showed anxiolytic-like properties by increasing the time spent in the open arm of the EPMT, and by reducing the latency to eat in a novel environment in the NSFT. In the EPMT, animals treated with UCM765 (10mg/kg) or MLT (20mg/kg) spent more time in the open arms compared to vehicle-treated animals, but to a lesser extent compared to DZ (1mg/kg). In the NSFT, all treatments similarly decreased the latency to eat in a novel environment compared to vehicle. UCM765 and MLT did not affect the total time and the number of entries into the central area of the OFT, but unlike DZ, did not impair locomotion. The anxiolytic effects of UCM765 and MLT in the EPMT and the NSFT were blocked using a pre-treatment with the MT(1)/MT(2) antagonist luzindole (10mg/kg) or the MT(2) antagonist 4P-PDOT (10mg/kg). These results demonstrated, for the first time, the anxiolytic properties of UCM765 and suggest that MT(2)-receptors may be considered a novel target for the development of anxiolytic drugs.

Effect of butylated hydroxytoluene and butylated hydroxyanisole on the mutagenicity of 3,2'-dimethyl-4-aminobiphenyl.

This study was undertaken to investigate the possible antimutagenic effects of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on 3,2'-dimethyl-4-aminobiphenyl (DMAB)-induced mutagenicity, using the Ames Salmonella/mammalian microsome system. The addition of 100-250 micrograms of BHT or 25-500 micrograms of BHA/plate was found to inhibit DMAB-induced mutagenicity in Salmonella strains TA 98 and TA 100. In TA 100, the mutagenicity was further inhibited with the addition of S9 prepared from the livers of rats fed a 0.6% BHT diet as compared to S9 from the animals fed a diet containing no BHT.

NPS R-568: a type II calcimimetic compound that acts on parathyroid cell calcium receptor of rats to reduce plasma levels of parathyroid hormone and calcium.

Calcimimetics like N-(3-[2-chlorophenyl]propyl)-(R)-alpha-methyl-3-methoxybenzylamine (NPS R-568) potentiate the effects of extracellular Ca(2+) on parathyroid Ca(2+) receptors and inhibit parathyroid hormone (PTH) secretion in vitro. When administered by gavage to normal rats in this study, NPS R-568 caused a rapid, dose-dependent (ED(50), 1.1 +/- 0.7 mg/kg) decrease in PTH levels that was paralleled by a subsequent decrease in plasma Ca(2+) (ED(50), 10.4 +/- 3.7 mg/kg). At higher doses (>/=3.3 mg/kg), PTH was reduced to a minimum level within 15 min, the duration of which was dose dependent. With doses of 10 to 100 mg/kg, the hypocalcemia was rapid in onset (<30 min) and, at 33 to 100 mg/kg, persisted for >24 h. Neither the magnitude nor the kinetics of the hypocalcemic response was affected by total nephrectomy, demonstrating that NPS R-568 does not induce hypocalcemia by acting on renal Ca(2+) receptors to increase Ca(2+) excretion. In contrast, parathyroidectomy (intact thyroid) abolished the hypocalcemic response to NPS R-568, regardless of whether the rats were hypocalcemic or rendered acutely normo- or hypercalcemic by calcium infusion before dosing. These data show that the parathyroid Ca(2+) receptor can be selectively activated in vivo with a small organic compound to decrease plasma levels of PTH and Ca(2+) and thus define the mechanism of action of this compound in vivo. Moreover, the data add pharmacological support to the view that the Ca(2+) receptor is the primary molecular entity regulating systemic Ca(2+) homeostasis.

Breakage and binding of DNA by reaction products of hypochlorous acid with aniline, 1-naphthylamine, or 1-naphthol.

Hypochlorous acid (HOCl) is a chemically reactive oxidant and a potent microbicidal agent that is synthesized in phagosomes of inflammatory neutrophils and released into extracellular spaces. Besides reducing pathogenicity by reacting with phagocytized infectious agents, HOCl may damage tissues and yield toxic products upon reaction with various other molecules, including xenobiotics. As model xenobiotics, the substituted aryl compounds aniline, 1-naphthylamine, and 1-naphthol (1-NOH) were investigated herein for their potential to react with HOCl and the transformed into genotoxic products. The compounds were first exposed to HOCl (25-150 microM) in phosphate buffer and afterward used to treat human fibroblasts or purified DNA. DNA single-strand breaks in cells and the binding of HOCl-reacted 1-[14C]NOH to purified DNA were assessed by DNA alkaline elution and scintillation spectrometry, respectively. It was found that neither HOCl nor compounds alone could break cellular DNA. But HOCl-reacted compounds produced up to 400 rad equivalents of DNA breaks. HOCl reaction products of aniline and the model bicyclic aryl compounds differed in their DNA-breaking characteristics. HOCl-reacted 1-[14C]NOH was stable and bound to DNA at up to 124 pmol/mg DNA. Sodium thiosulfate, glutathione, and taurine inhibited the transformation reactions; but only the former two blocked binding of HOCl-reacted 1-NOH to DNA. Ultraviolet spectra showed that HOCl reacted rapidly (less than 1 min) and equally well with 1-NOH at pH 7.2 or at an intraphagosomal pH of 5.0. Reaction concentrations of HOCl in this study were 2- to 11-fold lower than levels generated in vitro by stimulated neutrophils. These results show that certain aryl compounds can react readily with approximated physiological levels of HOCl (-OCl) to form relatively long-lived products that bind DNA and are genotoxic to human cells.

MRP2, a human conjugate export pump, is present and transports fluo 3 into apical vacuoles of Hep G2 cells.

The multidrug resistance protein 2 (MRP2, symbol ABCC2) transports anionic conjugates and certain amphiphilic anions across the apical membrane of polarized cells. Human hepatoma Hep G2 cells retain hepatic polarity and form apical vacuoles into which cholephilic substances are secreted. Immunofluorescence microscopy showed that human MRP2 was expressed in the apical vacuole membrane of polarized Hep G2 cells, whereas the isoform MRP3 was localized to the lateral membrane. Expression of both MRP2 and MRP3 was confirmed by immunoblotting and reverse transcription PCR. Fluo 3 secretion into the apical vacuoles was inhibited by cyclosporin A but not by selective inhibitors of multidrug resistance 1 P-glycoprotein. In addition, carboxyfluorescein, rhodamine 123, and the fluorescent bile salt derivatives ursodeoxycholyl-(Nepsilon-nitrobenzoxadiazolyl)-lysine and cholylglycylamido-fluorescein were secreted into the apical vacuoles; the latter two probably via the bile salt export pump. We conclude that MRP2 mediates fluo 3 secretion into the apical vacuoles of polarized Hep G2 cells. Thus the function of human MRP2 and the action of inhibitors can be analyzed by the secretion of fluorescent anions such as fluo 3.