Although the etiology of inflammatory bowel disease is still uncertain, increasing evidence indicates that the excessive activation of NLRP3 inflammasome plays a major role. Norisoboldine (NOR), an alkaloid isolated from Radix Linderae, has previously been demonstrated to inhibit inflammation and IL-1β production. The present study was to examine the effect of NOR on colitis and the underlying mechanism related to NLRP3 inflammasome activation. Our results showed that NOR alleviated colitis symptom in mice induced by 2, 4, 6-trinitrobenzene sulfonic acid (TNBS). Moreover, it significantly reduced expressions of cleaved IL-1β, NLRP3 and cleaved Caspase-1 but not ASC in colons of mice. In THP-1 cells, NOR suppressed the expressions of NLRP3, cleaved Caspase-1 and cleaved IL-1β but not ASC induced by lipopolysaccharide (LPS) and adenosine triphosphate (ATP). Furthermore, NOR could activate aryl hydrocarbon receptor (AhR) in THP-1 cells, inducing CYP1A1 mRNA expression, and promoting dissociation of AhR/HSP90 complexes, association of AhR and ARNT, AhR nuclear translocation, XRE reporter activity and binding activity of AhR/ARNT/XRE. Both siAhR and α-naphthoflavone (α-NF) markedly diminished the inhibition of NOR on NLRP3 inflammasome activation. In addition, NOR elevated Nrf2 level and reduced ROS level in LPS- and ATP-stimulated THP-1 cells, which was reversed by either siAhR or α-NF treatment. Finally, correlations between activation of AhR and attenuation of colitis, inhibition of NLRP3 inflammasome activation and up-regulation of Nrf2 level in colons were validated in mice with TNBS-induced colitis. Taken together, NOR ameliorated TNBS-induced colitis in mice through inhibiting NLRP3 inflammasome activation via regulating AhR/Nrf2/ROS signaling pathway.
Alkaloids ; administration & dosage ; Animals ; Colitis ; chemically induced ; drug therapy ; genetics ; immunology ; Drugs, Chinese Herbal ; administration & dosage ; Humans ; Inflammasomes ; drug effects ; immunology ; Interleukin-1beta ; genetics ; immunology ; Lindera ; chemistry ; Male ; Mice ; Mice, Inbred BALB C ; NF-kappa B ; genetics ; immunology ; Receptors, Aryl Hydrocarbon ; agonists ; genetics ; metabolism ; Trinitrobenzenesulfonic Acid ; adverse effects

Dioscin has a wide range of biological effects and broad application prospects. However the studies concerning the toxicology and mechanism of dioscin is small. This article is to study the hepatotoxicity of dioscin and the effect of dioscin treatment on expression of aryl hydrocarbon receptor (AhR) mRNA and CYP1A mRNA and protein in HepG2 cells in vitro. Dioscin 0.5-32 µmol · L(-1) exposed to HepG2 cells for 12 h, cell viability was examined by CCK-8 assay and the release rate of lactate dehydrogenase (LDH) was to evaluate cell membrane damage. HepG2 cells morphologic changes were quantified by inverted Microscope, and the effect on production of reactive oxygen species (ROS) was detected by flow cytometry. The mRNA expression of CYP1A and AhR was evaluated by RT-RCR. The protein expression of CYP1A1 was detected by western blot. The cell viability was significantly inhibited after HepG2 cells were exposed to dioscin 0.5-32 µmol · L(-1). Compared with the control, the LDH release rate and ROS were significantly increased. The expression of CYPlA and AhR mRNA was increased. The expression of CYP1Al protein was increased after dioscin treatment, and resveratrol, an AhR antagonist, could downregulate the expression of CYP1A1. It follows that large doses dioscin has potential hepatotoxicity. The possible mechanism may be dioscin can active aryl hydrocarbon receptor (AhR) and induce the expression of CYP1A.
Cell Survival ; drug effects ; Chemical and Drug Induced Liver Injury ; etiology ; Cytochrome P-450 CYP1A1 ; genetics ; Diosgenin ; analogs & derivatives ; toxicity ; Hep G2 Cells ; Humans ; L-Lactate Dehydrogenase ; secretion ; RNA, Messenger ; analysis ; Reactive Oxygen Species ; metabolism ; Receptors, Aryl Hydrocarbon ; genetics

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce drug transporter genes such as the ATP-binding cassette G member 2 (ABCG2), which contributes to multidrug resistance. We investigated the effect of TCDD pretreatment on drug transporters induction from cancer cells of various origins. Cell viabilities after treatment of cisplatin were measured to evaluate acquiring cisplatin resistance by TCDD. Acquring cisplatin resistance was found only in cisplatin senstivie cancer cells including gastric SNU601, colon LS180, brain CRT-MG and lymphoma Jurkat cells which showed a significant increase in cell viability after combined treatment with TCDD and cisplatin. High increase of ABCG2 gene expression was found in SNU601 and LS180 cells with a mild increase in the expression of the ABCC3, ABCC5,and SLC29A2 genes in SNU601 cells, and of major vault protein (MVP) in LS180 cells. The AhR inhibitor kaempferol suppressed the upregulation of ABCG2 expression and reversed the TCDD-induced increase in cell viability in LS180 cells. However, in CRT-MG cells, other transporter genes including ABCC1, ABCC5, ABCA3, ABCA2, ABCB4, ABCG1, and SLC29A1 were up-regulated. These findings suggested the acquiring cisplatin resistance by TCDD associated with cancer cell-type-specific induction of drug transporters.
ATP-Binding Cassette Transporters/genetics/*metabolism ; Cell Line, Tumor ; Cell Survival/drug effects ; Cisplatin/*pharmacology ; Drug Resistance, Neoplasm/drug effects ; Equilibrative-Nucleoside Transporter 2/genetics/metabolism ; Humans ; Jurkat Cells ; K562 Cells ; Kaempferols/pharmacology ; Multidrug Resistance-Associated Proteins/genetics/metabolism ; Neoplasm Proteins/genetics/*metabolism ; RNA, Messenger/metabolism ; Receptors, Aryl Hydrocarbon/metabolism ; Tetrachlorodibenzodioxin/*pharmacology ; Up-Regulation/*drug effects ; Vault Ribonucleoprotein Particles/genetics/metabolism

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce drug transporter genes such as the ATP-binding cassette G member 2 (ABCG2), which contributes to multidrug resistance. We investigated the effect of TCDD pretreatment on drug transporters induction from cancer cells of various origins. Cell viabilities after treatment of cisplatin were measured to evaluate acquiring cisplatin resistance by TCDD. Acquring cisplatin resistance was found only in cisplatin senstivie cancer cells including gastric SNU601, colon LS180, brain CRT-MG and lymphoma Jurkat cells which showed a significant increase in cell viability after combined treatment with TCDD and cisplatin. High increase of ABCG2 gene expression was found in SNU601 and LS180 cells with a mild increase in the expression of the ABCC3, ABCC5,and SLC29A2 genes in SNU601 cells, and of major vault protein (MVP) in LS180 cells. The AhR inhibitor kaempferol suppressed the upregulation of ABCG2 expression and reversed the TCDD-induced increase in cell viability in LS180 cells. However, in CRT-MG cells, other transporter genes including ABCC1, ABCC5, ABCA3, ABCA2, ABCB4, ABCG1, and SLC29A1 were up-regulated. These findings suggested the acquiring cisplatin resistance by TCDD associated with cancer cell-type-specific induction of drug transporters.
ATP-Binding Cassette Transporters/genetics/*metabolism ; Cell Line, Tumor ; Cell Survival/drug effects ; Cisplatin/*pharmacology ; Drug Resistance, Neoplasm/drug effects ; Equilibrative-Nucleoside Transporter 2/genetics/metabolism ; Humans ; Jurkat Cells ; K562 Cells ; Kaempferols/pharmacology ; Multidrug Resistance-Associated Proteins/genetics/metabolism ; Neoplasm Proteins/genetics/*metabolism ; RNA, Messenger/metabolism ; Receptors, Aryl Hydrocarbon/metabolism ; Tetrachlorodibenzodioxin/*pharmacology ; Up-Regulation/*drug effects ; Vault Ribonucleoprotein Particles/genetics/metabolism

This paper is to report the development of a high-throughput in vitro system to screen hPXR/CAR mediated CYP2B6 drug inducers, and the application of it into the quick determination of induction activity toward CYP2B6 by various commonly used traditional Chinese medicines (TCMs) extract. Dual reporter gene assays were performed. The hPXR/CAR expression vectors and the reporter vector pGL3-CYP2B6-Luc involved in the distal and proximal promoters of CYP2B6 were co-transfected into HepG2 cells. Relative luciferase activities in cell lysate were analyzed after 48 h treatment of blank vehicle or drugs to determine the induction activity toward CYP2B6 by various commonly used TCMs extract. The positive hPXR/hCAR activators rifampicin and CITCO were applied to make sure that the reporter gene model was successfully established. Then 5 kinds of commonly used TCM extracts and 1 herbal compound were successfully investigated, some were found to activate hPXR or hCAR and therefore have the potential to induce CYP2B6 enzyme. This is the first domestic article to report the hCAR3-mediated CYP2B6 induction model and the establishment of a reporter gene system for hPXR/CAR-mediated CYP2B6 induction can be an effective and systemic in vitro method to investigate the drug inducers of CYP2B6 and to explain the mechanism involved.
Aryl Hydrocarbon Hydroxylases ; genetics ; metabolism ; Cytochrome P-450 CYP2B6 ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Genes, Reporter ; Genetic Vectors ; Hep G2 Cells ; High-Throughput Screening Assays ; Humans ; Luciferases ; genetics ; metabolism ; Oximes ; pharmacology ; Plants, Medicinal ; chemistry ; Plasmids ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Receptors, Steroid ; genetics ; metabolism ; Rifampin ; pharmacology ; Thiazoles ; pharmacology ; Transfection

OBJECTIVEThe present paper aims to investigate the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and N-nitrosodiethylamine (DEN) on tumorigenesis and its potential mechanism.

METHODSThe potentials of TCDD and DEN in separation or in combination to induce malignant transformation were tested in Balb/c 3T3 cells by using a cell transformation assay method. The possible mechanism of observed effects was studied further by adding α-naphthoflavone (α-NF), a competitive binding agent of TCDD, to the Aryl hydrocarbon receptor (AhR) pathway. The mRNA expressions of Cyp1a1 and Cyp2a5 gene in Balb/c 3T3 cells treated by DEN and TCDD in separation or in combination with or without presence of α-NF were measured with fluorescence quantification RT-PCR technique.

RESULTSThe cell transformation frequency (TF) was significantly higher in case of induction with TCDD in combination with DEN, as compared to that with either TCDD or DEN alone. These effects were not inhibited via α-NF. The mRNA expression levels of both Cyp1a1 and Cyp2a5 were enhanced by TCDD treatment alone, but this inducible effect was blocked in cells treated by TCDD and DEN in combination.

CONCLUSIONTCDD and DEN had a significant synergistic effect on tumorigenesis when they were used in combination. AhR pathway may not be the key mechanism of this synergistic effect. Thus, it is necessary to further test the potential mechanism involved in cancer development.

3T3 Cells ; Animals ; Base Sequence ; Carcinogens ; toxicity ; Cell Transformation, Neoplastic ; Cytochrome P-450 Enzyme System ; genetics ; DNA Primers ; Diethylnitrosamine ; toxicity ; Drug Synergism ; Mice ; Mice, Inbred BALB C ; Polychlorinated Dibenzodioxins ; toxicity ; RNA, Messenger ; genetics ; Real-Time Polymerase Chain Reaction ; Receptors, Aryl Hydrocarbon ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

Zebrafish is widely used as a model organism in the process of drug discovery. It expresses drug metabolizing enzymes like cytochrome P450 (CYP450), uridine 5'-diphospho-glucuronosyltransferase (UGT) and nuclear receptors like pregnane X receptor (PXR), aryl hydrocarbon receptor (AHR), etc. This article summarized the profiles of main drug metabolizing enzymes and nuclear receptors, and reviewed the advances on xenobiotics metabolism in zebrafish.
Animals ; Cytochrome P-450 Enzyme System ; metabolism ; Embryo, Nonmammalian ; drug effects ; Glucuronosyltransferase ; metabolism ; Inactivation, Metabolic ; Pharmaceutical Preparations ; metabolism ; Polychlorinated Dibenzodioxins ; toxicity ; Receptors, Aryl Hydrocarbon ; metabolism ; Receptors, Cytoplasmic and Nuclear ; metabolism ; Receptors, Steroid ; metabolism ; Teratogens ; toxicity ; Xenobiotics ; metabolism ; Zebrafish ; embryology ; metabolism

OBJECTIVETo study the specific binding of the artificial clonal aryl hydrocarbon receptor translocator (ARNT) with the natural aryl hydrocarbon receptor (AhR) and the recolonization by polyclonal antibody. The dose-response relationship with tetrachlo-rodibenzo-dioxin (TCDD) was also studied to develop TCDD detection method and the binding degree related to dose response.

METHODS(1) The target genes including AhR-PAS, AhR-C and ARNT-PAS were amplified by RT-PCR by using the total RNA purified from the liver cells of C57BL/6J mice as templates to construct pGEX-5X1 recombinants. The recombinant plasmids were expressed in E. coli. (2) The rabbits were immuned by the clonal fusion proteins: AhR-PAS, AhR-C to prepare the polyclonal antibody. (3) The natural AhR from the hepatic cytosol of C57BL/6J mice was extracted. The artificial cloning expressed fusion protein:GST-ARNT-PAS and the natural AhR were incubated in different dose of TCDD. The quantity of the heterodimer through affinity adsorption and Western blots were measured.

RESULTS(1) The target proteins including AhR-PAS, AhR-C and ARNT-PAS were successfully cloned and expressed in E. coli. (2) The detection limit of polyclonal antibody AhR-PAS and AhR-C were 5 ng and 1 ng, respectively. (3) The total protein concentration prepared from the liver cells was 60.5 mg/ml. The artificial clonal protein ARNT-PAS could specifically bind to the natural AhR complex with the existence of TCDD. The detection limit of TCDD was 0.25 pmol which was 80 pg approximately.

CONCLUSIONA TCDD detection method based on the aryl hydrocarbon receptor system was established and the detection limit might reach pg grade.

Animals ; Cells, Cultured ; Limit of Detection ; Liver Extracts ; chemistry ; Mice ; Mice, Inbred C57BL ; Polychlorinated Dibenzodioxins ; analysis ; Rabbits ; Receptors, Aryl Hydrocarbon ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

This study is to evaluate the cytotoxicity of mitomycin C (MMC) and its analogue 5-(aziridin-1-yl)-3-hydroxymethyl-1-methylindole-4,7-dione (629) as well as the effect of transfection of constitutive androstane receptor (CAR) on their biological effects. HepG2 cells were transfected with the plasmids mCAR1/pCR3 mediated by liposome. Vector pCR3 was used as control. Transfected cells were screened by G418 resistance and limiting dilution. The expressions of plasmid mCAR1/pCR3 and CYP2B6 mRNA were detected by RT-PCR; Cytotoxicities of MMC and 629 in vitro were evaluated in g2car cells and HepG2 cells by MTT method under anaerobic and aerobic conditions. mRNA expression of CAR and CYP2B6 can not be detected in HepG2 cells and HepG2/pCR3 cells but can in g2car cells. It is shown that plasmid mCAR1/pCR3 was transfected into g2car cells successfully and target CYP2B6 was transactivated by CAR. To compare with aerobic and anaerobic, the cytotoxicities of MMC and 629 to HepG2 cells and g2car cells had significantly enhanced (P < 0.05), and transfect CAR gene can improve the cytotoxicity of MMC (P < 0.05), but not 629 (P > 0.05). Furthermore, CYP2B6 is one master enzyme for the metabolism of MMC and not 629. Transfection of CAR can increase expression of CYP2B6 mRNA in HepG2 cells, and can affect cytotoxicities of MMC and 629.
Antibiotics, Antineoplastic ; pharmacology ; Aryl Hydrocarbon Hydroxylases ; biosynthesis ; genetics ; Aziridines ; pharmacology ; Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Death ; drug effects ; Cell Hypoxia ; Cell Line, Tumor ; Cytochrome P-450 CYP2B6 ; Humans ; Indoles ; pharmacology ; Inhibitory Concentration 50 ; Liver Neoplasms ; metabolism ; pathology ; Mitomycin ; pharmacology ; Oxidoreductases, N-Demethylating ; biosynthesis ; genetics ; Plasmids ; RNA, Messenger ; metabolism ; Receptors, Cytoplasmic and Nuclear ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Transcription Factors ; biosynthesis ; genetics ; Transfection

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a prototypic halogenated aromatic hydrocarbon (HAH), is known as one of the most potent toxicants. At least a part of its toxic effects appears to be derived from its ability to induce TNF-alpha production. However, the signaling pathway of TCDD that leads to TNF-alpha expression has not been elucidated. In this study, we investigated the signaling mechanism of TCDD-induced TNF-alpha expression in PMA-differentiated THP-1 macrophages. TCDD induced both mRNA and protein expression of TNF-alpha in a dose- and time-dependent manner. Alpha-Naphthoflavone (NF), an aryl hydrocarbon receptor (AhR) inhibitor, prevented the TCDD-induced expression of TNF-alpha at both mRNA and protein levels. Genistein, a protein tyrosine kinase (PTK) inhibitor, and PD153035, an EGFR inhibitor, also blocked the increase of TNF-alpha expression by TCDD, indicating the role of EGFR in TCDD-induced TNF-alpha expression. On the other hand, PP2, a c-Src specific inhibitor, did not affect TCDD-induced TNF-alpha expression. EGFR phosphorylation was detected as early as 5 min after TCDD treatment. TCDD-induced EGFR activation was AhR-dependent since co-treatment with alpha-NF prevented it. ERK was found to be a downstream effector of EGFR activation in the signaling pathway leading to TNF-alpha production after TCDD stimulation. Activation of ERK was observed from 30 min after TCDD treatment. PD98059, an inhibitor of the MEK-ERK pathway, completely prevented the TNF-alpha mRNA and protein expression induced by TCDD, whereas inhibitors of JNK and p38 MAPK had no effect. PD153035, an EGFR inhibitor, as well as alpha-NF significantly reduced ERK phosphorylation, suggesting that ERK activation by TCDD was mediated by both EGFR and AhR. These results indicate that TNF-alpha production by TCDD in differentiated THP-1 macrophages is AhR-dependent and involves activation of EGFR and ERK, but not c-Src, JNK, nor p38 MAPK. A signaling pathway is proposed where TCDD induces sequential activation of AhR, EGFR and ERK, leading to the increased expression of TNF-alpha.
Animals ; Benzoflavones/pharmacology ; Cell Differentiation ; Cell Line, Tumor ; Enzyme Activation ; Genistein/pharmacology ; Hazardous Substances/*toxicity ; Humans ; MAP Kinase Signaling System/drug effects/physiology ; Macrophages/*metabolism ; Mice ; Phosphorylation ; Pyrimidines/pharmacology ; Quinazolines/pharmacology ; RNA, Messenger/metabolism ; Receptor, Epidermal Growth Factor/antagonists & inhibitors/metabolism ; Receptors, Aryl Hydrocarbon/antagonists & inhibitors ; Signal Transduction ; Tetrachlorodibenzodioxin/*toxicity ; Tumor Necrosis Factor-alpha/*biosynthesis ; src-Family Kinases/antagonists & inhibitors/metabolism