The efforts for therapeutic targeting of the aryl hydrocarbon receptor (AhR) have emerged in recent years. We investigated the effects of available antimigraine triptan drugs, having an indole core in their structure, on AhR signaling in human hepatic and intestinal cells. Activation of AhR in reporter gene assays was observed for Avitriptan and to a lesser extent for Donitriptan, while other triptans were very weak or no activators of AhR. Using competitive binding assay and by homology docking, we identified Avitriptan as a low-affinity ligand of AhR. Avitriptan triggered nuclear translocation of AhR and increased binding of AhR in CYP1A1 promotor DNA, as revealed by immune-fluorescence microscopy and chromatin immune-precipitation assay, respectively. Strong induction of CYP1A1 mRNA was achieved by Avitriptan in wild type but not in AhR-knockout, immortalized human hepatocytes, implying that induction of CYP1A1 is AhR-dependent. Increased levels of CYP1A1 mRNA by Avitriptan were observed in human colon carcinoma cells LS180 but not in primary cultures of human hepatocytes. Collectively, we show that Avitriptan is a weak ligand and activator of human AhR, which induces the expression of CYP1A1 in a cell-type specific manner. Our data warrant the potential off-label therapeutic application of Avitriptan as an AhR-agonist drug.

• Keywords
• Antimigraine drugs, Aryl Hydrocarbon Receptor, Triptans, repurposing,
• MeSH
• Enzyme Activation drug effects   MeSH
• Cytochrome P-450 CYP1A1 genetics   MeSH
• Hepatocytes metabolism   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Ligands MeSH
• Models, Molecular MeSH
• Organ Specificity MeSH
• Drug Repositioning MeSH
• Promoter Regions, Genetic drug effects   MeSH
• Receptors, Aryl Hydrocarbon agonists   chemistry   metabolism   MeSH
• Molecular Docking Simulation MeSH
• Intestinal Mucosa metabolism   MeSH
• Sulfonamides pharmacology   MeSH
• Basic Helix-Loop-Helix Transcription Factors agonists   chemistry   metabolism   MeSH
• Tryptamines pharmacology   MeSH
• Up-Regulation MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• AHR protein, human MeSH Browser
• avitriptan MeSH Browser
• CYP1A1 protein, human MeSH Browser
• Cytochrome P-450 CYP1A1 MeSH
• Ligands MeSH
• Receptors, Aryl Hydrocarbon MeSH
• Sulfonamides MeSH
• Basic Helix-Loop-Helix Transcription Factors MeSH
• Tryptamines MeSH

Novel methylindoles were identified as endobiotic and xenobiotic ligands of the human aryl hydrocarbon receptor (AhR). We examined the effects of 22 methylated and methoxylated indoles on the transcriptional activity of AhRs. Employing reporter gene assays in AZ-AHR transgenic cells, we determined full agonist, partial agonist, or antagonist activities of tested compounds, having substantially variable EC50, IC50, and relative efficacies. The most effective agonists (EMAX relative to 5 nM dioxin) of the AhR were 4-Me-indole (134%), 6-Me-indole (91%), and 7-MeO-indole (80%), respectively. The most effective antagonists of the AhR included 3-Me-indole (IC50; 19 μM), 2,3-diMe-indole (IC50; 11 μM), and 2,3,7-triMe-indole (IC50; 12 μM). Reverse transcription polymerase chain reaction analyses of CYP1A1 mRNA in LS180 cells confirmed the data from gene reporter assays. The compound leads, 4-Me-indole and 7-MeO-indole, induced substantial nuclear translocation of the AhR and enriched binding of the AhR to the CYP1A1 promoter, as observed using fluorescent immunohistochemistry and chromatin immunoprecipitation assays, respectively. Molecular modeling and docking studies suggest the agonists and antagonists likely share the same binding pocket but have unique binding modes that code for their affinity. Binding pocket analysis further revealed that 4-methylindole and 7-methoxyindole can simultaneously bind to the pocket and produce synergistic interactions. Together, these data show a dependence on subtle and specific chemical indole structures as AhR modulators and furthermore underscore the importance of complete evaluation of indole compounds as nuclear receptor ligands.

• MeSH
• Hep G2 Cells MeSH
• Cytochrome P-450 CYP1A1 metabolism   MeSH
• Indoles pharmacology   MeSH
• Humans MeSH
• Ligands MeSH
• RNA, Messenger metabolism   MeSH
• Cell Line, Tumor MeSH
• Promoter Regions, Genetic drug effects   MeSH
• Receptors, Aryl Hydrocarbon agonists   antagonists & inhibitors   MeSH
• Genes, Reporter drug effects   MeSH
• Basic Helix-Loop-Helix Transcription Factors agonists   antagonists & inhibitors   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Names of Substances
• AHR protein, human MeSH Browser
• Cytochrome P-450 CYP1A1 MeSH
• indole MeSH Browser
• Indoles MeSH
• Ligands MeSH
• RNA, Messenger MeSH
• Receptors, Aryl Hydrocarbon MeSH
• Basic Helix-Loop-Helix Transcription Factors MeSH

Atorvastatin, fluvastatin and rosuvastatin are drugs used for treatment of hypercholesterolemia. They cause numerous drug-drug interactions by inhibiting and inducing drug-metabolizing cytochromes P450. These three statins exist in four optical forms, but they are currently used as enantiopure drugs, i.e., only one single enantiomer. There are numerous evidences that efficacy, adverse effects and toxicity of drugs may be enantiospecific. Therefore, we investigated the effects of optical isomers of atorvastatin, fluvastatin and rosuvastatin on the expression of drug-metabolizing P450s in primary human hepatocytes, using western blots and RT-PCR for measurement of proteins and mRNAs, respectively. The activity of P450 transcriptional regulators, including pregnane X receptor (PXR), aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR), was assessed by gene reporter assays and EMSA. Transcriptional activity of AhR was not influenced by any statin tested. Basal transcriptional activity of GR was not affected by tested statins, but dexamethasone-inducible activity of GR was dose-dependently and enantioselectively inhibited by fluvastatin. Basal and ligand-inducible transcriptional activity of PXR was dose-dependently influenced by all tested statins, and the potency and efficacy between individual optical isomers varied depending on statin and optical isomer. The expression of CYP1A1 and CYP1A2 in human hepatocytes was not influenced by tested statins. All statins induced CYP2A6, CYP2B6 and CYP3A4, and the effects on CYP2C9 were rather modulatory. The effects varied between statins and enantiomers and induction potency decreased in order: atorvastatin (RR>RS = SR>SS) > fluvastatin (SR>RS = SS>RR) >> rosuvastatin (only RS active). The data presented here might be of toxicological and clinical importance.

• MeSH
• Atorvastatin pharmacology   MeSH
• Cytochrome P-450 CYP3A biosynthesis   MeSH
• Cytochrome P-450 CYP2A6 biosynthesis   MeSH
• Cytochrome P-450 CYP2B6 biosynthesis   MeSH
• Adult MeSH
• Enzyme Induction drug effects   MeSH
• Fluvastatin MeSH
• Hepatocytes cytology   enzymology   MeSH
• Indoles pharmacology   MeSH
• Cytochrome P-450 CYP2B6 Inducers pharmacology   MeSH
• Cytochrome P-450 CYP3A Inducers pharmacology   MeSH
• Fatty Acids, Monounsaturated pharmacology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Pregnane X Receptor MeSH
• Rosuvastatin Calcium pharmacology   MeSH
• Aged MeSH
• Stereoisomerism MeSH
• Receptors, Steroid biosynthesis   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Atorvastatin MeSH
• CYP2A6 protein, human MeSH Browser
• CYP2B6 protein, human MeSH Browser
• CYP3A4 protein, human MeSH Browser
• Cytochrome P-450 CYP3A MeSH
• Cytochrome P-450 CYP2A6 MeSH
• Cytochrome P-450 CYP2B6 MeSH
• Fluvastatin MeSH
• Indoles MeSH
• Cytochrome P-450 CYP2B6 Inducers MeSH
• Cytochrome P-450 CYP3A Inducers MeSH
• Fatty Acids, Monounsaturated MeSH
• Pregnane X Receptor MeSH
• Rosuvastatin Calcium MeSH
• Receptors, Steroid MeSH

Antifungal drug ketoconazole causes severe drug-drug interactions by influencing gene expression and catalytic activity of major drug-metabolizing enzyme cytochrome P450 CYP3A4. Ketoconazole is administered in the form of racemic mixture of two cis-enantiomers, i.e. (+)-ketoconazole and (-)-ketoconazole. Many enantiopure drugs were introduced to human pharmacotherapy in last two decades. In the current paper, we have examined the effects of ketoconazole cis-enantiomers on the expression of CYP3A4 in human hepatocytes and HepG2 cells and on catalytic activity of CYP3A4 in human liver microsomes. We show that both ketoconazole enantiomers induce CYP3A4 mRNA and protein in human hepatocytes and HepG2 cells. Gene reporter assays revealed partial agonist activity of ketoconazole enantiomers towards pregnane X receptor PXR. Catalytic activity of CYP3A4/5 towards two prototypic substrates of CYP3A enzymes, testosterone and midazolam, was determined in presence of both (+)-ketoconazole and (-)-ketoconazole in human liver microsomes. Overall, both ketoconazole cis-enantiomers induced CYP3A4 in human cells and inhibited CYP3A4 in human liver microsomes. While interaction of ketoconazole with PXR and induction of CYP3A4 did not display enantiospecific pattern, inhibition of CYP3A4 catalytic activity by ketoconazole differed for ketoconazole cis-enantiomers ((+)-ketoconazole IC₅₀ 1.69 µM, Ki 0.92 µM for testosterone, IC₅₀ 1.46 µM, Ki 2.52 µM for midazolam; (-)-ketoconazole IC₅₀ 0.90 µM, Ki 0.17 µM for testosterone, IC₅₀ 1.04 µM, Ki 1.51 µM for midazolam).

• MeSH
• Biocatalysis drug effects   MeSH
• Hep G2 Cells MeSH
• Cytochrome P-450 CYP3A genetics   metabolism   MeSH
• Transcription, Genetic drug effects   MeSH
• Hepatocytes drug effects   enzymology   MeSH
• Microsomes, Liver drug effects   metabolism   MeSH
• Ketoconazole chemistry   pharmacology   MeSH
• Kinetics MeSH
• Humans MeSH
• RNA, Messenger genetics   metabolism   MeSH
• Pregnane X Receptor MeSH
• Gene Expression Regulation, Enzymologic drug effects   MeSH
• Genes, Reporter MeSH
• Stereoisomerism MeSH
• Receptors, Steroid genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytochrome P-450 CYP3A MeSH
• Ketoconazole MeSH
• RNA, Messenger MeSH
• Pregnane X Receptor MeSH
• Receptors, Steroid MeSH

Benzimidazole drugs lansoprazole and omeprazole are used for treatment of various gastrointestinal pathologies. Both compounds cause drug-drug interactions because they activate aryl hydrocarbon receptor and induce CYP1A genes. In the current paper, we examined the effects of lansoprazole and omeprazole enantiomers on the expression of key drug-metabolizing enzyme CYP3A4 in human hepatocytes and human cancer cell lines. Lansoprazole enantiomers, but not omeprazole, were equipotent inducers of CYP3A4 mRNA in HepG2 cells. All forms (S-, R-, rac-) of lansoprazole and omeprazole induced CYP3A4 mRNA and protein in human hepatocytes. The quantitative profiles of CYP3A4 induction by individual forms of lansoprazole and omeprazole exerted enantiospecific patterns. Lansoprazole dose-dependently activated pregnane X receptor PXR in gene reporter assays, and slightly modulated rifampicin-inducible PXR activity, with similar potency for each enantiomer. Omeprazole dose-dependently activated PXR and inhibited rifampicin-inducible PXR activity. The effects of S-omeprazole were much stronger as compared to those of R-omeprazole. All forms of lansoprazole, but not omeprazole, slightly activated glucocorticoid receptor and augmented dexamethasone-induced GR transcriptional activity. Omeprazole and lansoprazole influenced basal and ligand inducible expression of tyrosine aminotransferase, a GR-target gene, in HepG2 cells and human hepatocytes. Overall, we demonstrate here that omeprazole and lansoprazole enantiomers induce CYP3A4 in HepG2 cells and human hepatocytes. The induction comprises differential interactions of omeprazole and lansoprazole with transcriptional regulators PXR and GR, and some of the effects were enantiospecific. The data presented here might be of toxicological and clinical importance, since the effects occurred in therapeutically relevant concentrations.

• MeSH
• Hep G2 Cells MeSH
• Cytochrome P-450 CYP3A genetics   metabolism   MeSH
• Hepatocytes drug effects   metabolism   MeSH
• Cells, Cultured MeSH
• Lansoprazole adverse effects   pharmacology   MeSH
• Humans MeSH
• Omeprazole adverse effects   pharmacology   MeSH
• Pregnane X Receptor MeSH
• Anti-Ulcer Agents adverse effects   pharmacology   MeSH
• Receptors, Glucocorticoid metabolism   MeSH
• Receptors, Steroid metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• CYP3A4 protein, human MeSH Browser
• Cytochrome P-450 CYP3A MeSH
• Lansoprazole MeSH
• Omeprazole MeSH
• Pregnane X Receptor MeSH
• Anti-Ulcer Agents MeSH
• Receptors, Glucocorticoid MeSH
• Receptors, Steroid MeSH