Up-regulation of CYP1A1 by rutaecarpine is dependent on aryl hydrocarbon receptor and calcium

Effects of xenobiotics on CYP1 enzyme-mediated biotransformation and bioactivation of estradiol

Endogenous estradiol (E2) exerts diverse physiological and pharmacological activities, commonly used for hormone replacement therapy. However, prolonged and excessive exposure to E2 potentially increases estrogenic cancer risk. Reportedly, CYP1 enzyme-mediated biotransformation of E2 is largely concerned with its balance between detoxification and carcinogenic pathways. Among the three key CYP1 enzymes (CYP1A1, CYP1A2, and CYP1B1), CYP1A1 and CYP1A2 mainly catalyze the formation of nontoxic 2-hydroxyestradiol (2-OH-E2), while CYP1B1 specifically catalyzes the formation of genotoxic 4-hydroxyestradiol (4-OH-E2). 4-OH-E2 can be further metabolized to electrophilic quinone intermediates accompanied by the generation of reactive oxygen species (ROS), triggering DNA damage. Since abnormal alterations in CYP1 activities can greatly affect the bioactivation process of E2, regulatory effects of xenobiotics on CYP1s are essential for E2-associated cancer development. To date, thousands of natural and synthetic compounds have been found to show potential inhibition and/or induction actions on the three CYP1 members. Generally, these chemicals share similar planar polycyclic skeletons, the structural motifs and substituent groups of which are important for their inhibitory/inductive efficiency and selectivity toward CYP1 enzymes. This review comprehensively summarizes these known inhibitors and/or inductors of E2-metabolizing CYP1s based on chemical categories and discusses their structure-activity relationships, which would contribute to better understanding of the correlation between xenobiotic-regulated CYP1 activities and estrogenic cancer susceptibility.

Molecular mechanisms of hepatotoxicity induced by compounds occurring in Evodiae Fructus

Evodiae Fructus (EF) is a common herbal medicine with thousands of years of medicinal history in China, which has been demonstrated with many promising pharmacological effects on cancer, cardiovascular diseases and Alzheimer's disease. However, there have been increasing reports of hepatotoxicity associated with EF consumption. Unfortunately, in a long term, many implicit constituents of EF as well as their toxic mechanisms remain poorly understood. Recently, metabolic activation of hepatotoxic compounds of EF to generate reactive metabolites (RMs) has been implicated. Herein, we capture metabolic reactions relevant to hepatotoxicity of these compounds. Initially, catalyzed by the hepatic cytochrome P450 enzymes (CYP450s), the hepatotoxic compounds of EF are oxidized to generate RMs. Subsequently, the highly electrophilic RMs could react with nucleophilic groups contained in biomolecules, such as hepatic proteins, enzymes, and nucleic acids to form conjugates and/or adducts, leading to a sequence of toxicological consequences. In addition, currently proposed biological pathogenesis, including oxidative stress, mitochondrial damage and dysfunction, endoplasmic reticulum (ER) stress, hepatic metabolism disorder, and cell apoptosis are represented. In short, this review updates the knowledge on the pathways of metabolic activation of seven hepatotoxic compounds of EF and provides considerable insights into the relevance of proposed molecular hepatotoxicity mechanisms from a biochemical standpoint, for the purpose of providing a theoretical guideline for the rational application of EF in clinics.

Rutaecarpine Inhibits U87 Glioblastoma Cell Migration by Activating the Aryl Hydrocarbon Receptor Signaling Pathway

Glioblastoma is the most frequent and aggressive primary astrocytoma in adults. The high migration ability of the tumor cells is an important reason for the high recurrence rate and poor prognosis of glioblastoma. Recently, emerging evidence has shown that the migration ability of glioblastoma cells was inhibited upon the activation of aryl hydrocarbon receptor (AhR), suggesting potential anti-tumor effects of AhR agonists. Rutaecarpine is a natural compound with potential tumor therapeutic effects which can possibly bind to AhR. However, its effect on the migration of glioblastoma is unclear. Therefore, we aim to explore the effects of rutaecarpine on the migration of human glioblastoma cells U87 and the involvement of the AhR signaling pathway. The results showed that: (i) compared with other structural related alkaloids, like evodiamine and dehydroevodiamine, rutaecarpine was a more potent AhR activator, and has a stronger inhibitory effect on the glioblastoma cell migration; (ii) rutaecarpine decreased the migration ability of U87 cells in an AhR-dependent manner; (iii) AhR mediated the expression of a tumor suppressor interleukin 24 (IL24) induced by rutaecarpine, and AhR-IL24 axis was involved in the anti-migratory effects of rutaecarpine on the glioblastoma. Besides IL24, other candidates AhR downstream genes both associated with cancer and migration were proposed to participate in the migration regulation of rutaecarpine by RNA-Seq and bioinformatic analysis. These data indicate that rutaecarpine is a naturally-derived AhR agonist that could inhibit the migration of U87 human glioblastoma cells mostly via the AhR-IL24 axis.

Pharmacological blockage of the AHR-CYP1A1 axis: a call for in vivo evidence

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that can be activated by structurally diverse compounds arising from the environment and the microbiota and host metabolism. Expanding evidence has been shown that the modulation of the canonical pathway of AHR occurs during several chronic diseases and that its abrogation might be of clinical interest for metabolic and inflammatory pathological processes. However, most of the evidence on the pharmacological abrogation of the AHR-CYP1A1 axis has been reported in vitro, and therefore, guidance for in vivo studies is needed. In this review, we cover the state-of-the-art of the pharmacodynamic and pharmacokinetic properties of AHR antagonists and CYP1A1 inhibitors in different in vivo rodent (mouse or rat) models of disease. This review will serve as a road map for those researchers embracing this emerging therapeutic area targeting the AHR. Moreover, it is a timely opportunity as the first AHR antagonists have recently entered the clinical stage of drug development.

Novel polar AhR-active chemicals detected in sediments of an industrial area using effect-directed analysis based on in vitro bioassays with full-scan high resolution mass spectrometric screening

Studies investigating aryl hydrocarbon receptor (AhR)-active compounds in the environment typically focus on non- and mid-polar substances, such as PAHs; while, information on polar AhR agonists remains limited. Here, we identified polar AhR agonists in sediments collected from the inland creeks of an industrialized area (Lake Sihwa, Korea) using effect-directed analysis combined with full-scan screening analysis (FSA; using LC-QTOFMS). Strong AhR-mediated potencies were observed for the polar and latter fractions of RP-HPLC (F3.5-F3.8) from sediment organic extracts in the H4IIE-luc in vitro bioassays. FSA was performed on the corresponding fractions. Twenty-eight tentative AhR agonists were chosen using a five-step process. Toxicological confirmation using bioassay revealed that canrenone, rutaecarpine, ciprofloxacin, mepanipyrim, genistein, protopine, hydrocortisone, and medroxyprogesterone were significantly active. The relative potencies of these AhR-active compounds compared to that of benzo[a]pyrene ranged from 0.00002 to 2.0. Potency balance analysis showed that polar AhR agonists explained, on average, ~6% of total AhR-mediated potencies in samples. Some novel polar AhR agonists also exhibited endocrine-disrupting potentials capable of binding to estrogen and glucocorticoid receptors, as identified by QSAR modeling. In conclusion, the focused studies on distributions, sources, fate, and ecotoxicological effects of novel polar AhR agonists in the environment are necessary.

Gene coexpression networks reveal molecular interactions underlying cichlid jaw modularity

Background

The oral and pharyngeal jaw of cichlid fishes are a classic example of evolutionary modularity as their functional decoupling boosted trophic diversification and contributed to the success of cichlid adaptive radiations. Most studies until now have focused on the functional, morphological, or genetic aspects of cichlid jaw modularity. Here we extend this concept to include transcriptional modularity by sequencing whole transcriptomes of the two jaws and comparing their gene coexpression networks.

Results

We show that transcriptional decoupling of gene expression underlies the functional decoupling of cichlid oral and pharyngeal jaw apparatus and the two units are evolving independently in recently diverged cichlid species from Lake Tanganyika. Oral and pharyngeal jaw coexpression networks reflect the common origin of the jaw regulatory program as there is high preservation of gene coexpression modules between the two sets of jaws. However, there is substantial rewiring of genetic architecture within those modules. We define a global jaw coexpression network and highlight jaw-specific and species-specific modules within it. Furthermore, we annotate a comprehensive in silico gene regulatory network linking the Wnt and AHR signalling pathways to jaw morphogenesis and response to environmental cues, respectively. Components of these pathways are significantly differentially expressed between the oral and pharyngeal jaw apparatus.

Conclusion

This study describes the concerted expression of many genes in cichlid oral and pharyngeal jaw apparatus at the onset of the independent life of cichlid fishes. Our findings suggest that – on the basis of an ancestral gill arch network—transcriptional rewiring may have driven the modular evolution of the oral and pharyngeal jaws, highlighting the evolutionary significance of gene network reuse. The gene coexpression and in silico regulatory networks presented here are intended as resource for future studies on the genetics of vertebrate jaw morphogenesis and trophic adaptation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-021-01787-9.

Traditional uses, phytochemistry, pharmacology, pharmacokinetics and toxicology of the fruit of Tetradium ruticarpum: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Tetradium ruticarpum (FTR) known as Tetradii fructus or Evodiae fructus (Wu-Zhu-Yu in Chinese) is a versatile herbal medicine which has been prescribed in Chinese herbal formulas and recognized in Japanese Kampo. FTR has been clinically used to treat various diseases such as headache, vomit, diarrhea, abdominal pain, dysmenorrhea and pelvic inflammation for thousands of years.

AIM OF THE REVIEW

The present paper aimed to provide comprehensive information on the ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics, drug interaction and toxicology of FTR in order to build up a foundation on the mechanism of ethnopharmacological uses as well as to explore the trends and perspectives for further studies.

MATERIALS AND METHODS

This review collected the literatures published prior to July 2020 on the phytochemistry, pharmacology, pharmacokinetics and toxicity of FTR. All relevant information on FTR was gathered from worldwide accepted scientific search engines and databases, including Web of Science, PubMed, Elsevier, ACS, ResearchGate, Google Scholar, and Chinese National Knowledge Infrastructure (CNKI). Information was also obtained from local books, PhD. and MSc. Dissertations as well as from Pharmacopeias.

RESULTS

FTR has been used as an herbal medicine for centuries in East Asia. A total of 165 chemical compounds have been isolated so far and the main chemical compounds of FTR include alkaloids, terpenoids, flavonoids, phenolic acids, steroids, and phenylpropanoids. Crude extracts, processed products (medicinal slices) and pure components of FTR exhibit a wide range of pharmacological activities such as antitumor, anti-inflammatory, antibacterial, anti-obesity, antioxidant, insecticide, regulating central nervous system (CNS) homeostasis, cardiovascular protection. Furthermore, bioactive components isolated from FTR can induce drug interaction and hepatic injury.

CONCLUSIONS

Therapeutic potential of FTR has been demonstrated with the pharmacological effects on cancer, inflammation, cardiovascular diseases, CNS, bacterial infection and obesity. Pharmacological and pharmacokinetic studies of FTR mostly focus on its main active alkaloids. Further in-depth studies on combined medication and processing approaches mechanisms, pharmacological and toxic effects not limited to the alkaloids, and toxic components of FTR should be designed.

Evodiamine and rutaecarpine from Tetradium ruticarpum in the treatment of liver diseases

BACKGROUND

Liver is the pivotal organ responsible for plasma protein production, biliary secretion, xenobiotic elimination, glucose and lipid homeostasis. Dysregulation of these functions usually leads to liver diseases and further related complications. The incidence of liver diseases is increasing worldwide, with high morbidity and mortality when at advanced stages, and has become significant public health concern and substential economic burden. Thus, novel therapeutic strategies for managing liver diseases progression are urgently required. T. ruticarpum is one of the most famous and frequently used herbal medicine and has been prescribed in traditional Chinese medicine (TCM) formulas for the treatment of various ailments, including liver diseases. A considerable amount of bioactive ingredients have been isolated and identified from the roots of T. ruticarpum, including alkaloids, saponins, phenols, volatile oils and other compounds. Among these compounds, evodiamine (EVO) and rutaecarpine (RUT) are believed to be the most bioactive compounds.

PURPOSE

To summarize recent findings regarding to the metabolism, pharmacological/toxicological effects of EVO and RUT and to highlight the potential therapeutic effects of them against liver diseases.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "T. ruticarpum", "Wu Zhu Yu", "evodiamine", "rutaecarpine", "liver" and combinations to include published studies of EVO and RUT primarily from 2004-2019. Several critical previous studies beyond this period were also included.

RESULTS

Evodiamine (EVO) and rutaecarpine (RUT) are believed to be the most bioactive alkaloids in T. ruticarpum, having anti-inflammation, anti-fibrosis, anti-lipotoxicity, anti-cancer activities, and thus having potential to improve liver disorders. In the current review, we comprehensively summarized recent progresses in the studies of EVO- and RUT-mediated promising hepatoprotective effects and also provide novel insights regarding the potential use of EVO and RUT as therapeutic options for the treatment of liver diseases.

CONCLUSION

With further in-depth pharmacology and pharmacokinetic studies, we believe that natural products in T. ruticarpum and their derivatives will become promising medicines with improved clinical efficacy for the treatment of liver diseases in the immediate future.

Structure-Activity Relationships of the Main Bioactive Constituents of Euodia rutaecarpa on Aryl Hydrocarbon Receptor Activation and Associated Bile Acid Homeostasis

Rutaecarpine (RUT), evodiamine (EOD), and dehydroevodiamine (DHED) are the three main bioactive indoloquinazoline alkaloids isolated from Euodia rutaecarpa, a widely prescribed traditional Chinese medicine. Here, the structure-activity relationships of these analogs for aryl hydrocarbon receptor (AHR) activation were explored by use of Ahr-deficient (Ahr^-/-) mice, primary hepatocyte cultures, luciferase reporter gene assays, in silico ligand-docking studies, and metabolomics. In vitro, both mRNA analysis of AHR target genes in mouse primary hepatocytes and luciferase reporter assays in hepatocarcinoma cell lines demonstrated that RUT, EOD, and DHED significantly activated AHR, with an efficacy order of RUT > DHED > EOD. Ligand-docking analysis predicted that the methyl substitute at the N-14 atom was a key factor affecting AHR activation. In vivo, EOD was poorly orally absorbed and failed to activate AHR, whereas RUT and DHED markedly upregulated expression of the hepatic AHR gene battery in wild-type mice, but not in Ahr^-/- mice. Furthermore, RUT, EOD, and DHED were not hepatotoxic at the doses used; however, RUT and DHED disrupted bile acid homeostasis in an AHR-dependent manner. These findings revealed that the methyl group at the N-14 atom of these analogs and their pharmacokinetic behaviors were the main determinants for AHR activation, and suggest that attention should be given to monitoring bile acid metabolism in the clinical use of E. rutaecarpa.

Sinomenine induces the generation of intestinal Treg cells and attenuates arthritis via activation of aryl hydrocarbon receptor

Sinomenine (SIN), an anti-arthritis drug, has previously been proven to exert immunomodulatory activity in rats by inducing intestinal regulatory T-cells (Treg cells). Here, we assessed the effect of SIN on the generation and function of Treg cells in autoimmune arthritis, and the underlying mechanisms in view of aryl hydrocarbon receptor (AhR). The proportions of Treg cells and IL-17-producing T-cells (Th17 cells) differentiated from naive T-cells were analyzed by flow cytometric analysis. The AhR agonistic effect of SIN was tested by analyzing the activation of downstream signaling pathways and target genes. The dependence of intestinal Treg cell induction and arthritis alleviation by SIN on AhR activation was confirmed in a mouse collagen-induced arthritis (CIA) model. SIN promoted the differentiation and function of intestinal Treg cells in vitro. It induced the expression and activity of AhR target gene, promoted AhR/Hsp90 dissociation and AhR nuclear translocation, induced XRE reporter activity, and facilitated AhR/XRE binding in vitro, displaying the potential to be an agonist of AhR. In CIA mice, SIN induced the generation of intestinal Treg cells, and facilitated the immunosuppressive function of these Treg cells as shown by an adoptive transfer test. In addition, the induction of intestinal Treg cells and the anti-arthritic effect of SIN in CIA mice could be largely diminished by the AhR antagonist resveratrol. SIN attenuates arthritis by promoting the generation and function of Treg cells in an AhR-dependent manner.

Are aryl hydrocarbon receptor and G-protein-coupled receptor 30 involved in the regulation of seasonal testis activity in photosensitive rodent-the bank vole (Myodes glareolus)?

Within the reproductive system both aryl hydrocarbon receptor (AHR) and G-protein-coupled receptor 30 (GPR30) contribute to estrogen signaling and controlling of reproductive physiology. The specific question is whether and how AHR and GPR30 are involved in regulation of testis function in seasonally breeding rodents. Bank vole testes were obtained from animals reared under 18 hours light:6 hours dark (LD) and 6 hours light:18 hours dark (SD) conditions. Aryl hydrocarbon receptor and GPR30 expression were analyzed by quantitative reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry and/or immunofluorescent staining. In addition, the activity of enzymes involved in the intracellular signal transduction; extracellular signal-regulated kinase (ERK), protein kinase (PKA), matrix metalloproteinase 9 (MMP 9) and the concentrations of cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), and calcium (Ca(2+)) were examined by immunohistochemical, immunoenzymatic, and colorimetric assays, respectively. Aryl hydrocarbon receptor and GPR30 were expressed in testes of actively reproducing voles and regressed ones although their expression at the messenger RNA and AHR also at protein level appeared to be photoperiod-dependent. A specific cellular localization and expression of AHR and GPR30 correlated with the expression of ERK, PKA, and MMP 9. Moreover, we found robust differences in the levels of cAMP, cGMP, and Ca(2+) in testicular homogenates between LD and SD voles. In the testes of LD voles, the levels of second messengers were always higher compared to SD. In vole testis, AHR and GPR30 can induce signaling pathways that involve ERK, PKA, MMP 9 and cAMP, cGMP, Ca(2+). In addition, in AHR, signaling the engagement of both photoperiod and estrogens, whereas in GPR30, signaling only estrogens is reported. It is likely that in vole, because of a differential activity of signaling molecules, signal transduction via AHR rather than through GPR30 plays a role in regulation of seasonal changes of testis physiology.

Endosulfan Induces CYP1A1 Expression Mediated through Aryl Hydrocarbon Receptor Signal Transduction by Protein Kinase C

CYP1A1 is a phase I xenobiotic-metabolizing enzyme whose expression is mainly driven by AhR. Endosulfan is an organochlorine pesticide used agriculturally for a wide range of crops. In this study, we investigated the effect of endosulfan on CYP1A1 expression and regulation. Endosulfan significantly increased CYP1A1 enzyme activity as well as mRNA and protein levels. In addition, endosulfan markedly induced XRE transcriptional activity. CH-223191, an AhR antagonist, blocked the endosulfan-induced increase in CYP1A1 mRNA and protein expression. Moreover, endosulfan did not induce CYP1A1 gene expression in AhR-deficient mutant cells. Furthermore, endosulfan enhanced the phosphorylation of calcium calmodulin (CaM)-dependent protein kinase (CaMK) and protein kinase C (PKC). In conclusion, endosulfan-induced up-regulation of CYP1A1 is associated with AhR activation, which may be mediated by PKC-dependent pathways.

Caffeic acid phenethyl ester inhibits 3-MC-induced CYP1A1 expression through induction of hypoxia-inducible factor-1α

Caffeic acid phenethyl ester (CAPE), a natural component of propolis, is reported to have anticarcinogenic properties, although its precise chemopreventive mechanism remains unclear. In this study, we examined the effects of CAPE on 3-methylcholanthrene (3-MC)-induced CYP1A1 expression and activities. CAPE reduced the formation of the benzo[a]pyrene-DNA adduct. Moreover, CAPE inhibited 3-MC-induced CYP1A1 activity, mRNA expression, protein level, and promoter activity. CAPE treatment also decreased 3-MC-inducible xenobiotic-response element (XRE)-linked luciferase, aryl hydrocarbons receptor (AhR) transactivation and nuclear localization. CAPE induced hypoxia inducible factor-1α (HIF-1α) protein level and HIF-1α responsible element (HRE) transcriptional activity. CAPE-mediated HIF-1α reduced 3-MC-inducible CYP1A1 protein expression. Taken together, CAPE decreases 3-MC-mediated CYP1A1 expression, and this inhibitory response is associated with inhibition of AhR and HIF-1α induction.

The Repellent DEET Potentiates Carbamate Effects via Insect Muscarinic Receptor Interactions: An Alternative Strategy to Control Insect Vector-Borne Diseases

Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with non-pyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calcium-dependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dose-dependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of mosquitoes. Our findings reveal an unusual allosterically potentiating action of the repellent DEET, which involves a selective site in insect. These results open exciting research areas in public health particularly in the control of the pyrethroid-resistant insect-vector borne diseases. Mixing low doses of DEET and a non-pyrethroid insecticide will lead to improvement in the efficiency treatments thus reducing both the concentration of active ingredients and side effects for non-target organisms. The discovery of this insect specific site may pave the way for the development of new strategies essential in the management of chemical use against resistant mosquitoes.

Rutaecarpine prevented dysfunction of endothelial gap junction induced by Ox-LDL via activation of TRPV1

Gap junctions, which is formed by connexins, has been proved to play an important role in the atherogenesis development. Rutaecarpine was reported to inhibited monocyte migration, which indicates its potential for anti-atherosclerosis activity. This study evaluated the effect of rutaecarpine on endothelial dysfunction, and focused on the regulation of connexin expression in endothelial cells by rutaecarpine. Endothelia damage was induced by exposing HUVEC-12 to Ox-LDL (100mg/l) for 24h, which decreased the expression of protective proteins Cx37 and Cx40, but induced atherogenic Cx43 expression, in both mRNA and protein levels, concomitant with the impaired propidium iodide diffusion through the gap junctions. Pretreatment with rutaecarpine effectively recovered the expression of Cx37 and Cx40, but inhibited Cx43 expression, thereby improving gap junction communication and significantly prevented the endothelial dysfunction. Consequently, the cell viability and nitric oxide production were increased, lactate dehydrogenase production was decreased and monocyte adhesion was inhibited. These protective effects of rutaecarpine were remarkably attenuated by pretreatment with capsazepine, a competitive antagonist of transient receptor potential vanilloid subtype 1 (TRPV1). In summary, this study is the first to report that rutaecarpine prevents endothelial injury and gap junction dysfunction induced by Ox-LDL in vitro, which is related to regulation of connexin expression patterns via TRPV1 activation. These results suggest that rutaecarpine has the potential for use as an anti-atherosclerosis agent with a novel mechanism.

Genome-wide RNAi high-throughput screen identifies proteins necessary for the AHR-dependent induction of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin

The aryl hydrocarbon receptor (AHR) has a plethora of physiological roles, and upon dysregulation, carcinogenesis can occur. One target gene of AHR encodes the xenobiotic and drug-metabolizing enzyme CYP1A1, which is inducible by the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) via the AHR. An siRNA library targeted against over 5600 gene candidates in the druggable genome was used to transfect mouse Hepa-1 cells, which were then treated with TCDD, and subsequently assayed for CYP1A1-dependent ethoxyresorufin-o-deethylase (EROD) activity. Following redundant siRNA activity (RSA) statistical analysis, we identified 93 hits that reduced EROD activity with a p value ≤ .005 and substantiated 39 of these as positive hits in a secondary screening using endoribonuclease-prepared siRNAs (esiRNAs). Twelve of the corresponding gene products were subsequently confirmed to be necessary for the induction of CYP1A1 messenger RNA by TCDD. None of the candidates were deficient in aryl hydrocarbon nuclear translocator expression. However 6 gene products including UBE2i, RAB40C, CRYGD, DCTN4, RBM5, and RAD50 are required for the expression of AHR as well as for induction of CYP1A1. We also found 2 gene products, ARMC8 and TCF20, to be required for the induction of CYP1A1, but our data are ambiguous as to whether they are required for the expression of AHR. In contrast, SIN3A, PDC, TMEM5, and CD9 are not required for AHR expression but are required for the induction of CYP1A1, implicating a direct role in Cyp1a1 transcription. Our methods, although applied to Cyp1a1, could be modified for identifying proteins that regulate other inducible genes.

Simultaneous Quantification of Limonin, Two Indolequinazoline Alkaloids, and Four Quinolone Alkaloids in Evodia rutaecarpa (Juss.) Benth by HPLC-DAD Method

A simple and efficient HPLC-DAD (225 nm) method was developed and validated for the simultaneous determination of limonin and six key alkaloids (evodiamine, rutaecarpine, 1-methyl-2-undecyl-4(1H)-quinolone, evocarpine, 1-methy-2-[(6Z,9Z)]-6,9-pentadecadienyl-4-(1H)-quinolone, and dihydroevocarpine) in Evodia rutaecarpa (Juss.) Benth, which has been widely used as one of the Traditional Chinese Medicines. The chromatographic separation was carried out on a Hypersil BDS C18 column, and gradient elution was employed with a mobile phase containing acetonitrile and water. Contents of the analytes in 18 batches of samples were analyzed by ultrasonic extraction with ethanol and water mixture (80 : 20, v/v) followed by HPLC analysis. Separation of the seven analytes was achieved within 60 min with good linearity (r > 0.999). The RSD of both the intraday and interday precision was below 1.85%. The accuracy at different concentrations was within the range of 97.91 to 100.49%. Hierarchical clustering analysis was performed to differentiate and classify the samples based on the contents of the seven constituents. This study indicated that the quality control of E. rutaecarpa could be simplified to the measurement of four constituents, and that limonin, 1-methyl-2-undecyl-4(1H)-quinolone, and dihydroevocarpine should also be served as the chemical markers together with evodiamine for the quality control of Evodia rutaecarpa (Juss.) Benth.

Rutaecarpine effects on expression of hepatic phase-1, phase-2 metabolism and transporter genes as a basis of herb-drug interactions

ETHNOPHARMACOLOGICAL RELEVANCE

Rutaecarpine is an alkaloid of Evodia rutaecarpa which is traditionally used to treat human diseases. Rutaecarpine has been used in combination with other drugs in the treatment of disorders and found to produce herb-drug interactions. The basis of these herb-drug interactions is not completely understood.

AIM OF STUDY

To examine the effects of rutaecarpine on the expression of drug processing genes, including Phase-1 (P450 enzyme genes), Phase-2 (glucuronidation and sulfation genes) and Phase-3 (drug transporters) in liver of mice.

MATERIALS AND METHODS

Mice were orally administered rutaecarpine at the doses of 10, 20, and 30 mg/kg for consecutive 7 days. Twenty-four hours after the last dose, blood and liver were collected. Total RNA was isolated, purified, and subjected to real-time RT-PCR analysis of genes of interest.

RESULTS

Rutaecarpine administration induced Cyp1a2, 2b10 and 2e1 as previously reported. Cyp3a11 and Cyp4a10 were also induced. For phase-2 enzyme genes, rutaecarpine increased glucuronyltransferases (Ugt1a1 and Ugt1a6), but had no effects on sulfotransferase (Sult1a1 and Sult1b1). Most interestingly, rutaecarpine increased hepatic uptake of organic anion transporting peptides (Oatp1a1, Oayp1a4, Oatp1b2, and Oatp2b1) and induced efflux transporter such as multidrug resistance-associated proteins (Mrp1, Mrp2, Mrp3, and Mrp4), especially at the doses of 20mg/kg and above.

CONCLUSION

The interactions of rutaecarpine with drugs involve not only the induction of cytochrome P450 enzyme genes, but also the induction of hepatic transporters and phase-2 enzyme genes. The effects of rutaecarpine on these drug processing genes could play integrated roles in producing herb-drug interactions.

CCAAT/ enhancer-binding protein β activation by capsaicin contributes to the regulation of CYP1A1 expression, mediated by the aryl hydrocarbon receptor

BACKGROUND AND PURPOSE

Capsaicin, a constituent of peppers, has been linked to the suppression of tumorigenesis and carcinogenesis. The influence of capsaicin on cytochrome P450 (CYP) 1A1, which is involved in metabolism of carcinogens, and the underlying mechanisms remain unclear. Here, we examined the effect of capsaicin on CYP1A1 expression in mouse hepatoma cells.

EXPERIMENTAL APPROACH

Murine hepatoma Hepa-1c1c7 cells were incubated with capsaicin and/or 3-methylcholanthrene (3-MC). Effects of capsaicin on CYP1A1 levels were determined by analysing mRNA expression, transcription activity and protein expression. Regulation of CYP1A1 was investigated by determining transcriptional factor expression, activation and binding activity with cotreatment with target signal antagonists.

KEY RESULTS

Capsaicin alone slightly induced CYP1A1 activity, mRNA expression, protein level and promoter activity. Treatment with transient receptor potential vanilloid type-1 receptor (TRPV1) or aryl hydrocarbon receptor (AhR) antagonist decreased induction of CYP1A1 expression by capsaicin. Additionally, capsaicin significantly inhibited 3-MC-induced CYP1A1 mRNA and protein level and xenobiotic response element-luciferase activity. Capsaicin also inhibited 3-MC-induced AhR transactivation and nuclear localization of AhRs. Moreover, capsaicin increased Ca(2+) /calmodulin (CaM)-dependent protein kinase (CaMK) and CCAAT/ enhancer-binding protein β (C/EBPβ) activation, downstream of TRPV1 receptors. Capsaicin-induced C/EBPβ activation inhibited induction of CYP1A1 mRNA and protein by 3-MC.

CONCLUSIONS AND IMPLICATIONS

Capsaicin alone weakly induced CYP1A1 expression, and 3-MC-induced CYP1A1 levels were suppressed by capsaicin. Activation of C/EBPβ and inhibition of 3-MC-induced AhR transactivation by capsaicin contributed to the suppression of CYP1A1 expression. Capsaicin has a potential chemopreventive effect through inhibiting induction of CYP1A1 by poly aryl hydrocarbons.

Induction of intracellular calcium concentration by environmental benzo(a)pyrene involves a β2-adrenergic receptor/adenylyl cyclase/Epac-1/inositol 1,4,5-trisphosphate pathway in endothelial cells

Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (B(a)P) are widely distributed environmental contaminants, known as potent ligands of the aryl hydrocarbon receptor (AhR). These chemicals trigger an early and transient increase of intracellular calcium concentration ([Ca(2+)](i)), required for AhR-related effects of PAHs. The mechanisms involved in this calcium mobilization were investigated in the present study. We demonstrated that B(a)P-mediated [Ca(2+)](i) induction was prevented in endothelial HMEC-1 cells by counteracting β2-adrenoreceptor (β2ADR) activity using pharmacological antagonists, anti-β2ADR antibodies, or siRNA-mediated knockdown of β2ADR expression; by contrast, it was strongly potentiated by β2ADR overexpression in human kidney HEK293 cells. B(a)P was shown, moreover, to directly bind to β2ADR, as assessed by in vitro binding assays and molecular modeling. Pharmacological inhibition and/or siRNA-mediated silencing of various signaling actors acting downstream of β2ADR in a sequential manner, such as G protein, adenylyl cyclase, Epac-1 protein, and inositol 1,4,5-trisphosphate (IP(3))/IP(3) receptor, were next demonstrated to prevent B(a)P-induced calcium signal. Inhibition or knockdown of these signaling elements, as well as the use of chemical β-blockers, were finally shown to counteract B(a)P-mediated induction of cytochrome P-450 1B1, a prototypical AhR target gene. Taken together, our results show that B(a)P binds directly to β2ADR and consequently utilizes β2ADR machinery to mobilize [Ca(2+)](i), through activation of a G protein/adenylyl cyclase/cAMP/Epac-1/IP(3) pathway. This β2ADR-dependent signaling pathway activated by PAHs may likely be crucial for PAH-mediated up-regulation of AhR target genes, thus suggesting a contribution of β2ADR to the health-threatening effects of these environmental pollutants.

A common carcinogen benzo[a]pyrene causes p53 overexpression in mouse cervix via DNA damage

Benzo[a]pyrene (BaP) is cytotoxic and/or genotoxic to lung, stomach and skin tissue in the body. However, the effect of BaP on cervical tissue remains unclear. The present study detected DNA damage and the expression of the p53 gene in BaP-induced cervical tissue in female mice. Animals were intraperitoneally injected and orally gavaged with BaP at the doses of 2.5, 5, and 10mg/kg twice a week for 14 weeks. The single-cell gel electrophoresis (SCGE) assay was used to detect the DNA damage. Immunohistochemistry (IHC) and in situ hybridization (ISH) were used to detect the expression of p53 protein and p53 mRNA, respectively. The results showed that BaP induced a significant and dose-dependent increase of the number of cells with DNA damaged and the tail length as well as Comet tail moment in cervical tissue. The expression level of p53 protein and mRNA was increased. The results demonstrate that BaP may show toxic effect on the cervix by increasing DNA damage and the expression of the p53 gene.

RNAi-based screening identifies kinases interfering with dioxin-mediated up-regulation of CYP1A1 activity

Background

The aryl hydrocarbon receptor (AhR) is a transcription factor activated by several environmental pollutants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and involved in carcinogenesis and various physiological processes, including immune response and endocrine functions. Characterization of kinases-related AhR transduction pathway remains an important purpose.

Results

We performed a kinome-wide siRNA screen in human mammary MCF-7 cells to identify non redundant protein kinases implicated in the up-regulation of cytochrome P-450 (CYP) 1A1 activity, an AhR referent target, in response to TCDD exposure. To this aim, we monitored CYP1A1-related ethoxyresorufin-O-deethylase (EROD) activity and quantified cell density. This normalization was crucial since it allowed us to focus only on siRNA affecting EROD activity and discard siRNA affecting cell density. Analyses of the cell density data allowed us to identify several hits already well-characterized as effectors of the cell cycle and original hits. Collectively, these data fully validated the protocol and the siRNA library. Next, 22 novel candidates were identified as kinases potentially implicated in the up-regulation of CYP1A1 in response to TCDD, without alteration of cell survival or cell proliferation. The siRNA library screen gave a limited number of hits (approximately 3%). Interestingly, four of them are able to bind calmodulin among which the IP3 kinase A (ITPKA) and pregnancy up-regulated non-ubiquitously expressed CaM kinase (PNCK, also named CaMKIβ). Remarkably, for both proteins, their kinase activity depends on the calmodulin binding. Involvement of ITPKA and PNCK in TCDD-mediated CYP1A1 up-regulation was further validated by screening-independent expression knock-down. PNCK was finally shown to regulate activation of CaMKIα, a CaMKI isoform previously reported to interplay with the AhR pathway.

Conclusions

These data fully support a role for both IP3-related kinase and CaMK isoforms in the AhR signaling cascade. More generally, this study also highlights the interest of large scale loss-of-function screens for characterizing the molecular mechanism of action of environmental contaminants.

CH223191 is a ligand-selective antagonist of the Ah (Dioxin) receptor

The aryl hydrocarbon (dioxin) receptor (AhR) is a ligand-dependent transcription factor that produces a wide range of biological and toxic effects in many species and tissues. Whereas the best-characterized high-affinity ligands include structurally related halogenated aromatic hydrocarbons (HAHs) and polycyclic aromatic hydrocarbons (PAHs), the AhR is promiscuous and can also be activated by structurally diverse exogenous and endogenous chemicals. However, little is known about how these diverse ligands actually bind to and activate the AhR. Utilizing AhR ligand binding, DNA binding, and reporter gene expression assays, we have identified a novel ligand-selective antagonist (CH223191) that preferentially inhibits the ability of some classes of AhR agonists (2,3,7,8-tetrachlorodibenzo-p-dioxin and related HAHs), but not others (PAHs, flavonoids, or indirubin), to bind to and/or activate the AhR and AhR signal transduction. HAH-specific antagonism of AhR-dependent reporter gene expression by CH223191 was observed with mouse, rat, human, and guinea pig cell lines. Ligand- and species-selective antagonism was also observed with the AhR antagonists 3'-methoxy-4'-nitroflavone and 6,2',4',-trimethoxyflavone. Our results suggest that the differences in the binding by various ligands to the AhR contribute to the observed structural diversity of AhR ligands and could contribute in ligand-specific variation in AhR functionality and the toxic and biological effects of various classes of AhR agonists.

Akti-1/2, an allosteric inhibitor of Akt 1 and 2, efficiently inhibits CaMKIα activity and aryl hydrocarbon receptor pathway

Deregulation of the phosphatidylinositol 3 (PI3) kinase/Akt pathway, resulting in enhanced Akt activity, is one of the most frequent changes in human cancer. Akt has therefore attracted significant attention as an anticancer target in recent years and many Akt inhibitors have been identified, especially Akti-1/2, a non-ATP competitive inhibitor of Akt isoforms 1 and 2. In this study, our results suggest that caution may be required when using Akti-1/2 as a specific inhibitor of Akt since it perfectly inhibits Ca(2+)/CaM-dependent protein kinase (CaMK) Iα activity. Akti-1/2 was thus able to inhibit recombinant CaMKIα activity as efficiently as the CaMK inhibitor KN-93. Moreover, Akti-1/2 prevented the nuclear translocation of aryl hydrocarbon receptor (AhR) in MCF-7 cells in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure, which has been demonstrated to require CaMKI activity. In addition, our results, obtained with a large panel of structurally-unrelated PI3K inhibitors, make unlikely any contribution of PI3K/Akt activity to the AhR pathway. To the best of our knowledge, this is the first report showing that Akti-1/2 has off-target effects at concentration equipotent with Akt inhibition. This may impact on the therapeutic application of Akti-1/2 and structurally-related compounds.