CYP Activity Research Articles

Evaluation of Beta-Cyfluthrin Resistance of Cigarette Beetle (Coleoptera: Anobiidae) from Cigarette Manufacturing Factories of China and Underlying Metabolic Mechanisms Responsible for Resistance.

Beta-cyfluthrin, as a synthetic pyrethroid, has been widely used in cigarette manufacturing factories in China to control Lasioderma serricorne (F.) (Coleoptera: Anobiidae). In this study, spray toxicity bioassays and filter paper residual contact toxicity bioassays were conducted to investigate the beta-cyfluthrin sensitivity level of five field strains of L. serricorne collected from cigarette manufacturing factories in China. Bioassay results indicated that five field strains had developed different levels of resistance to beta-cyfluthrin with RR50 of 3.51-10.20 at 2 hr after application and 4.05-49.50 at 24 hr after application in spray toxicity bioassays, and RR50 of 4.74-14.47 at 2 hr exposure in filter paper residual contact bioassays. In addition, we examined CarE, GST, and CYP450 enzyme activity and content of L. serricorne adults and larvae. Enzyme-linked immunosorbent assay results suggested that there was no significant difference in GST, CYP450, and CarE content of L. serricorne adults between field strains and reference sensitive strain. Biochemical assay results indicated that CYP450 activity of L. serricorne adults and larvae of five field strains was significantly higher than that of reference sensitive strain, with increased CYP450 activity of 1.08-1.82-fold in adults and 1.08-2.12-fold in larvae. The results implied that elevated CYP450 activity may contribute to metabolic resistance of L. serricorne to pyrethroid. Our study indicated that there was no clear evidence that the enhanced CarE and GST activity was associated with pyrethroid resistance of L. serricorne.

Comparison of gene expression and biotransformation activity of HepaRG cells under static and dynamic culture conditions

Flow conditions have been shown to be important in improving longevity and functionality of primary hepatocytes, but the impact of flow on HepaRG cells is largely unknown. We studied the expression of genes encoding CYP enzymes and transporter proteins and CYP1 and CYP3A4 activity during 8 weeks of culture in HepaRG cells cultured under static conditions (conventional 24-/96-well plate culture with common bicarbonate/CO2 buffering) and under flow conditions in an organ-on-chip (OOC) device. Since the OOC-device is a closed system, bicarbonate/CO2 buffering was not possible, requiring application of another buffering agent, such as HEPES. In order to disentangle the effects of HEPES from the effects of flow, we also applied HEPES-supplemented medium in static cultures and studied gene expression and CYP activity. We found that cells cultured under flow conditions in the OOC-device, as well as cells cultured under static conditions with HEPES-supplemented medium, showed more stable gene expression levels. Furthermore, only cells cultured in the OOC-device showed relatively high baseline CYP1 activity, and their gene expression levels of selected CYPs and transporters were most similar to gene expression levels in human primary hepatocytes. However, there was a decrease in baseline CYP3A4 activity under flow conditions compared to HepaRG cells cultured under static conditions. Altogether, the present study shows that HepaRG cells cultured in the OOC-device were more stable than in static cultures, being a promising in vitro model to study hepatoxicity of chemicals upon chronic exposure.

Sulfated modification enhances the modulatory effect of yam polysaccharide on gut microbiota in cyclophosphamide-treated mice

Our previous study has demonstrated that sulfated yam polysaccharide (SCYP) had a stronger immunomodulatory activity than yam polysaccharide (CYP). In order to investigate how the sulfated modification influence the immunological activity of CYP, this research was mainly focused on the study of gut microbiotal. The results showed that SCYP treatment could increase the digestive enzyme activities of colon contents and restore the production of short-chain fatty acids (SCFAs) in mice that were decreased by cyclophosphamide (Cy) treatment. Furthermore, SCYP treatment could modulate the structure of the gut microbiota, which was mainly manifest in the result of an increased abundances of Lactobacillus, Bacteroidetes and Akkermansia, and the decrease of the proportion of Proteobacteria and Verrucomicrobia in the microbial community. Diversity and overall structure of microbial community were also improved by SCYP treatment based on alpha-diversity and beta-diversity analysis results. The biomarkers of the gut microbial that were regulated by SCYP have been identified by linear discriminant analysis (LDA) effect size (LEfSe). These findings further indicate that there is great potential for SCYP to be developed into prebiotics or functional foods.

In vitro study on the effect of cornin on the activity of cytochrome P450 enzymes

BackgroundCornin is a commonly used herb in cardiology for its cardioprotective effect. The effect of herbs on the activity of cytochrome P450 enzymes (CYP450s) can induce adverse drug-drug interaction even treatment failure. Therefore, it is necessary to investigate the effect of cornin on the activity of CYP450s, which can provide more guidance for the clinical application of cornin.MethodsCornin (100 μM) was incubated with eight isoforms of CYP450s, including CYP1A2, 2A6, 3A4, 2C8, 2C9, 2C19, 2D6, and 2E1, in pooled human liver microsomes. The inhibition model and corresponding parameters were also investigated.ResultsCornin exerted significant inhibitory effect on the activity of CYP3A4, 2C9, and 2E1 in a dose-dependent manner with the IC50 values of 9.20, 22.91, and 14.28 μM, respectively (p < 0.05). Cornin inhibited the activity of CYP3A4 non-competitively with the Ki value of 4.69 μM, while the inhibition of CYP2C9 and 2E1 by cornin was competitive with the Ki value of 11.31 and 6.54 μM, respectively. Additionally, the inhibition of CYP3A4 by cornin was found to be time-dependent with the KI/Kinact value of 6.40/0.055 min− 1·μM− 1.ConclusionsThe inhibitory effect of cornin on the activity of CYP3A4, 2C9, and 2E1 indicated the potential drug-drug interaction between cornin and drugs metabolized by these CYP450s, which needs further investigation and validation.

Potential cytochrome P450-mediated pharmacokinetic interactions between herbs, food, and dietary supplements and cancer treatments.

Herbs, food and dietary supplements (HFDS), can interact significantly with anticancer drug treatments via cytochrome p450 isoforms (CYP) CYP3A4, CYP2D6, CYP1A2, and CYP2C8. The objective of this review was to assess the influence of HFDS compounds on these cytochromes. Interactions with CYP activities were searched for 189 herbs and food products, 72 dietary supplements in Web of Knowledge® databases. Analyses were made from 140 of 3125 clinical trials and 236 of 3374 in vitro, animal model studies or case reports. 18 trials were found to report direct interactions between 9 HFDS with 8 anticancer drugs. 21 HFDS were found to interact with CYP3A4, a major metabolic pathway for many anticancer drugs. All 261 HFDS were classified for their interaction with the main cytochromes P450 involved in the metabolism of anticancer drugs. We provided an easy-to-use colour-coded table to easily match potential interactions between 261 HFDS and 117 anticancer drugs.

Creation of a new class of radiosensitizers for glioblastoma based on the mibefradil pharmacophore.

Glioblastoma (GBM) is the most common primary malignant tumor of the central nervous system with a dismal prognosis. Locoregional failure is common despite high doses of radiation therapy, which has prompted great interest in developing novel strategies to radiosensitize these cancers. Our group previously identified a calcium channel blocker (CCB), mibefradil, as a potential GBM radiosensitizer. We discovered that mibefradil selectively inhibits a key DNA repair pathway, alternative non-homologous end joining. We then initiated a phase I clinical trial that revealed promising initial efficacy of mibefradil, but further development was hampered by dose-limiting toxicities, including CCB-related cardiotoxicity, off-target hERG channel and cytochrome P450 enzymes (CYPs) interactions. Here, we show that mibefradil inhibits DNA repair independent of its CCB activity, and report a series of mibefradil analogues which lack CCB activity and demonstrate reduced hERG and CYP activity while retaining potency as DNA repair inhibitors. We present in vivo pharmacokinetic studies of the top analogues with evidence of brain penetration. We also report a targeted siRNA-based screen which suggests a possible role for mTOR and Akt in DNA repair inhibition by this class of drugs. Taken together, these data reveal a new class of mibefradil-based DNA repair inhibitors which can be further advanced into pre-clinical testing and eventually clinical trials, as potential GBM radiosensitizers.

The contribution of detoxification pathways to pyrethroid resistance in Hyalella azteca

Chronic exposure to pyrethroid insecticides can result in strong selective pressures on non-target species in aquatic systems and drive the evolution of resistance and population-level changes. Characterizing the underlying mechanisms of resistance is essential to better understanding the potential consequences of contaminant-driven microevolution. The current study found that multiple mechanisms enhance the overall tolerance of Hyalella azteca to the pyrethroid permethrin. In H. azteca containing mutations in the voltage-gated sodium channel (VGSC), both adaptation and acclimation played a role in mitigating the adverse effects of pyrethroid exposures. Pyrethroid resistance is primarily attributed to the heritable mutation at a single locus of the VGSC, resulting in reduced target-site sensitivity. However, additional pyrethroid tolerance was conferred through enhanced enzyme-mediated detoxification. Cytochrome P450 monooxygenases (CYP450) and general esterases (GE) significantly contributed to the detoxification of permethrin in H. azteca. Over time, VGSC mutated H. azteca retained most of their pyrethroid resistance, though there was some increased sensitivity from parent to offspring when reared in the absence of pyrethroid exposure. Permethrin median lethal concentrations (LC50s) declined from 1809 ng/L in parent (P0) individuals to 1123 ng/L in the first filial (F1) generation, and this reduction in tolerance was likely related to alterations in acclimation mechanisms, rather than changes to target-site sensitivity. Enzyme bioassays indicated decreased CYP450 and GE activity from P0 to F1, whereas the VGSC mutation was retained. The permethrin LC50s in resistant H. azteca were still two orders-of-magnitude higher than non-resistant populations indicating that the largest proportion of resistance was maintained through the inherited VGSC mutation. Thus, the noted variation in tolerance in H. azteca is likely associated with inducible traits controlling enzyme pathways. A better understanding of the mechanistic and genomic basis of acclimation is necessary to more accurately predict the ecological and evolutionary consequences of contaminant-driven change in H. azteca.

Isolation of Primary Rat Hepatocytes with Multiparameter Perfusion Control.

Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure for primary hepatocyte isolation is technically challenging, especially in portal vein cannulation. The procedure is also prone to occasional contamination and variations in perfusion conditions due to difficulties in the assembly, optimization, or maintenance of the perfusion setup. Here, a detailed protocol for an improved two-step collagenase perfusion procedure with multiparameter perfusion control is presented. Primary rat hepatocytes were successfully and reliably isolated by taking the necessary technical precautions at critical steps of the procedure, and by reducing the operational difficulty and mitigating the variability of perfusion parameters through the adoption of a special intravenous catheter, standardized sterile disposable tubing, temperature control, and real-time monitoring and alarm system. The isolated primary rat hepatocytes consistently exhibit high cell viability (85%-95%), yield (2-5 x 108 cells per 200-300 g rat) and functionality (albumin, urea and CYP activity). The procedure was complemented by an integrated perfusion system, which is compact enough to be set up in the laminar flow hood to ensure aseptic operation.

Early closure mechanisms of the ductus arteriosus in immature infants.

According to experimental studies, cardiopulmonary distress decreases after closure of patent ductus arteriosus. However, early closure of the ductus using ibuprofen or indomethacin has failed to increase survival without serious morbidity. We review relevant data aiming to define optimal early management strategies that promote early closure of ductus arteriosus without serious adverse effects. Literature in English was searched selectively focusing on the potential of using acetaminophen for early closure of the ductus. Prophylactic ibuprofen or indomethacin intended to close the ductus, predisposes infants to ischaemia, bleeding and immune dysfunction. Acetaminophen appears to have a similar efficacy as indomethacin or ibuprofen, and all three dose-dependently constrict the ductus. Ibuprofen and indomethacin cause non-specific inhibition of prostaglandin synthesis, while acetaminophen predominantly inhibits prostaglandin E synthesis. Owing to low CYP450 activity in infancy, acetaminophen toxicity has been rarely evident. However, increasing the dosage increases the oxidative stress. We review prophylactic treatments that may increase the safety and efficacy of acetaminophen. These include vitamin A, cysteine and glutamine, and low-dose corticosteroid supplementation. The current challenge is to define a safe perinatal management practice that promotes cardiorespiratory adaptation in immature infants, particularly the seamless closure of the ductus before significant cardiopulmonary distress develops.

Effects of long-term alcohol exposure on the pharmacokinetic profiles of ketamine and norketamine in rats.

Alcohol abuse has become a serious health issue worldwide. Ketamine can reduce addiction risk among patients with alcohol use disorders. This study aimed to determine the effects of alcohol on the pharmacokinetics of ketamine during long-term alcohol exposure. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of ketamine and norketamine was developed and validated. A total of 15 rats were given 40% alcohol for 3 weeks. The pharmacokinetics of ketamine were measured at time zero, 1 week, 2 weeks, and 3 weeks after alcohol exposure. The metabolic capability of liver CYP450 was evaluated using three probe drugs: metoprolol, phenacetin, and tolbutamide. During drinking of 40% alcohol, the AUC(0-t), AUC(0-∞), and Cmax of ketamine and norketamine significantly increased, while V and CL significantly decreased with time (p<0.001). The pharmacokinetic changes of norketamine were highly consistent with ketamine. Additionally, the concentration ratio of norketamine/ketamine in sample time also decreased over time. However, there were no pharmacokinetic changes of three probe drugs, which indicated there was no significant change of liver CYPs activities. Alcohol significantly increases plasma concentration of ketamine and norketamine. The effect of alcohol on pharmacokinetics of ketamine should be considered in clinical therapy.

Preliminary in vitro assessment of pharmacokinetic drug-drug interactions of EST64401 and EST64514, two sigma-1 receptor antagonists

EST64401 and EST64514 are two selective sigma-1 receptor ligands that showed a good profile in a lead optimization process for oral pain treatment. Their potential for pharmacokinetic-based drug-drug interactions was assessed to anticipate clinical interactions. Both compounds showed a low potential for CYP inhibition with percentages of inhibition <50% at 1 µM in recombinant human CYPs (CYP1A2, 2C9, 2C19, 2D6 and 3A4) and IC50 ≥75 µM for CYP3A4 and 2D6 in human liver microsomes. No CYP induction was observed for CYP1A2, 2B6 and 3A4 at concentrations ≤25 µM (EST64401) or ≤50 µM (EST64514) in human hepatocytes using as endpoints CYP activities and mRNA levels. More than one enzyme participated in compound metabolism. The main enzymes involved were CYP3A4 for EST64401 and CYP2D6 besides CYP3A4 for EST64514. Neither EST64401 nor EST64514 seemed to be substrates of P-gp or BCRP in Caco-2 cells (efflux ratio ≤2). Transporter inhibition was observed at concentrations ≥20 µM; EST64401 only inhibiting P-gp at higher concentrations (≥125 µM). Preliminary in vitro interaction studies suggest a similar profile for EST64401 and EST64514. Therefore, other properties will have to be considered for compound differentiation and selection for further development.

Anthraquinones inhibit cytochromes P450 enzyme activity in silico and in vitro.

Anthraquinones exhibit various pharmacological activities (e.g., antioxidant and laxative) and are commonly found in consumer products including foods, dietary supplements, drugs, and traditional medicines. Despite their widespread use, there are limited data available on their toxicokinetic properties. Cytochrome P450 enzymes (CYPs) in the liver play major roles in metabolizing exogenous chemicals (e.g., pharmaceuticals, food ingredients, and environmental pollutants) and endogenous biomolecules (e.g., steroid hormones and cholesterol). Inhibition of CYP activities may lead to serious interactions among these compounds. Here, in silico (quantitative structure-activity relationship modeling) and in vitro (human recombinant enzymes and liver microsomes) methods were used to identify inhibitors of five major CYP isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) among 22 anthraquinones. First, in silico prediction and in vitro human recombinant enzyme assays were conducted for all compounds, and results showed that most of the anthraquinones were potent CYP1A2 inhibitors. Second, five selected anthraquinones (emodin, aloe-emodin, rhein, purpurin, and rubiadin) were further evaluated in human liver microsomes. Finally, plasma concentrations of the five anthraquinones in animal and humans were identified in the literature and compared to their in vitro inhibition potency (IC50 values) towards CYP activities. Emodin, rhein, and aloe-emodin inhibited activities of multiple CYPs in human liver microsomes and potential in vivo inhibition may occur due to their high plasma concentrations. These in silico and in vitro results enabled rapid identification of potential CYP inhibitors and prioritized future in-depth studies.

Pogostone inhibits the activity of CYP3A4, 2C9, and 2E1 in vitro

Context Pogostone possesses various pharmacological activities, which makes it widely used in the clinic. Its effect on the activity of cytochrome P450 enzymes (CYP450s) could guide its clinical combination. Objective To investigate the effect of pogostone on the activity of human CYP450s. Materials and methods The effect of pogostone on the activity of CYP450s was evaluated in human liver microsomes (HLMs) compared with blank HLMs (negative control) and specific inhibitors (positive control). The corresponding parameters were obtained with 0–100 μM pogostone and various concentrations of substrates. Results Pogostone was found to inhibit the activity of CYP3A4, 2C9, and 2E1 with the IC50 values of 11.41, 12.11, and 14.90 μM, respectively. The inhibition of CYP3A4 by pogostone was revealed to be performed in a non-competitive and time-dependent manner with the Ki value of 5.69 μM and the KI/Kinact value of 5.86/0.056/(μM/min). For the inhibition of CYP2C9 and 2E1, pogostone acted as a competitive inhibitor with the Ki value of 6.46 and 7.67 μM and was not affected by the incubation time. Discussion and conclusions The inhibitory effect of pogostone on the activity of CYP3A4, 2C9, and 2E1 has been disclosed in this study, implying the potential risk during the co-administration of pogostone and drugs metabolized by these CYP450s. The study design provides a reference for further in vivo investigations to validate the potential interaction.

Cytochrome P450 expression, induction and activity in human induced pluripotent stem cell-derived intestinal organoids and comparison with primary human intestinal epithelial cells and Caco-2 cells

Human intestinal organoids (HIOs) are a promising in vitro model consisting of different intestinal cell types with a 3D microarchitecture resembling native tissue. In the current study, we aimed to assess the expression of the most common intestinal CYP enzymes in a human induced pluripotent stem cell (hiPSC)-derived HIO model, and the suitability of that model to study chemical-induced changes in CYP expression and activity. We compared this model with the commonly used human colonic adenocarcinoma cell line Caco-2 and with a human primary intestinal epithelial cell (IEC)-based model, closely resembling in vivo tissue. We optimized an existing protocol to differentiate hiPSCs into HIOs and demonstrated that obtained HIOs contain a polarized epithelium with tight junctions consisting of enterocytes, goblet cells, enteroendocrine cells and Paneth cells. We extensively characterized the gene expression of CYPs and activity of CYP3A4/5, indicating relatively high gene expression levels of the most important intestinal CYP enzymes in HIOs compared to the other models. Furthermore, we showed that CYP1A1 and CYP1B1 were induced by β-naphtoflavone in all three models, whereas CYP3A4 was induced by phenobarbital and rifampicin in HIOs, in the IEC-based model (although not statistically significant), but not in Caco-2 cells. Interestingly, CYP2B6 expression was not induced in any of the models by the well-known liver CYP2B6 inducer phenobarbital. In conclusion, our study indicates that hiPSC-based HIOs are a useful in vitro intestinal model to study biotransformation of chemicals in the intestine.

Assessment of Herb-drug Interactions Based on the Pharmacokinetic Changes of Probe Drug, Midazolam.

In healthy volunteers, the probe drug method is widely practised to assess the pharmacokinetic mediated herb-drug interactions (HDI). We analyzed the clinical evidence of CYP3 A4 probe drug, Midazolam. Literatures, where Midazolam was used as a probe drug for prediction of herb-drug interaction, were surveyed through an online database such as google scholar, Scopus, Cochrane, PubMed and clinicaltrials.gov. Midazolam was considered a sensitive probe for CYP3A4 substrates due to its bioavailability. We observed that not all the herbs are causing drug interaction. However, significant changes of the Midazolam pharmacokinetics were found after high-dose and long-term intake of some herbs and food supplements, suggesting the induction and/or inhibition of CYP activities. Probe drug technique is one of the easiest ways for predicting CYP enzyme-mediated herb-drug interactions. Midazolam shows a good response in clinical studies because of short halflife and low harmfulness compared with other probe drugs.

CYP2C and CYP2B Mediated Metabolic Activation of Retrorsine in Cyp3a Knockout Mice.

Retrorsine is one of the hepatotoxic pyrrolizidine alkaloids, which could be converted into a highly reactive metabolite, dehydroretrorsine, by CYP3A, and to a lesser extent by CYP2C and CYP2B. We employed Cyp3a knockout (3AKO) mice to investigate whether the absence of CYP3A could attenuate dehydroretrorsine formation and the role of CYP2C and CYP2B in the formation. Blood and liver samples were collected after intragastrical administration of 35 mg/kg retrorsine or saline for seven days in wild-type (WT) and 3AKO mice. Blood pyrrole-protein adducts were semi quantified by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. The formations of glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (GSH-DHP) and the activities of CYP3A, CYP2B and CYP2C were evaluated in the liver microsomes of WT and 3AKO mice before and after treatment. The metabolic phenotype of retrorsine was determined in human liver microsomes. The gene and protein expression of retrorsine metabolism-related CYP450s in the liver was measured by quantitative real-time PCR method and western blotting method. The serum cytokine level was detected by the ELISA method to reveal the potential mechanism of Cyp3a, Cyp2b and Cyp2c downregulation. After an oral administration of 35 mg/kg retrorsine for seven days, the blood exposures of DHP adducts between WT and 3AKO mice were similar, consistent with the comparable formation of GSH-DHP in their liver microsomes. The chemical inhibitor experiment in liver microsomes indicated the predominant role of CYP3A and CYP2C in GSH-DHP formation in WT and 3AKO mice, respectively. Real-time qPCR analysis showed that the expressions of Cyp2b10 and Cyp2cs increased 2.3-161-fold in 3AKO mice, which was consistent with protein changes. The increased CYP2B activity in 3AKO mice supported the potential role of CYP2B in GSH-DHP formation. After a seven-day treatment of retrorsine, the yields of GSH-DHP were lower than the untreated ones in both alleles, accompanied by the decreased mRNA of Cyp3a, Cyp2b and Cyp2c. The increased serum IL6 might mediate the retrorsine-induced downregulation of Cyp450s. These data demonstrated the increased transcription of Cyp2c and Cyp2b caused by Cyp3a ablation, which played a vital role in the metabolic activation of retrorsine, and long-term exposure of retrorsine can reduce the CYP450 activities.

Impact of Plasmodium vivax malaria and antimalarial treatment on cytochrome P450 activity in Brazilian patients.

To investigate the impact of Plasmodium vivax malaria and chloroquine-primaquine chemotherapy on CYP2D6 and CYP2C19 activity in patients from the Brazilian Amazon. Adult patients (n = 30) were given subtherapeutic doses of CYP2D6 and CYP2C19 phenotypic probes metoprolol (10 mg) and omeprazole (2 mg) in three different stages of vivax malaria illness: acute disease (study phase 1), post chemotherapy (phase 2) and convalescence (stage 3). Plasma concentrations of probes and CYP-hydroxylated metabolites (α-OH metoprolol and 5-OH omeprazole) were measured using LC/MS/MS. Two pharmacokinetic metrics were used to estimate CYP activity: (a) ratio of plasma concentrations of probe/metabolite at 240 minutes after administration of the probes and (b) ratio of areas under the time-concentration curves for probe/metabolite (AUC0-12h ). For statistical analysis, the pharmacokinetic metrics were normalized to the respective values in phase 3. Taqman assays were used for CYP2D6 and CYP2C19 genotyping. Cytokines levels were measured using cytometric bead array. Both pharmacokinetic metrics for metoprolol and omeprazole, and plasma concentrations of cytokines IL-6, IL-8 and IL-10 varied significantly across the three study phases (ANOVA P < 0.0001). Post hoc tests showed greater metoprolol:α-OH metoprolol ratios in phases 1 and 2 compared to phase 3, larger omeprazole:5-OH omeprazole ratios in phase 1 than in phases 2 and 3, and higher circulating IL-6, IL-8 and IL-10 in phase 1 than in phases 2 and 3. P. vivax malaria and treatment altered CYP2D6 and CYP2C19 metabolic phenotypes. CYP2C19 inhibition is attributed to a higher level of circulating proinflammatory cytokines, while suppression of CYP2D6 is ascribed mainly to chloroquine exposure.

Role of Citrus Limonoid as a Possible Bioavailability Enhancer

The oral delivery is the most practical route to deliver drugs into the body, however drug-metabolizing enzymes and drug transporters can play important roles in modulating drug absorption. This study intended to find a natural bioenhancer for improving drug bioavailability. Two limonoids, including limonin deepoxy and nomilin, isolated from pomelo pulp were studied and the inhibition effects on human CYP3A4 and P-gp were investigated. Testosterone 6β-hydroxylation was performed in recombinant human CYP3A4 to discover the effects on CYP activity. Daunorubicin transport in Caco-2 and calcein-AM uptake in LLC-PK1and LLC-GA5-COL300 were conducted to evaluate the effects on P-gp function. The results show that both limonin deepoxy and nomilin could inhibit CYP3A4 and only nomilin exhibited mechanism-based inhibition. Nomilin was able to inhibit human P-gp in the concentration-dependent manner. Taken together, nomilin demonstrated strong activities on both CYP3A4 and P-gp, indicating that nomilin could possibly be used as a bioavailability enhancer.

A polycyclic aromatic hydrocarbon-enriched environmental chemical mixture enhances AhR, antiapoptotic signaling and a proliferative phenotype in breast cancer cells.

Emerging evidence suggests the role of environmental chemicals, in particular endocrine-disrupting chemicals (EDCs), in progression of breast cancer and treatment resistance, which can impact survival outcomes. However, most research tends to focus on tumor etiology and the effect of single chemicals, offering little insight into the effects of realistic complex mixture exposures on tumor progression. Herein, we investigated the effect of a polycyclic aromatic hydrocarbon (PAH)-enriched EDC mixture in a panel of normal and breast cancer cells and in a tumor organoid model. Cells or organoids in culture were treated with EDC mixture at doses estimated from US adult intake of the top four PAH compounds within the mixture from the National Health and Nutrition Examination Survey database. We demonstrate that low-dose PAH mixture (6, 30 and 300 nM) increased aryl hydrocarbon receptor (AhR) expression and CYP activity in estrogen receptor (ER) positive but not normal mammary or ER-negative breast cancer cells, and that upregulated AhR signaling corresponded with increased cell proliferation and expression of antiapoptotic and antioxidant proteins XIAP and SOD1. We employed a mathematical model to validate PAH-mediated increases in AhR and XIAP expression in the MCF-7 ER-positive cell line. Furthermore, the PAH mixture caused significant growth increases in ER-negative breast cancer cell derived 3D tumor organoids, providing further evidence for the role of a natural-derived PAH mixture in enhancing a tumor proliferative phenotype. Together, our integrated cell signaling, computational and phenotype analysis reveals the underlying mechanisms of EDC mixtures in breast cancer progression and survival.

Synergistic effect of fenpropathrin and paclobutrazol on early life stages of zebrafish (Danio rerio)

Aquatic organisms are usually exposed to various co-existing pollutants. However, toxic effects of pesticide mixtures on aquatic organisms and its potential underlying mechanism still remain unclear. The joint effects of fenpropathrin (FEN) and paclobutrazol (PAC) on zebrafish (Danio rerio) using diverse toxicological endpoints were investigated in the current work. Our data exhibited that the 96-h LC50 values of FEN to zebrafish at multiple life phases ranged from 0.0029 (0.0013–0.0042) to 0.16 (0.082–0.23) mg a.i. L−1, which were lower by comparison to PAC ranging from 13.16 (8.564–21.03) to 23.43 (17.94–29.91) mg a.i. L−1. Combination of FEN and PAC displayed synergistic effect on embryonic zebrafish. Activities of T-SOD, Cu/Zn-SOD and CYP450 were remarkably changed in the majority of single and mixture treatments by comparison to the untreated group. The mRNA levels of 17 genes related to oxidative stress, cellular apoptosis, immune system and endocrine system were assessed, and the data suggested that embryonic zebrafish were affected by both single pesticides and their mixtures. Five genes (P53, tsh, ERα, crh and cxcl-clc) showed greater alterations when exposed to pesticide mixtures by comparison to their individual chemicals. Therefore, it is urgently necessary to conduct more studies on mixture toxicities of different pesticides to explore the chemical mixtures with synergistic interactions.