Drug-metabolizing Enzymes Research Articles

Mixed Ru(II)-Ir(III) Complexes as Photoactive Inhibitors of the Major Human Drug Metabolizing Enzyme CYP3A4.

Cytochrome P450 3A4 (CYP3A4) is a crucial enzyme in human drug metabolism. To garner photochemical control over the inhibition of CYP3A4, a potent Ir(III)-based inhibitor of CYP3A4 was complexed with two Ru(II)-based photocaging groups. Chemical, photochemical, and biological properties of the photocaged inhibitors were characterized. Importantly, mixed Ru(II)-Ir(III) complexes strongly absorb green light, which facilitates the photochemical release of the Ir(III) inhibitor from the Ru(II) caging fragment [Ru(tpy)(Me2bpy)]2+, where tpy = 2,2':6',2″-terpyridine and Me2bpy = 6,6'-dimethyl-2,2'-bipyridine. Emission turn on, type II heme binding, and more potent inhibition under light vs dark conditions were observed. The study also demonstrated that a Ru(II)-Ir(III) conjugate can be photoactivated to exert cytotoxic effects on MCF-7 breast cancer cells upon green light exposure. Additionally, a synthesized analogue with one [Ru(TPA)]2+ fragment (TPA = tris(pyridin-2-ylmethyl)amine) and two Ir(III) centers, although resistant to photochemical release, showed strong inhibition of CYP3A4 both in purified form and in CYP3A4-overexpressing HepG2 cells, with nanomolar potency. These mixed Ru(II)-Ir(III) compounds can permeate cell membranes and inhibit CYP3A4, presenting a new class of bioactive compounds.

Age-Dependent Changes in Cytochrome P450 Abundance and Composition in Human Liver.

Cytochrome P450 (CYP) superfamily represents the major drug-metabolizing enzymes responsible for metabolizing over 65% of therapeutic drugs, including those for pediatric use. CYP-ontogeny based physiologically based pharmacokinetic (PBPK) modeling has emerged as useful approach to mechanistically extrapolate adult pharmacokinetic data to children. However, these models integrate physiological differences in the pediatric population including age-dependent differences in the abundances of CYP enzymes. Conventionally, developmental changes in CYP enzymes have been reported using protein abundance and activity data from subcellular fractions such as microsomes, which are prone to high technical variability. Similarly, the available pediatric pharmacokinetic data suffer from the lack of specific CYP substrates, especially in younger children. In the present study, we used viable hepatocytes from 50 pediatric (age, 1 day-18 years) and 8 adult human donors and carried out global proteomics-based quantification of all major hepatic CYP enzymes, including orphan enzymes that have not been studied previously. While CYPs 2B6, 3A5, 4A11, 4F3, and 4V2 did not show a significant association with age, all other quantified isoforms either increased or decreased with age. CYPs 1A2, 2C8, 2C18, and 2C19 were absent or barely detected in the neonatal group, while CYP3A7 was the highest in this group. The >1 to 2 years age group showed the highest total abundance of all CYP enzymes. The age-dependent differences in CYP enzymes reported in this study can be used to develop ontogeny-based PBPK models, which in turn can help improve pediatric dose prediction based on adult dosing, leading to safer drug pharmacology in children. SIGNIFICANCE STATEMENT: We quantified the age-dependent differences in the abundances of hepatic CYP enzymes using a large set of viable pediatric and adult hepatocytes using quantitative global proteomics. We report for the first time the ontogeny in the abundance of CYP enzymes in human hepatocytes, especially, orphan CYPs 20A1, 27A1, 51A1, 7B1, and 8B1 and CYP4 subfamily of enzymes. Our study provides important data about CYP ontogeny that can be used for the better prediction of pediatric pharmacokinetics using physiologically based pharmacokinetic modeling.

Gene-based drug therapy for children and youth treated with psychoactive medications.

Psychoactive medications are increasingly used to treat children and youth with mental health conditions, but individual variations in response highlight the need for precision medicine. Pharmacogenetic (PGx) testing is a key component of precision medicine. The number of commercial pharmacogenetic testing companies promoting PGx, with the promise of achieving individualized and effective treatment of mental health conditions, has grown exponentially in recent years. Scientific evidence supporting the use of PGx to manage mental health conditions is limited, especially for paediatric populations. This practice point outlines steps guiding the use and interpretation of PGx testing for psychoactive medications in clinical settings, along with key supportive resources. Practice guidelines have been developed for variants in pharmacogenes encoding cytochrome P450 drug-metabolizing enzymes (e.g., CYP2C19, CYP2D6, CYP2C9) as one determinant of drug concentrations in blood, which can support both drug choice and dosing strategy for certain anti-psychotics, anti-depressants, and anti-epileptics. Adverse drug reactions to some anti-epileptic drugs (e.g., carbamazepine and phenytoin) have been associated with certain human leukocyte antigen types and variants in DNA polymerase gamma (POLG; valproic acid). Evidence remains limited for genetic variants of drug target proteins, making it challenging to identify patients with altered treatment responses at a therapeutic blood concentration.

The Aryl Hydrocarbon Receptor and Its Crosstalk: A Chemopreventive Target of Naturally Occurring and Modified Phytochemicals.

The aryl hydrocarbon receptor (AhR) is an environmentally sensitive transcription factor (TF) historically associated with carcinogenesis initiation via the activation of numerous carcinogens. Nowadays, the AhR has been attributed to multiple endogenous functions to maintain cellular homeostasis. Moreover, crosstalk, often reciprocal, has been found between the AhR and several other TFs, particularly estrogen receptors (ERs) and nuclear factor erythroid 2-related factor-2 (Nrf2). Adequate modulation of these signaling pathways seems to be an attractive strategy for cancer chemoprevention. Several naturally occurring and synthetically modified AhR or ER ligands and Nrf2 modulators have been described. Sulfur-containing derivatives of glucosinolates, such as indole-3-carbinol (I3C), and stilbene derivatives are particularly interesting in this context. I3C and its condensation product, 3,3'-diindolylmethane (DIM), are classic examples of blocking agents that increase drug-metabolizing enzyme activity through activation of the AhR. Still, they also affect multiple essential signaling pathways in preventing hormone-dependent cancer. Resveratrol is a competitive antagonist of several classic AhR ligands. Its analogs, with ortho-methoxy substituents, exert stronger antiproliferative and proapoptotic activity. In addition, they modulate AhR activity and estrogen metabolism. Their activity seems related to a number of methoxy groups introduced into the stilbene structure. This review summarizes the data on the chemopreventive potential of these classes of phytochemicals, in the context of AhR and its crosstalk modulation.

In Vitro Interaction of Binuclear Copper Complexes with Liver Drug-Metabolizing Cytochromes P450.

Two copper(II) mixed ligand complexes with dicarboxylate bridges were prepared and studied, namely [Cu2(μ-fu)(pmdien)2(H2O)2](ClO4)2 (complex No. 5) and [Cu2(μ-dtdp)(pmdien)2(H2O)2](ClO4)2 (complex No. 6), where H2fu = fumaric acid, pmdien = N,N,N',N″,N″ pentamethyldiethylenetriamine, and H2dtdp = 3,3'-dithiodipropionic acid. The copper atoms are coordinated in the same mode by the tridentate pmdien ligand and oxygen of water molecules, and they only differ in the dicarboxylate bridge. This work is focused on the study of the inhibitory effect of these potential antimicrobial drugs on the activity of the most important human liver drug-metabolizing enzymes, cytochromes P450 (CYP), especially their forms CYP2C8, CYP2C19, and CYP3A4. The obtained results allow us to estimate the probability of potential drug interactions with simultaneously administrated drugs that are metabolized by these CYP enzymes. In conclusion, the presence of adverse effects due to drug-drug interactions with concomitantly used drugs cannot be excluded, and hence, topical application may be recommended as a relatively safe approach.

Drug metabolizing enzymes pharmacogenetic variation-informed antidepressant therapy approach for common mental disorders: A systematic review and meta-analysis

ImportanceCurrently, 30–50 % of individuals with depression and 40 % with anxiety—collectively referred to as common mental disorders (CMDs), exhibit inadequate responses to antidepressant treatments. ObjectiveTo assess the effectiveness and safety of drug-metabolizing enzyme pharmacogenetic variation informed treatment (PGxIT) versus usual antidepressant treatment (UT) in patients with CMDs. Data sourcesA literature search was conducted in the MEDLINE, Scopus, and Cochrane Library databases from inception until January 30, 2024. Study selectionStudies were selected based on CMD diagnoses, reporting on the genetic variations of drug-metabolizing enzyme (DME) genes in relation to antidepressants, involving PGxIT and UT groups with human subjects, and published in English. Data extraction and synthesisData extraction and quality assessment were performed independently by two authors. A pooled risk ratio (RR) with 95 % CI was estimated using both random and fixed-effect models, and heterogeneity was assessed using Cochran's Q test and the I2 statistic. The publication bias of eligible studies was assessed using post hoc Doi plots and the LFK index. ResultsThis systematic review included 18 studies (n = 7021). The PGxIT demonstrated greater efficacy in the remission of symptoms of depressive disorder at 8 weeks (RR 1.523 [95 % CI: 1.255–1.843]; I2 = 48 %) and 12 weeks (RR 1.631 [95 % CI: 1.001–2.657]; I2 = 86 %; p < 0.01), and symptoms of anxiety disorder compared to UT. Additionally, the risk of adverse drug events (ADEs) was significantly lower in the PGxIT group (RR = 0.65 [95 % CI: 0.52–0.82]; I2 = 0 %) than in the UT group. The certainty of evidence for both outcomes was moderate. Conclusions and relevanceThis systematic review and meta-analysis suggest that pharmacogenetically guided antidepressant treatment, based on genetic variation in drug-metabolizing enzymes, is associated with superior efficacy in the remission of symptoms for patients with depressive disorders and a reduction in ADEs compared to usual treatment and the findings of the systematic review for remission in anxiety disorders indicate that, PGx guided treatment is also associated with increased remission of symptoms in anxiety disorders compared to usual treatment.

Prediction of the drug intestinal absorption and drug-induced intestinal toxicity with the use of cultured human/animal crypt-derived intestinal stem cells

Prediction of intestinal drug absorption and drug-induced intestinal toxicity is critical for the development of orally-administered drugs. However, it is difficult to accurately predict these events because of large species differences and a lack of appropriate in vitro assay. Then, we proposed the use of human crypt-derived intestinal cells for the prediction of intestinal absorption and the risk of intestinal toxicity. 3D human intestinal spheroids were established from fresh surgical specimens of proximal jejunum and terminal ileum using the conditioned media containing Wnt3a, R-spondin 3, and noggin. To generate 2D monolayer, spheroids were enzymatically dissociated into single cells and plated onto Matrigel-precoated culture plates/inserts. We have confirmed the activities of typical drug-metabolizing enzymes and uptake/efflux transporters in human jejunal spheroid-derived differentiated cells. Intestinal availability (Fg) estimated from the apical-to-basal permeation clearance across the jejunal monolayer showed a good correlation with in vivo human Fg values for five CYP3A substrate drugs. As for the prediction of intestinal toxicity, we found that the degree of ATP decreases in intestinal spheroids incubated with different EGFR-TKIs varied greatly depending on the drugs and the rank order of the extent of ATP decrease corresponded with that of frequency of clinically-observed diarrhea. We also constructed enterochromaffin (EC) cell-rich spheroids and quantified serotonin release from EC cells upon exposure to drugs for the prediction of drug-induced nausea and vomiting. As a result, we found that the serotonin release was related to the high/low risk of nausea and vomiting of each ALK/ROS1 kinase inhibitors.

Prediction of Cytochrome P450 Substrates Using the Explainable Multitask Deep Learning Models.

Cytochromes P450 (P450s or CYPs) are the most important phase I metabolic enzymes in the human body and are responsible for metabolizing ∼75% of the clinically used drugs. P450-mediated metabolism is also closely associated with the formation of toxic metabolites and drug-drug interactions. Therefore, it is of high importance to predict if a compound is the substrate of a given P450 in the early stage of drug development. In this study, we built the multitask learning models to simultaneously predict the substrates of five major drug-metabolizing P450 enzymes, namely, CYP3A4, 2C9, 2C19, 2D6, and 1A2, based on the collected substrate data sets. Compared to the single-task model and conventional machine learning models, the multitask fingerprints and graph neural networks model achieved superior performance with the average AUC values of 90.8% on the test set. Notably, the multitask model demonstrated its good performance on the small amount of substrate data sets such as CYP1A2, 2C9, and 2C19. In addition, the Shapley additive explanation and the attention mechanism were used to reveal specific substructures associated with P450 substrates, which were further confirmed and complemented by the substructure mining tool and the literature.

Enhanced Maturity and Functionality of Vascularized Human Liver Organoids through 3D Bioprinting and Pillar Plate Culture.

Liver tissues, composed of hepatocytes, cholangiocytes, stellate cells, Kupffer cells, and sinusoidal endothelial cells, are differentiated from endodermal and mesodermal germ layers. By mimicking the developmental process of the liver, various differentiation protocols have been published to generate human liver organoids (HLOs) in vitro using induced pluripotent stem cells (iPSCs). However, HLOs derived solely from the endodermal germ layer often encounter technical hurdles, such as insufficient maturity and functionality, limiting their utility for disease modeling and hepatotoxicity assays. To overcome this, we separately differentiated EpCAM+ endodermal progenitor cells (EPCs) and mesoderm-derived vascular progenitor cells (VPCs) from the same human iPSC line. These cells were then mixed in BME-2 matrix and concurrently differentiated into vascular human liver organoids (vHLOs). Remarkably, vHLOs exhibited significantly higher maturity than vasculature-free HLOs, as demonstrated by increased coagulation factor secretion, albumin secretion, drug-metabolizing enzyme (DME) expression, and bile acid transportation. To enhance assay throughput and miniaturize vHLO culture, we 3D bioprinted expandable HLOs (eHLOs) in BME-2 matrix on a pillar plate platform derived from EPCs and VPCs and compared with HLOs derived from endoderm alone. Compared to HLOs cultured in a 50 μL BME-2 matrix dome in a 24-well plate, vHLOs cultured on the pillar plate exhibited superior maturity, likely due to enhanced nutrient and signaling molecule diffusion. The integration of physiologically relevant patterned liver organoids with the unique pillar plate platform enhanced the capabilities for high-throughput screening and disease modeling.

Developmental Expression of Drug Transporters and Conjugating Enzymes Involved in Enterohepatic Recycling: Implication for Pediatric Drug Dosing.

Around 50% of the drugs used in children have never been tested for safety and efficacy in this vulnerable population. Immature drug elimination pathways can lead to drug toxicity when pediatric doses are determined using empirical methods such as body-surface area or body-weight-normalized adult dosing. In the absence of clinical data, physiologically-based pharmacokinetic (PBPK) modeling has emerged as a useful tool to predict drug pharmacokinetics in children. These models utilize developmental physiological data, including age-dependent differences in the abundance of drug-metabolizing enzymes and transporters (DMET), to mechanistically extrapolate adult pharmacokinetic data to children. The reported abundance data of hepatic DMET proteins in subcellular fractions isolated from frozen tissue are prone to high technical variability. Therefore, we carried out the proteomics-based quantification of hepatic drug transporters and conjugating enzymes in 50 pediatric and 8 adult human hepatocyte samples. Out of the 34 studied proteins, 28 showed a significant increase or decrease with age. While MRP6, OAT7, and SULT1E1 were highest in < 1-year-old samples, the abundance of P-gp and UGT1A4 was negligible in < 1-year-old samples and increased significantly after 1 year of age. Incorporation of the age-dependent abundance data in PBPK models can help improve pediatric dose prediction, leading to safer drug pharmacotherapy in children.

Refining Hepatocyte Models to Capture the Impact of CYP2D6*10 Utilizing a PITCh System.

CYP2D6 variants contain various single nucleotide polymorphisms as well as differing levels of metabolic activity. Among these, one of the less active variants CYP2D6*10 (100C > T) is the most prevalent mutation in East Asians, including Japanese. This mutation leads to an amino acid substitution from proline to serine, which reduces the stability of CYP2D6 and consequently decreases its metabolic activity. In this study, we used a genome editing technology called the Precise Integration into Target Chromosome (PITCh) system to stably express six drug-metabolizing enzymes (CYP3A4, POR, uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1), CYP1A2, CYP2C19, CYP2C9, and CYP2D6*10) in HepG2 (CYP2D6*10 KI-HepG2) cells to examine the effect of CYP2D6*10 on drug metabolism prediction. The protein expression levels of CYP2D6 in CYP2D6*10 KI-HepG2 cells were reduced relative to those in the CYP3A4-POR-UGT1A1-CYP1A2-CYP2C19-CYP2C9-CYP2D6 knock-in-HepG2 (CYPs-UGT1A1 KI-HepG2) cells. Consistent with the CYP2D6 protein expression results, CYP2D6 metabolic activity in CYP2D6*10 KI-HepG2 cells was reduced relative to CYPs-UGT1A1 KI-HepG2 cells. We successfully generated CYP2D6*10 KI-HepG2 cells with highly expressed, functional CYP2D6*10, as well as CYP1A2, 2C9, 2C19 and 3A4. CYP2D6*10 KI-HepG2 cells could be an invaluable model for hepatic metabolism and hepatotoxicity studies in East Asians, including Japanese.

Blood-Brain Barrier Permeability is Affected by Changes in Tight Junction Protein Expression at High-Altitude Hypoxic Conditions-this may have Implications for Brain Drug Transport.

Changes to blood-brain barrier structure and function may affect the delivery of drugs into the brain. It is worthwhile to exploring more study on how the blood-brain barrier changes in structure and function and how that affects drug transport in high-altitude hypoxic environment. The DIA high-throughput sequencing technique indicate that the rats blood-brain barrier has been identified to have 7252 proteins overall and 8 tight junction proteins, among which Claudin-7 was a plateau-specific tight junction protein under high-altitude hypoxia, and based on the interaction network study, 2421 proteins are found to interact with one another, with ZO-1 being the primary target. The results of the projected gene function analysis demonstrated that changes in tight junction proteins are related to the control of TRP channels by inflammatory mediators, the wnt signaling pathway, the ABC transporter system, and drug metabolism-CYP450 enzyme regulation. Additionally, the electron microscopy, the Evans blue combination with confocal laser scanning microscopy, and the Western Blot and RT-qPCR revealed that high-altitude hypoxic environment induces blood-brain barrier tight junctions to open, blood-brain barrier permeability increases, ZO-1, Occludin, Claudin-5 protein and mRNA expression decreased. Our research implies that structural and functional alterations in the blood-brain barrier induced by high altitude hypoxia may impact drug transport inside the central nervous system, and that drug transporters and drug-metabolizing enzymes may be key players in this process.

Uncovering the mechanism of troglitazone-mediated idiosyncratic drug-induced liver injury with individual-centric models

Idiosyncratic drug-induced liver injury is a rare and unpredictable event. Deciphering its initiating-mechanism is a hard task as its occurrence is individual dependent. Thus, studies that utilize models that are not individual-centric might drive to a general mechanistic conclusion that is not necessarily true. Here, we use the individual-centric spheroid model to analyze the initiating-mechanism of troglitazone-mediated iDILI risk. Individual-centric spheroid models were generated using a proprietary cell educating technology. These educated spheroids contain hepatocytes, hepatic stellate cells, activated monocyte-derived macrophages, and dendritic cells under physiological conditions. We show that phases 1 and 2 drug-metabolizing enzymes were induced in an individual-dependent manner. However, we did not observe any association of DEMs induction and troglitazone (TGZ)-mediated iDILI risk. We analyzed TGZ-mediated iDILI and found that a 44-year-old male showed iDILI risk that is associated with TGZ-mediated suppression of IL-12 expression by autologous macrophages and dendritic cells. We performed a rescue experiment and showed that treatment of spheroids from this 44-year-old male with TGZ and recombinant IL-12 suppressed iDILI risk. We confirmed the mechanism in another 31-year-old female with iDILI risk. We demonstrate here that individual-centric spheroid are versatile models that allow to predict iDILI risk and to analyze a direct effect of the drug on activated macrophages and dendritic cells to uncover the initiating-mechanism of iDILI occurrence. This model opens perspectives for a personalized strategy to mitigate iDILI risk.

When less is more: The association between the expression of polymorphic CYPs and AFB1-induced HCC.

An individual's genetic fingerprint is emerging as a pivotal predictor of numerous disease- and treatment-related factors. Single nucleotide polymorphisms (SNPs) in drug-metabolizing enzymes play key roles in an individual's exposure to a malignancy-associated risk, such as Aflatoxin B1 (AFB1)-induced hepatocellular carcinoma (HCC). This study aimed at reviewing literature on the polymorphisms that exist in CYP enzymes and their possible link with susceptibility to AFB1-induced HCC. A set of keywords associated with the study subject of interest was used to search the Google Scholar and the PubMed database. The last ten years' worth of research projects were included in the results filter. The research involved HCC patients and any connection between polymorphic forms of CYP enzymes and their susceptibility to AFB1-induced HCC, including older but significant data. Variations in CYP1A2 and CYP3A4 were reported to impact the rate and magnitude of AFB1 bio-activation, thus influencing an individual's vulnerability to develop HCC. In HCC patients, the activity of CYP isoforms varies, where increased activity has been reported with CYP2C9, CYP2D6, and CYP2E1, while CYP1A2, CYP2C8, and CYP2C19 exhibit decreased activity. CYP2D6*10 frequency has been discovered to differ considerably in HCC patients. Rs2740574 (an upstream polymorphism in CYP3A4 as detected in CYP3A4*1B) and rs776746 (which affects CYP3A5 RNA splicing), both of which influence CYP3A expression, thus impacting the variability of AFB1-epoxide adducts in HCC patients. CYP1A2 is the primary enzyme accountable for the formation of harmful AFBO globally. CYP3A4, CYP3A5, CYP3A7, CYP2B7, and CYP3A3 are also implicated in the bio-activation of AFB1 to mutagenic metabolites. It is thought that CYP3A4 is the protein that interacts with AFB1 metabolism the most. Polymorphic variants of CYP enzymes have a functional impact on the susceptibility to AFB1-induced HCC. Outlining such variation and their implications may provide deeper insights into approaching HCC in a more personalized manner for guiding future risk-assessment, diagnosis, and treatment.

The Comparative Metabolism of a Novel Hepatocellular Carcinoma Therapeutic Agent, 2,3-Diamino-N-(4-(benzo[d]thiazol-2-yl)phenyl)propanamide, in Human and Animal Hepatocytes.

[2,3-diamino-N-(4-(benzo[d]thiazol-2-yl)phenyl)propanamide], named as ETN101, is a novel therapeutic agent for hepatocellular carcinoma. In vitro studies examined ETN101 metabolites in human, mouse, rat, dog, and monkey hepatocytes and identified the drug-metabolizing enzymes involved using cDNA-expressed human recombinant cytochrome P450s (CYPs), carboxylesterases (CESs), N-acetyltransferase (NAT) 1, and human liver cytosol. ETN101 showed similar metabolic stability across hepatocytes from five species, with particularly comparable stability in humans, rats, and monkeys. Its half-life was 75.0 min in humans, 68.9 in rats, 73.1 in monkeys, 120.4 in mice, and 112.7 in dogs. Thirty-four ETN101 metabolites, including the major metabolite M1, were identified using liquid chromatography-high-resolution mass spectrometry. ETN101 was primarily metabolized to M1 and CYP1A2 is exclusively responsible for M1 metabolism. Both NAT1 and NAT2 were responsible for the N-acetylation of M1 to M2. ETN101 remained stable in human CESs. In conclusion, this study provides comprehensive insights into the metabolic characteristics of ETN101, valuable for its toxicological and clinical development.

Dissecting molecular mechanisms underlying the inhibition of β-glucuronidase by alkaloids from Hibiscus trionum: Integrating in vitro and in silico perspectives

β-Glucuronidase, a crucial enzyme in drug metabolism and detoxification, represents a promising target for therapeutic intervention due to its potential to modulate drug pharmacokinetics and enhance therapeutic efficacy. Herein, we assessed the inhibitory potential of phytochemicals from Hibiscus trionum against β-glucuronidase. Grossamide and grossamide K emerged as the most potent β-glucuronidase inhibitors with IC50 values of 0.73 ± 0.03 and 1.24 ± 0.03 μM, respectively. The investigated alkaloids effectively inhibited β-glucuronidase-catalyzed PNPG hydrolysis through a noncompetitive inhibition mode, whereas steppogenin displayed a mixed inhibition mechanism. Molecular docking analyses highlighted grossamide and grossamide K as inhibitors with the lowest binding free energy, all compounds successfully docked into the same main binding site occupied by the reference drug Epigallocatechin gallate (EGCG). We explored the interaction dynamics of isolated compounds with β-glucuronidase through a 200 ns molecular dynamics (MD) simulation. Analysis of various MD parameters revealed that grossamide and grossamide K maintained stable trajectories and demonstrated significant energy stabilization upon binding to β-glucuronidase. Additionally, these compounds exhibited the lowest average interaction energies with the target enzyme. The MM/PBSA calculations further supported these findings, showing the lowest binding free energies for grossamide and grossamide K. These computational results are consistent with experimental data, suggesting that grossamide and grossamide K could be potent inhibitors of β-glucuronidase.

Establishing the capacity to monitor proteins relevant to the study of drug exposure and response using liver-derived extracellular vesicles.

Drug exposure and response is determined by pharmacokinetic (PK) and pharmacodynamic (PD) profiles. Interindividual differences in abundance of drug metabolizing enzymes (DMEs) and drug target proteins underpin PK and PD variability and impact treatment efficacy and tolerability. Extracellular vesicles (EVs) carry protein cargo inherited from originating cells and may be useful for defining differences in key proteins related to hepatic drug metabolism and the treatment of metabolic-associated fatty liver disease (MAFLD). We sought to quantify these proteins in liver-derived EVs and establish the profile relative to paired tissue. EVs were recovered from human liver tissue samples (LT-EV, n = 11). Targeted liquid chromatography with tandem mass spectrometry (LC-MS/MS) assays were employed for absolute quantification of proteins in EV isolates and matched liver tissue. DMEs and MAFLD drug targets were readily detected and quantified in LT-EVs. Twelve of 15 DMEs exhibited moderate to strong correlation (Spearman ⍴ = 0.618-0.973) between tissue and EVs. Correlation in protein abundance was influenced by the extent of extra-hepatic expression of the target. This study provides evidence that key proteins related to PK and PD profiles can be measured in liver-derived EVs and abundance of liver-enriched DMEs are robustly correlated between paired tissue and EVs. The robust detection of protein markers related to drug PD profile in MAFLD opens the possibility to track within-subject changes in MAFLD and lays the foundation for future development of a liver-derived EV liquid biopsy to assess markers of drug exposure and response in vivo.

Pharmacogenomic associations of cyclophosphamide pharmacokinetic candidate genes with 4hydroxycyclophosphamide formation in children with Cancer.

4-hydroxycyclophosphamide (4HCY) is the principal precursor to the cytotoxic metabolite of cyclophosphamide (CY), which is often used as first-line treatment of children with cancer. There is conflicting data regarding the relationship between CY efficacy, toxicity, and pharmacokinetics with the genes encoding proteins involved in 4HCY pharmacokinetics, specifically its formation and elimination. We evaluated germline pharmacogenetics in children with various malignancies receiving their first CY dose. Using linear regression, we analyzed the associations between two pharmacokinetic outcomes - how fast a child cleared CY (i.e., CY clearance) and the ratio of the 4HCY/CY exposure, specifically area under the plasma concentration-time curve (AUC), and 372 single nucleotide polymorphisms (SNP) in 14 drug-metabolizing transporters or enzymes involved in 4HCY formation or elimination. Age was associated with the ratio of 4HCY/CY AUC (P = 0.004); Chemotherapy regimen was associated with CY clearance (P = 0.003). No SNPs were associated with CY clearance or the ratio of 4HCY/CY AUC after controlling for a false discovery rate. Age and chemotherapy regimen, but not germline pharmacogenomics, were associated with CY clearance or the ratio of 4HCY/CY AUC. Other methods, such as metabolomics or lipidomics, should be explored.

OCT1 (SLC22A1) transporter kinetics and regulation in primary human hepatocyte 3D spheroids

3D spheroids of primary human hepatocytes (3D PHH) retain a differentiated phenotype with largely conserved metabolic function and proteomic fingerprint over weeks in culture. As a result, 3D PHH are gaining importance as a model for mechanistic liver homeostasis studies and in vitro to in vivo extrapolation (IVIVE) in drug discovery. However, the kinetics and regulation of drug transporters have not yet been assessed in 3D PHH. Here, we used organic cation transporter 1 (OCT1/SLC22A1) as a model to study both transport kinetics and the long-term regulation of transporter activity via relevant signalling pathways. The kinetics of the OCT1 transporter was studied using the fluorescent model substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP+) and known OCT1 inhibitors in individual 3D PHH. For long-term studies, 3D PHH were treated with xenobiotics for seven days, after which protein expression and OCT1 function were assessed. Global proteomic analysis was used to track hepatic phenotypes as well as prototypical changes in other regulated proteins, such as P-glycoprotein and Cytochrome P450 3A4. ASP+ kinetics indicated a fully functional OCT1 transporter with a Km value of 14 ± 4.0µM as the mean from three donors. Co-incubation with known OCT1 inhibitors decreased the uptake of ASP+ in the 3D PHH spheroids by 35–52%. The long-term exposure studies showed that OCT1 is relatively stable upon activation of nuclear receptor signalling or exposure to compounds that could induce inflammation, steatosis or liver injury. Our results demonstrate that 3D PHH spheroids express physiologically relevant levels of fully active OCT1 and that its transporter kinetics can be accurately studied in the 3D PHH configuration. We also confirm that OCT1 remains stable and functional during the activation of key metabolic pathways that alter the expression and function of other drug transporters and drug-metabolizing enzymes. These results will expand the range of studies that can be performed using 3D PHH.

Roles of Individual Human Cytochrome P450 Enzymes in Drug Metabolism.

Our knowledge of the roles of individual cytochrome P450 (P450) enzymes in drug metabolism has developed considerably in the past 30 years, and this base has been of considerable use in avoiding serious issues with drug interactions and issues due to variations. Some newer approaches are being considered for "phenotyping" metabolism reactions with new drug candidates. Endogenous biomarkers are being used for noninvasive estimation of levels of individual P450 enzymes. There is also the matter of some remaining "orphan" P450s, which have yet to be assigned reactions. Practical problems that continue in drug development include predicting drug-drug interactions, predicting the effects of polymorphic and other P450 variations, and evaluating interspecies differences in drug metabolism, particularly in the context of "metabolism in safety testing" regulatory issues ["disproportionate (human) metabolites"]. SIGNIFICANCE STATEMENT: Cytochrome P450 enzymes are the major catalysts involved in drug metabolism. The characterization of their individual roles has major implications in drug development and clinical practice.