Uridine diphosphate glucuronosyltransferase 1A1 prevents the progression of liver injury.

BACKGROUND: Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) plays a crucial role in metabolizing and detoxifying endogenous and exogenous substances. However, its contribution to the progression of liver damage remains unclear. AIM: To determine the role and mechanism of UGT1A1 in liver damage progression. METHODS: We investigated the relationship between UGT1A1 expression and liver injury through clinical research. Additionally, the impact and mechanism of UGT1A1 on the progression of liver injury was analyzed through a mouse model study. RESULTS: Patients with UGT1A1 gene mutations showed varying degrees of liver damage, while patients with acute-on-chronic liver failure (ACLF) exhibited relatively reduced levels of UGT1A1 protein in the liver as compared to patients with chronic hepatitis. This suggests that low UGT1A1 levels may be associated with the progression of liver damage. In mouse models of liver injury induced by carbon tetrachloride (CCl4) and concanavalin A (ConA), the hepatic levels of UGT1A1 protein were found to be increased. In mice with lipopolysaccharide or liver steatosis-mediated liver-injury progression, the hepatic protein levels of UGT1A1 were decreased, which is consistent with the observations in patients with ACLF. UGT1A1 knockout exacerbated CCl4- and ConA-induced liver injury, hepatocyte apoptosis and necroptosis in mice, intensified hepatocyte endoplasmic reticulum (ER) stress and oxidative stress, and disrupted lipid metabolism. CONCLUSION: UGT1A1 is upregulated as a compensatory response during liver injury, and interference with this upregulation process may worsen liver injury. UGT1A1 reduces ER stress, oxidative stress, and lipid metabolism disorder, thereby mitigating hepatocyte apoptosis and necroptosis.

Non-canonical transcriptional regulation of the poor prognostic factor UGT2B17 in chronic lymphocytic leukemic and normal B cells.

BACKGROUND: High expression of the glycosyltransferase UGT2B17 represents an independent adverse prognostic marker in chronic lymphocytic leukemia (CLL). It also constitutes a predictive marker for therapeutic response and a drug resistance mechanism. The key determinants driving expression of the UGT2B17 gene in normal and leukemic B-cells remain undefined. The UGT2B17 transcriptome is complex and is comprised of at least 10 alternative transcripts, identified by previous RNA-sequencing of liver and intestine. We hypothesized that the transcriptional program regulating UGT2B17 in B-lymphocytes is distinct from the canonical expression previously characterized in the liver. RESULTS: RNA-sequencing and genomics data revealed a specific genomic landscape at the UGT2B17 locus in normal and leukemic B-cells. RNA-sequencing and quantitative PCR data indicated that the UGT2B17 enzyme is solely encoded by alternative transcripts expressed in CLL patient cells and not by the canonical transcript widely expressed in the liver and intestine. Chromatin accessible regions (ATAC-Seq) in CLL cells mapped with alternative promoters and non-coding exons, which may be derived from endogenous retrotransposon elements. By luciferase reporter assays, we identified key cis-regulatory STAT3, RELA and interferon regulatory factor (IRF) binding sequences driving the expression of UGT2B17 in lymphoblastoid and leukemic B-cells. Electrophoretic mobility shift assays and pharmacological inhibition demonstrated key roles for the CLL prosurvival transcription factors STAT3 and NF-κB in the leukemic expression of UGT2B17. CONCLUSIONS: UGT2B17 expression in B-CLL is driven by key regulators of CLL progression. Our data suggest that a NF-κB/STAT3/IRF/UGT2B17 axis may represent a novel B-cell pathway promoting disease progression and drug resistance.

Activation of the YY1-UGT2B7 Axis Promotes Mammary Estrogen Homeostasis Dysregulation and Exacerbates Breast Tumor Metastasis.

Metastasis is the most common pathway of cancer death. The lack of effective predictors of breast cancer metastasis is a pressing issue in clinical practice. Therefore, exploring the mechanism of breast cancer metastasis to uncover reliable predictors is very important for the clinical treatment of breast cancer patients. In this study, tandem mass tag quantitative proteomics technology was used to detect protein content in primary breast tumor tissue samples from patients with metastatic and nonmetastatic breast cancer at diagnosis. We found that the high expression of yin-yang 1(YY1) is strongly associated with poor prognosis in high-grade breast cancer. YY1 expression was detected in both clinical tumor tissue samples and tumor tissue samples from mammary-specific polyomavirus middle T antigen overexpression mouse model mice. We demonstrated that upregulation of YY1 expression was closely associated with breast cancer metastasis and that high YY1 expression could promote the migratory invasive ability of breast cancer cells. Mechanistically, YY1 directly binds to the UGT2B7 mRNA initiation sequence ATTCAT, thereby transcriptionally regulating the inhibition of UGT2B7 expression. UGT2B7 can regulate the development of breast cancer by regulating estrogen homeostasis in the breast, and the abnormal accumulation of estrogen, especially 4-OHE2, promotes the migration and invasion of breast cancer cells, ultimately causing the development of breast cancer metastasis. In conclusion, YY1 can regulate the UGT2B7-estrogen metabolic axis and induce disturbances in estrogen metabolism in breast tumors, ultimately leading to breast cancer metastasis. Disturbances in estrogen metabolism in the breast tissue may be an important risk factor for breast tumor progression and metastasis SIGNIFICANCE STATEMENT: In this study, we propose for the first time a regulatory relationship between YY1 and the UGT2B7/estrogen metabolism axis and explore the molecular mechanism. Our study shows that the YY1/UGT2B7/estrogen axis plays an important role in the development and metastasis of breast cancer. This study further elucidates the potential mechanisms of YY1-mediated breast cancer metastasis and the possibility and promise of YY1 as a predictor of cancer metastasis.

Human UDP-glucuronosyltransferase 1As catalyze aristolochic acid D O-glucuronidation to form a lesser nephrotoxic glucuronide.

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochic acids (AAs) are naturally occurring nitro phenanthrene carboxylic acids primarily found in plants of the Aristolochiaceae family. Aristolochic acid D (AAD) is a major constituent in the roots and rhizomes of the Chinese herb Xixin (the roots and rhizomes of Asarum heterotropoides F. Schmidt), which is a key material for preparing a suite of marketed Chinese medicines. Structurally, AAD is nearly identical to the nephrotoxic aristolochic acid I (AAI), with an additional phenolic group at the C-6 site. Although the nephrotoxicity and metabolic pathways of AAI have been well-investigated, the metabolic pathway(s) of AAD in humans and the influence of AAD metabolism on its nephrotoxicity has not been investigated yet. AIM OF THE STUDY: To identify the major metabolites of AAD in human tissues and to characterize AAD O-glucuronidation kinetics in different enzyme sources, as well as to explore the influence of AAD O-glucuronidation on its nephrotoxicity. MATERIALS AND METHODS: The O-glucuronide of AAD was biosynthesized and its chemical structure was fully characterized by both 1H-NMR and 13C-NMR. Reaction phenotyping assays, chemical inhibition assays, and enzyme kinetics analyses were conducted to assess the crucial enzymes involved in AAD O-glucuronidation in humans. Docking simulations were performed to mimic the catalytic conformations of AAD in human UDP-glucuronosyltransferases (UGTs), while the predicted binding energies and distances between the deprotonated C-6 phenolic group of AAD and the glucuronyl moiety of UDPGA in each tested human UGT isoenzyme were measured. The mitochondrial membrane potentials (MMP) and reactive oxygen species (ROS) levels in HK-2 cells treated with either AAI, or AAD, or AAD O-glucuronide were tested, to elucidate the impact of O-glucuronidation on the nephrotoxicity of AAD. RESULTS: AAD could be rapidly metabolized in human liver and intestinal microsomes (HLM and HIM, respectively) to form a mono-glucuronide, which was purified and fully characterized as AAD-6-O-ß-D-glucuronide (AADG) by NMR. UGT1A1 was the predominant enzyme responsible for AAD-6-O-glucuronidation, while UGT1A9 contributed to a lesser extent. AAD-6-O-glucuronidation in HLM, HIM, UGT1A1 and UGT1A9 followed Michaelis-Menten kinetics, with the Km values of 4.27 µM, 9.05 µM, 3.87 µM, and 7.00 µM, respectively. Docking simulations suggested that AAD was accessible to the catalytic cavity of UGT1A1 or UGT1A9 and formed catalytic conformations. Further investigations showed that both AAI and AAD could trigger the elevated intracellular ROS levels and induce mitochondrial dysfunction and in HK-2 cells, but AADG was hardly to trigger ROS accumulation and mitochondrial dysfunction. CONCLUSION: Collectively, UGT1A-catalyzed AAD 6-O-glucuronidation represents a crucial detoxification pathway of this naturally occurring AAI analogs in humans, which is very different from that of AAI.

[UGT1A1 gene mutation spectrum with indirect hyperbilirubinemia in children].

Objective: To explore the relevancy between the uridine diphosphate-glucuronylgly-cosyltransferase 1A1 (UGT1A1) gene mutation and the phenotype of indirect hyperbilirubinemia in children. Methods: Sixteen cases with indirect hyperbilirubinemia who visited the Department of Gastroenterology, Children's Hospital of Nanjing Medical University from July 2013 to November 2019 were retrospectively analyzed and were divided into Gilbert syndrome (GS), Crigler-Najjar syndrome type II (CNS-II), and indirect hyperbilirubinemia groups unexplained by UGT1A1 gene mutations. The differences in gene mutation site information and general clinical data were compared. The association between gene mutation spectrum and bilirubin level was explored by t-test analysis. Results: Ten of the sixteen cases with indirect hyperbilirubinemia had GS, three had CNS-II, and three had indirect hyperbilirubinemia unexplained by UGT1A1 gene mutations. A total of six mutation types were detected, of which c.211G > A accounted for 37.5% (6/16), c.1456T > G accounted for 62.5% (10/16), and TATA accounted for 37.5% (6/16), respectively. Compared with the GS group, the CNS group had early disease onset incidence, high serum total bilirubin (t = 5.539, P < 0.05), and indirect bilirubin (t = 5.312, P < 0.05). However, there was no significant difference in direct bilirubin levels (t = 1.223, P > 0.05) and age of onset (t = 0.3611, P > 0.05) between the two groups. There was no significant correlation between the number of UGT1A1 gene mutations and serum bilirubin levels. Children with c.1456T > G homozygous mutations had the highest serum bilirubin levels. Conclusion: The common pathogenic variants of the UGT1A1 gene sequence are c.1456T > G, c.211G > A, and TATA, indicating that these site mutations are related to the occurrence of indirect hyperbilirubinemia and have important guiding significance for the etiological analysis of indirect hyperbilirubinemia in children.

Individual Irinotecan Therapy Under the Guidance of Pre-Treated UGT1A1*6 Genotyping in Gastric Cancer.

Background: Severe delayed diarrhea and hematological toxicity limit the use of irinotecan. Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) is a critical enzyme in irinotecan metabolism. The study aims to investigate the safety and efficacy of irinotecan under the guidance of the pre-treatment UGT1A1 genotype in the second-line treatment of gastric cancer. Methods: This study involved 110 patients. Irinotecan was injected intravenously every 3 weeks, and the dose of irinotecan was determined by polymorphism of the UGT1A1 gene, which was divided into three groups (125 mg/m2: GG type; 100 mg/m2: GA type; 75 mg/m2: AA type). The primary end point was overall survival (OS), the secondary end points were progression-free survival (PFS) and safety. Results: One hundred and seven patients received irinotecan treatment and three patients with AA type received paclitaxel treatment. Among 107 patients, there were no significant differences in PFS (4.8 m vs 4.9 m vs 4.4 m; p = 0.5249) and OS (9.3 m vs 9.3 m vs NA; p = 0.6821) among patients with GG/GA/AA subtypes after dose adjustment. For the patient with homozygosity mutation, treatment was switched to paclitaxel. There were no significant differences in PFS and OS among patients with different alleles or after dose adjustment (p > 0.05). There was a significant difference in the risk of delayed diarrhea (p = 0.000), leukopenia (p = 0.003) and neutropenia (p = 0.000) in patients with different UGT1A1*6 genotypes, while no difference in patients with different UGT1A1*28 genotypes. Additionally, grade 3/4 diarrhea, neutropenia, and leukopenia were significantly more common in AA genotype patients compared to GG (2%, 19%, 24%) or GA (23%, 31%, 31%) genotype patients. Conclusion: Individual irinotecan treatment shows encouraging survival and tolerability outcomes in patients with GG/GA subtype. Irinotecan may be not suitable for patients with AA subtype.

Model-Based Prediction of Irinotecan-Induced Grade 4 Neutropenia in Cancer Patients: Influence of Incorporating Germline Genetic Factors in the Model.

Neutropenia is the major dose-limiting toxicity of irinotecan-based therapy. The objective of this study was to assess whether inclusion of germline genetic variants into a population pharmacokinetic/pharmacodynamic model can improve prediction of irinotecan-induced grade 4 neutropenia and identify novel variants of clinical value. A semimechanistic population pharmacokinetic/pharmacodynamic model was used to predict neutrophil response over time in 197 patients receiving irinotecan. Covariate analysis was performed for demographic/clinical factors and 4,781 genetic variants in 84 drug response- and toxicity-related genes to identify covariates associated with neutrophil response. We evaluated the predictive value of the model for grade 4 neutropenia reflecting different clinical scenarios of available data on identified demographic/clinical covariates, baseline and post-treatment absolute neutrophil counts (ANCs), individual pharmacokinetics, and germline genetic variation. Adding 8 genetic identified covariates (rs10929302 (UGT1A1), rs1042482 (DPYD), rs2859101 (HLA-DQB3), rs61754806 (NR3C1), rs9266271 (HLA-B), rs7294 (VKORC1), rs1051713 (ALOX5), and ABCB1 rare variant burden) to a model using only baseline ANCs improved prediction of irinotecan-induced grade 4 neutropenia from area under the receiver operating characteristic curve (AUC-ROC) of 50-64% (95% confidence interval (CI), 54-74%). Individual pharmacokinetics further improved the prediction to 74% (95% CI, 64-84%). When weekly ANC was available, the identified covariates and individual pharmacokinetics yielded no additional contribution to the prediction. The model including only ANCs at baseline and at week 1 achieved an AUC-ROC of 78% (95% CI, 69-88%). Germline DNA genetic variants may contribute to the prediction of irinotecan-induced grade 4 neutropenia when incorporated into a population pharmacokinetic/pharmacodynamic model. This approach is generalizable to drugs that induce neutropenia and ultimately allows for personalized intervention to enhance patient safety.

UGT1A1 Testing in Breast Cancer: should it become routine practice in patients treated with antibody-drug conjugates?

The use of genetic testing to personalize therapeutic strategies in cancer is rapidly evolving and thus changing the landscape of treatment of oncologic patients. The UGT1A1 gene is an important component for the metabolism and glucoronidation of certain drugs, including irinotecan and sacituzumab govitecan (SG); therefore, various UGT1A1 polymorphisms leading to decreased function of the UGT1A1 enzyme may lead to increased risk of treatment-related side effects. Testing for UGT1A1 polymorphism is not routinely adopted in clinical practice; that is due to the lack of concise studies and recommendations concerning the clinical relevance of this test and its impact on the quality of life of cancer patients. The knowledge regarding UGT1A1 polymorphism and its clinical relevance will be reviewed in this article, as well as the published literature on the association between UGT1A1 polymorphism and the toxicity risk of irinotecan as well as sacituzumab govitecan. The current recommendations and guidelines on UGT1A1 testing will be discussed in detail in the hopes of providing guidance to oncologists in their clinical practice.

Role of microsomal metabolism in bromfenac-induced cytotoxicity.

This study delves into the intricate mechanisms underlying drug-induced liver injury (DILI) with a specific focus on bromfenac, the withdrawn nonsteroidal anti-inflammatory drug. DILI is a pervasive concern in drug development, prompting market withdrawals and posing significant challenges to healthcare. Despite the withdrawal of bromfenac due to DILI, the exact role of its microsomal metabolism in inducing hepatotoxicity remains unclear. Herein, employing HepG2 cells with human liver microsomes and UDP-glucuronic acid (UDPGA), our investigation revealed a substantial increase in bromfenac-induced cytotoxicity in the presence of UDPGA, pointing to the significance of UDP-glucuronosyltransferase (UGT)-dependent metabolism in augmenting toxicity. Notably, among the recombinant UGTs examined, UGT2B7 emerged as a pivotal enzyme in the metabolic activation of bromfenac. Metabolite identification studies disclosed the formation of reactive intermediates, with bromfenac indolinone (lactam) identified as a potential mediator of hepatotoxic effects. Moreover, in cytotoxicity experiments, the toxicity of bromfenac lactam exhibited a 34-fold increase, relative to bromfenac. The toxicity of bromfenac lactam was mitigated by nicotinamide adenine dinucleotide phosphate-dependent metabolism. This finding underscores the role of UGT-dependent metabolism in generating reactive metabolites that contribute to the observed hepatotoxicity associated with bromfenac. Understanding these metabolic pathways and the involvement of specific enzymes, such as UGT2B7, provides crucial insights into the mechanisms of bromfenac-induced liver injury. In conclusion, this research sheds light on the metabolic intricacies leading to cytotoxicity induced by bromfenac, especially emphasizing the role of UGT-dependent metabolism and the formation of reactive intermediates like bromfenac lactam. These findings offer insight into the mechanistic basis of DILI and emphasize the importance of understanding metabolism-mediated toxicity.

Hepatic glucuronidation of tetrabromobisphenol A and tetrachlorobisphenol A: interspecies differences in humans and laboratory animals and responsible UDP-glucuronosyltransferase isoforms in humans.

Tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA), bisphenol A (BPA) analogs, are endocrine-disrupting chemicals predominantly metabolized into glucuronides by UDP-glucuronosyltransferase (UGT) enzymes in humans and rats. In the present study, TBBPA and TCBPA glucuronidation by the liver microsomes of humans and laboratory animals (monkeys, dogs, minipigs, rats, mice, and hamsters) and recombinant human hepatic UGTs (10 isoforms) were examined. TBBPA glucuronidation by the liver microsomes followed the Michaelis-Menten model kinetics in humans, rats, and hamsters and the biphasic model in monkeys, dogs, minipigs, and mice. The CLint values based on the Eadie-Hofstee plots were mice (147) > monkeys (122) > minipigs (108) > humans (100) and rats (98) > dogs (81) > hamsters (47). TCBPA glucuronidation kinetics by the liver microsomes followed the biphasic model in all species except for minipigs, which followed the Michaelis-Menten model. The CLint values were monkeys (172) > rats (151) > mice (134) > minipigs (104), dogs (102), and humans (100) > hamsters (88). Among recombinant human UGTs examined, UGT1A1 and UGT1A9 showed higher TBBPA and TCBPA glucuronidation abilities. The kinetics of TBBPA and TCBPA glucuronidation followed the substrate inhibition model in UGT1A1 and the Michaelis-Menten model in UGT1A9. The CLint values were UGT1A1 (100) > UGT1A9 (42) for TBBPA glucuronidation and UGT1A1 (100) > UGT1A9 (53) for TCBPA glucuronidation, and the activities at high substrate concentration ranges were higher in UGT1A9 than in UGT1A1 for both TBBPA and TCBPA. These results suggest that the glucuronidation abilities toward TBBPA and TCBPA in the liver differ extensively across species, and that UGT1A1 and UGT1A9 expressed in the liver mainly contribute to the metabolism and detoxification of TBBPA and TCBPA in humans.

A high-affinity fluorescent probe for human uridine-disphosphate glucuronosyltransferase 1A9 function monitoring under environmental pollutant exposure.

Uridine-disphosphate glucuronosyltransferase 1A9 (UGT1A9), an important detoxification and inactivation enzyme for toxicants, regulates the exposure level of environmental pollutants in the human body and induces various toxicological consequences. However, an effective tool for high-throughput monitoring of UGT1A9 function under exposure to environmental pollutants is still lacking. In this study, 1,3-dichloro-7-hydroxy-9,9-dimethylacridin-2(9H)-one (DDAO) was found to exhibit excellent specificity and high affinity towards human UGT1A9. Remarkable changes in absorption and fluorescence signals after reacting with UGT1A9 were observed, due to the intramolecular charge transfer (ICT) mechanism. Importantly, DDAO was successfully applied to monitor the biological functions of UGT1A9 in response to environmental pollutant exposure not only in microsome samples, but also in living cells by using a high-throughput screening method. Meanwhile, the identified pollutants that disturb UGT1A9 functions were found to significantly influence the exposure level and retention time of bisphenol S/bisphenol A in living cells. Furthermore, the molecular mechanism underlying the inhibition of UGT1A9 by these pollutant-derived disruptors was elucidated by molecular docking and molecular dynamics simulations. Collectively, a fluorescent probe to characterize the responses of UGT1A9 towards environmental pollutants was developed, which was beneficial for elucidating the health hazards of environmental pollutants from a new perspective.

Promiscuity and Quantitative Contribution of UGT2B17 in Drug and Steroid Metabolism Determined by Experimental and Computational Approaches.

Uridine 5'-diphospho-glulcuronosyltransferase 2B17 (UGT2B17) is important in the metabolism of steroids and orally administered drugs due to its high interindividual variability. However, the structural basis governing the substrate selectivity or inhibition of UGT2B17 remains poorly understood. This study investigated 76 FDA-approved drugs and 20 steroids known to undergo glucuronidation for their metabolism by UGT2B17. Specifically, we assessed the substrate selectivity for UGT2B17 over other UGT enzymes using recombinant human UGT2B17 (rUGT2B17), human intestinal microsomes, and human liver microsomes. The quantitative contribution of intestinal UGT2B17 in the glucuronidation of these compounds was characterized using intestinal microsomes isolated from UGT2B17 expressors and nonexpressors. In addition, a structure-based pharmacophore model for UGT2B17 substrates was built and validated using the studied pool of substrates and nonsubstrates. The results show that UGT2B17 could metabolize 23 out of 96 compounds from various chemical classes, including alcohols and carboxylic acids, particularly in the intestine. Interestingly, amines were less susceptible to UGT2B17 metabolism, though they could inhibit the enzyme. Three main pharmacophoric features of UGT2B17 substrates include (1) the presence of an accessible -OH or -COOH group near His35 residue, (2) a hydrophobic functional group at ∼4.5-5 Šfrom feature 1, and (3) an aromatic ring ∼5-7 Šfrom feature 2. Most of the studied compounds inhibited UGT2B17 activity irrespective of their substrate potential, indicating the possibility of multiple mechanisms. These data suggest that UGT2B17 is promiscuous in substrate selectivity and inhibition and has a high potential to produce significant variability in the absorption and disposition of orally administered drugs.

Efficient Production of Flavonoid Glucuronides in Escherichia coli Using Flavonoid O-Glucuronosyltransferases Characterized from Marchantia polymorpha.

As a model liverwort, Marchantia polymorpha contains various flavone glucuronides with cardiovascular-promoting effects and anti-inflammatory properties. However, the related glucuronosyltransferases have not yet been reported. In this study, two bifunctional UDP-glucuronic acid/UDP-glucose:flavonoid glucuronosyltransferases/glucosyltransferases, MpUGT742A1 and MpUGT736B1, were identified from M. polymorpha. Extensive enzymatic assays found that MpUGT742A1 and MpUGT736B1 exhibited efficient glucuronidation activity for flavones, flavonols, and flavanones and showed promiscuous regioselectivity at positions 3, 6, 7, 3', and 4'. These enzymes catalyzed the production of a variety of flavonoid glucuronides with medicinal value, including apigenin-7-O-glucuronide and scutellarein-7-O-glucuronide. With the use of MpUGT736B1, apigenin-4'-O-glucuronide and apigenin-7,4'-di-O-glucuronide were prepared by scaled-up enzymatic catalysis and structurally identified by NMR spectroscopy. MpUGT742A1 also displayed glucosyltransferase activity on the 7-OH position of the flavanones using UDP-glucose as the sugar donor. Furthermore, we constructed four recombinant strains by combining the pathway for increasing the UDP-glucuronic acid supply with the two novel UGTs MpUGT742A1 and MpUGT736B1. When apigenin was used as a substrate, the extracellular apigenin-4'-O-glucuronide and apigenin-7,4'-di-O-glucuronide production obtained from the Escherichia coli strain BB2 reached 598 and 81 mg/L, respectively. Our study provides new candidate genes and strategies for the biosynthesis of flavonoid glucuronides.

Bile duct ligation elevates 5-HT levels in cerebral cortex of rats partly due to impairment of brain UGT1A6 expression and activity via ammonia accumulation.

Hepatic encephalopathy (HE) is often associated with endogenous serotonin (5-HT) disorders. However, the reason for elevated brain 5-HT levels due to liver failure remains unclear. This study aimed to investigate the mechanism by which liver failure increases brain 5-HT levels and the role in behavioral abnormalities in HE. Using bile duct ligation (BDL) rats as a HE model, we verified the elevated 5-HT levels in the cortex but not in the hippocampus and striatum, and found that this cortical 5-HT overload may be caused by BDL-mediated inhibition of UDP-glucuronosyltransferase 1A6 (UGT1A6) expression and activity in the cortex. The intraventricular injection of the UGT1A6 inhibitor diclofenac into rats demonstrated that the inhibition of brain UGT1A6 activity significantly increased cerebral 5-HT levels and induced HE-like behaviors. Co-immunofluorescence experiments demonstrated that UGT1A6 is primarily expressed in astrocytes. In vitro studies confirmed that NH4Cl activates the ROS-ERK pathway to downregulate UGT1A6 activity and expression in U251 cells, which can be reversed by the oxidative stress antagonist N-acetyl-l-cysteine and the ERK inhibitor U0126. Silencing Hepatocyte Nuclear Factor 4α (HNF4α) suppressed UGT1A6 expression whilst overexpressing HNF4α increased Ugt1a6 promotor activity. Meanwhile, both NH4Cl and the ERK activator TBHQ downregulated HNF4α and UGT1A6 expression. In the cortex of hyperammonemic rats, we also found activation of the ROS-ERK pathway, decreases in HNF4α and UGT1A6 expression, and increases in brain 5-HT content. These results prove that the ammonia-mediated ROS-ERK pathway activation inhibits HNF4α expression to downregulate UGT1A6 expression and activity, thereby increasing cerebral 5-HT content and inducing manic-like HE symptoms. This is the first study to reveal the mechanism of elevated cortical 5-HT concentration in a state of liver failure and elucidate its association with manic-like behaviors in HE.

Associations between UGT1A1, SLCO1B1, SLCO1B3, BLVRA and HMOX1 polymorphisms and susceptibility to neonatal severe hyperbilirubinemia in Chinese Han population.

BACKGROUND: Severe neonatal hyperbilirubinemia could lead to kernicterus and neonatal death. This study aimed to analyze the association between single nucleotide polymorphisms in genes involved in bilirubin metabolism and the incidence of severe hyperbilirubinemia. METHODS: A total of 144 neonates with severe hyperbilirubinemia and 50 neonates without or mild hyperbilirubinemia were enrolled in 3 institutions between 2019 and 2020. Twelve polymorphisms of 5 genes (UGT1A1, SLCO1B1, SLCO1B3, BLVRA, and HMOX1) were analyzed by PCR amplification of genomic DNA. Genotyping was performed using an improved multiplex ligation detection reaction technique based on ligase detection reaction. RESULTS: The frequencies of the A allele in UGT1A1-rs4148323 and the C allele in SLCO1B3-rs2417940 in the severe hyperbilirubinemia group (30.2% and 90.6%, respectively) were significantly higher than those in the controls (30.2% vs.13.0%, 90.6% vs. 78.0%, respectively, both p < 0.05). Haplotype analysis showed the ACG haplotype of UGT1A1 were associated with an increased hyperbilirubinemia risk (OR 3.122, p = 0.001), whereas the GCG haplotype was related to a reduced risk (OR 0.523, p = 0.018). CONCLUSION: The frequencies of the A allele in rs4148323 and the C allele in rs2417940 are highly associated with the incidence of severe hyperbilirubinemia in Chinese Han neonates. TRIAL REGISTRATION: Trial registration number:ChiCTR1800020424; Date of registration:2018-12-29.

Exploring the impact of CYP2D6 and UGT2B7 gene-drug interactions, and CYP-mediated DDI on oxycodone and oxymorphone pharmacokinetics using physiologically-based pharmacokinetic modeling and simulation.

Oxycodone is one of the most commonly used opioids to treat moderate to severe pain. It is metabolized mainly by CYP3A4 and CYP2D6, while only a small fraction of the dose is excreted unchanged into the urine. Oxymorphone, the metabolite primarily formed by CYP2D6, has a 40- to 60-fold higher mu-opioid receptor affinity than the parent compound. While CYP2D6-mediated gene-drug-interactions (GDIs) and drug-drug interactions (DDIs) are well-studied, they only account for a portion of the variability in oxycodone and oxymorphone exposure. The combined impact of CYP2D6-mediated GDIs and DDIs, CYP3A4-mediated DDIs, and UGT2B7 GDIs is not fully understood yet and hard to study in head-to-head clinical trials given the relatively large number of scenarios. Instead, we propose the use of a physiologically-based pharmacokinetic model that integrates available information on oxycodone's metabolism to characterize and predict the impact of DDIs and GDIs on the exposure of oxycodone and its major, pharmacologically-active metabolite oxymorphone. To this end, we first developed and verified a PBPK model for oxycodone and its metabolites using published clinical data. The verified model was then applied to determine the dose-exposure relationship of oxycodone and oxymorphone stratified by CYP2D6 and UGT2B7 phenotypes respectively, and administered perpetrators of CYP-based drug interactions. Our simulations demonstrate that the combination of CYP2D6 UM and a UGT2B7Y (268) mutation may lead to a 2.3-fold increase in oxymorphone exposure compared to individuals who are phenotyped as CYP2D6 NM / UGT2B7 NM. The extent of oxymorphone exposure increases up to 3.2-fold in individuals concurrently taking CYP3A4 inhibitors, such as ketoconazole. Inhibition of the CYP3A4 pathway results in a relative increase in the partial metabolic clearance of oxycodone to oxymorphone. Oxymorphone is impacted to a higher extent by GDIs and DDIs than oxycodone. We predict oxymorphone exposure to be highest in CYP2D6 UMs/UGT2B7 PMs in the presence of ketoconazole (strong CYP3A4 index inhibitor) and lowest in CYP2D6 PMs/UGT2B7 NMs in the presence of rifampicin (strong CYP3A4 index inducer) covering a 55-fold exposure range.

Applied physiologically-based pharmacokinetic modeling to assess uridine diphosphate-glucuronosyltransferase-mediated drug-drug interactions for Vericiguat.

Vericiguat (Verquvo; US: Merck, other countries: Bayer) is a novel drug for the treatment of chronic heart failure. Preclinical studies have demonstrated that the primary route of metabolism for vericiguat is glucuronidation, mainly catalyzed by uridine diphosphate-glucuronosyltransferase (UGT)1A9 and to a lesser extent UGT1A1. Whereas a drug-drug interaction (DDI) study of the UGT1A9 inhibitor mefenamic acid showed a 20% exposure increase, the effect of UGT1A1 inhibitors has not been assessed clinically. This modeling study describes a physiologically-based pharmacokinetic (PBPK) approach to complement the clinical DDI liability assessment and support prescription labeling. A PBPK model of vericiguat was developed based on in vitro and clinical data, verified against data from the mefenamic acid DDI study, and applied to assess the UGT1A1 DDI liability by running an in silico DDI study with the UGT1A1 inhibitor atazanavir. A minor effect with an area under the plasma concentration-time curve (AUC) ratio of 1.12 and a peak plasma concentration ratio of 1.04 was predicted, which indicates that there is no clinically relevant DDI interaction anticipated. Additionally, the effect of potential genetic polymorphisms of UGT1A1 and UGT1A9 was evaluated, which showed that an average modest increase of up to 1.7-fold in AUC may be expected in the case of concomitantly reduced UGT1A1 and UGT1A9 activity for subpopulations expressing non-wild-type variants for both isoforms. This study is a first cornerstone to qualify the PK-Sim platform for use of UGT-mediated DDI predictions, including PBPK models of perpetrators, such as mefenamic acid and atazanavir, and sensitive UGT substrates, such as dapagliflozin and raltegravir.

Medicinal Chemistry and NMR Driven Discovery of Novel UDP-glucuronosyltransferase 1A Inhibitors That Overcome Therapeutic Resistance in Cells.

The UDP glucuronosyltransferases (UGT) deactivate many therapeutics via glucuronidation while being required for clearance of normal metabolites and xenobiotics. There are 19 UGT enzymes categorized into UGT1A and UGT2B families based on sequence conservation. This presents a challenge in terms of targeting specific UGTs to overcome drug resistance without eliciting overt toxicity. Here, we identified for the first time that UGT1A4 is highly elevated in acute myeloid leukemia (AML) patients and its reduction corresponded to objective clinical responses. To develop inhibitors to UGT1A4, we leveraged previous NMR-based fragment screening data against the C-terminal domain of UGT1A (UGT1A-C). NMR and medicinal chemistry strategies identified novel chemical matter based on fragment compounds with the capacity to bind ∼20 fold more tightly to UGT1A-C (Kd âˆ¼ 600 µM vs ∼30 µM). Some compounds differentially inhibited UGT1A4 versus UGT1A1 enzyme activity and restored drug sensitivity in resistant human cancer cells. NMR-based NOE experiments revealed these novel compounds recognised a region distal to the catalytic site suggestive of allosteric regulation. This binding region is poorly conserved between UGT1A and UGT2B C-terminal sequences, which otherwise exhibit high similarity. Consistently, these compounds did not bind to the C-terminal domain of UGT2B7 nor a triple mutant of UGT1A-C replaced with UGT2B7 residues in this region. Overall, we discovered a site on UGTs that can be leveraged to differentially target UGT1As and UGT2Bs, identified UGT1A4 as a therapeutic target, and found new chemical matter that binds the UGT1A C-terminus, inhibits glucuronidation and restores drug sensitivity.

Ciprofol is primarily glucuronidated by UGT1A9 and predicted not to cause drug-drug interactions with typical substrates of CYP1A2, CYP2B6, and CYP2C19.

Ciprofol is a novel intravenous anesthetic agent. Its major glucuronide metabolite, M4, is found in plasma and urine. However, the specific isoforms of UDP-glucuronosyltransferases (UGTs) that metabolize ciprofol to M4 remain unknown. This study systematically characterized UGTs that contribute to the formation of M4 using human liver microsomes (HLM), human intestinal microsomes (HIM), and human recombinant UGTs. The inhibitory potential of ciprofol and M4 against major human UGTs and cytochrome P450 enzymes (P450s) was also explored. In vitro-in vivo extrapolation (IVIVE) and physiologically-based pharmacokinetic (PBPK) simulations were performed to predict potential in vivo drug-drug interactions (DDIs) caused by ciprofol. Glucuronidation of ciprofol followed Michaelis-Menten kinetics in both HLM and HIM with apparent Km values of 345 and 412 µM, Vmax values of 2214 and 444 nmol min-1·mg protein-1, respectively. The in vitro intrinsic clearances (CLint = Vmax/Km) for ciprofol glucuronidation by HLM and HIM were 6.4 and 1.1 µL min-1·mg protein-1, respectively. Human recombinant UGT studies revealed that UGT1A9 is the predominant isoform mediating M4 formation, followed by UGT1A7, with UGT1A8 playing a minor role. Ciprofol competitively inhibited CYP1A2 (Ki = 12 µM) and CYP2B6 (Ki = 4.7 µM), and noncompetitively inhibited CYP2C19 (Ki = 29 µM). No time-dependent inhibition by ciprofol was noted for CYP1A2, CYP2B6, or CYP2C19. In contrast, M4 showed limited or no inhibitory effects against selected P450s. Neither ciprofol nor M4 inhibited UGTs significantly. Initial IVIVE suggested potential ciprofol-mediated inhibition of CYP1A2, CYP2B6, and CYP2C19 inhibition in vivo. However, PBPK simulations showed no significant effect on phenacetin, bupropion, and S-mephenytoin exposure or peak plasma concentration. Our findings are pertinent for future DDI studies of ciprofol as either a perpetrator or victim drug.

A phase-II study based on dose adjustment according to UGT1A1 polymorphism: is irinotecan underdosed in first-line FOLFIRI regimen for mCRC?

PURPOSE: Irinotecan has considerable importance in the treatment of metastatic colorectal cancer (mCRC). UDP-glucoronyltransferase (UGT) 1A1 is responsible for the inactivation of SN-38, a metabolite of irinotecan. Depending on UGT1A1 polymorphism, the activity of the UGT enzyme can be reduced leading to more frequent occurrence of adverse events related to irinotecan. The present study aimed to assess the safety and efficacy of different doses of irinotecan adjusted according to UGT1A1 polymorphism. METHODS: Thirty-four patients treated with FOLFIRI as first-line treatment for mCRC were included in this study. The irinotecan dosage was adapted on the basis of UGT1A1 polymorphisms: *1/*1 (370 mg/m2); *1/*28 (310 mg/m2), and *28/*28 (180 mg/m2). The incidence of grades 3 and 4 toxicities (neutropenia, febrile neutropenia, and diarrhoea) was recorded. Response was assessed according to the RECIST 1.1 criteria. RESULTS: On the basis of UGT1A1 genotyping, 20 patients were *1/*1 (58.8%), 12 were *1/*28 (35.3%) and 2 were *28/*28 (5.9%). Seven patients experienced at least one severe toxicity, i.e., 21% of the population, amounting to eleven adverse events. Concerning the response rate, 15 patients (44%) had partial or complete response. CONCLUSION: This study demonstrates that mCRC patients treated with FOLFIRI can tolerate a higher dose of irinotecan than the standard dose, i.e., > 180 mg/m2, on the basis of their UGT1A1 genotype, without increased toxicities. TRIAL REGISTRATION: NCT01963182 (registered on 16/10/2013, Clermont-Ferrand, France).