Role for protein kinase C delta in the functional activity of human UGT1A6: implications for drug–drug interactions between PKC inhibitors and UGT1A6

1. Many UDP-glucuronosyltransferases (UGTs) require phosphorylation by protein kinase C (PKC) for glucuronidation activity. Inhibition of UGT phosphorylation by PKC inhibitor drugs may represent a novel mechanism for drug–drug interactions.

2. The potential for PKC-mediated inhibition of human UGT1A6, an isoform involved in the glucuronidation of drugs such as acetaminophen (paracetamol) and endogenous substrates including serotonin, was evaluated using various cell model systems.

3. Of ten different PKC inhibitors screened for their effects on acetaminophen glucuronidation by human LS180 colon cells, only rottlerin (PKC δ selective inhibitor; IC₅₀?=?9.0?±?1.2 μM) and the non-selective PKC inhibitors (calphostin-C, curcumin and hypericin) decreased glucuronidation by more than 50%.

4. Using UGT1A6-infected Sf9 insect cells, calphostin-C and hypericin showed three times more potent inhibition of serotonin glucuronidation in treated whole cells versus cell lysates. However, both curcumin and rottlerin showed significant direct inhibition and so (indirect) PKC effects could not be differentiated in this model system.

5. Of nine PKC isoforms co-expressed with UGT1A6 in human embryonic kidney 293T cells only PKC δ increased protein-normalized UGT1A6-mediated serotonin glucuronidation significantly (by 63% ± 4%).

6. These results identify an important role for PKC δ in UGT1A6-mediated glucuronidation and suggest that PKC δ inhibitors could interfere with glucuronidation of UGT1A6 substrates.

     

UGT1A6、UGT1A9基因多态性对汉族癫痫患者丙戊酸血药浓度的影响

目的:考察尿苷二磷酸葡萄糖醛酸转移酶(UGT)1A6和1A9基因多态性对汉族癫痫患者丙戊酸血药浓度的影响。方法:选取2014年1月—2015年4月于我院门诊就诊的汉族癫痫患者107例,均使用丙戊酸单药治疗,治疗时间为3个月~6年。采用酶放大免疫法测定患者体内丙戊酸稳态血药浓度,采用基质辅助激光解吸电离飞行时间质谱法检测其UGT1A6(rs2070959、rs6759892)和UGT1A9(rs13418420、rs2741045、rs2741049、rs6731242、rs72551330)基因型,并考察基因多态性与丙戊酸标准化血药浓度(CDR)的相关性。结果:未检出UGT1A9 rs72551330突变型,其余6个位点基因型频率均符合Hardy-Weinberg平衡(P>0.05)。UGT1A6 rs2070959、rs6759892突变基因携带(AG+GG或TG+GG型)者丙戊酸CDR值显著低于其野生纯合子携带(AA或TT型)者,差异均有统计学意义(P<0.05);而携带UGT1A9 rs13418420、rs2741045、rs2741049和rs6731242野生纯合子和突变基因的患者丙戊酸CDR值比较,差异均无统计学意义(P>0.05)。结论:汉族癫痫患者UGT1A6 rs2070959、rs6759892基因多态性与丙戊酸血药浓度有关,且UGT1A6 rs2070959、rs6759892突变基因携带者可能需要更高的丙戊酸剂量。     

TPMT, UGT1A1 and DPYD: genotyping to ensure safer cancer therapy?

The Food and Drug Administration (FDA) has approved label changes for two anticancer drugs, 6-mercaptopurine (6-MP) and irinotecan, to include pharmacogenetic testing as a potential means to reduce the rate of severe toxic events. Comprehensive evaluation of the clinical benefit and cost effectiveness of screening strategies with these tests has not been completed. However, the FDA decided that evidence indicates sufficient benefit to warrant informing prescribers, pharmacists and patients of the availability of pharmacogenetic tests and their possible role in the selection and dosing of these anticancer agents. Reviewing the gene-drug-phenotype relationships of 6-MP, irinotecan and 5-fluorouracil reveals properties of these relationships that lead to a clinically useful pharmacogenetic test. Research in the near future should clarify the role of pharmacogenetic testing in reducing the risk of severe toxicity and determine how these same tests might identify a subset of patients who should safely receive higher doses of treatment to derive the same benefit as the rest of the patient population.     

Cytochrome P450 3A and P-glycoprotein drug–drug interactions with voclosporin

Aims

Voclosporin is a novel calcineurin inhibitor intended for prevention of organ graft rejection and treatment of lupus nephritis. Pharmacokinetic drug interactions between voclosporin and a CYP3A inhibitor, inducer and substrate and a P-glycoprotein inhibitor and substrate were evaluated.

Methods

Voclosporin 0.4 mg kg⁻¹ was administered to 24 subjects in each of five studies, as follows: every 12 h (Q12H) alone and concomitantly with ketoconazole 400 mg once daily (QD); single dose before and single dose after rifampin 600 mg QD; Q12H where midazolam 7.5 mg was administered as a single dose alone before voclosporin and with last the dose of voclosporin; Q12H alone and concomitantly with verapamil 80 mg every 8 h; and Q12H with digoxin 0.25 mg QD. The noncompartmental pharmacokinetic parameters maximal concentration (C_max) and area under the concentration–time curve (AUC) were obtained, and geometric least squares mean ratios and 90% confidence intervals were evaluated.

Results

Ketoconazole increased voclosporin C_max (6.4-fold) and AUC (18-fold); rifampin reduced voclosporin AUC (0.9-fold); voclosporin did not change exposure of midazolam or α-hydroxy-midazolam; verapamil increased voclosporin C_max (2.1-fold) and AUC (2.7-fold); and voclosporin increased digoxin C_max (0.5-fold), AUC (0.25-fold) and urinary excretion (0.2-fold).

Conclusions

Administration of voclosporin concomitantly with strong inhibitors and inducers of CYP3A resulted in increased and decreased exposures, respectively, and should be considered contraindicated. Drug–drug interactions involving voclosporin and CYP3A substrates are not expected. Administration of voclosporin concomitantly with inhibitors and substrates of P-glycoprotein resulted in increased voclosporin and substrate exposures, respectively. Appropriate concentration and safety monitoring is recommended with co-administration of voclosporin and P-glycoprotein substrates and inhibitors.     

Are the adverse drug reactions of amoxycillin and amoxycillin-clavulanic acid similar?

In an attempt to assess the relative toxicity of amoxycillin and amoxycillin-clavulanic acid, we compared the adverse drug reactions reports collected using the spontaneous reporting system of a Regional Drug Surveillance Centre of Spain for both drugs between November 1986 and December 1992. During the 7-year period 1986-92, the 247 reports of amoxycillin-clavulanic acid represent twice the number of reports of amoxycillin alone, and the number of reports related with sales received concerning the association were higher than those concerning amoxycillin alone. The adverse effects classified as severe were quantitatively and qualitatively similar for both drugs and gastrointestinal and skin are the most common system-organ affected by both drugs. With amoxycillin-clavulanic acid there is a higher proportion of stomatological reactions reported and a later onset of adverse drug reactions related with oropharyngeal lesions, and the reaction of the resistance mechanism when compared with the other organs and systems affected. The duration of the adverse drug reactions to amoxycillin-clavulanic acid is longer than for amoxycillin alone. In conclusion: (i) the adverse drug reactions profile of both drugs is different; (ii) the higher reporting rate for amoxycillin-clavulanic acid may be due to more recent marketing; and (iii) amoxycillin-clavulanic acid produces proportionately more gastrointestinal and fewer skin adverse reactions than amoxycillin alone.     

胆红素代谢酶UGT1A1介导的中药不良反应研究进展

尿苷二磷酸葡萄糖醛酸转移酶1A1（UGT1A1）是哺乳动物体内分布的一种重要的Ⅱ相代谢酶,其不仅介导了大量临床药物、毒物的代谢清除,还是机体参与内源性毒性物质胆红素代谢清除的唯一代谢酶。药物或食品中的化学成分对UGT1A1的强烈抑制会引发多种不良反应,如药物/草药-药物相互作用、高胆红素血症、肝功能异常及神经毒性等。近年来,研究发现许多草药提取物及其化学成分可通过强效抑制UGT1A1引发药物-草药相互作用等不良反应。结合药物代谢及药物毒理学相关领域的新近研究进展,系统总结了UGT1A1抑制剂筛选与评价常用方法,以及中草药化学成分对UGT1A1抑制作用的研究进展。上述信息对于临床安全合理的使用中草药,尤其是在中西药联用或中药方剂使用过程中尽可能避免因UGT1A1抑制引发的不良反应,具有重要指导意义。     

白杨黄素和天然香豆素类对大鼠和人原代培养的肝细胞UGT1A1和UGT1A6活性的影响

二磷酸尿核苷葡萄糖醛酸基转移酶(UGTs)是许多组织细胞内质网中的一种二相药物代谢酶,其家族中的UGT1和UGT2亚型在有毒物质的代谢过程中具有重要的生理意义。研究了白杨黄素和6种天然香豆素类化合物(缴形酮、香豆素、勒素、cis- avicennol、香柠檬烯和前胡醚)对人和大鼠原代培养的肝细胞中UGT1A1和(或)UGT1A6的影响。     

UGT1A1基因多态性对新生儿高胆红素血症的影响

新生儿高胆红素血症是新生儿期常见的临床症状,在生后第1周常见,在生后的前5d对近60%的足月儿和80%的早产儿产生影响[1]。胆红素是有毒副作用的内源性化合物,对新生儿脑组织尤为敏感[2]。严重的未结合胆红素血症导致胆红素脑病、遗留听力、运动或智力障碍等后遗症,严重者可造成死亡。肝脏摄入不足、胆红素共轭减少和肝肠循环增加,可用来解释大多数情况下的病理性黄疸的原因,但仍有一部分病因不     

PXR–ABC drug transporters/CYP-mediated ursolic acid transport and metabolism in vitro and vivo

The transporting kinetics and metabolic kinetics of ursolic acid were studied in transgenic cell models. Then, the pharmacokinetics features of ursolic acid and the expression of ATP-binding cassette transporters (ABC transporter) and cytochrome P450 (CYP) enzymes in tissues after pregnane X receptor (PXR) activation by 5-pregnen-3β-ol-20-one-16α-carbonitrile (PCN) were investigated in rats. After silencing of PXR in Caco2–siRNA–PXR cells, there was a decrease in the protein abundance of P-glycoprotein, breast cancer-resistant protein, multidrug resistance-associated protein 2 (MRP2), and CYP2C9. The apparent permeability (PDR) values of 10, 20, and 50 µM ursolic acid in Caco2 cells were 2.19 ± 0.44, 1.40 ± 0.17, and 1.25 ± 0.07, respectively, whereas in Caco2–siRNA–PXR cells, they were 1.85 ± 0.36, 1.24 ± 0.11, and 1.19 ± 0.04, respectively. PXR–RXRα would significantly activate ABC transporter expression in Caco2 cells. Compared with Caco2 cells, when the concentrations of ursolic acid were 10, 20, and 50 µM, the PDR values increased in Caco2–PXR–RXRα cells after PXR activation: 1.60 ± 0.31 versus 1.97 ± 0.21, 1.46 ± 0.08 versus 2.01 ± 0.19, and 1.32 ± 0.26 versus 2.09 ± 0.22, respectively. Simultaneously, PXR–RXRα would activate the expression of CYP2C9; metabolic kinetics of ursolic acid in CYP metabolizing enzyme lysate of Caco2 cells and Caco2–PXR–RXR cells was studied and it was found that the K_m values were 81.99 ± 44.32 and 60.05 ± 29.62 µg/ml, and V_max values were 3.77 ± 0.86 and 3.41 ± 0.96 µg · ml⁻¹ · min⁻¹, respectively. However, in human CYP metabolizing recombinase, we found that both CYP2C9 and CYP34A were involved in the metabolism of ursolic acid. V_m and K_m values for CYP3A4 and CYP2C9 were 3.57 ± 1.12 µg · ml⁻¹ · min⁻¹ and 81.71 ± 18.38 µg/ml, 3.85 ± 1.46 µg · ml⁻¹ · min⁻¹ and 62.18 ± 14.56 µg/ml, respectively. As a strong agonist for mouse pxr, PCN could significantly affect pharmacokinetics of ursolic acid in rats, and it showed discrepant effects on messenger RNA expression of cyp and transporters in tissues.     

伊立替康不良反应与UGT1A1基因多态性关系的研究

目的:研究应用伊立替康化疗的患者不良反应的发生率及严重程度与UGT1A1基因启动子区多态性的关系。方法:选择56例我院晚期胃肠道肿瘤和小细胞肺癌患者,使用含伊立替康的方案化疗,观察并记录患者化疗中出现的不良反应;外周血中抽提基因组DNA,测定UGT1A1基因多态性,分析基因型与不良反应的关系。结果:42例患者(75.0%)UGT1A1*28为野生型TA6/6;13例患者(23.2%)为杂合突变型TA6/7;1例患者(1.8%)为纯合突变型TA7/7;UGT1A1*6野生型有44例(78.6%),杂合突变型有10例(17.9%),纯合突变型有2例(3.6%)。UGT1A1*28野生型、突变型患者发生Ⅲ度以上白细胞和/或中性粒细胞减少者分别为6、3例(14.3%vs.21.4%,P>0.01),其中纯和突变型患者发生Ⅲ度以上白细胞和/或中性粒细胞减少者为1例(100%);发生Ⅲ度以上腹泻者分别为6、2例(14.3%vs.14.3%,P>0.01),其中纯和突变型患者发生Ⅲ度以上腹泻为1例(100%)。UGT1A1*6野生型、突变型患者发生Ⅲ度以上中性粒细胞减少者分别为3、8例(6.8%vs.66.6%,P<0.01),发生Ⅲ度以上腹泻者分别为2、7例(4.5%vs.58.3%,P<0.01)。结论:晚期胃肠道肿瘤和小细胞肺癌患者中,UGT1A1基因野生型最为常见,杂合突变型次之,而纯合突变型很少见。TA7/7纯合突变型患者应用伊立替康化疗发生Ⅲ度以上白细胞和/或中性粒细胞减少和腹泻的风险增加,而TA6/7杂合突变型与TA6/6野生型相似,并不增加患者发生Ⅲ度以上中性粒细胞减少和腹泻的风险。UGT1A1*6突变型应用伊立替康化疗发生Ⅲ度以上中性粒细胞减少和腹泻的风险较野生型明显增加。     

Pharmacokinetics and bioavailability of indapamide — A new antihypertensive drug

Summary Two formulations of indapamide tablets (2.5 mg) were given as a 5.0 mg dose and the subsequent blood levels were compared to those obtained after administration of a 5.0 mg solution. The study was conducted as a randomized three-way crossover design using healthy male volunteers. The drug was well tolerated by all the subjects involved. The area under the blood concentration versus time curve, extrapolated to infinity was essentially the same for all three formulations (4.2, 4.7, and 4.4 µg-h/ml). Statistical comparison of the blood levels from the two tablets showed that one tablet had a significantly greater maximum blood concentration (263 vs 231 ng/ml) and a significantly shorter time of maximum blood concentration (2.3 vs 3.5 h). C_max (333 ng/ml) and t_max (0.7 h) values for the solution were significantly higher than either tablet. The average half-life (-phase) for all three formulations was 15 h, while the average systemic clearance was 20 ml/min. Indapamide has a low clearance rate and there was no evidence that the drug undergoes a first-pass effect.     

新疆多民族UGT1A9基因多态性与丙泊酚血药浓度相关性

目的:探讨新疆多民族患者尿苷二磷酸葡萄糖醛酸转移酶(UGT)1A9基因多态性与丙泊酚血药浓度的相关性。方法:选取2019年12月至2021年3月新疆医科大学附属肿瘤医院102例多民族患者，采用气-质联用(LC-MS)法检测患者5个时间点，即麻醉诱导前(T₀)、睫毛反射消失前(T₁)、血浆清除率至40～50 L·kg^-1·h^-1时(T₂)、停药即刻(T₃)和停药后30 min时(T₄)外周血中丙泊酚的血药浓度。同时提取患者外周血DNA,采用基质辅助激光解吸电离飞行时间质谱(MAL-DI-TOF-MS)法检测对UGT1A9(rs 2741049、rs 3806598、rs 6731242、rs 3832043)4个基因位点进行基因多态性检测。统计基因分型结果，将影响血药浓度的所有因素进行单因素分析。结果:rs 2741049,rs 3806598,rs 6731242,rs 3832043四个位点基因型频率均符合Hardy-Weinber...     

A drug transporter for all ages? ABCB1 and the developmental pharmacogenetics of cyclosporine

Evaluation of: Fanta S, Niemi M, J?nsson S et al.: Pharmacogenetics of cyclosporine in children suggests an age-dependent influence of ABCB1polymorphisms. Pharmacogenet. Genomics 18(2), 77-90 (2008). The clinical use of the immunosuppressive agent cyclosporine is complicated by its toxicity, narrow therapeutic window and highly variable pharmacokinetics between individuals. In adults, genetic polymorphisms in the genes encoding the cyclosporine-metabolizing enzymes CYP3A4 and CYP3A5, as well as the ABCB1 gene, which encodes the efflux-pump P-glycoprotein, seem to have a limited effect, if any, on cyclosporine pharmacokinetics. However, the authors have now reported for the first time an association between cyclosporine oral bioavailability and the ABCB1 c.1236C>T and c.2677G>T polymorphisms, as well as the related haplotype c.1199G-c.1236C-c.2677G-c.3435C, in children with end-stage renal disease older than 8 years of age. Carriers of the variant alleles had a cyclosporine oral bioavailability that was around 1.5-times higher compared with noncarriers. This association was not observed in children younger than 8 years of age. In addition, no relation between cyclosporine disposition and genetic variation in the CYP3A4, CYP3A5, ABCC2, SLCO1B1 and NR1I2 genes was observed. These data suggest that the effect of ABCB1 polymorphisms on cyclosporine pharmacokinetics is related to age, and thus developmental stage. Although further study is necessary to establish the predictive value of ABCB1 genotyping for individualization of cyclosporine therapy in children older than 8 years, an important step towards further personalized immunosuppressive drug therapy has been made.     

CYP3A5、UGT1A1、UGT2B7基因多态性与肾移植受者 他克莫司血药浓度的相关性研究

目的:探讨CYP3A5、UGT1A1、UGT2B7基因多态性与肾移植受者他克莫司血药浓度的相关性.方法:共纳入124例肾移植术后采用他克莫司十霉酚酸酯+泼尼松三联治疗方案的患者.采用酶放大免疫测定法(Emit)检测他克莫司血药浓度;采用实时荧光定量PCR方法和Taqman基因分型技术测定CYP3A5*3、UGT1A1*6、UGT2B7*3、UGT1A1*28、UGT2B7*2基因多态性;应用Kruskal-Wallis H检验法分析5个SNPs基因多态性与他克莫司血药浓度的相关性.结果:CYP3A5*3突变型的他克莫司血药浓度GG/AG(7.75±2.56)/(6.75±1.85) ng· mL-1显著高于野生型AA (5.00±1.81)ng·mL-1 (P＜0.01);UGT1A1*6基因型GG/AG的血药浓度分别为(7.15±2.72)/(6.74±1.81)ng·mL-1,显著高于基因型AA(4.45±0.49)ng·mL-1(P=0.022).UGT2B7*3基因型GG/GT的血药浓度分别为(7.00±1.95)、(7.48±2.22)ng·mL-1,显著高于基因型TT(6.78+3.00)ng·mL-1(P=0.014).UGT1A1*28与UGT2B7*2基因多态性与他克莫司血药浓度无显著相关性(P＞0.05).结论:他克莫司血药浓度与CYP3A5*3、UGT1A1*6、UGT2B7*3基因多态性相关.     

染料木素临床不良反应与CYP1A2、UGT1A7基因多态性研究

目的：探讨染料木素临床不良反应与CYP1A2、UGT1A7基因多态性的相关性。方法：114例健康志愿者随机分为试验组与对照组,试验组分别口服染料木素一个剂量50、100、200mg,每人服药1次,观察3d了解有无不良反应发生;用限制性片段长度多态性聚合酶链反应（RFLR-PCR）扩增基因片段并酶切电泳观察分析CYP1A2G2964A、C734A和UGT1A7Trp208Arg的多态性。结果：试验组及对照组的基因型及等位基因分布差异无统计学意义（P〉0.05）。试验组受试者根据有无不良反应的出现分为两组基因,CYP1A2G2964A基因：不良反应组14例受试者中有10例的基因型为G/A（占71.43%）,而无不良反应组41例受试者中有22例的基因型为G/G（占53.66%）;CYP1A2C734A基因：不良反应组13例受试者中有7例的基因型为C/A（占53.85%）,而无不良反应组32例受试者中有16例的基因型为A/A（占50.00%）;UGT1A7Trp208Arg基因：不良反应组15例受试者中有12例的基因型为Trp/Trp（占80.00%）,并且无不良反应组53例受试者中有32例的基因型也为Trp/Trp（占60.38%）。结论：染料木素不良反应组中CYP1A2G2964A基因以G/A型较高,CYP1A2C734A基因以G/G型较高;UGT1A7基因以Trp/Trp型较高。     

Renal drug metabolism in humans: the potential for drug–endobiotic interactions involving cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT)

Although knowledge of human renal cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes and their role in xenobiotic and endobiotic metabolism is limited compared with hepatic drug and chemical metabolism, accumulating evidence indicates that human kidney has significant metabolic capacity. Of the drug metabolizing P450s in families 1 to 3, there is definitive evidence for only CYP 2B6 and 3A5 expression in human kidney. CYP 1A1, 1A2, 1B1, 2A6, 2C19, 2D6 and 2E1 are not expressed in human kidney, while data for CYP 2C8, 2C9 and 3A4 expression are equivocal. It is further known that several P450 enzymes involved in the metabolism of arachidonic acid and eicosanoids are expressed in human kidney, CYP 4A11, 4F2, 4F8, 4F11 and 4F12. With the current limited evidence of drug substrates for human renal P450s drug–endobiotic interactions arising from inhibition of renal P450s, particularly effects on arachidonic acid metabolism, appear unlikely. With respect to the UGTs, 1A5, 1A6, 1A7, 1A9, 2B4, 2B7 and 2B17 are expressed in human kidney, whereas UGT 1A1, 1A3, 1A4, 1A8, 1A10, 2B10, 2B11 and 2B15 are not. The most abundantly expressed renal UGTs are 1A9 and 2B7, which play a significant role in the glucuronidation of drugs, arachidonic acid, prostaglandins, leukotrienes and P450 derived arachidonic acid metabolites. Modulation by drug substrates (e.g. NSAIDs) of the intrarenal activity of UGT1A9 and UGT2B7 has the potential to perturb the metabolism of renal mediators including aldosterone, prostaglandins and 20-hydroxyeicosatetraenoic acid, thus disrupting renal homeostasis.     

焦磷酸测序技术检测UGT1A3和UGT2B7在中国汉族人群中的基因多态性

目的建立焦磷酸测序技术(pyrosequencing)研究二相代谢酶UGT1A3和UGT2B7基因多态性在中国汉族人群中的分布。方法应用带生物素标记扩增引物并经PCR扩增和Beads分离,制备UGT1A3和UGT2B7焦磷酸测序单倍摸板。在PYroMarkID焦磷酸测序上进行焦磷酸测序,检测233血样的DNA标本的17个SNP位点,以确定血样DNA标本的的基因型。结果 233例血样的DNA标本中,UGT1A3等位基因有9种表型,分别为UGT1A3*1*1、UGT1A3*1*2、UGT1A3*1*3、UGT1A3*1*4、UGT1A3*1*5、UGT1A3*2*3、UGT1A3*2*4、UGT1A3*3*3和UGT1A3*3*5。UGT2B7-1和UGT2B7-2各有3种基因型,分别为G/G型、G/T型、T/T和C/C型、C/T型、T/T型。结论我国汉族人群中UGT1A3和UGT2B7基因突变较高。