Pharmacogenetics of <Emphasis Type="Italic">SLCO1B1</Emphasis>: haplotypes,htSNPs and hepatic expression in three distinct Asian populations

Objective The aim of this study was to characterize the population frequency of SLCO1B1 polymorphic variants in three distinct healthy Asian populations, namely Chinese (n = 100), Malay (n = 100) and Indian (n = 100), and to explore the association between haplotype-tagged single nucleotide polymorphisms (htSNPs) on hepatic SLCO1B1 mRNA expression. Methods The distribution of polymorphic variants in the SLCO1B1 gene at eight loci that spanned approximately 48 kb was investigated in the three different Asian ethnic groups and in 32 non-cancerous liver tissues from Chinese patients. Results Of the 26 polymorphisms screened, we found eight polymorphic variants that differed in genotypic and allelic frequencies between the Chinese, Malay and Indian populations. Significant interethnic differences were observed in the genotype frequency distributions across the promoter SNP [g.-11187G>A (P = 0.030)] as well as three coding region SNPs [c.388G>A (P < 0.001); c.571T>C (P < 0.001); c.597C>T (P < 0.001)] in the healthy subjects. Haplotype analysis revealed 12 different haplotypes in both the Chinese and Malay populations and 18 haplotypes in the Indian population. In both the Malay and Indian populations, the htSNPs were c.388A>G, c.571T>C and c.597C>T, whereas in the Chinese population they were g.-11187G>A, c.388A>G and c.597C>T. The c.388A>G and c.597C>T htSNPs accounted for more than 70% of the variations between the three major haplotypes in each Asian ethnic group. In terms of the c.388A>G htSNPs, genotypic-phenotypic association analyses revealed that there was no effect on SLCO1B1 expression in hepatic tissues; in addition, no genotypic-phenotypic associations were evident with regards to the c.597C>T htSNP. Conclusion Future studies should investigate the phenotypic effects of the c.388A>G htSNP on the disposition of OATP1B1 substrates in Asian populations. An erratum to this article can be found at     

The effects of a single nucleotide polymorphism in SLCO1B1 on the pharmacodynamics of pravastatin

AIM

To determine whether the SNP rs4149056 in SLCO1B1 alters the pharmacodynamics of pravastatin.

METHODS

rs4149056 was genotyped in 626 pravastatin-treated participants in the WOSCOPS trial and the response after 1 year of treatment was compared between the different genotypes.

RESULTS

Pravastatin reduced serum LDL cholesterol by 22.2% in TT homozygotes, by 22.2% in TC heterozygotes and by 17.7% in CC homozygotes (TT + TC vs. CC P value 0.33). There were no significant differences in the response of total cholesterol, LDL, HDL, triglycerides or CRP to pravastatin between the genotypes.

CONCLUSION

The rs4149056 SNP did not significantly affect the pharmacodynamics of pravastatin.     

6种药物对有机阴离子转运多肽OATP1B1及其基因多态性A388G、T521C转运作用的影响

目的 研究6种药物对有机阴离子转运多肽OATP1B1及其基因多态性A388G、T521C转运作用的影响。方法 体外培养稳定高表达OATP1B1和OATP1B1基因多态性A388G、T521C的人胚肾细胞（HEK293）株,高表达空白载体（Mock）的HEK293细胞为空白对照,实时荧光定量PCR（qRT-PCR）法检测各转运体细胞中mRNA表达;放射性标记化合物³Hestrone sulfate作为转运底物、利福平作为阳性抑制剂验证各高表达细胞的转运活性;测定30 μmol·L^-1的达比加群、辛伐他汀、替格瑞洛、卡培他滨、多西他赛、依那普利对各细胞³H-estrone sulfate摄入活性的抑制作用,并依据抑制试验结果,进一步测定辛伐他汀、替格瑞洛、多西他赛对转运体细胞的半数抑制浓度（IC₅₀）。结果 HEK293细胞内导入的各种转运体基因都呈现良好的复制表达;OATP1B1、OATP1B1/A388G、OATP1B1/T521C对底物³H-estrone sulfate（5 μmol·L^-1）的转运活性分别为Mock细胞的39、49和48倍,30 μmol·L^-1利福平添加后,可将细胞的转运活性抑制到50%以下;辛伐他汀、替格瑞洛、多西他赛对OATP1B1的抑制作用较强,30 μmol·L^-1给药的转运活性分别为对照组的（40.09±1.95）%、（33.82±0.61）%、（45.08±0.22）%;辛伐他汀对OATP1B1、OATP1B1/A388G、OATP1B1/T521C的IC₅₀分别为14.2、＞100、＞100 μmol·L^-1,替格瑞洛的IC₅₀分别为19.1、68.4、＞100 μmol·L^-1,多西他赛的IC₅₀分别为17.6、22.9、19.3 μmol·L^-1。结论 OATP1B1基因多态性在一定程度上改变了抑制剂对转运体活性的影响程度。     

有机阴离子转运多肽1B3的研究进展

有机阴离子转运多肽1B3(organic anion transporting polypeptide 1B3,OATP1B3)属于溶质转运体(solute carrier,SLC)超家族,主要负责将内、外源物质转运至肝细胞代谢。OATP1B3是肝脏特异性转运体,通常局限性地分布于肝细胞窦状隙侧肝细胞膜上,近期研究发现在前列腺癌、结肠癌、肺癌等肿瘤组织和细胞中也存在着高表达。溶质转运体1B3(SLCO1B3)具有明显的基因多态性,334T>G和699G>A单体型可明显影响OATP1B3的转运活性,从而介导药物-药物相互作用的发生,导致临床用药的个体差异。此外,OATP1B3可通过作用于孕烷X受体(pregnane X receptor,PXR)和组成性雄甾烷受体(constitutive androstane receptor,CAR)等核受体配体的转运,影响体内PXR和CAR的转录活性,从而调控药物代谢酶如细胞色素P450 3A4(CYP3A4)的表达。本文将对OATP1B3近年来的研究进展进行综述。     

Extreme differences in SLCO1B3 functional polymorphisms in Roma and Hungarian populations

Variants in SLCO1B3 transporter are linked to disposition and uptake of drugs and show high degree of heterogeneity between populations. A total of 467 Roma and 448 Hungarian subjects were genotyped for SLCO1B3 c.334T>G and c.1683-5676A>G variant alleles by PCR-RFLP assay and direct sequencing. We found significant differences in the frequencies of homozygous variant genotypes of SLCO1B3 334GG (41.54% vs. 8.04%, p < 0.001) and 1683-5676GG (0.43% vs. 2.01%, p = 0.028) between Romas and Hungarians. A significantly increased prevalence was found in SLCO1B3 1683-5676G allele frequency in Hungarians compared to the Roma population (15.07% vs. 3.43%, p ≤ 0.001). The frequency of SLCO1B3 334G allele was significantly increased in Roma population compared to Hungarians (70.56% vs. 52.23%, p = 0.001). The LD values between the examined SNPs were 80 and 90 in Roma and in Hungarian samples, respectively. Our results highlight notable pharmacogenetic differences between Roma and Hungarian populations, which may have therapeutic implications.     

Substrate-dependent effects of molecular-targeted anticancer agents on activity of organic anion transporting polypeptide 1B1

1. Organic anion-transporting polypeptide 1B1 (OATP1B1) plays an important role in the hepatic uptake of a broad range of substrate drugs. In vitro experiments show that molecular-targeted agents do not always have similar effects on OATP1B1 activity.

2. The purpose of this study was to clarify whether the effects of molecular-targeted agents on OATP1B1 are substrate-dependent. We used OATP1B1-transfected cells to compare the effects of molecular-targeted agents on OATP1B1-mediated uptake of fluorescein (FL), 2′,7′-dichlorofluorescein (DCF), atorvastatin, SN-38 and valsartan.

3. Cabozantinib, cediranib, neratinib, pazopanib, regorafenib, sorafenib and tivantinib did not affect or only slightly affected OATP1B1-mediated substrate uptake. Nilotinib and lenvatinib moderately and strongly inhibited OATP1B1-mediated substrate uptake, respectively. In contrast, afatinib stimulated OATP1B1-mediated uptake of FL and SN-38, ceritinib stimulated that of valsartan, and nintedanib stimulated that of FL and valsartan. In addition, the effects of afatinib, ceritinib and nintedanib on OATP1B1 activity differed markedly depending on the type of substrate. Afatinib, ceritinib and nintedanib had a substrate-dependent effect on OATP1B1 activity.

4. We conclude that the evaluation of OATP1B1 activity using only a single probe substrate for some molecular-targeted agents may lead to a faulty understanding of their mechanisms of drug interactions.     

Effect of organic anion transporting polypeptide 1B1 inhibition on the pharmacokinetics of rosuvastatin via HNF1a by ursodeoxycholic acid in vivo

AIM： The inhibition of organic anion transporting polypeptide 1B1 （OATP1B1） on the pharmacokinetics of rosuvastatin is unknown. Hence, the effect of ursodeoxycholic acid （UDCA） on the kinetics of rosuvastatin in healthy volunteers is to be investigated. METHODS： The inhibition effect of long term use of UDCA on rosuvastatin kinetics was studied in 12 subjects in a randomized, crossover study. Each subject received 500 mg UDCA once daily continuously for 14 days. A single oral dose of 20 mg rosuvastatin was given on study day 15 and 34 separated by 2 weeks. Plasma concentrations of rosuvastatin were above the limits of quantitation for up to 72 h after dosing. RESULTS： UDCA significantly increased AUC0-72 and AUC0-∞ of rosuvastatin to 146% ± 55% （P = 0.008） and 167% ± 73% （ P = 0.004） compared with those of the control group and CL/F decreased 75% ± 19% （P = 0. 003）. The results confirmed the in vitro study that UDCA inhibited OATP1B1 activity via hepatic nuclear factor 1a （HNF1a）.[第一段]     

Pharmacokinetics and response to pravastatin in paediatric patients with familial hypercholesterolaemia and in paediatric cardiac transplant recipients in relation to polymorphisms of the SLCO1B1 and ABCB1 genes

AIMS: Our aim was to investigate associations between the single nucleotide polymorphisms (SNPs) in the SLCO1B1 (encoding OATP1B1) and ABCB1 (encoding P-glycoprotein) genes with the pharmacokinetics and efficacy of pravastatin in children with heterozygous familial hypercholesterolaemia (HeFH) and in paediatric cardiac transplant recipients. METHODS: Twenty children with HeFH (aged 4.9-15.6 years) and 12 cardiac transplant recipients (aged 4.4-18.7 years and receiving triple immunosuppressive medication) who had participated in previous pharmacokinetic and pharmacodynamic studies with pravastatin were genotyped for the -11187G > A and 521T > C SNPs in the SLCO1B1 gene and for the 2677G > T/A and 3435C > T SNPs in the ABCB1 gene. RESULTS: Two HeFH patients with the -11187GA genotype had a 81% lower peak plasma pravastatin concentration (Cmax) (difference in means -13.9 ng ml(-1), 95% CI -21.1, -6.7; P < 0.001) and a 74% smaller area under the plasma concentration-time curve (AUC0, infinity) (-25.3 ng ml(-1) h, 95% CI -35.6, -15.0; P < 0.0001) and significantly greater increase in high density lipoprotein (HDL) cholesterol after 2 months treatment with pravastatin than patients with the reference genotype. No significant differences were seen in the pharmacokinetics or effects of pravastatin between HeFH patients with the SLCO1B1 521TC and 521TT genotypes. The cardiac transplant recipients with the SLCO1B1 521TC genotype (n = 3) had a 46% lower Cmax (-67.7 ng ml(-1), 95% CI -135.7, 0.3; P = 0.055) and 62% lower AUC(0,24 h) (-228.5 ng ml(-1) h, 95% CI -402.7, -54.3; P = 0.016) and a shorter half-life (t1/2) (0.9 +/- 0.1 vs. 1.3 +/- 0.4 h, P = 0.015) of pravastatin than those with the reference genotype. Decreases in total and low-density lipoprotein cholesterol by pravastatin were significantly smaller, and the increase in HDL-cholesterol was greater in the transplant recipients with the 521TC genotype compared with patients with the 521TT reference genotype. CONCLUSIONS: In children with HeFH and in paediatric cardiac transplant recipients receiving immunosuppressive medication, the -11187G > A and SLCO1B1 521T > C SNPs were associated with decreased plasma concentrations of pravastatin. These differences are opposite to those seen previously in healthy adults. The mechanisms underlying these phenomena are unclear and warrant further study.     

Stimulatory effect on the transport mediated by organic anion transporting polypeptide 2B1

Drug-drug interaction(DDI)is one of causes of adverse drug events and can result in lifethreatening consequences.Organic anion-transporting polypeptide(OATP)2B1 is a major uptake transporter in the intestine and contributes to transport various clinically used therapeutic agents.The intestine has a high risk of DDI,because it has a special propensity to be exposed to a high concentration of drugs.Thus,understanding drug interaction mediated by OATP2B1 in the absorption process is important for the prevention of adverse drug events,including decrease in the therapeutic effect of co-administered drugs.Acute drug interaction occurs through the direct inhibitory effect on transporters,including OATP2B1.Moreover,some compounds such as clinically used drugs and food components have an acute stimulatory effect on transport of co-administered drugs by OATP2B1.This review summarizes the acute stimulatory effect on the transport mediated by OATP2B1 and discusses the mechanisms of the acute stimulatory effects of compounds.There are two types of acute stimulatory effects,substrate-independent and-dependent interactions on OATP2B1 function.The facilitating translocation of OATP2B1 to the plasma membrane is one of causes for the substrate-independent acute stimulatory effect.On the contrary,the substrate-dependent effect is based on the direct binding to the substrate-binding site or allosteric progesterone-binding site of OATP2B1.     

High plasma pravastatin concentrations are associated with single nucleotide polymorphisms and haplotypes of organic anion transporting polypeptide-C (OATP-C, SLCO1B1)

This study aimed to characterize possible relationships between polymorphisms in the drug transporter genes organic anion transporting polypeptide-C (OATP-C, SLCO1B1), OATP-B (SLCO2B1), multidrug resistance-associated protein 2 (MRP2, ABCC2) and multidrug resistance transporter (MDR1, ABCB1) and the pharmacokinetics of pravastatin. We studied 41 healthy Caucasian volunteers who had previously participated in pharmacokinetic studies with pravastatin. Six volunteers had a very high pravastatin AUC value and were defined as outliers according to statistical criteria. The OATP-C gene was sequenced completely in all subjects, and they were also genotyped for selected single nucleotide polymorphisms (SNP) in the OATP-B, MDR1 and MRP2 genes. Of the six outliers, five were heterozygous for the OATP-C 521T>C (Val174Ala) SNP (allele frequency 42%) and three were heterozygous for a new SNP in the promoter region of OATP-C (-11187G>A, allele frequency 25%). Among the remaining 35 subjects, two were homozygous and six were heterozygous carriers of the 521T>C SNP (allele frequency 14%, P = 0.0384 versus outliers) and three were heterozygous carriers of the -11187G>A SNP (allele frequency 4%, P = 0.0380 versus outliers). In subjects with the -11187GA or 521TC genotype, the mean pravastatin AUC0-12 was 98% (P = 0.0061) or 106% (P = 0.0034) higher, respectively, compared to subjects with the reference genotype. These results were substantiated by haplotype analysis. In heterozygous carriers of *15B (containing the 388A>G and 521T>C variants), the mean pravastatin AUC0-12 was 93% (P = 0.024) higher compared to non-carriers and, in heterozygous carriers of *17 (containing the -11187G>A, 388A>G and 521T>C variants), it was 130% (P = 0.0053) higher compared to non-carriers. No significant associations were found between OATP-B, MRP2 or MDR1 polymorphisms and the pharmacokinetics of pravastatin. These results suggest that haplotypes are more informative in predicting the OATP-C phenotype than single SNPs.     

The effect of SLCO1B1 polymorphism on repaglinide pharmacokinetics persists over a wide dose range

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Organic anion transporting polypeptide 1B1 is an influx transporter expressed on the basolateral membrane of hepatocytes.
• A common single nucleotide polymorphism, c.521T→C (p.Val174Ala), of the SLCO1B1 gene has been associated with increased plasma repaglinide concentrations in healthy volunteers.
• Previous studies at low repaglinide doses have suggested that the effect of SLCO1B1 c.521T→C polymorphism on the pharmacokinetics of repaglinide could be dose-dependent.

WHAT THIS STUDY ADDS

• Repaglinide peak plasma concentration and area under the plasma concentration–time curve increased linearly along with repaglinide dose ranging from 0.25 to 2 mg in both the predominant c.521TT and rare c.521CC genotype group.
• The effect of SLCO1B1 c.521T→C polymorphism on repaglinide pharmacokinetics persists over a wide dose range.

AIMS

To establish whether the effect of SLCO1B1[encoding organic anion transporting polypeptide 1B1 (OATP1B1)] c.521T→C (p.Val174Ala) polymorphism on the pharmacokinetics of repaglinide is dose-dependent.

METHODS

Twelve healthy volunteers with the SLCO1B1 c.521TT genotype (controls) and eight with the c.521CC genotype ingested a single 0.25-, 0.5-, 1- or 2-mg dose of repaglinide in a dose-escalation study with a wash-out period of ≥1 week.

RESULTS

The mean area under the plasma concentration–time curve from time 0 to infinity (AUC_0–∞) of 0.25, 0.5, 1 or 2 mg repaglinide was 82% (95% confidence interval 47, 125), 72% (24, 138), 56% (24, 95) or 108% (59, 171) (P ≤ 0.001) larger in participants with the SLCO1B1 c.521CC genotype than in those with the c.521TT genotype, respectively. Repaglinide peak plasma concentration and AUC_0–∞ increased linearly along with repaglinide dose in both genotype groups (r > 0.88, P < 0.001). There was a tendency towards lower blood glucose concentrations after repaglinide administration in the participants with the c.521CC genotype than in those with the c.521TT genotype.

CONCLUSIONS

The effect of SLCO1B1 c.521T→C polymorphism on the pharmacokinetics of repaglinide persists throughout the clinically relevant dose range.     

Insulin stimulates transport of organic anion compounds mediated by organic anion transporting polypeptide 2B1 in the human intestinal cell line Caco-2

Organic anion transporting polypeptide 2B1 (OATP2B1) is the major uptake transporter in the intestine, and transports various clinically used therapeutic agents. Insulin acts through the insulin receptor in targeted cells, and Rab8A is one of the insulin signaling pathways. The small intestine in humans also expresses insulin receptor and Rab8A. It has been reported that insulin stimulates peptide transporter 1 (PEPT1) expression at the apical membrane and increases uptake of PEPT1 substrates in small intestine epithelial model cells (Caco-2 cells). However, the effect of insulin on OATP2B1 in the small intestine has not been fully investigated. We found that Rab8A was associated with OATP2B1-mediated estrone-3-sulfate (E3S) uptake. Insulin stimulated the uptake of E3S by Caco-2 cells and the enhancement was sustained for 120 min. The Vmax value of E3S uptake significantly increased upon insulin exposure. Caco-2 cells treated with insulin showed increased OATP2B1 expression at the cell surface. The apical-to-basal transport of E3S was also increased by insulin. The increase of E3S transport was inhibited by the cold condition (4 °C) or the OATP2B1 inhibitor, taurocholate. These results indicate that insulin acts on the small intestine to increase OATP2B1-mediated absorption.     

No significant effect of SLCO1B1 polymorphism on the pharmacokinetics of rosiglitazone and pioglitazone

AIMS

To examine possible effects of polymorphism in the SLCO1B1 gene, encoding the hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1, on the pharmacokinetics of rosiglitazone and pioglitazone in a prospective genotype panel study.

METHODS

Sixteen healthy volunteers with the homozygous SLCO1B1 c.521TT genotype (controls), 12 with the heterozygous c.521TC genotype and four with the homozygous c.521CC genotype ingested a single 4-mg dose of rosiglitazone and a single 15-mg dose of pioglitazone in a cross-over study with a wash-out period of at least 1 week.

RESULTS

SLCO1B1 polymorphism had no statistically significant effect on any of the pharmacokinetic variables of rosiglitazone, pioglitazone or their metabolites. The mean ± SD area under the plasma rosiglitazone concentration–time curve from time 0 to infinity (AUC_0–∞) was 2024 ± 561 ng ml⁻¹ h in the c.521TT subjects, 1763 ± 288 ng ml⁻¹ h in the c.521TC subjects (geometric mean ratio c.521TC/c.521TT 0.89; 95% confidence interval 0.72, 1.11) and 1729 ± 346 ng ml⁻¹ h in the c.521CC subjects (c.521CC/c.521TT 0.87; 0.63, 1.20). The AUC_0–∞ of pioglitazone averaged 6244 ± 1909 ng ml⁻¹ h in the c.521TT subjects, 5123 ± 1165 ng ml⁻¹ h in the c.521TC subjects (c.521TC/c.521TT 0.83; 0.65, 1.06) and 4851 ± 1123 ng ml⁻¹ h in the c.521CC subjects (c.521CC/c.521TT 0.79; 0.55, 1.14). There was a significant correlation between the AUC_0–∞ of rosiglitazone and pioglitazone (r = 0.717, P < 0.001).

CONCLUSIONS

The SLCO1B1 c.521T→C SNP does not affect the pharmacokinetics of rosiglitazone or pioglitazone, indicating that OATP1B1 plays no significant role in the disposition of these drugs.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• A common single nucleotide polymorphism (SNP) (c.521T→C) of the SLCO1B1 gene, encoding the hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1, has been associated with marked changes in the pharmacokinetics of the antidiabetic drug repaglinide.
• Rosiglitazone and pioglitazone are competitive inhibitors of OATP1B1 and might thus be its substrates.
• Gemfibrozil, an inhibitor of OATP1B1 in vitro, considerably increases the plasma concentrations of rosiglitazone and pioglitazone in vivo in humans.

WHAT THIS STUDY ADDS

• The SLCO1B1 c.521T→C SNP was not associated with changes in rosiglitazone or pioglitazone pharmacokinetics in healthy volunteers.
• OATP1B1 is thus unlikely to play an important role in the disposition of rosiglitazone or pioglitazone.

     

Contribution of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 to hepatic uptake of nateglinide, and the prediction of drug-drug interactions via these transporters

Objectives We have investigated the contributions of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 to the hepatic uptake of nateglinide, and the possibility of drug–drug interactions via these transporters. Methods Uptake studies using transporter‐expressing HEK293 cells and cryopreserved human hepatocytes were performed to examine the contributions of each transporter. Inhibition studies using cryopreserved human hepatocytes were performed to examine the possibility of drug–drug interactions. Key findings The rate of saturable hepatic uptake of nateglinide using human hepatocytes was 47.6%. A certain increase in uptake was observed in the examination using transporter‐expressing HEK293 cells, indicating contributions of OATP1B1 and OATP1B3 to hepatic nateglinide uptake. The 50% inhibitory concentration (IC50) values of nateglinide using cryopreserved human hepatocytes for uptake of estrone 3‐sulfate (substrate of OATP1B1), and cholecystokinin octapeptide (substrate of OATP1B3) were 168 and 17.4 µmol/l, respectively. Moreover, ciclosporin inhibited saturable hepatic uptake of nateglinide with an IC50 value of 6.05 µmol/l. The calculated 1 + I_in,max,u/IC50 values for inhibition of OATP1B1 and OATP1B3 by nateglinide, and the inhibition of saturable uptake of nateglinide by ciclosporin, were all close to 1, indicating a low clinical risk of drug–drug interaction with nateglinide taken up via OATP1B1 and OATP1B3. Conclusions OATP1B1 and OATP1B3 may have contributed to the hepatic uptake of nateglinide, but the possibility of drug–drug interactions appeared to be low.     

OATP1B1基因多态性对匹伐他汀钙片在中国汉族健康受试者体内的药代动力学影响

目的:研究有机阴离子转运多肽OATP1B1基因多态性对匹伐他汀钙片在中国汉族健康受试者体内的药代动力学影响.方法:用PCR-RFLP对筛选出的36名合格受试者进行OATP1B1 A388G、OATP1B1 T521C基因分型,受试者单剂量口服匹伐他汀钙片2 mg,用HPLC-MS-MS法测定血浆匹伐他汀钙片浓度.结果:匹伐他汀钙片药代动力学参数显示,与388AA型相比,388AG型AUC0-10增加26%,t1/2增加30%;与521TT型相比,521TC型AUC0-10增加23.6%,CL/F降低20.8%.可能由于突变例数太少,导致OATP1B1 A388G和OATP1B1 T521C突变组和野生组各药代动力学参数(t1/2、tmax、Cmax、AUC0-t、AUC0-inf、CL/F、Vd/F)之间差异无明显统计学意义.结论:OATP1B1基因多态性可能对中国汉族人群中匹伐他汀钙片代谢无影响.     

Analyses of single nucleotide polymorphisms and haplotype linkage of the humanABCB1 (MDR1) gene in Korean

Single nucleotide polymorphisms (SNPs) in theMDR1 gene that are responsible for drug efflux can cause toxicity. Therefore, this study determined the SNPs of the KoreanMDR1 gene, and analyzed the haplotypes and a linkage disequilibrium (LD) of the SNPs determined. The frequency of 9 SNPs from theMDR1 gene was determined by PCR-RFLP analyses of 100 to 500 healthy individuals. The frequcies of the SNPs were C3435T (47.7%), G2677T (37.6%), G2677A (4.4%), T1236C (21.7%), T129C (8%), A2956G (2.5%), T307C (1.5%), A41aG (9.2%), C145G (0%), and G4030C (0%). Analyses of the haplotype structure and an estimation of the LD of the combined polymorphisms demonstrated that the frequency of the 1236T-2677G-3435T haplotype is much higher in Koreans (14.1%) than in Chinese and western black Africans and the C3435T SNP in Koreans appears to have LD with T129C in Koreans for the first time. These results provide insight into the genetic variation ofMDR1 in Koreans, and demonstrated the possibility of a new LD in this gene.     

Lack of effect of genetic polymorphisms of SLCO1B1 on the lipid-lowering response to pitavastatin in Chinese patients

Aim:

To investigate the SLCO1B1 388A>G and 521T>C polymorphisms in hyperlipidemia patients and evaluate the effect of the two polymorphisms on the lipid-lowering efficacy of pitavastatin.

Methods:

The functional polymorphisms of SLCO1B1 (388A>G and 521T>C) were genotyped in 140 Chinese patients with essential hyperlipidemia using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and one-step tetra-primers ARMS-PCR. Eighty-five patients were enrolled in the clinical trial and given 2 mg of pitavastatin daily for 8 weeks. Total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) serum levels were measured at baseline, after 4 weeks and after 8 weeks of treatment.

Results:

The allele frequencies of SLCO1B1 388A>G and 521T>C in essential hyperlipidemia patients were 71.1% and 11.1%, respectively. The 4- and 8-week treatment with pitavastatin significantly reduced TC, TG, and LDL levels, but there was no statistical difference among patients with wild type, SLCO1B1 388A>G or SLCO1B1 521T>C in the lipid-lowering efficacy of pitavastatin.

Conclusion:

The present study found that the allele frequencies of SLCO1B1 388A>G and 521T>C in Chinese patients with essential hyperlipidemia are comparable to those in healthy Chinese population. SLCO1B1 388A>G and 521T>C do not affect the lipid-lowering efficacy of pitavastatin.     

Influence of SLCO1B1, 1B3, 2B1 and ABCC2 genetic polymorphisms on mycophenolic acid pharmacokinetics in Japanese renal transplant recipients

Objective We investigated the association between mycophenolic acid (MPA) pharmacokinetics and organic anion-transporting polypeptide (OATP/SLCO)1B1, 1B3, 2B1 and multidrug resistance-association protein 2 (MRP2/ABCC2) genetic polymorphisms and diarrhea. Methods Eighty-seven renal allograft recipients were given repeated doses of mycophenolate mofetil every 12 h at a designated time (09:00 and 21:00). The pharmacokinetics of MPA were analyzed on day 28 posttransplantation. Results The dose-adjusted area under the cuve (AUC)_6–12 of MPA, an estimate of enterohepatic recirculation, was greater in SLCO1B3 T334G GG (or G699A AA) carriers than in TT carriers (or G699A GG) (40 vs. 25 ng·h/mL per milligram, respectively, P = 0.0497). None of the polymorphism of SLCO1B1, SLCO2B1, or ABCC2 C-24T were associated with MPA pharmacokinetics or diarrhea. However, the oral clearance of MPA in recipients having both the SLCO1B3 T334G GG genotype and the ABCC2 C-24T T allele was significantly lower than in patients having both the SLCO1B3 T334G TT and ABCC2 C-24T CC genotypes (0.15 vs. 0.18 L/h per kilogram, respectively, P = 0.0010). Conclusions MPA excretion into bile in patients with SLCO1B3 T334G GG (or G699A AA) was higher than in those with T334G TT (or G699A GG), probably resulting in a higher AUC_6–12 value of MPA. MPA uptake into hepatocytes and excretion into bile at first pass may be greater in SLCO1B3 T334G GG carriers than in TT carriers. In addition, the ABCC2 C-24T polymorphism also seems to be associated with enhanced enterohepatic circulation of MPA. The SLCO1B3 and ABCC2 transporters rather than uridine diphosphate-glucuronosyltransferase (UGT) may partly affect interindividual variety in plasma MPA concentration.     

Role of the SLCO1B1 haplotypes on the rifampicin-induced CYP3A activity

Rifampin, a member of the rifamycin class of antibiotics, is well known for its ability to activate the pregnant X receptor and induce drug-metabolizing enzymes and transporters. Available data suggest rifampin entry into hepatocytes is mediated by OATP1B1. Accordingly, it is therefore plausible that modulation of the intracellular concentration of rifampin by OATP1B1 genetic polymorphisms would influence the degree of CYP3A induction. AIM： To study the association between haplotypes of the SLCO1B1 and the rifampicin-mediated inducible CYP3A4 activity. A single-point determination of midazolam plasma concentration method was developed to assess the constitutive and inducible CYP3A4 activity. A pharmacokinetic study of a single dose of 450 mg rifampicin was conducted to evaluate the mechanism of rifampicin-midazolam interaction in different SLCO1B1 genotypic subjects.METHODS： Twenty-three healthy volunteers with different SLCO1B1 haplotypes （7 for SLCO1B1 ＊ 1a/＊ 1a, 7 for SLCO1B1 ＊ 1b/＊ 1b, 7 for SLCO1B1 ＊ 1b / ＊ 15 and 2 for SLCO1B1 ＊ 15/＊ 15） were enrolled in this study. Each was given a single oral dose of 7.5 nag naidazolam on day 0 and day 6. Rifampicin of 450 nag was given from day 1 to day 5. Plasma concentrations of midazolam were measured for up to 8 hours by LC-MS, and its pharmacokinetic parameters were analyzed. Plasma concentrations of a single oral dose of 450 nag rifampicin were measured for up to 12 hours.[第一段]     

Comparison of SLCO1B1 sequence variability among German, Turkish, and African populations

Background OATP1B1 is one of the key hepatocellular uptake transporters providing extraction of diverse compounds, including bile acids, xenobiotics, and a variety of drugs, from portal venous blood into the liver. Polymorphisms of the SLCO1B1 gene have been demonstrated to influence in vitro transport function and the pharmacokinetic profile of compounds. Objective The goal of our study was the comparison of SLCO1B1 gene sequence variability in three ethnic groups as a basis for future genetic association studies. Methods Eighteen exonic SLCO1B1 single nucleotide polymorphisms (SNPs) were genotyped by PCR and RFLP analysis in 300 German, 94 Turkish, and 115 African subjects. Calculation of pairwise linkage disequilibrium and estimation of population haplotype frequencies were carried out, and haplotype block structure was determined. Results Only eight genotyped SNPs (c.388A>G, c.411G>A, c.463C>A, c.521T>C, c.571C>T, c.597C>T, c.1463G>>C, c.1929A>C) were found in at least one of our German, Turkish, or African samples. A total of 12 haplotypes with a frequency ≥1% in at least one of the three populations could be inferred. Between the Caucasian and African samples, significant differences in sequence variability were observed leading to a different haplotype profile in these populations. Conclusion Our results demonstrate a high sequence variability of OATP1B1 within different popuations. In the future, distinct haplotypes should be taken into account when studying the effect of OATP1B1 on drugs in different populations.